Examples

Get started

A very simple hello world label

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LABEL

/**
 * Basic example to create a "Hello world" label
 */
void lv_example_get_started_1(void)
{
    /*Change the active screen's background color*/
    lv_obj_set_style_bg_color(lv_scr_act(), lv_color_hex(0x003a57), LV_PART_MAIN);

    /*Create a white label, set its text and align it to the center*/
    lv_obj_t * label = lv_label_create(lv_scr_act());
    lv_label_set_text(label, "Hello world");
    lv_obj_set_style_text_color(lv_scr_act(), lv_color_hex(0xffffff), LV_PART_MAIN);
    lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);
}

#endif

# Change the active screen's background color
scr = lv.scr_act()
scr.set_style_bg_color(lv.color_hex(0x003a57), lv.PART.MAIN)

# Create a white label, set its text and align it to the center
label = lv.label(lv.scr_act())
label.set_text("Hello world")
label.set_style_text_color(lv.color_hex(0xffffff), lv.PART.MAIN)
label.align(lv.ALIGN.CENTER, 0, 0)

A button with a label and react on click event

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_BTN

static void btn_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * btn = lv_event_get_target(e);
    if(code == LV_EVENT_CLICKED) {
        static uint8_t cnt = 0;
        cnt++;

        /*Get the first child of the button which is the label and change its text*/
        lv_obj_t * label = lv_obj_get_child(btn, 0);
        lv_label_set_text_fmt(label, "Button: %d", cnt);
    }
}

/**
 * Create a button with a label and react on click event.
 */
void lv_example_get_started_2(void)
{
    lv_obj_t * btn = lv_btn_create(lv_scr_act());     /*Add a button the current screen*/
    lv_obj_set_pos(btn, 10, 10);                            /*Set its position*/
    lv_obj_set_size(btn, 120, 50);                          /*Set its size*/
    lv_obj_add_event(btn, btn_event_cb, LV_EVENT_ALL, NULL);           /*Assign a callback to the button*/

    lv_obj_t * label = lv_label_create(btn);          /*Add a label to the button*/
    lv_label_set_text(label, "Button");                     /*Set the labels text*/
    lv_obj_center(label);
}

#endif

class CounterBtn():
    def __init__(self):
        self.cnt = 0
        #
        # Create a button with a label and react on click event.
        #

        btn = lv.btn(lv.scr_act())                               # Add a button the current screen
        btn.set_pos(10, 10)                                      # Set its position
        btn.set_size(120, 50)                                    # Set its size
        btn.align(lv.ALIGN.CENTER,0,0)
        btn.add_event(self.btn_event_cb, lv.EVENT.ALL, None)  # Assign a callback to the button
        label = lv.label(btn)                                    # Add a label to the button
        label.set_text("Button")                                 # Set the labels text
        label.center()

    def btn_event_cb(self,e):
        code = e.get_code()
        btn = e.get_target_obj()
        if code == lv.EVENT.CLICKED:
            self.cnt += 1

        # Get the first child of the button which is the label and change its text
        label = btn.get_child(0)
        label.set_text("Button: " + str(self.cnt))


counterBtn = CounterBtn()

Create styles from scratch for buttons

#include "../lv_examples.h"
#if LV_USE_BTN && LV_BUILD_EXAMPLES

static lv_style_t style_btn;
static lv_style_t style_btn_pressed;
static lv_style_t style_btn_red;

static lv_color_t darken(const lv_color_filter_dsc_t * dsc, lv_color_t color, lv_opa_t opa)
{
    LV_UNUSED(dsc);
    return lv_color_darken(color, opa);
}

static void style_init(void)
{
    /*Create a simple button style*/
    lv_style_init(&style_btn);
    lv_style_set_radius(&style_btn, 10);
    lv_style_set_bg_opa(&style_btn, LV_OPA_COVER);
    lv_style_set_bg_color(&style_btn, lv_palette_lighten(LV_PALETTE_GREY, 3));
    lv_style_set_bg_grad_color(&style_btn, lv_palette_main(LV_PALETTE_GREY));
    lv_style_set_bg_grad_dir(&style_btn, LV_GRAD_DIR_VER);

    lv_style_set_border_color(&style_btn, lv_color_black());
    lv_style_set_border_opa(&style_btn, LV_OPA_20);
    lv_style_set_border_width(&style_btn, 2);

    lv_style_set_text_color(&style_btn, lv_color_black());

    /*Create a style for the pressed state.
     *Use a color filter to simply modify all colors in this state*/
    static lv_color_filter_dsc_t color_filter;
    lv_color_filter_dsc_init(&color_filter, darken);
    lv_style_init(&style_btn_pressed);
    lv_style_set_color_filter_dsc(&style_btn_pressed, &color_filter);
    lv_style_set_color_filter_opa(&style_btn_pressed, LV_OPA_20);

    /*Create a red style. Change only some colors.*/
    lv_style_init(&style_btn_red);
    lv_style_set_bg_color(&style_btn_red, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_bg_grad_color(&style_btn_red, lv_palette_lighten(LV_PALETTE_RED, 3));
}

/**
 * Create styles from scratch for buttons.
 */
void lv_example_get_started_3(void)
{
    /*Initialize the style*/
    style_init();

    /*Create a button and use the new styles*/
    lv_obj_t * btn = lv_btn_create(lv_scr_act());
    /* Remove the styles coming from the theme
     * Note that size and position are also stored as style properties
     * so lv_obj_remove_style_all will remove the set size and position too */
    lv_obj_remove_style_all(btn);
    lv_obj_set_pos(btn, 10, 10);
    lv_obj_set_size(btn, 120, 50);
    lv_obj_add_style(btn, &style_btn, 0);
    lv_obj_add_style(btn, &style_btn_pressed, LV_STATE_PRESSED);

    /*Add a label to the button*/
    lv_obj_t * label = lv_label_create(btn);
    lv_label_set_text(label, "Button");
    lv_obj_center(label);

    /*Create another button and use the red style too*/
    lv_obj_t * btn2 = lv_btn_create(lv_scr_act());
    lv_obj_remove_style_all(btn2);                      /*Remove the styles coming from the theme*/
    lv_obj_set_pos(btn2, 10, 80);
    lv_obj_set_size(btn2, 120, 50);
    lv_obj_add_style(btn2, &style_btn, 0);
    lv_obj_add_style(btn2, &style_btn_red, 0);
    lv_obj_add_style(btn2, &style_btn_pressed, LV_STATE_PRESSED);
    lv_obj_set_style_radius(btn2, LV_RADIUS_CIRCLE, 0); /*Add a local style too*/

    label = lv_label_create(btn2);
    lv_label_set_text(label, "Button 2");
    lv_obj_center(label);
}

#endif

#
# Create styles from scratch for buttons.
#
style_btn =  lv.style_t()
style_btn_red = lv.style_t()
style_btn_pressed = lv.style_t()

# Create a simple button style
style_btn.init()
style_btn.set_radius(10)
style_btn.set_bg_opa(lv.OPA.COVER)
style_btn.set_bg_color(lv.palette_lighten(lv.PALETTE.GREY, 3))
style_btn.set_bg_grad_color(lv.palette_main(lv.PALETTE.GREY))
style_btn.set_bg_grad_dir(lv.GRAD_DIR.VER)

# Add a border
style_btn.set_border_color(lv.color_white())
style_btn.set_border_opa(lv.OPA._70)
style_btn.set_border_width(2)

# Set the text style
style_btn.set_text_color(lv.color_white())

# Create a red style. Change only some colors.
style_btn_red.init()
style_btn_red.set_bg_color(lv.palette_main(lv.PALETTE.RED))
style_btn_red.set_bg_grad_color(lv.palette_lighten(lv.PALETTE.RED, 2))

# Create a style for the pressed state.
style_btn_pressed.init()
style_btn_pressed.set_bg_color(lv.palette_main(lv.PALETTE.BLUE))
style_btn_pressed.set_bg_grad_color(lv.palette_darken(lv.PALETTE.RED, 3))

# Create a button and use the new styles
btn = lv.btn(lv.scr_act())                  # Add a button the current screen
# Remove the styles coming from the theme
# Note that size and position are also stored as style properties
# so lv_obj_remove_style_all will remove the set size and position too
btn.remove_style_all()                      # Remove the styles coming from the theme
btn.set_pos(10, 10)                         # Set its position
btn.set_size(120, 50)                       # Set its size
btn.add_style(style_btn, 0)
btn.add_style(style_btn_pressed, lv.STATE.PRESSED)

label = lv.label(btn)                       # Add a label to the button
label.set_text("Button")                    # Set the labels text
label.center()

# Create a slider in the center of the display
slider = lv.slider(lv.scr_act())
slider.set_width(200)                                              # Set the width
slider.center()                                                    # Align to the center of the parent (screen)

# Create another button and use the red style too
btn2 = lv.btn(lv.scr_act())
btn2.remove_style_all()                     # Remove the styles coming from the theme
btn2.set_pos(10, 80)                        # Set its position
btn2.set_size(120, 50)                      # Set its size
btn2.add_style(style_btn, 0)
btn2.add_style(style_btn_red, 0)
btn2.add_style(style_btn_pressed, lv.STATE.PRESSED)
btn2.set_style_radius(lv.RADIUS_CIRCLE, 0)  # Add a local style

label = lv.label(btn2)                      # Add a label to the button
label.set_text("Button 2")                  # Set the labels text
label.center()

Create a slider and write its value on a label

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SLIDER

static lv_obj_t * label;

static void slider_event_cb(lv_event_t * e)
{
    lv_obj_t * slider = lv_event_get_target(e);

    /*Refresh the text*/
    lv_label_set_text_fmt(label, "%"LV_PRId32, lv_slider_get_value(slider));
    lv_obj_align_to(label, slider, LV_ALIGN_OUT_TOP_MID, 0, -15);    /*Align top of the slider*/
}

/**
 * Create a slider and write its value on a label.
 */
void lv_example_get_started_4(void)
{
    /*Create a slider in the center of the display*/
    lv_obj_t * slider = lv_slider_create(lv_scr_act());
    lv_obj_set_width(slider, 200);                          /*Set the width*/
    lv_obj_center(slider);                                  /*Align to the center of the parent (screen)*/
    lv_obj_add_event(slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);     /*Assign an event function*/

    /*Create a label above the slider*/
    label = lv_label_create(lv_scr_act());
    lv_label_set_text(label, "0");
    lv_obj_align_to(label, slider, LV_ALIGN_OUT_TOP_MID, 0, -15);    /*Align top of the slider*/
}

#endif

def slider_event_cb(e):
    slider = e.get_target_obj()

    # Refresh the text
    label.set_text(str(slider.get_value()))

#
# Create a slider and write its value on a label.
#

# Create a slider in the center of the display
slider = lv.slider(lv.scr_act())
slider.set_width(200)                                              # Set the width
slider.center()                                                    # Align to the center of the parent (screen)
slider.add_event(slider_event_cb, lv.EVENT.VALUE_CHANGED, None) # Assign an event function

# Create a label above the slider
label = lv.label(lv.scr_act())
label.set_text("0")
label.align_to(slider, lv.ALIGN.OUT_TOP_MID, 0, -15)               # Align below the slider

Styles

Size styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMG

/**
 * Using the Size, Position and Padding style properties
 */
void lv_example_style_1(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_radius(&style, 5);

    /*Make a gradient*/
    lv_style_set_width(&style, 150);
    lv_style_set_height(&style, LV_SIZE_CONTENT);

    lv_style_set_pad_ver(&style, 20);
    lv_style_set_pad_left(&style, 5);

    lv_style_set_x(&style, lv_pct(50));
    lv_style_set_y(&style, 80);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);

    lv_obj_t * label = lv_label_create(obj);
    lv_label_set_text(label, "Hello");
}

#endif

#
# Using the Size, Position and Padding style properties
#
style = lv.style_t()
style.init()
style.set_radius(5)

# Make a gradient
style.set_width(150)
style.set_height(lv.SIZE_CONTENT)

style.set_pad_ver(20)
style.set_pad_left(5)

style.set_x(lv.pct(50))
style.set_y(80)

# Create an object with the new style
obj = lv.obj(lv.scr_act())
obj.add_style(style, 0)

label = lv.label(obj)
label.set_text("Hello")

Background styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Using the background style properties
 */
void lv_example_style_2(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_radius(&style, 5);

    /*Make a gradient*/
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    static lv_grad_dsc_t grad;
    grad.dir = LV_GRAD_DIR_VER;
    grad.stops_count = 2;
    grad.stops[0].color = lv_palette_lighten(LV_PALETTE_GREY, 1);
    grad.stops[1].color = lv_palette_main(LV_PALETTE_BLUE);

    /*Shift the gradient to the bottom*/
    grad.stops[0].frac  = 128;
    grad.stops[1].frac  = 192;

    lv_style_set_bg_grad(&style, &grad);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}

#endif

#
# Using the background style properties
#
style = lv.style_t()
style.init()
style.set_radius(5)

# Make a gradient
style.set_bg_opa(lv.OPA.COVER)
style.set_bg_color(lv.palette_lighten(lv.PALETTE.GREY, 1))
style.set_bg_grad_color(lv.palette_main(lv.PALETTE.BLUE))
style.set_bg_grad_dir(lv.GRAD_DIR.VER)

# Shift the gradient to the bottom
style.set_bg_main_stop(128)
style.set_bg_grad_stop(192)

# Create an object with the new style
obj = lv.obj(lv.scr_act())
obj.add_style(style, 0)
obj.center()

Border styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Using the border style properties
 */
void lv_example_style_3(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    /*Set a background color and a radius*/
    lv_style_set_radius(&style, 10);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 1));

    /*Add border to the bottom+right*/
    lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_border_width(&style, 5);
    lv_style_set_border_opa(&style, LV_OPA_50);
    lv_style_set_border_side(&style, LV_BORDER_SIDE_BOTTOM | LV_BORDER_SIDE_RIGHT);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}

#endif

#
# Using the border style properties
#
style = lv.style_t()
style.init()

# Set a background color and a radius
style.set_radius(10)
style.set_bg_opa(lv.OPA.COVER)
style.set_bg_color(lv.palette_lighten(lv.PALETTE.GREY, 1))

# Add border to the bottom+right
style.set_border_color(lv.palette_main(lv.PALETTE.BLUE))
style.set_border_width(5)
style.set_border_opa(lv.OPA._50)
style.set_border_side(lv.BORDER_SIDE.BOTTOM | lv.BORDER_SIDE.RIGHT)

# Create an object with the new style
obj = lv.obj(lv.scr_act())
obj.add_style(style, 0)
obj.center()

Outline styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Using the outline style properties
 */
void lv_example_style_4(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    /*Set a background color and a radius*/
    lv_style_set_radius(&style, 5);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 1));

    /*Add outline*/
    lv_style_set_outline_width(&style, 2);
    lv_style_set_outline_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_outline_pad(&style, 8);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}

#endif

#
# Using the outline style properties
#

style = lv.style_t()
style.init()

# Set a background color and a radius
style.set_radius(5)
style.set_bg_opa(lv.OPA.COVER)
style.set_bg_color(lv.palette_lighten(lv.PALETTE.GREY, 1))

# Add outline
style.set_outline_width(2)
style.set_outline_color(lv.palette_main(lv.PALETTE.BLUE))
style.set_outline_pad(8)

# Create an object with the new style
obj = lv.obj(lv.scr_act())
obj.add_style(style, 0)
obj.center()

Shadow styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Using the Shadow style properties
 */
void lv_example_style_5(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    /*Set a background color and a radius*/
    lv_style_set_radius(&style, 5);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 1));

    /*Add a shadow*/
    lv_style_set_shadow_width(&style, 55);
    lv_style_set_shadow_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    //    lv_style_set_shadow_ofs_x(&style, 10);
    //    lv_style_set_shadow_ofs_y(&style, 20);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}

#endif

#
# Using the Shadow style properties
#

style = lv.style_t()
style.init()

# Set a background color and a radius
style.set_radius(5)
style.set_bg_opa(lv.OPA.COVER)
style.set_bg_color(lv.palette_lighten(lv.PALETTE.GREY, 1))

# Add a shadow
style.set_shadow_width(8)
style.set_shadow_color(lv.palette_main(lv.PALETTE.BLUE))
style.set_shadow_ofs_x(10)
style.set_shadow_ofs_y(20)

# Create an object with the new style
obj = lv.obj(lv.scr_act())
obj.add_style(style, 0)
obj.center()

Image styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMG

/**
 * Using the Image style properties
 */
void lv_example_style_6(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    /*Set a background color and a radius*/
    lv_style_set_radius(&style, 5);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 3));
    lv_style_set_border_width(&style, 2);
    lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_BLUE));

    lv_style_set_img_recolor(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_img_recolor_opa(&style, LV_OPA_50);
    lv_style_set_transform_angle(&style, 300);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_img_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);

    LV_IMG_DECLARE(img_cogwheel_argb);
    lv_img_set_src(obj, &img_cogwheel_argb);

    lv_obj_center(obj);
}

#endif

# Create an image from the png file
try:
    with open('../assets/img_cogwheel_argb.png', 'rb') as f:
        png_data = f.read()
except:
    print("Could not find img_cogwheel_argb.png")
    sys.exit()

img_cogwheel_argb = lv.img_dsc_t({
  'data_size': len(png_data),
  'data': png_data
})

#
# Using the Image style properties
#
style = lv.style_t()
style.init()

# Set a background color and a radius
style.set_radius(5)
style.set_bg_opa(lv.OPA.COVER)
style.set_bg_color(lv.palette_lighten(lv.PALETTE.GREY, 3))
style.set_border_width(2)
style.set_border_color(lv.palette_main(lv.PALETTE.BLUE))

style.set_img_recolor(lv.palette_main(lv.PALETTE.BLUE))
style.set_img_recolor_opa(lv.OPA._50)
style.set_transform_angle(300)

# Create an object with the new style
obj = lv.img(lv.scr_act())
obj.add_style(style, 0)

obj.set_src(img_cogwheel_argb)

obj.center()

Arc styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_ARC

/**
 * Using the Arc style properties
 */
void lv_example_style_7(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    lv_style_set_arc_color(&style, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_arc_width(&style, 4);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_arc_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_center(obj);
}
#endif

#
# Using the Arc style properties
#
style = lv.style_t()
style.init()

style.set_arc_color(lv.palette_main(lv.PALETTE.RED))
style.set_arc_width(4)

# Create an object with the new style
obj = lv.arc(lv.scr_act())
obj.add_style(style, 0)
obj.center()

Text styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LABEL

/**
 * Using the text style properties
 */
void lv_example_style_8(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    lv_style_set_radius(&style, 5);
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_palette_lighten(LV_PALETTE_GREY, 2));
    lv_style_set_border_width(&style, 2);
    lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_pad_all(&style, 10);

    lv_style_set_text_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_text_letter_space(&style, 5);
    lv_style_set_text_line_space(&style, 20);
    lv_style_set_text_decor(&style, LV_TEXT_DECOR_UNDERLINE);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_label_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);
    lv_label_set_text(obj, "Text of\n"
                      "a label");

    lv_obj_center(obj);
}

#endif

#
# Using the text style properties
#

style = lv.style_t()
style.init()

style.set_radius(5)
style.set_bg_opa(lv.OPA.COVER)
style.set_bg_color(lv.palette_lighten(lv.PALETTE.GREY, 3))
style.set_border_width(2)
style.set_border_color(lv.palette_main(lv.PALETTE.BLUE))
style.set_pad_all(10)

style.set_text_color(lv.palette_main(lv.PALETTE.BLUE))
style.set_text_letter_space(5)
style.set_text_line_space(20)
style.set_text_decor(lv.TEXT_DECOR.UNDERLINE)

# Create an object with the new style
obj = lv.label(lv.scr_act())
obj.add_style(style, 0)
obj.set_text("Text of\n"
             "a label")

obj.center()

Line styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LINE

/**
 * Using the line style properties
 */
void lv_example_style_9(void)
{
    static lv_style_t style;
    lv_style_init(&style);

    lv_style_set_line_color(&style, lv_palette_main(LV_PALETTE_GREY));
    lv_style_set_line_width(&style, 6);
    lv_style_set_line_rounded(&style, true);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_line_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);

    static lv_point_t p[] = {{10, 30}, {30, 50}, {100, 0}};
    lv_line_set_points(obj, p, 3);

    lv_obj_center(obj);
}

#endif

#
# Using the line style properties
#

style = lv.style_t()
style.init()

style.set_line_color(lv.palette_main(lv.PALETTE.GREY))
style.set_line_width(6)
style.set_line_rounded(True)

# Create an object with the new style
obj = lv.line(lv.scr_act())
obj.add_style(style, 0)
p =  [ {"x":10, "y":30},
       {"x":30, "y":50},
       {"x":100, "y":0}]

obj.set_points(p, 3)

obj.center()

Transition

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMG

/**
 * Creating a transition
 */
void lv_example_style_10(void)
{
    static const lv_style_prop_t props[] = {LV_STYLE_BG_COLOR, LV_STYLE_BORDER_COLOR, LV_STYLE_BORDER_WIDTH, 0};

    /* A default transition
     * Make it fast (100ms) and start with some delay (200 ms)*/
    static lv_style_transition_dsc_t trans_def;
    lv_style_transition_dsc_init(&trans_def, props, lv_anim_path_linear, 100, 200, NULL);

    /* A special transition when going to pressed state
     * Make it slow (500 ms) but start  without delay*/
    static lv_style_transition_dsc_t trans_pr;
    lv_style_transition_dsc_init(&trans_pr, props, lv_anim_path_linear, 500, 0, NULL);

    static lv_style_t style_def;
    lv_style_init(&style_def);
    lv_style_set_transition(&style_def, &trans_def);

    static lv_style_t style_pr;
    lv_style_init(&style_pr);
    lv_style_set_bg_color(&style_pr, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_border_width(&style_pr, 6);
    lv_style_set_border_color(&style_pr, lv_palette_darken(LV_PALETTE_RED, 3));
    lv_style_set_transition(&style_pr, &trans_pr);

    /*Create an object with the new style_pr*/
    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj, &style_def, 0);
    lv_obj_add_style(obj, &style_pr, LV_STATE_PRESSED);

    lv_obj_center(obj);
}

#endif

#
# Creating a transition
#

props = [lv.STYLE.BG_COLOR, lv.STYLE.BORDER_COLOR, lv.STYLE.BORDER_WIDTH, 0]

# A default transition
# Make it fast (100ms) and start with some delay (200 ms)

trans_def = lv.style_transition_dsc_t()
trans_def.init(props, lv.anim_t.path_linear, 100, 200, None)

# A special transition when going to pressed state
# Make it slow (500 ms) but start  without delay

trans_pr = lv.style_transition_dsc_t()
trans_pr.init(props, lv.anim_t.path_linear, 500, 0, None)

style_def = lv.style_t()
style_def.init()
style_def.set_transition(trans_def)

style_pr = lv.style_t()
style_pr.init()
style_pr.set_bg_color(lv.palette_main(lv.PALETTE.RED))
style_pr.set_border_width(6)
style_pr.set_border_color(lv.palette_darken(lv.PALETTE.RED, 3))
style_pr.set_transition(trans_pr)

# Create an object with the new style_pr
obj = lv.obj(lv.scr_act())
obj.add_style(style_def, 0)
obj.add_style(style_pr, lv.STATE.PRESSED)

obj.center()

Using multiple styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMG

/**
 * Using multiple styles
 */
void lv_example_style_11(void)
{
    /*A base style*/
    static lv_style_t style_base;
    lv_style_init(&style_base);
    lv_style_set_bg_color(&style_base, lv_palette_main(LV_PALETTE_LIGHT_BLUE));
    lv_style_set_border_color(&style_base, lv_palette_darken(LV_PALETTE_LIGHT_BLUE, 3));
    lv_style_set_border_width(&style_base, 2);
    lv_style_set_radius(&style_base, 10);
    lv_style_set_shadow_width(&style_base, 10);
    lv_style_set_shadow_ofs_y(&style_base, 5);
    lv_style_set_shadow_opa(&style_base, LV_OPA_50);
    lv_style_set_text_color(&style_base, lv_color_white());
    lv_style_set_width(&style_base, 100);
    lv_style_set_height(&style_base, LV_SIZE_CONTENT);

    /*Set only the properties that should be different*/
    static lv_style_t style_warning;
    lv_style_init(&style_warning);
    lv_style_set_bg_color(&style_warning, lv_palette_main(LV_PALETTE_YELLOW));
    lv_style_set_border_color(&style_warning, lv_palette_darken(LV_PALETTE_YELLOW, 3));
    lv_style_set_text_color(&style_warning, lv_palette_darken(LV_PALETTE_YELLOW, 4));

    /*Create an object with the base style only*/
    lv_obj_t * obj_base = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj_base, &style_base, 0);
    lv_obj_align(obj_base, LV_ALIGN_LEFT_MID, 20, 0);

    lv_obj_t * label = lv_label_create(obj_base);
    lv_label_set_text(label, "Base");
    lv_obj_center(label);

    /*Create another object with the base style and earnings style too*/
    lv_obj_t * obj_warning = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj_warning, &style_base, 0);
    lv_obj_add_style(obj_warning, &style_warning, 0);
    lv_obj_align(obj_warning, LV_ALIGN_RIGHT_MID, -20, 0);

    label = lv_label_create(obj_warning);
    lv_label_set_text(label, "Warning");
    lv_obj_center(label);
}

#endif

#
# Using multiple styles
#
# A base style

style_base = lv.style_t()
style_base.init()
style_base.set_bg_color(lv.palette_main(lv.PALETTE.LIGHT_BLUE))
style_base.set_border_color(lv.palette_darken(lv.PALETTE.LIGHT_BLUE, 3))
style_base.set_border_width(2)
style_base.set_radius(10)
style_base.set_shadow_width(10)
style_base.set_shadow_ofs_y(5)
style_base.set_shadow_opa(lv.OPA._50)
style_base.set_text_color(lv.color_white())
style_base.set_width(100)
style_base.set_height(lv.SIZE_CONTENT)

# Set only the properties that should be different
style_warning = lv.style_t()
style_warning.init()
style_warning.set_bg_color(lv.palette_main(lv.PALETTE.YELLOW))
style_warning.set_border_color(lv.palette_darken(lv.PALETTE.YELLOW, 3))
style_warning.set_text_color(lv.palette_darken(lv.PALETTE.YELLOW, 4))

# Create an object with the base style only
obj_base = lv.obj(lv.scr_act())
obj_base.add_style(style_base, 0)
obj_base.align(lv.ALIGN.LEFT_MID, 20, 0)

label = lv.label(obj_base)
label.set_text("Base")
label.center()

# Create another object with the base style and earnings style too
obj_warning = lv.obj(lv.scr_act())
obj_warning.add_style(style_base, 0)
obj_warning.add_style(style_warning, 0)
obj_warning.align(lv.ALIGN.RIGHT_MID, -20, 0)

label = lv.label(obj_warning)
label.set_text("Warning")
label.center()

Local styles

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMG

/**
 * Local styles
 */
void lv_example_style_12(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_bg_color(&style, lv_palette_main(LV_PALETTE_GREEN));
    lv_style_set_border_color(&style, lv_palette_lighten(LV_PALETTE_GREEN, 3));
    lv_style_set_border_width(&style, 3);

    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj, &style, 0);

    /*Overwrite the background color locally*/
    lv_obj_set_style_bg_color(obj, lv_palette_main(LV_PALETTE_ORANGE), LV_PART_MAIN);

    lv_obj_center(obj);
}

#endif

#
# Local styles
#

style = lv.style_t()
style.init()
style.set_bg_color(lv.palette_main(lv.PALETTE.GREEN))
style.set_border_color(lv.palette_lighten(lv.PALETTE.GREEN, 3))
style.set_border_width(3)

obj = lv.obj(lv.scr_act())
obj.add_style(style, 0)

# Overwrite the background color locally
obj.set_style_bg_color(lv.palette_main(lv.PALETTE.ORANGE), lv.PART.MAIN)

obj.center()

Add styles to parts and states

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMG

/**
 * Add styles to parts and states
 */
void lv_example_style_13(void)
{
    static lv_style_t style_indic;
    lv_style_init(&style_indic);
    lv_style_set_bg_color(&style_indic, lv_palette_lighten(LV_PALETTE_RED, 3));
    lv_style_set_bg_grad_color(&style_indic, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_bg_grad_dir(&style_indic, LV_GRAD_DIR_HOR);

    static lv_style_t style_indic_pr;
    lv_style_init(&style_indic_pr);
    lv_style_set_shadow_color(&style_indic_pr, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_shadow_width(&style_indic_pr, 10);
    lv_style_set_shadow_spread(&style_indic_pr, 3);

    /*Create an object with the new style_pr*/
    lv_obj_t * obj = lv_slider_create(lv_scr_act());
    lv_obj_add_style(obj, &style_indic, LV_PART_INDICATOR);
    lv_obj_add_style(obj, &style_indic_pr, LV_PART_INDICATOR | LV_STATE_PRESSED);
    lv_slider_set_value(obj, 70, LV_ANIM_OFF);
    lv_obj_center(obj);
}

#endif

#
# Add styles to parts and states
#

style_indic = lv.style_t()
style_indic.init()
style_indic.set_bg_color(lv.palette_lighten(lv.PALETTE.RED, 3))
style_indic.set_bg_grad_color(lv.palette_main(lv.PALETTE.RED))
style_indic.set_bg_grad_dir(lv.GRAD_DIR.HOR)

style_indic_pr = lv.style_t()
style_indic_pr.init()
style_indic_pr.set_shadow_color(lv.palette_main(lv.PALETTE.RED))
style_indic_pr.set_shadow_width(10)
style_indic_pr.set_shadow_spread(3)

# Create an object with the new style_pr
obj = lv.slider(lv.scr_act())
obj.add_style(style_indic, lv.PART.INDICATOR)
obj.add_style(style_indic_pr, lv.PART.INDICATOR | lv.STATE.PRESSED)
obj.set_value(70, lv.ANIM.OFF)
obj.center()

Extending the current theme

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_IMG


static lv_style_t style_btn;

/*Will be called when the styles of the base theme are already added
  to add new styles*/
static void new_theme_apply_cb(lv_theme_t * th, lv_obj_t * obj)
{
    LV_UNUSED(th);

    if(lv_obj_check_type(obj, &lv_btn_class)) {
        lv_obj_add_style(obj, &style_btn, 0);
    }
}

static void new_theme_init_and_set(void)
{
    /*Initialize the styles*/
    lv_style_init(&style_btn);
    lv_style_set_bg_color(&style_btn, lv_palette_main(LV_PALETTE_GREEN));
    lv_style_set_border_color(&style_btn, lv_palette_darken(LV_PALETTE_GREEN, 3));
    lv_style_set_border_width(&style_btn, 3);

    /*Initialize the new theme from the current theme*/
    lv_theme_t * th_act = lv_disp_get_theme(NULL);
    static lv_theme_t th_new;
    th_new = *th_act;

    /*Set the parent theme and the style apply callback for the new theme*/
    lv_theme_set_parent(&th_new, th_act);
    lv_theme_set_apply_cb(&th_new, new_theme_apply_cb);

    /*Assign the new theme to the current display*/
    lv_disp_set_theme(NULL, &th_new);
}



/**
 * Extending the current theme
 */
void lv_example_style_14(void)
{
    lv_obj_t * btn;
    lv_obj_t * label;

    btn = lv_btn_create(lv_scr_act());
    lv_obj_align(btn, LV_ALIGN_TOP_MID, 0, 20);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Original theme");

    new_theme_init_and_set();

    btn = lv_btn_create(lv_scr_act());
    lv_obj_align(btn, LV_ALIGN_BOTTOM_MID, 0, -20);

    label = lv_label_create(btn);
    lv_label_set_text(label, "New theme");
}

#endif

# Will be called when the styles of the base theme are already added
# to add new styles


class NewTheme(lv.theme_t):
    def __init__(self):
        super().__init__()
        # Initialize the styles
        self.style_btn = lv.style_t()
        self.style_btn.init()
        self.style_btn.set_bg_color(lv.palette_main(lv.PALETTE.GREEN))
        self.style_btn.set_border_color(lv.palette_darken(lv.PALETTE.GREEN, 3))
        self.style_btn.set_border_width(3)

        # This theme is based on active theme
        th_act = lv.theme_get_from_obj(lv.scr_act())
        # This theme will be applied only after base theme is applied
        self.set_parent(th_act)


class ExampleStyle_14:

    def __init__(self):
        #
        # Extending the current theme
        #

        btn = lv.btn(lv.scr_act())
        btn.align(lv.ALIGN.TOP_MID, 0, 20)

        label = lv.label(btn)
        label.set_text("Original theme")

        self.new_theme_init_and_set()

        btn = lv.btn(lv.scr_act())
        btn.align(lv.ALIGN.BOTTOM_MID, 0, -20)

        label = lv.label(btn)
        label.set_text("New theme")

    def new_theme_apply_cb(self, th, obj):
        print(th,obj)
        if obj.get_class() == lv.btn_class:
            obj.add_style(self.th_new.style_btn, 0)

    def new_theme_init_and_set(self):
        print("new_theme_init_and_set")
        # Initialize the new theme from the current theme
        self.th_new = NewTheme()
        self.th_new.set_apply_cb(self.new_theme_apply_cb)
        lv.disp_get_default().set_theme(self.th_new)


exampleStyle_14 = ExampleStyle_14()

Opacity and Transformations

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_BTN && LV_USE_LABEL



/**
 * Opacity and Transformations
 */
void lv_example_style_15(void)
{
    lv_obj_t * btn;
    lv_obj_t * label;

    /*Normal button*/
    btn = lv_btn_create(lv_scr_act());
    lv_obj_set_size(btn, 100, 40);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, -70);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Normal");
    lv_obj_center(label);

    /*Set opacity
     *The button and the label is rendered to a layer first and that layer is blended*/
    btn = lv_btn_create(lv_scr_act());
    lv_obj_set_size(btn, 100, 40);
    lv_obj_set_style_opa(btn, LV_OPA_50, 0);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, 0);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Opa:50%");
    lv_obj_center(label);

    /*Set transformations
     *The button and the label is rendered to a layer first and that layer is transformed*/
    btn = lv_btn_create(lv_scr_act());
    lv_obj_set_size(btn, 100, 40);
    lv_obj_set_style_transform_angle(btn, 150, 0);        /*15 deg*/
    lv_obj_set_style_transform_zoom(btn, 256 + 64, 0);   /*1.25x*/
    lv_obj_set_style_transform_pivot_x(btn, 50, 0);
    lv_obj_set_style_transform_pivot_y(btn, 20, 0);
    lv_obj_set_style_opa(btn, LV_OPA_50, 0);
    lv_obj_align(btn, LV_ALIGN_CENTER, 0, 70);

    label = lv_label_create(btn);
    lv_label_set_text(label, "Transf.");
    lv_obj_center(label);
}

#endif

#
# Opacity and Transformations
#

# Normal button
btn = lv.btn(lv.scr_act())
btn.set_size(100, 40)
btn.align(lv.ALIGN.CENTER, 0, -70)

label = lv.label(btn)
label.set_text("Normal")
label.center()

# Set opacity
# The button and the label is rendered to a layer first and that layer is blended
btn = lv.btn(lv.scr_act())
btn.set_size(100, 40)
btn.set_style_opa(lv.OPA._50, 0)
btn.align(lv.ALIGN.CENTER, 0, 0)

label = lv.label(btn)
label.set_text("Opa:50%")
label.center()

# Set transformations
# The button and the label is rendered to a layer first and that layer is transformed
btn = lv.btn(lv.scr_act())
btn.set_size(100, 40)
btn.set_style_transform_angle(150, 0)             # 15 deg
btn.set_style_transform_zoom(256 + 64, 0)         # 1.25x
btn.set_style_transform_pivot_x(50, 0)
btn.set_style_transform_pivot_y(20, 0)
btn.set_style_opa(lv.OPA._50, 0)
btn.align(lv.ALIGN.CENTER, 0, 70)

label = lv.label(btn)
label.set_text("Transf.")
label.center()

Animations

Start animation on an event

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH

static void anim_x_cb(void * var, int32_t v)
{
    lv_obj_set_x(var, v);
}

static void sw_event_cb(lv_event_t * e)
{
    lv_obj_t * sw = lv_event_get_target(e);
    lv_obj_t * label = lv_event_get_user_data(e);

    if(lv_obj_has_state(sw, LV_STATE_CHECKED)) {
        lv_anim_t a;
        lv_anim_init(&a);
        lv_anim_set_var(&a, label);
        lv_anim_set_values(&a, lv_obj_get_x(label), 100);
        lv_anim_set_time(&a, 500);
        lv_anim_set_exec_cb(&a, anim_x_cb);
        lv_anim_set_path_cb(&a, lv_anim_path_overshoot);
        lv_anim_start(&a);
    }
    else {
        lv_anim_t a;
        lv_anim_init(&a);
        lv_anim_set_var(&a, label);
        lv_anim_set_values(&a, lv_obj_get_x(label), -lv_obj_get_width(label));
        lv_anim_set_time(&a, 500);
        lv_anim_set_exec_cb(&a, anim_x_cb);
        lv_anim_set_path_cb(&a, lv_anim_path_ease_in);
        lv_anim_start(&a);
    }

}

/**
 * Start animation on an event
 */
void lv_example_anim_1(void)
{
    lv_obj_t * label = lv_label_create(lv_scr_act());
    lv_label_set_text(label, "Hello animations!");
    lv_obj_set_pos(label, 100, 10);


    lv_obj_t * sw = lv_switch_create(lv_scr_act());
    lv_obj_center(sw);
    lv_obj_add_state(sw, LV_STATE_CHECKED);
    lv_obj_add_event(sw, sw_event_cb, LV_EVENT_VALUE_CHANGED, label);
}

#endif

def anim_x_cb(label, v):
    label.set_x(v)

def sw_event_cb(e,label):
    sw = e.get_target_obj()

    if sw.has_state(lv.STATE.CHECKED):
        a = lv.anim_t()
        a.init()
        a.set_var(label)
        a.set_values(label.get_x(), 100)
        a.set_time(500)
        a.set_path_cb(lv.anim_t.path_overshoot)
        a.set_custom_exec_cb(lambda a,val: anim_x_cb(label,val))
        lv.anim_t.start(a)
    else:
        a = lv.anim_t()
        a.init()
        a.set_var(label)
        a.set_values(label.get_x(), -label.get_width())
        a.set_time(500)
        a.set_path_cb(lv.anim_t.path_ease_in)
        a.set_custom_exec_cb(lambda a,val: anim_x_cb(label,val))
        lv.anim_t.start(a)

#
# Start animation on an event
#

label = lv.label(lv.scr_act())
label.set_text("Hello animations!")
label.set_pos(100, 10)


sw = lv.switch(lv.scr_act())
sw.center()
sw.add_state(lv.STATE.CHECKED)
sw.add_event(lambda e: sw_event_cb(e,label), lv.EVENT.VALUE_CHANGED, None)

Playback animation

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH


static void anim_x_cb(void * var, int32_t v)
{
    lv_obj_set_x(var, v);
}

static void anim_size_cb(void * var, int32_t v)
{
    lv_obj_set_size(var, v, v);
}

/**
 * Create a playback animation
 */
void lv_example_anim_2(void)
{

    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_set_style_bg_color(obj, lv_palette_main(LV_PALETTE_RED), 0);
    lv_obj_set_style_radius(obj, LV_RADIUS_CIRCLE, 0);

    lv_obj_align(obj, LV_ALIGN_LEFT_MID, 10, 0);

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, obj);
    lv_anim_set_values(&a, 10, 50);
    lv_anim_set_time(&a, 1000);
    lv_anim_set_playback_delay(&a, 100);
    lv_anim_set_playback_time(&a, 300);
    lv_anim_set_repeat_delay(&a, 500);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);
    lv_anim_set_path_cb(&a, lv_anim_path_ease_in_out);

    lv_anim_set_exec_cb(&a, anim_size_cb);
    lv_anim_start(&a);
    lv_anim_set_exec_cb(&a, anim_x_cb);
    lv_anim_set_values(&a, 10, 240);
    lv_anim_start(&a);
}

#endif

def anim_x_cb(obj, v):
    obj.set_x(v)

def anim_size_cb(obj, v):
    obj.set_size(v, v)


#
# Create a playback animation
#
obj = lv.obj(lv.scr_act())
obj.set_style_bg_color(lv.palette_main(lv.PALETTE.RED), 0)
obj.set_style_radius(lv.RADIUS_CIRCLE, 0)

obj.align(lv.ALIGN.LEFT_MID, 10, 0)

a1 = lv.anim_t()
a1.init()
a1.set_var(obj)
a1.set_values(10, 50)
a1.set_time(1000)
a1.set_playback_delay(100)
a1.set_playback_time(300)
a1.set_repeat_delay(500)
a1.set_repeat_count(lv.ANIM_REPEAT_INFINITE)
a1.set_path_cb(lv.anim_t.path_ease_in_out)
a1.set_custom_exec_cb(lambda a1,val: anim_size_cb(obj,val))
lv.anim_t.start(a1)

a2 = lv.anim_t()
a2.init()
a2.set_var(obj)
a2.set_values(10, 240)
a2.set_time(1000)
a2.set_playback_delay(100)
a2.set_playback_time(300)
a2.set_repeat_delay(500)
a2.set_repeat_count(lv.ANIM_REPEAT_INFINITE)
a2.set_path_cb(lv.anim_t.path_ease_in_out)
a2.set_custom_exec_cb(lambda a1,val: anim_x_cb(obj,val))
lv.anim_t.start(a2)

Animation timeline

#include "../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

static lv_anim_timeline_t * anim_timeline = NULL;

static lv_obj_t * obj1 = NULL;
static lv_obj_t * obj2 = NULL;
static lv_obj_t * obj3 = NULL;

static const lv_coord_t obj_width = 90;
static const lv_coord_t obj_height = 70;

static void set_width(void * var, int32_t v)
{
    lv_obj_set_width((lv_obj_t *)var, v);
}

static void set_height(void * var, int32_t v)
{
    lv_obj_set_height((lv_obj_t *)var, v);
}

static void anim_timeline_create(void)
{
    /* obj1 */
    lv_anim_t a1;
    lv_anim_init(&a1);
    lv_anim_set_var(&a1, obj1);
    lv_anim_set_values(&a1, 0, obj_width);
    lv_anim_set_early_apply(&a1, false);
    lv_anim_set_exec_cb(&a1, (lv_anim_exec_xcb_t)set_width);
    lv_anim_set_path_cb(&a1, lv_anim_path_overshoot);
    lv_anim_set_time(&a1, 300);

    lv_anim_t a2;
    lv_anim_init(&a2);
    lv_anim_set_var(&a2, obj1);
    lv_anim_set_values(&a2, 0, obj_height);
    lv_anim_set_early_apply(&a2, false);
    lv_anim_set_exec_cb(&a2, (lv_anim_exec_xcb_t)set_height);
    lv_anim_set_path_cb(&a2, lv_anim_path_ease_out);
    lv_anim_set_time(&a2, 300);

    /* obj2 */
    lv_anim_t a3;
    lv_anim_init(&a3);
    lv_anim_set_var(&a3, obj2);
    lv_anim_set_values(&a3, 0, obj_width);
    lv_anim_set_early_apply(&a3, false);
    lv_anim_set_exec_cb(&a3, (lv_anim_exec_xcb_t)set_width);
    lv_anim_set_path_cb(&a3, lv_anim_path_overshoot);
    lv_anim_set_time(&a3, 300);

    lv_anim_t a4;
    lv_anim_init(&a4);
    lv_anim_set_var(&a4, obj2);
    lv_anim_set_values(&a4, 0, obj_height);
    lv_anim_set_early_apply(&a4, false);
    lv_anim_set_exec_cb(&a4, (lv_anim_exec_xcb_t)set_height);
    lv_anim_set_path_cb(&a4, lv_anim_path_ease_out);
    lv_anim_set_time(&a4, 300);

    /* obj3 */
    lv_anim_t a5;
    lv_anim_init(&a5);
    lv_anim_set_var(&a5, obj3);
    lv_anim_set_values(&a5, 0, obj_width);
    lv_anim_set_early_apply(&a5, false);
    lv_anim_set_exec_cb(&a5, (lv_anim_exec_xcb_t)set_width);
    lv_anim_set_path_cb(&a5, lv_anim_path_overshoot);
    lv_anim_set_time(&a5, 300);

    lv_anim_t a6;
    lv_anim_init(&a6);
    lv_anim_set_var(&a6, obj3);
    lv_anim_set_values(&a6, 0, obj_height);
    lv_anim_set_early_apply(&a6, false);
    lv_anim_set_exec_cb(&a6, (lv_anim_exec_xcb_t)set_height);
    lv_anim_set_path_cb(&a6, lv_anim_path_ease_out);
    lv_anim_set_time(&a6, 300);

    /* Create anim timeline */
    anim_timeline = lv_anim_timeline_create();
    lv_anim_timeline_add(anim_timeline, 0, &a1);
    lv_anim_timeline_add(anim_timeline, 0, &a2);
    lv_anim_timeline_add(anim_timeline, 200, &a3);
    lv_anim_timeline_add(anim_timeline, 200, &a4);
    lv_anim_timeline_add(anim_timeline, 400, &a5);
    lv_anim_timeline_add(anim_timeline, 400, &a6);
}

static void btn_start_event_handler(lv_event_t * e)
{
    lv_obj_t * btn = lv_event_get_target(e);

    if(!anim_timeline) {
        anim_timeline_create();
    }

    bool reverse = lv_obj_has_state(btn, LV_STATE_CHECKED);
    lv_anim_timeline_set_reverse(anim_timeline, reverse);
    lv_anim_timeline_start(anim_timeline);
}

static void btn_del_event_handler(lv_event_t * e)
{
    LV_UNUSED(e);
    if(anim_timeline) {
        lv_anim_timeline_del(anim_timeline);
        anim_timeline = NULL;
    }
}

static void btn_stop_event_handler(lv_event_t * e)
{
    LV_UNUSED(e);
    if(anim_timeline) {
        lv_anim_timeline_stop(anim_timeline);
    }
}

static void slider_prg_event_handler(lv_event_t * e)
{
    lv_obj_t * slider = lv_event_get_target(e);

    if(!anim_timeline) {
        anim_timeline_create();
    }

    int32_t progress = lv_slider_get_value(slider);
    lv_anim_timeline_set_progress(anim_timeline, progress);
}

/**
 * Create an animation timeline
 */
void lv_example_anim_timeline_1(void)
{
    lv_obj_t * par = lv_scr_act();
    lv_obj_set_flex_flow(par, LV_FLEX_FLOW_ROW);
    lv_obj_set_flex_align(par, LV_FLEX_ALIGN_SPACE_AROUND, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);

    /* create btn_start */
    lv_obj_t * btn_start = lv_btn_create(par);
    lv_obj_add_event(btn_start, btn_start_event_handler, LV_EVENT_VALUE_CHANGED, NULL);
    lv_obj_add_flag(btn_start, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_add_flag(btn_start, LV_OBJ_FLAG_CHECKABLE);
    lv_obj_align(btn_start, LV_ALIGN_TOP_MID, -100, 20);

    lv_obj_t * label_start = lv_label_create(btn_start);
    lv_label_set_text(label_start, "Start");
    lv_obj_center(label_start);

    /* create btn_del */
    lv_obj_t * btn_del = lv_btn_create(par);
    lv_obj_add_event(btn_del, btn_del_event_handler, LV_EVENT_CLICKED, NULL);
    lv_obj_add_flag(btn_del, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_align(btn_del, LV_ALIGN_TOP_MID, 0, 20);

    lv_obj_t * label_del = lv_label_create(btn_del);
    lv_label_set_text(label_del, "Delete");
    lv_obj_center(label_del);

    /* create btn_stop */
    lv_obj_t * btn_stop = lv_btn_create(par);
    lv_obj_add_event(btn_stop, btn_stop_event_handler, LV_EVENT_CLICKED, NULL);
    lv_obj_add_flag(btn_stop, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_align(btn_stop, LV_ALIGN_TOP_MID, 100, 20);

    lv_obj_t * label_stop = lv_label_create(btn_stop);
    lv_label_set_text(label_stop, "Stop");
    lv_obj_center(label_stop);

    /* create slider_prg */
    lv_obj_t * slider_prg = lv_slider_create(par);
    lv_obj_add_event(slider_prg, slider_prg_event_handler, LV_EVENT_VALUE_CHANGED, NULL);
    lv_obj_add_flag(slider_prg, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_align(slider_prg, LV_ALIGN_BOTTOM_MID, 0, -20);
    lv_slider_set_range(slider_prg, 0, 65535);

    /* create 3 objects */
    obj1 = lv_obj_create(par);
    lv_obj_set_size(obj1, obj_width, obj_height);

    obj2 = lv_obj_create(par);
    lv_obj_set_size(obj2, obj_width, obj_height);

    obj3 = lv_obj_create(par);
    lv_obj_set_size(obj3, obj_width, obj_height);
}

#endif

class LV_ExampleAnimTimeline_1(object):

    def __init__(self):
        self.obj_width = 120
        self.obj_height = 150
        #
        # Create an animation timeline
        #

        self.par = lv.scr_act()
        self.par.set_flex_flow(lv.FLEX_FLOW.ROW)
        self.par.set_flex_align(lv.FLEX_ALIGN.SPACE_AROUND, lv.FLEX_ALIGN.CENTER, lv.FLEX_ALIGN.CENTER)

        self.btn_run = lv.btn(self.par)
        self.btn_run.add_event(self.btn_run_event_handler, lv.EVENT.VALUE_CHANGED, None)
        self.btn_run.add_flag(lv.obj.FLAG.IGNORE_LAYOUT)
        self.btn_run.add_flag(lv.obj.FLAG.CHECKABLE)
        self.btn_run.align(lv.ALIGN.TOP_MID, -50, 20)

        self.label_run = lv.label(self.btn_run)
        self.label_run.set_text("Run")
        self.label_run.center()

        self.btn_del = lv.btn(self.par)
        self.btn_del.add_event(self.btn_del_event_handler, lv.EVENT.CLICKED, None)
        self.btn_del.add_flag(lv.obj.FLAG.IGNORE_LAYOUT)
        self.btn_del.align(lv.ALIGN.TOP_MID, 50, 20)

        self.label_del = lv.label(self.btn_del)
        self.label_del.set_text("Stop")
        self.label_del.center()

        self.slider = lv.slider(self.par)
        self.slider.add_event(self.slider_prg_event_handler, lv.EVENT.VALUE_CHANGED, None)
        self.slider.add_flag(lv.obj.FLAG.IGNORE_LAYOUT)
        self.slider.align(lv.ALIGN.BOTTOM_RIGHT, -20, -20)
        self.slider.set_range(0, 65535)

        self.obj1 = lv.obj(self.par)
        self.obj1.set_size(self.obj_width, self.obj_height)

        self.obj2 = lv.obj(self.par)
        self.obj2.set_size(self.obj_width, self.obj_height)

        self.obj3 = lv.obj(self.par)
        self.obj3.set_size(self.obj_width, self.obj_height)

        self.anim_timeline = None

    def set_width(self,obj, v):
        obj.set_width(v)

    def set_height(self,obj, v):
        obj.set_height(v)

    def anim_timeline_create(self):
        # obj1
        self.a1 = lv.anim_t()
        self.a1.init()
        self.a1.set_values(0, self.obj_width)
        self.a1.set_early_apply(False)
        self.a1.set_custom_exec_cb(lambda a,v: self.set_width(self.obj1,v))
        self.a1.set_path_cb(lv.anim_t.path_overshoot)
        self.a1.set_time(300)

        self.a2 = lv.anim_t()
        self.a2.init()
        self.a2.set_values(0, self.obj_height)
        self.a2.set_early_apply(False)
        self.a2.set_custom_exec_cb(lambda a,v: self.set_height(self.obj1,v))
        self.a2.set_path_cb(lv.anim_t.path_ease_out)
        self.a2.set_time(300)

        # obj2
        self.a3=lv.anim_t()
        self.a3.init()
        self.a3.set_values(0, self.obj_width)
        self.a3.set_early_apply(False)
        self.a3.set_custom_exec_cb(lambda a,v: self.set_width(self.obj2,v))
        self.a3.set_path_cb(lv.anim_t.path_overshoot)
        self.a3.set_time(300)

        self.a4 = lv.anim_t()
        self.a4.init()
        self.a4.set_values(0, self.obj_height)
        self.a4.set_early_apply(False)
        self.a4.set_custom_exec_cb(lambda a,v: self.set_height(self.obj2,v))
        self.a4.set_path_cb(lv.anim_t.path_ease_out)
        self.a4.set_time(300)

        # obj3
        self.a5 = lv.anim_t()
        self.a5.init()
        self.a5.set_values(0, self.obj_width)
        self.a5.set_early_apply(False)
        self.a5.set_custom_exec_cb(lambda a,v: self.set_width(self.obj3,v))
        self.a5.set_path_cb(lv.anim_t.path_overshoot)
        self.a5.set_time(300)

        self.a6 = lv.anim_t()
        self.a6.init()
        self.a6.set_values(0, self.obj_height)
        self.a6.set_early_apply(False)
        self.a6.set_custom_exec_cb(lambda a,v: self.set_height(self.obj3,v))
        self.a6.set_path_cb(lv.anim_t.path_ease_out)
        self.a6.set_time(300)

        # Create anim timeline
        print("Create new anim_timeline")
        self.anim_timeline = lv.anim_timeline_create()
        self.anim_timeline.add(0, self.a1)
        self.anim_timeline.add(0, self.a2)
        self.anim_timeline.add(200, self.a3)
        self.anim_timeline.add(200, self.a4)
        self.anim_timeline.add(400, self.a5)
        self.anim_timeline.add(400, self.a6)

    def slider_prg_event_handler(self,e):
        slider = e.get_target_obj()

        if  not self.anim_timeline:
            self.anim_timeline_create()

        progress = slider.get_value()
        self.anim_timeline.set_progress(progress)


    def btn_run_event_handler(self,e):
        btn = e.get_target_obj()
        if not self.anim_timeline:
            self.anim_timeline_create()

        reverse = btn.has_state(lv.STATE.CHECKED)
        self.anim_timeline.set_reverse(reverse)
        self.anim_timeline.start()

    def btn_del_event_handler(self,e):
        if self.anim_timeline:
            self.anim_timeline._del()
        self.anim_timeline = None


lv_example_anim_timeline_1 = LV_ExampleAnimTimeline_1()

Events

Button click event

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH

static void event_cb(lv_event_t * e)
{
    LV_LOG_USER("Clicked");

    static uint32_t cnt = 1;
    lv_obj_t * btn = lv_event_get_target(e);
    lv_obj_t * label = lv_obj_get_child(btn, 0);
    lv_label_set_text_fmt(label, "%"LV_PRIu32, cnt);
    cnt++;
}

/**
 * Add click event to a button
 */
void lv_example_event_1(void)
{
    lv_obj_t * btn = lv_btn_create(lv_scr_act());
    lv_obj_set_size(btn, 100, 50);
    lv_obj_center(btn);
    lv_obj_add_event(btn, event_cb, LV_EVENT_CLICKED, NULL);

    lv_obj_t * label = lv_label_create(btn);
    lv_label_set_text(label, "Click me!");
    lv_obj_center(label);
}

#endif

class Event_1():
    def __init__(self):
        self.cnt = 1
        #
        # Add click event to a button
        #

        btn = lv.btn(lv.scr_act())
        btn.set_size(100, 50)
        btn.center()
        btn.add_event(self.event_cb, lv.EVENT.CLICKED, None)

        label = lv.label(btn)
        label.set_text("Click me!")
        label.center()

    def event_cb(self,e):
        print("Clicked")

        btn = e.get_target_obj()
        label = btn.get_child(0)
        label.set_text(str(self.cnt))
        self.cnt += 1

evt1 = Event_1()

Handle multiple events

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH

static void event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * label = lv_event_get_user_data(e);

    switch(code) {
        case LV_EVENT_PRESSED:
            lv_label_set_text(label, "The last button event:\nLV_EVENT_PRESSED");
            break;
        case LV_EVENT_CLICKED:
            lv_label_set_text(label, "The last button event:\nLV_EVENT_CLICKED");
            break;
        case LV_EVENT_LONG_PRESSED:
            lv_label_set_text(label, "The last button event:\nLV_EVENT_LONG_PRESSED");
            break;
        case LV_EVENT_LONG_PRESSED_REPEAT:
            lv_label_set_text(label, "The last button event:\nLV_EVENT_LONG_PRESSED_REPEAT");
            break;
        default:
            break;
    }
}

/**
 * Handle multiple events
 */
void lv_example_event_2(void)
{
    lv_obj_t * btn = lv_btn_create(lv_scr_act());
    lv_obj_set_size(btn, 100, 50);
    lv_obj_center(btn);

    lv_obj_t * btn_label = lv_label_create(btn);
    lv_label_set_text(btn_label, "Click me!");
    lv_obj_center(btn_label);

    lv_obj_t * info_label = lv_label_create(lv_scr_act());
    lv_label_set_text(info_label, "The last button event:\nNone");

    lv_obj_add_event(btn, event_cb, LV_EVENT_ALL, info_label);
}

#endif

def event_cb(e,label):
    code = e.get_code()
    if code == lv.EVENT.PRESSED:
        label.set_text("The last button event:\nLV_EVENT_PRESSED")
    elif code == lv.EVENT.CLICKED:
        label.set_text("The last button event:\nLV_EVENT_CLICKED")
    elif code == lv.EVENT.LONG_PRESSED:
        label.set_text("The last button event:\nLV_EVENT_LONG_PRESSED")
    elif code == lv.EVENT.LONG_PRESSED_REPEAT:
        label.set_text("The last button event:\nLV_EVENT_LONG_PRESSED_REPEAT")
btn = lv.btn(lv.scr_act())
btn.set_size(100, 50)
btn.center()

btn_label = lv.label(btn)
btn_label.set_text("Click me!")
btn_label.center()

info_label = lv.label(lv.scr_act())
info_label.set_text("The last button event:\nNone")

btn.add_event(lambda e: event_cb(e,info_label), lv.EVENT.ALL, None)

Event bubbling

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_FLEX

static void event_cb(lv_event_t * e)
{
    /*The original target of the event. Can be the buttons or the container*/
    lv_obj_t * target = lv_event_get_target(e);

    /*The current target is always the container as the event is added to it*/
    lv_obj_t * cont = lv_event_get_current_target(e);

    /*If container was clicked do nothing*/
    if(target == cont) return;

    /*Make the clicked buttons red*/
    lv_obj_set_style_bg_color(target, lv_palette_main(LV_PALETTE_RED), 0);
}

/**
 * Demonstrate event bubbling
 */
void lv_example_event_3(void)
{

    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 290, 200);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_ROW_WRAP);

    uint32_t i;
    for(i = 0; i < 30; i++) {
        lv_obj_t * btn = lv_btn_create(cont);
        lv_obj_set_size(btn, 70, 50);
        lv_obj_add_flag(btn, LV_OBJ_FLAG_EVENT_BUBBLE);

        lv_obj_t * label = lv_label_create(btn);
        lv_label_set_text_fmt(label, "%"LV_PRIu32, i);
        lv_obj_center(label);
    }

    lv_obj_add_event(cont, event_cb, LV_EVENT_CLICKED, NULL);
}

#endif

def event_cb(e):

    # The original target of the event. Can be the buttons or the container
    target = e.get_target_obj()

    # The current target is always the container as the event is added to it
    cont = e.get_current_target_obj()

    # If container was clicked do nothing
    if target == cont:
        return

    # Make the clicked buttons red
    target.set_style_bg_color(lv.palette_main(lv.PALETTE.RED), 0)

#
# Demonstrate event bubbling
#

cont = lv.obj(lv.scr_act())
cont.set_size(290, 200)
cont.center()
cont.set_flex_flow(lv.FLEX_FLOW.ROW_WRAP)

for i in range(30):
    btn = lv.btn(cont)
    btn.set_size(70, 50)
    btn.add_flag(lv.obj.FLAG.EVENT_BUBBLE)

    label = lv.label(btn)
    label.set_text("{:d}".format(i))
    label.center()

cont.add_event(event_cb, lv.EVENT.CLICKED, None)

Draw event

#include "../lv_examples.h"

#if LV_BUILD_EXAMPLES

static uint32_t size = 0;
static bool size_dec = false;

static void timer_cb(lv_timer_t * timer)
{
    lv_obj_invalidate(timer->user_data);
    if(size_dec) size--;
    else size++;

    if(size == 50) size_dec = true;
    else if(size == 0) size_dec = false;
}

static void event_cb(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    lv_obj_draw_part_dsc_t * dsc = lv_event_get_draw_part_dsc(e);
    if(dsc->class_p == &lv_obj_class && dsc->part == LV_PART_MAIN) {
        lv_draw_rect_dsc_t draw_dsc;
        lv_draw_rect_dsc_init(&draw_dsc);
        draw_dsc.bg_color = lv_color_hex(0xffaaaa);
        draw_dsc.radius = LV_RADIUS_CIRCLE;
        draw_dsc.border_color = lv_color_hex(0xff5555);
        draw_dsc.border_width = 2;
        draw_dsc.outline_color = lv_color_hex(0xff0000);
        draw_dsc.outline_pad = 3;
        draw_dsc.outline_width = 2;

        lv_area_t a;
        a.x1 = 0;
        a.y1 = 0;
        a.x2 = size;
        a.y2 = size;
        lv_area_align(&obj->coords, &a, LV_ALIGN_CENTER, 0, 0);

        lv_draw_rect(dsc->draw_ctx, &draw_dsc, &a);
    }
}

/**
 * Demonstrate the usage of draw event
 */
void lv_example_event_4(void)
{
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 200, 200);
    lv_obj_center(cont);
    lv_obj_add_event(cont, event_cb, LV_EVENT_DRAW_PART_END, NULL);
    lv_timer_create(timer_cb, 30, cont);
}

#endif

class LV_Example_Event_4:

    def __init__(self):
        #
        # Demonstrate the usage of draw event
        #
        self.size = 0
        self.size_dec = False
        self.cont = lv.obj(lv.scr_act())
        self.cont.set_size(200, 200)
        self.cont.center()
        self.cont.add_event(self.event_cb, lv.EVENT.DRAW_PART_END, None)
        lv.timer_create(self.timer_cb, 30, None)

    def timer_cb(self,timer) :
        self.cont.invalidate()
        if self.size_dec :
            self.size -= 1
        else :
            self.size += 1

        if self.size == 50 :
            self.size_dec = True
        elif self.size == 0:
            self.size_dec = False

    def event_cb(self,e) :
        obj = e.get_target_obj()
        dsc = e.get_draw_part_dsc()
        if dsc.class_p == lv.obj_class and dsc.part == lv.PART.MAIN :
            draw_dsc = lv.draw_rect_dsc_t()
            draw_dsc.init()
            draw_dsc.bg_color = lv.color_hex(0xffaaaa)
            draw_dsc.radius = lv.RADIUS_CIRCLE
            draw_dsc.border_color = lv.color_hex(0xff5555)
            draw_dsc.border_width = 2
            draw_dsc.outline_color = lv.color_hex(0xff0000)
            draw_dsc.outline_pad = 3
            draw_dsc.outline_width = 2

            a = lv.area_t()
            a.x1 = 0
            a.y1 = 0
            a.x2 = self.size
            a.y2 = self.size
            coords = lv.area_t()
            obj.get_coords(coords)
            coords.align(a, lv.ALIGN.CENTER, 0, 0)

            dsc.draw_ctx.rect(draw_dsc, a)

lv_example_event_4 = LV_Example_Event_4()

Layouts

Flex

A simple row and a column layout with flexbox

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * A simple row and a column layout with flexbox
 */
void lv_example_flex_1(void)
{
    /*Create a container with ROW flex direction*/
    lv_obj_t * cont_row = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont_row, 300, 75);
    lv_obj_align(cont_row, LV_ALIGN_TOP_MID, 0, 5);
    lv_obj_set_flex_flow(cont_row, LV_FLEX_FLOW_ROW);

    /*Create a container with COLUMN flex direction*/
    lv_obj_t * cont_col = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont_col, 200, 150);
    lv_obj_align_to(cont_col, cont_row, LV_ALIGN_OUT_BOTTOM_MID, 0, 5);
    lv_obj_set_flex_flow(cont_col, LV_FLEX_FLOW_COLUMN);

    uint32_t i;
    for(i = 0; i < 10; i++) {
        lv_obj_t * obj;
        lv_obj_t * label;

        /*Add items to the row*/
        obj = lv_btn_create(cont_row);
        lv_obj_set_size(obj, 100, LV_PCT(100));

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "Item: %"LV_PRIu32"", i);
        lv_obj_center(label);

        /*Add items to the column*/
        obj = lv_btn_create(cont_col);
        lv_obj_set_size(obj, LV_PCT(100), LV_SIZE_CONTENT);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "Item: %"LV_PRIu32, i);
        lv_obj_center(label);
    }
}

#endif

#
# A simple row and a column layout with flexbox
#

# Create a container with ROW flex direction
cont_row = lv.obj(lv.scr_act())
cont_row.set_size(300, 75)
cont_row.align(lv.ALIGN.TOP_MID, 0, 5)
cont_row.set_flex_flow(lv.FLEX_FLOW.ROW)

# Create a container with COLUMN flex direction
cont_col = lv.obj(lv.scr_act())
cont_col.set_size(200, 150)
cont_col.align_to(cont_row, lv.ALIGN.OUT_BOTTOM_MID, 0, 5)
cont_col.set_flex_flow(lv.FLEX_FLOW.COLUMN)

for i in range(10):
    # Add items to the row
    obj = lv.btn(cont_row)
    obj.set_size(100, lv.pct(100))

    label = lv.label(obj)
    label.set_text("Item: {:d}".format(i))
    label.center()

    # Add items to the column
    obj = lv.btn(cont_col)
    obj.set_size(lv.pct(100), lv.SIZE_CONTENT)

    label = lv.label(obj)
    label.set_text("Item: {:d}".format(i))
    label.center()

Arrange items in rows with wrap and even spacing

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * Arrange items in rows with wrap and place the items to get even space around them.
 */
void lv_example_flex_2(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_flex_flow(&style, LV_FLEX_FLOW_ROW_WRAP);
    lv_style_set_flex_main_place(&style, LV_FLEX_ALIGN_SPACE_EVENLY);
    lv_style_set_layout(&style, LV_LAYOUT_FLEX);

    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_add_style(cont, &style, 0);

    uint32_t i;
    for(i = 0; i < 8; i++) {
        lv_obj_t * obj = lv_obj_create(cont);
        lv_obj_set_size(obj, 70, LV_SIZE_CONTENT);
        lv_obj_add_flag(obj, LV_OBJ_FLAG_CHECKABLE);

        lv_obj_t * label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%"LV_PRIu32, i);
        lv_obj_center(label);
    }
}

#endif

#
# Arrange items in rows with wrap and place the items to get even space around them.
#
style = lv.style_t()
style.init()
style.set_flex_flow(lv.FLEX_FLOW.ROW_WRAP)
style.set_flex_main_place(lv.FLEX_ALIGN.SPACE_EVENLY)
style.set_layout(lv.LAYOUT_FLEX.value)

cont = lv.obj(lv.scr_act())
cont.set_size(300, 220)
cont.center()
cont.add_style(style, 0)

for i in range(8):
    obj = lv.obj(cont)
    obj.set_size(70, lv.SIZE_CONTENT)

    label = lv.label(obj)
    label.set_text("{:d}".format(i))
    label.center()

Demonstrate flex grow

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * Demonstrate flex grow.
 */
void lv_example_flex_3(void)
{
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_ROW);

    lv_obj_t * obj;
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, 40, 40);           /*Fix size*/

    obj = lv_obj_create(cont);
    lv_obj_set_height(obj, 40);
    lv_obj_set_flex_grow(obj, 1);           /*1 portion from the free space*/

    obj = lv_obj_create(cont);
    lv_obj_set_height(obj, 40);
    lv_obj_set_flex_grow(obj, 2);           /*2 portion from the free space*/

    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, 40, 40);           /*Fix size. It is flushed to the right by the "grow" items*/
}

#endif

#
# Demonstrate flex grow.
#

cont = lv.obj(lv.scr_act())
cont.set_size(300, 220)
cont.center()
cont.set_flex_flow(lv.FLEX_FLOW.ROW)

obj = lv.obj(cont)
obj.set_size(40, 40)           # Fix size

obj = lv.obj(cont)
obj.set_height(40)
obj.set_flex_grow(1)           # 1 portion from the free space

obj = lv.obj(cont)
obj.set_height(40)
obj.set_flex_grow(2)           # 2 portion from the free space

obj = lv.obj(cont)
obj.set_size(40, 40)           # Fix size. It is flushed to the right by the "grow" items

Demonstrate flex grow.

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * Reverse the order of flex items
 */
void lv_example_flex_4(void)
{

    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_COLUMN_REVERSE);

    uint32_t i;
    for(i = 0; i < 6; i++) {
        lv_obj_t * obj = lv_obj_create(cont);
        lv_obj_set_size(obj, 100, 50);

        lv_obj_t * label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "Item: %"LV_PRIu32, i);
        lv_obj_center(label);
    }
}

#endif

#
# Reverse the order of flex items
#
cont = lv.obj(lv.scr_act())
cont.set_size(300, 220)
cont.center()
cont.set_flex_flow(lv.FLEX_FLOW.COLUMN_REVERSE)

for i  in range(6):
    obj = lv.obj(cont)
    obj.set_size(100, 50)

    label = lv.label(obj)
    label.set_text("Item: " + str(i))
    label.center()

Demonstrate column and row gap style properties

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

static void row_gap_anim(void * obj, int32_t v)
{
    lv_obj_set_style_pad_row(obj, v, 0);
}

static void column_gap_anim(void * obj, int32_t v)
{
    lv_obj_set_style_pad_column(obj, v, 0);
}

/**
 * Demonstrate the effect of column and row gap style properties
 */
void lv_example_flex_5(void)
{
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_ROW_WRAP);

    uint32_t i;
    for(i = 0; i < 9; i++) {
        lv_obj_t * obj = lv_obj_create(cont);
        lv_obj_set_size(obj, 70, LV_SIZE_CONTENT);

        lv_obj_t * label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%"LV_PRIu32, i);
        lv_obj_center(label);
    }

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, cont);
    lv_anim_set_values(&a, 0, 10);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);

    lv_anim_set_exec_cb(&a, row_gap_anim);
    lv_anim_set_time(&a, 500);
    lv_anim_set_playback_time(&a, 500);
    lv_anim_start(&a);

    lv_anim_set_exec_cb(&a, column_gap_anim);
    lv_anim_set_time(&a, 3000);
    lv_anim_set_playback_time(&a, 3000);
    lv_anim_start(&a);
}

#endif

def row_gap_anim(obj, v):
    obj.set_style_pad_row(v, 0)


def column_gap_anim(obj, v):
    obj.set_style_pad_column(v, 0)

#
# Demonstrate the effect of column and row gap style properties
#

cont = lv.obj(lv.scr_act())
cont.set_size(300, 220)
cont.center()
cont.set_flex_flow(lv.FLEX_FLOW.ROW_WRAP)

for i in range(9):
    obj = lv.obj(cont)
    obj.set_size(70, lv.SIZE_CONTENT)

    label = lv.label(obj)
    label.set_text(str(i))
    label.center()

a_row = lv.anim_t()
a_row.init()
a_row.set_var(cont)
a_row.set_values(0, 10)
a_row.set_repeat_count(lv.ANIM_REPEAT_INFINITE)

a_row.set_time(500)
a_row.set_playback_time(500)
a_row.set_custom_exec_cb(lambda a,val: row_gap_anim(cont,val))
lv.anim_t.start(a_row)

a_col = lv.anim_t()
a_col.init()
a_col.set_var(cont)
a_col.set_values(0, 10)
a_col.set_repeat_count(lv.ANIM_REPEAT_INFINITE)

a_col.set_time(3000)
a_col.set_playback_time(3000)
a_col.set_custom_exec_cb(lambda a,val: column_gap_anim(cont,val))

lv.anim_t.start(a_col)

RTL base direction changes order of the items

#include "../../lv_examples.h"
#if LV_USE_FLEX && LV_BUILD_EXAMPLES

/**
 * RTL base direction changes order of the items.
 * Also demonstrate how horizontal scrolling works with RTL.
 */
void lv_example_flex_6(void)
{
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_style_base_dir(cont, LV_BASE_DIR_RTL, 0);
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_ROW_WRAP);

    uint32_t i;
    for(i = 0; i < 20; i++) {
        lv_obj_t * obj = lv_obj_create(cont);
        lv_obj_set_size(obj, 70, LV_SIZE_CONTENT);

        lv_obj_t * label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%"LV_PRIu32, i);
        lv_obj_center(label);
    }
}
#endif

#
# RTL base direction changes order of the items.
# Also demonstrate how horizontal scrolling works with RTL.
#

cont = lv.obj(lv.scr_act())
cont.set_style_base_dir(lv.BASE_DIR.RTL,0)
cont.set_size(300, 220)
cont.center()
cont.set_flex_flow(lv.FLEX_FLOW.ROW_WRAP)

for i in range(20):
    obj = lv.obj(cont)
    obj.set_size(70, lv.SIZE_CONTENT)

    label = lv.label(obj)
    label.set_text(str(i))
    label.center()

Grid

A simple grid

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

/**
 * A simple grid
 */
void lv_example_grid_1(void)
{
    static lv_coord_t col_dsc[] = {70, 70, 70, LV_GRID_TEMPLATE_LAST};
    static lv_coord_t row_dsc[] = {50, 50, 50, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_style_grid_column_dsc_array(cont, col_dsc, 0);
    lv_obj_set_style_grid_row_dsc_array(cont, row_dsc, 0);
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_layout(cont, LV_LAYOUT_GRID);

    lv_obj_t * label;
    lv_obj_t * obj;

    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_btn_create(cont);
        /*Stretch the cell horizontally and vertically too
         *Set span to 1 to make the cell 1 column/row sized*/
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "c%d, r%d", col, row);
        lv_obj_center(label);
    }
}

#endif

#
# A simple grid
#

col_dsc = [70, 70, 70, lv.GRID_TEMPLATE_LAST]
row_dsc = [50, 50, 50, lv.GRID_TEMPLATE_LAST]

# Create a container with grid
cont = lv.obj(lv.scr_act())
cont.set_style_grid_column_dsc_array(col_dsc, 0)
cont.set_style_grid_row_dsc_array(row_dsc, 0)
cont.set_size(300, 220)
cont.center()
cont.set_layout(lv.LAYOUT_GRID.value)

for i in range(9):
    col = i % 3
    row = i // 3

    obj = lv.btn(cont)
    # Stretch the cell horizontally and vertically too
    # Set span to 1 to make the cell 1 column/row sized
    obj.set_grid_cell(lv.GRID_ALIGN.STRETCH, col, 1,
                      lv.GRID_ALIGN.STRETCH, row, 1)

    label = lv.label(obj)
    label.set_text("c" +str(col) +  "r" +str(row))
    label.center()

Demonstrate cell placement and span

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES


/**
 * Demonstrate cell placement and span
 */
void lv_example_grid_2(void)
{
    static lv_coord_t col_dsc[] = {70, 70, 70, LV_GRID_TEMPLATE_LAST};
    static lv_coord_t row_dsc[] = {50, 50, 50, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);

    lv_obj_t * label;
    lv_obj_t * obj;

    /*Cell to 0;0 and align to to the start (left/top) horizontally and vertically too*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_START, 0, 1,
                         LV_GRID_ALIGN_START, 0, 1);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c0, r0");

    /*Cell to 1;0 and align to to the start (left) horizontally and center vertically too*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_START, 1, 1,
                         LV_GRID_ALIGN_CENTER, 0, 1);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c1, r0");

    /*Cell to 2;0 and align to to the start (left) horizontally and end (bottom) vertically too*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_START, 2, 1,
                         LV_GRID_ALIGN_END, 0, 1);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c2, r0");

    /*Cell to 1;1 but 2 column wide (span = 2).Set width and height to stretched.*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, 1, 2,
                         LV_GRID_ALIGN_STRETCH, 1, 1);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c1-2, r1");

    /*Cell to 0;1 but 2 rows tall (span = 2).Set width and height to stretched.*/
    obj = lv_obj_create(cont);
    lv_obj_set_size(obj, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, 0, 1,
                         LV_GRID_ALIGN_STRETCH, 1, 2);
    label = lv_label_create(obj);
    lv_label_set_text(label, "c0\nr1-2");
}

#endif

#
# Demonstrate cell placement and span
#

col_dsc = [70, 70, 70, lv.GRID_TEMPLATE_LAST]
row_dsc = [50, 50, 50, lv.GRID_TEMPLATE_LAST]

# Create a container with grid
cont = lv.obj(lv.scr_act())
cont.set_grid_dsc_array(col_dsc, row_dsc)
cont.set_size(300, 220)
cont.center()

# Cell to 0;0 and align to the start (left/top) horizontally and vertically too
obj = lv.obj(cont)
obj.set_size(lv.SIZE_CONTENT, lv.SIZE_CONTENT)
obj.set_grid_cell(lv.GRID_ALIGN.START, 0, 1,
                  lv.GRID_ALIGN.START, 0, 1)
label = lv.label(obj)
label.set_text("c0, r0")

# Cell to 1;0 and align to the start (left) horizontally and center vertically too
obj = lv.obj(cont)
obj.set_size(lv.SIZE_CONTENT, lv.SIZE_CONTENT)
obj.set_grid_cell(lv.GRID_ALIGN.START, 1, 1,
                  lv.GRID_ALIGN.CENTER, 0, 1)
label = lv.label(obj)
label.set_text("c1, r0")

# Cell to 2;0 and align to the start (left) horizontally and end (bottom) vertically too
obj = lv.obj(cont)
obj.set_size(lv.SIZE_CONTENT, lv.SIZE_CONTENT)
obj.set_grid_cell(lv.GRID_ALIGN.START, 2, 1,
                  lv.GRID_ALIGN.END, 0, 1)
label = lv.label(obj)
label.set_text("c2, r0")

# Cell to 1;1 but 2 column wide (span = 2).Set width and height to stretched.
obj = lv.obj(cont)
obj.set_size(lv.SIZE_CONTENT, lv.SIZE_CONTENT)
obj.set_grid_cell(lv.GRID_ALIGN.STRETCH, 1, 2,
                  lv.GRID_ALIGN.STRETCH, 1, 1)
label = lv.label(obj)
label.set_text("c1-2, r1")

# Cell to 0;1 but 2 rows tall (span = 2).Set width and height to stretched.
obj = lv.obj(cont)
obj.set_size(lv.SIZE_CONTENT, lv.SIZE_CONTENT)
obj.set_grid_cell(lv.GRID_ALIGN.STRETCH, 0, 1,
                  lv.GRID_ALIGN.STRETCH, 1, 2)
label = lv.label(obj)
label.set_text("c0\nr1-2")

Demonstrate grid's -free unit-

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

/**
 * Demonstrate grid's "free unit"
 */
void lv_example_grid_3(void)
{
    /*Column 1: fix width 60 px
     *Column 2: 1 unit from the remaining free space
     *Column 3: 2 unit from the remaining free space*/
    static lv_coord_t col_dsc[] = {60, LV_GRID_FR(1), LV_GRID_FR(2), LV_GRID_TEMPLATE_LAST};

    /*Row 1: fix width 50 px
     *Row 2: 1 unit from the remaining free space
     *Row 3: fix width 50 px*/
    static lv_coord_t row_dsc[] = {50, LV_GRID_FR(1), 50, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);

    lv_obj_t * label;
    lv_obj_t * obj;
    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_obj_create(cont);
        /*Stretch the cell horizontally and vertically too
         *Set span to 1 to make the cell 1 column/row sized*/
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%d,%d", col, row);
        lv_obj_center(label);
    }
}

#endif

#
# Demonstrate grid's "free unit"
#

# Column 1: fix width 60 px
# Column 2: 1 unit from the remaining free space
# Column 3: 2 unit from the remaining free space

col_dsc = [60, lv.grid_fr(1), lv.grid_fr(2), lv.GRID_TEMPLATE_LAST]

# Row 1: fix width 60 px
# Row 2: 1 unit from the remaining free space
# Row 3: fix width 60 px

row_dsc = [40, lv.grid_fr(1), 40, lv.GRID_TEMPLATE_LAST]

# Create a container with grid
cont = lv.obj(lv.scr_act())
cont.set_size(300, 220)
cont.center()
cont.set_grid_dsc_array(col_dsc, row_dsc)

for i in range(9):
    col = i % 3
    row = i // 3

    obj = lv.obj(cont)
    # Stretch the cell horizontally and vertically too
    # Set span to 1 to make the cell 1 column/row sized
    obj.set_grid_cell(lv.GRID_ALIGN.STRETCH, col, 1,
                      lv.GRID_ALIGN.STRETCH, row, 1)

    label = lv.label(obj)
    label.set_text("%d,%d"%(col, row))
    label.center()

Demonstrate track placement

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

/**
 * Demonstrate track placement
 */
void lv_example_grid_4(void)
{
    static lv_coord_t col_dsc[] = {60, 60, 60, LV_GRID_TEMPLATE_LAST};
    static lv_coord_t row_dsc[] = {45, 45, 45, LV_GRID_TEMPLATE_LAST};


    /*Add space between the columns and move the rows to the bottom (end)*/

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_grid_align(cont, LV_GRID_ALIGN_SPACE_BETWEEN, LV_GRID_ALIGN_END);
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);

    lv_obj_t * label;
    lv_obj_t * obj;
    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_obj_create(cont);
        /*Stretch the cell horizontally and vertically too
         *Set span to 1 to make the cell 1 column/row sized*/
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%d,%d", col, row);
        lv_obj_center(label);
    }
}

#endif

#
# Demonstrate track placement
#

col_dsc = [60, 60, 60, lv.GRID_TEMPLATE_LAST]
row_dsc = [40, 40, 40, lv.GRID_TEMPLATE_LAST]


# Add space between the columns and move the rows to the bottom (end)

# Create a container with grid
cont = lv.obj(lv.scr_act())
cont.set_grid_align(lv.GRID_ALIGN.SPACE_BETWEEN, lv.GRID_ALIGN.END)
cont.set_grid_dsc_array(col_dsc, row_dsc)
cont.set_size(300, 220)
cont.center()


for i in range(9):
    col = i % 3
    row = i // 3

    obj = lv.obj(cont)
    # Stretch the cell horizontally and vertically too
    # Set span to 1 to make the cell 1 column/row sized
    obj.set_grid_cell(lv.GRID_ALIGN.STRETCH, col, 1,
                      lv.GRID_ALIGN.STRETCH, row, 1)

    label = lv.label(obj)
    label.set_text("{:d}{:d}".format(col, row))
    label.center()

Demonstrate column and row gap

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

static void row_gap_anim(void * obj, int32_t v)
{
    lv_obj_set_style_pad_row(obj, v, 0);
}

static void column_gap_anim(void * obj, int32_t v)
{
    lv_obj_set_style_pad_column(obj, v, 0);
}

/**
 * Demonstrate column and row gap
 */
void lv_example_grid_5(void)
{

    /*60x60 cells*/
    static lv_coord_t col_dsc[] = {60, 60, 60, LV_GRID_TEMPLATE_LAST};
    static lv_coord_t row_dsc[] = {45, 45, 45, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);

    lv_obj_t * label;
    lv_obj_t * obj;
    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_obj_create(cont);
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);
        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%d,%d", col, row);
        lv_obj_center(label);
    }

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, cont);
    lv_anim_set_values(&a, 0, 10);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);

    lv_anim_set_exec_cb(&a, row_gap_anim);
    lv_anim_set_time(&a, 500);
    lv_anim_set_playback_time(&a, 500);
    lv_anim_start(&a);

    lv_anim_set_exec_cb(&a, column_gap_anim);
    lv_anim_set_time(&a, 3000);
    lv_anim_set_playback_time(&a, 3000);
    lv_anim_start(&a);
}

#endif

def row_gap_anim(obj, v):
    obj.set_style_pad_row(v, 0)

def column_gap_anim(obj, v):
    obj.set_style_pad_column(v, 0)

#
# Demonstrate column and row gap
#

# 60x60 cells
col_dsc = [60, 60, 60, lv.GRID_TEMPLATE_LAST]
row_dsc = [40, 40, 40, lv.GRID_TEMPLATE_LAST]

# Create a container with grid
cont = lv.obj(lv.scr_act())
cont.set_size(300, 220)
cont.center()
cont.set_grid_dsc_array(col_dsc, row_dsc)

for i in range(9):
    col = i % 3
    row = i // 3

    obj = lv.obj(cont)
    obj.set_grid_cell(lv.GRID_ALIGN.STRETCH, col, 1,
                      lv.GRID_ALIGN.STRETCH, row, 1)
    label = lv.label(obj)
    label.set_text("{:d},{:d}".format(col, row))
    label.center()

    a_row = lv.anim_t()
    a_row.init()
    a_row.set_var(cont)
    a_row.set_values(0, 10)
    a_row.set_repeat_count(lv.ANIM_REPEAT_INFINITE)
    a_row.set_time(500)
    a_row.set_playback_time(500)
    a_row. set_custom_exec_cb(lambda a,val: row_gap_anim(cont,val))
    lv.anim_t.start(a_row)

    a_col = lv.anim_t()
    a_col.init()
    a_col.set_var(cont)
    a_col.set_values(0, 10)
    a_col.set_repeat_count(lv.ANIM_REPEAT_INFINITE)
    a_col.set_time(500)
    a_col.set_playback_time(500)
    a_col. set_custom_exec_cb(lambda a,val: column_gap_anim(cont,val))
    lv.anim_t.start(a_col)

Demonstrate RTL direction on grid

#include "../../lv_examples.h"
#if LV_USE_GRID && LV_BUILD_EXAMPLES

/**
 * Demonstrate RTL direction on grid
 */
void lv_example_grid_6(void)
{

    static lv_coord_t col_dsc[] = {60, 60, 60, LV_GRID_TEMPLATE_LAST};
    static lv_coord_t row_dsc[] = {45, 45, 45, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 300, 220);
    lv_obj_center(cont);
    lv_obj_set_style_base_dir(cont, LV_BASE_DIR_RTL, 0);
    lv_obj_set_grid_dsc_array(cont, col_dsc, row_dsc);

    lv_obj_t * label;
    lv_obj_t * obj;
    uint32_t i;
    for(i = 0; i < 9; i++) {
        uint8_t col = i % 3;
        uint8_t row = i / 3;

        obj = lv_obj_create(cont);
        /*Stretch the cell horizontally and vertically too
         *Set span to 1 to make the cell 1 column/row sized*/
        lv_obj_set_grid_cell(obj, LV_GRID_ALIGN_STRETCH, col, 1,
                             LV_GRID_ALIGN_STRETCH, row, 1);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "%d,%d", col, row);
        lv_obj_center(label);
    }
}

#endif

#
# Demonstrate RTL direction on grid
#
col_dsc = [60, 60, 60, lv.GRID_TEMPLATE_LAST]
row_dsc = [40, 40, 40, lv.GRID_TEMPLATE_LAST]

# Create a container with grid
cont = lv.obj(lv.scr_act())
cont.set_size(300, 220)
cont.center()
cont.set_style_base_dir(lv.BASE_DIR.RTL,0)
cont.set_grid_dsc_array(col_dsc, row_dsc)

for i in range(9):
    col = i % 3
    row = i // 3

    obj = lv.obj(cont)
    # Stretch the cell horizontally and vertically too
    # Set span to 1 to make the cell 1 column/row sized
    obj.set_grid_cell(lv.GRID_ALIGN.STRETCH, col, 1,
                      lv.GRID_ALIGN.STRETCH, row, 1)

    label = lv.label(obj)
    label.set_text("{:d},{:d}".format(col, row))
    label.center()

Scrolling

Nested scrolling

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

/**
 * Demonstrate how scrolling appears automatically
 */
void lv_example_scroll_1(void)
{
    /*Create an object with the new style*/
    lv_obj_t * panel = lv_obj_create(lv_scr_act());
    lv_obj_set_size(panel, 200, 200);
    lv_obj_center(panel);

    lv_obj_t * child;
    lv_obj_t * label;

    child = lv_obj_create(panel);
    lv_obj_set_pos(child, 0, 0);
    lv_obj_set_size(child, 70, 70);
    label = lv_label_create(child);
    lv_label_set_text(label, "Zero");
    lv_obj_center(label);

    child = lv_obj_create(panel);
    lv_obj_set_pos(child, 160, 80);
    lv_obj_set_size(child, 80, 80);

    lv_obj_t * child2 = lv_btn_create(child);
    lv_obj_set_size(child2, 100, 50);

    label = lv_label_create(child2);
    lv_label_set_text(label, "Right");
    lv_obj_center(label);

    child = lv_obj_create(panel);
    lv_obj_set_pos(child, 40, 160);
    lv_obj_set_size(child, 100, 70);
    label = lv_label_create(child);
    lv_label_set_text(label, "Bottom");
    lv_obj_center(label);
}

#endif

#
# Demonstrate how scrolling appears automatically
#
# Create an object with the new style
panel = lv.obj(lv.scr_act())
panel.set_size(200, 200)
panel.center()

child = lv.obj(panel)
child.set_pos(0, 0);
child.set_size(70, 70)
label = lv.label(child)
label.set_text("Zero")
label.center()

child = lv.obj(panel)
child.set_pos(160, 80)
child.set_size(80, 80)

child2 = lv.btn(child)
child2.set_size(100, 50)

label = lv.label(child2)
label.set_text("Right")
label.center()

child = lv.obj(panel)
child.set_pos(40, 160)
child.set_size(100, 70)
label = lv.label(child)
label.set_text("Bottom")
label.center()

Snapping

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_FLEX

static void sw_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * sw = lv_event_get_target(e);

    if(code == LV_EVENT_VALUE_CHANGED) {
        lv_obj_t * list = lv_event_get_user_data(e);

        if(lv_obj_has_state(sw, LV_STATE_CHECKED)) lv_obj_add_flag(list, LV_OBJ_FLAG_SCROLL_ONE);
        else lv_obj_clear_flag(list, LV_OBJ_FLAG_SCROLL_ONE);
    }
}

/**
 * Show an example to scroll snap
 */
void lv_example_scroll_2(void)
{
    lv_obj_t * panel = lv_obj_create(lv_scr_act());
    lv_obj_set_size(panel, 280, 120);
    lv_obj_set_scroll_snap_x(panel, LV_SCROLL_SNAP_CENTER);
    lv_obj_set_flex_flow(panel, LV_FLEX_FLOW_ROW);
    lv_obj_align(panel, LV_ALIGN_CENTER, 0, 20);

    uint32_t i;
    for(i = 0; i < 10; i++) {
        lv_obj_t * btn = lv_btn_create(panel);
        lv_obj_set_size(btn, 150, lv_pct(100));

        lv_obj_t * label = lv_label_create(btn);
        if(i == 3) {
            lv_label_set_text_fmt(label, "Panel %"LV_PRIu32"\nno snap", i);
            lv_obj_clear_flag(btn, LV_OBJ_FLAG_SNAPPABLE);
        }
        else {
            lv_label_set_text_fmt(label, "Panel %"LV_PRIu32, i);
        }

        lv_obj_center(label);
    }
    lv_obj_update_snap(panel, LV_ANIM_ON);

#if LV_USE_SWITCH
    /*Switch between "One scroll" and "Normal scroll" mode*/
    lv_obj_t * sw = lv_switch_create(lv_scr_act());
    lv_obj_align(sw, LV_ALIGN_TOP_RIGHT, -20, 10);
    lv_obj_add_event(sw, sw_event_cb, LV_EVENT_ALL, panel);
    lv_obj_t * label = lv_label_create(lv_scr_act());
    lv_label_set_text(label, "One scroll");
    lv_obj_align_to(label, sw, LV_ALIGN_OUT_BOTTOM_MID, 0, 5);
#endif
}

#endif

def sw_event_cb(e,panel):

    code = e.get_code()
    sw = e.get_target_obj()

    if code == lv.EVENT.VALUE_CHANGED:

        if sw.has_state(lv.STATE.CHECKED):
            panel.add_flag(lv.obj.FLAG.SCROLL_ONE)
        else:
            panel.clear_flag(lv.obj.FLAG.SCROLL_ONE)


#
# Show an example to scroll snap
#

panel = lv.obj(lv.scr_act())
panel.set_size(280, 150)
panel.set_scroll_snap_x(lv.SCROLL_SNAP.CENTER)
panel.set_flex_flow(lv.FLEX_FLOW.ROW)
panel.center()

for i in range(10):
    btn = lv.btn(panel)
    btn.set_size(150, 100)

    label = lv.label(btn)
    if i == 3:
        label.set_text("Panel {:d}\nno snap".format(i))
        btn.clear_flag(lv.obj.FLAG.SNAPPABLE)
    else:
        label.set_text("Panel {:d}".format(i))
    label.center()

panel.update_snap(lv.ANIM.ON)


# Switch between "One scroll" and "Normal scroll" mode
sw = lv.switch(lv.scr_act())
sw.align(lv.ALIGN.TOP_RIGHT, -20, 10)
sw.add_event(lambda evt:  sw_event_cb(evt,panel), lv.EVENT.ALL, None)
label = lv.label(lv.scr_act())
label.set_text("One scroll")
label.align_to(sw, lv.ALIGN.OUT_BOTTOM_MID, 0, 5)

Floating button

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LIST

static uint32_t btn_cnt = 1;

static void float_btn_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * float_btn = lv_event_get_target(e);

    if(code == LV_EVENT_CLICKED) {
        lv_obj_t * list = lv_event_get_user_data(e);
        char buf[32];
        lv_snprintf(buf, sizeof(buf), "Track %d", (int)btn_cnt);
        lv_obj_t * list_btn = lv_list_add_btn(list, LV_SYMBOL_AUDIO, buf);
        btn_cnt++;

        lv_obj_move_foreground(float_btn);

        lv_obj_scroll_to_view(list_btn, LV_ANIM_ON);
    }
}

/**
 * Create a list with a floating button
 */
void lv_example_scroll_3(void)
{
    lv_obj_t * list = lv_list_create(lv_scr_act());
    lv_obj_set_size(list, 280, 220);
    lv_obj_center(list);

    for(btn_cnt = 1; btn_cnt <= 2; btn_cnt++) {
        char buf[32];
        lv_snprintf(buf, sizeof(buf), "Track %d", (int)btn_cnt);
        lv_list_add_btn(list, LV_SYMBOL_AUDIO, buf);
    }

    lv_obj_t * float_btn = lv_btn_create(list);
    lv_obj_set_size(float_btn, 50, 50);
    lv_obj_add_flag(float_btn, LV_OBJ_FLAG_FLOATING);
    lv_obj_align(float_btn, LV_ALIGN_BOTTOM_RIGHT, 0, -lv_obj_get_style_pad_right(list, LV_PART_MAIN));
    lv_obj_add_event(float_btn, float_btn_event_cb, LV_EVENT_ALL, list);
    lv_obj_set_style_radius(float_btn, LV_RADIUS_CIRCLE, 0);
    lv_obj_set_style_bg_img_src(float_btn, LV_SYMBOL_PLUS, 0);
    lv_obj_set_style_text_font(float_btn, lv_theme_get_font_large(float_btn), 0);
}

#endif

class ScrollExample_3():
    def __init__(self):
        self.btn_cnt = 1
        #
        # Create a list with a floating button
        #

        list = lv.list(lv.scr_act())
        list.set_size(280, 220)
        list.center()

        for btn_cnt in range(2):
            list.add_btn(lv.SYMBOL.AUDIO,"Track {:d}".format(btn_cnt))

        float_btn = lv.btn(list)
        float_btn.set_size(50, 50)
        float_btn.add_flag(lv.obj.FLAG.FLOATING)
        float_btn.align(lv.ALIGN.BOTTOM_RIGHT, 0, -list.get_style_pad_right(lv.PART.MAIN))
        float_btn.add_event(lambda evt: self.float_btn_event_cb(evt,list), lv.EVENT.ALL, None)
        float_btn.set_style_radius(lv.RADIUS_CIRCLE, 0)
        float_btn.set_style_bg_img_src(lv.SYMBOL.PLUS, 0)
        float_btn.set_style_text_font(lv.theme_get_font_large(float_btn), 0)

    def float_btn_event_cb(self,e,list):
        code = e.get_code()
        float_btn = e.get_target_obj()

        if code == lv.EVENT.CLICKED:
            list_btn = list.add_btn(lv.SYMBOL.AUDIO, "Track {:d}".format(self.btn_cnt))
            self.btn_cnt += 1

            float_btn.move_foreground()

            list_btn.scroll_to_view(lv.ANIM.ON)

scroll_example_3 = ScrollExample_3()

Styling the scrollbars

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LIST


/**
 * Styling the scrollbars
 */
void lv_example_scroll_4(void)
{
    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_set_size(obj, 200, 100);
    lv_obj_center(obj);

    lv_obj_t * label = lv_label_create(obj);
    lv_label_set_text(label,
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                      "Etiam dictum, tortor vestibulum lacinia laoreet, mi neque consectetur neque, vel mattis odio dolor egestas ligula. \n"
                      "Sed vestibulum sapien nulla, id convallis ex porttitor nec. \n"
                      "Duis et massa eu libero accumsan faucibus a in arcu. \n"
                      "Ut pulvinar odio lorem, vel tempus turpis condimentum quis. Nam consectetur condimentum sem in auctor. \n"
                      "Sed nisl augue, venenatis in blandit et, gravida ac tortor. \n"
                      "Etiam dapibus elementum suscipit. \n"
                      "Proin mollis sollicitudin convallis. \n"
                      "Integer dapibus tempus arcu nec viverra. \n"
                      "Donec molestie nulla enim, eu interdum velit placerat quis. \n"
                      "Donec id efficitur risus, at molestie turpis. \n"
                      "Suspendisse vestibulum consectetur nunc ut commodo. \n"
                      "Fusce molestie rhoncus nisi sit amet tincidunt. \n"
                      "Suspendisse a nunc ut magna ornare volutpat.");


    /*Remove the style of scrollbar to have clean start*/
    lv_obj_remove_style(obj, NULL, LV_PART_SCROLLBAR | LV_STATE_ANY);

    /*Create a transition the animate the some properties on state change*/
    static const lv_style_prop_t props[] = {LV_STYLE_BG_OPA, LV_STYLE_WIDTH, 0};
    static lv_style_transition_dsc_t trans;
    lv_style_transition_dsc_init(&trans, props, lv_anim_path_linear, 200, 0, NULL);

    /*Create a style for the scrollbars*/
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_width(&style, 4);      /*Width of the scrollbar*/
    lv_style_set_pad_right(&style, 5);  /*Space from the parallel side*/
    lv_style_set_pad_top(&style, 5);    /*Space from the perpendicular side*/

    lv_style_set_radius(&style, 2);
    lv_style_set_bg_opa(&style, LV_OPA_70);
    lv_style_set_bg_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_border_color(&style, lv_palette_darken(LV_PALETTE_BLUE, 3));
    lv_style_set_border_width(&style, 2);
    lv_style_set_shadow_width(&style, 8);
    lv_style_set_shadow_spread(&style, 2);
    lv_style_set_shadow_color(&style, lv_palette_darken(LV_PALETTE_BLUE, 1));

    lv_style_set_transition(&style, &trans);

    /*Make the scrollbars wider and use 100% opacity when scrolled*/
    static lv_style_t style_scrolled;
    lv_style_init(&style_scrolled);
    lv_style_set_width(&style_scrolled, 8);
    lv_style_set_bg_opa(&style_scrolled, LV_OPA_COVER);

    lv_obj_add_style(obj, &style, LV_PART_SCROLLBAR);
    lv_obj_add_style(obj, &style_scrolled, LV_PART_SCROLLBAR | LV_STATE_SCROLLED);
}

#endif

#
# Styling the scrollbars
#
obj = lv.obj(lv.scr_act())
obj.set_size(200, 100)
obj.center()

label = lv.label(obj)
label.set_text(
"""
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Sed nisl augue, venenatis in blandit et, gravida ac tortor.
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""")


# Remove the style of scrollbar to have clean start
obj.remove_style(None, lv.PART.SCROLLBAR | lv.STATE.ANY)

# Create a transition the animate the some properties on state change
props = [lv.STYLE.BG_OPA, lv.STYLE.WIDTH, 0]
trans = lv.style_transition_dsc_t()
trans.init(props, lv.anim_t.path_linear, 200, 0, None)

# Create a style for the scrollbars
style = lv.style_t()
style.init()
style.set_width(4)               # Width of the scrollbar
style.set_pad_right(5)           # Space from the parallel side
style.set_pad_top(5)             # Space from the perpendicular side

style.set_radius(2)
style.set_bg_opa(lv.OPA._70)
style.set_bg_color(lv.palette_main(lv.PALETTE.BLUE))
style.set_border_color(lv.palette_darken(lv.PALETTE.BLUE, 3))
style.set_border_width(2)
style.set_shadow_width(8)
style.set_shadow_spread(2)
style.set_shadow_color(lv.palette_darken(lv.PALETTE.BLUE, 1))

style.set_transition(trans)

# Make the scrollbars wider and use 100% opacity when scrolled
style_scrolled = lv.style_t()
style_scrolled.init()
style_scrolled.set_width(8)
style_scrolled.set_bg_opa(lv.OPA.COVER)

obj.add_style(style, lv.PART.SCROLLBAR)
obj.add_style(style_scrolled, lv.PART.SCROLLBAR | lv.STATE.SCROLLED)

Right to left scrolling

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_FONT_DEJAVU_16_PERSIAN_HEBREW


/**
 * Scrolling with Right To Left base direction
 */
void lv_example_scroll_5(void)
{
    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_set_style_base_dir(obj, LV_BASE_DIR_RTL, 0);
    lv_obj_set_size(obj, 200, 100);
    lv_obj_center(obj);

    lv_obj_t * label = lv_label_create(obj);
    lv_label_set_text(label,
                      "میکروکُنترولر (به انگلیسی: Microcontroller) گونه‌ای ریزپردازنده است که دارای حافظهٔ دسترسی تصادفی (RAM) و حافظهٔ فقط‌خواندنی (ROM)، تایمر، پورت‌های ورودی و خروجی (I/O) و درگاه ترتیبی (Serial Port پورت سریال)، درون خود تراشه است، و می‌تواند به تنهایی ابزارهای دیگر را کنترل کند. به عبارت دیگر یک میکروکنترلر، مدار مجتمع کوچکی است که از یک CPU کوچک و اجزای دیگری مانند تایمر، درگاه‌های ورودی و خروجی آنالوگ و دیجیتال و حافظه تشکیل شده‌است.");
    lv_obj_set_width(label, 400);
    lv_obj_set_style_text_font(label, &lv_font_dejavu_16_persian_hebrew, 0);

}

#endif

#
# Scrolling with Right To Left base direction
#
obj = lv.obj(lv.scr_act())
obj.set_style_base_dir(lv.BASE_DIR.RTL, 0)
obj.set_size(200, 100)
obj.center()

label = lv.label(obj)
label.set_text("میکروکُنترولر (به انگلیسی: Microcontroller) گونه‌ای ریزپردازنده است که دارای حافظهٔ دسترسی تصادفی (RAM) و حافظهٔ فقط‌خواندنی (ROM)، تایمر، پورت‌های ورودی و خروجی (I/O) و درگاه ترتیبی (Serial Port پورت سریال)، درون خود تراشه است، و می‌تواند به تنهایی ابزارهای دیگر را کنترل کند. به عبارت دیگر یک میکروکنترلر، مدار مجتمع کوچکی است که از یک CPU کوچک و اجزای دیگری مانند تایمر، درگاه‌های ورودی و خروجی آنالوگ و دیجیتال و حافظه تشکیل شده‌است.")
label.set_width(400)
label.set_style_text_font(lv.font_dejavu_16_persian_hebrew, 0)

Translate on scroll

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_FLEX

static void scroll_event_cb(lv_event_t * e)
{
    lv_obj_t * cont = lv_event_get_target(e);

    lv_area_t cont_a;
    lv_obj_get_coords(cont, &cont_a);
    lv_coord_t cont_y_center = cont_a.y1 + lv_area_get_height(&cont_a) / 2;

    lv_coord_t r = lv_obj_get_height(cont) * 7 / 10;
    uint32_t i;
    uint32_t child_cnt = lv_obj_get_child_cnt(cont);
    for(i = 0; i < child_cnt; i++) {
        lv_obj_t * child = lv_obj_get_child(cont, i);
        lv_area_t child_a;
        lv_obj_get_coords(child, &child_a);

        lv_coord_t child_y_center = child_a.y1 + lv_area_get_height(&child_a) / 2;

        lv_coord_t diff_y = child_y_center - cont_y_center;
        diff_y = LV_ABS(diff_y);

        /*Get the x of diff_y on a circle.*/
        lv_coord_t x;
        /*If diff_y is out of the circle use the last point of the circle (the radius)*/
        if(diff_y >= r) {
            x = r;
        }
        else {
            /*Use Pythagoras theorem to get x from radius and y*/
            uint32_t x_sqr = r * r - diff_y * diff_y;
            lv_sqrt_res_t res;
            lv_sqrt(x_sqr, &res, 0x8000);   /*Use lvgl's built in sqrt root function*/
            x = r - res.i;
        }

        /*Translate the item by the calculated X coordinate*/
        lv_obj_set_style_translate_x(child, x, 0);

        /*Use some opacity with larger translations*/
        lv_opa_t opa = lv_map(x, 0, r, LV_OPA_TRANSP, LV_OPA_COVER);
        lv_obj_set_style_opa(child, LV_OPA_COVER - opa, 0);
    }
}

/**
 * Translate the object as they scroll
 */
void lv_example_scroll_6(void)
{
    lv_obj_t * cont = lv_obj_create(lv_scr_act());
    lv_obj_set_size(cont, 200, 200);
    lv_obj_center(cont);
    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_COLUMN);
    lv_obj_add_event(cont, scroll_event_cb, LV_EVENT_SCROLL, NULL);
    lv_obj_set_style_radius(cont, LV_RADIUS_CIRCLE, 0);
    lv_obj_set_style_clip_corner(cont, true, 0);
    lv_obj_set_scroll_dir(cont, LV_DIR_VER);
    lv_obj_set_scroll_snap_y(cont, LV_SCROLL_SNAP_CENTER);
    lv_obj_set_scrollbar_mode(cont, LV_SCROLLBAR_MODE_OFF);

    uint32_t i;
    for(i = 0; i < 20; i++) {
        lv_obj_t * btn = lv_btn_create(cont);
        lv_obj_set_width(btn, lv_pct(100));

        lv_obj_t * label = lv_label_create(btn);
        lv_label_set_text_fmt(label, "Button %"LV_PRIu32, i);
    }

    /*Update the buttons position manually for first*/
    lv_obj_send_event(cont, LV_EVENT_SCROLL, NULL);

    /*Be sure the fist button is in the middle*/
    lv_obj_scroll_to_view(lv_obj_get_child(cont, 0), LV_ANIM_OFF);
}

#endif

def scroll_event_cb(e):

    cont = e.get_target_obj()

    cont_a = lv.area_t()
    cont.get_coords(cont_a)
    cont_y_center = cont_a.y1 + cont_a.get_height() // 2

    r = cont.get_height() * 7 // 10

    child_cnt = cont.get_child_cnt()
    for i in range(child_cnt):
        child = cont.get_child(i)
        child_a = lv.area_t()
        child.get_coords(child_a)

        child_y_center = child_a.y1 + child_a.get_height() // 2

        diff_y = child_y_center - cont_y_center
        diff_y = abs(diff_y)

        # Get the x of diff_y on a circle.

        # If diff_y is out of the circle use the last point of the circle (the radius)
        if diff_y >= r:
            x = r
        else:
            # Use Pythagoras theorem to get x from radius and y
            x_sqr = r * r - diff_y * diff_y
            res = lv.sqrt_res_t()
            lv.sqrt(x_sqr, res, 0x8000)   # Use lvgl's built in sqrt root function
            x = r - res.i

        # Translate the item by the calculated X coordinate
        child.set_style_translate_x(x, 0)

        # Use some opacity with larger translations
        opa = lv.map(x, 0, r, lv.OPA.TRANSP, lv.OPA.COVER)
        child.set_style_opa(lv.OPA.COVER - opa, 0)

#
# Translate the object as they scroll
#

cont = lv.obj(lv.scr_act())
cont.set_size(200, 200)
cont.center()
cont.set_flex_flow(lv.FLEX_FLOW.COLUMN)
cont.add_event(scroll_event_cb, lv.EVENT.SCROLL, None)
cont.set_style_radius(lv.RADIUS_CIRCLE, 0)
cont.set_style_clip_corner(True, 0)
cont.set_scroll_dir(lv.DIR.VER)
cont.set_scroll_snap_y(lv.SCROLL_SNAP.CENTER)
cont.set_scrollbar_mode(lv.SCROLLBAR_MODE.OFF)

for i in range(20):
    btn = lv.btn(cont)
    btn.set_width(lv.pct(100))

    label = lv.label(btn)
    label.set_text("Button " + str(i))

    # Update the buttons position manually for first*
    cont.send_event(lv.EVENT.SCROLL, None)

    # Be sure the fist button is in the middle
    #lv.obj.scroll_to_view(cont.get_child(0), lv.ANIM.OFF)
    cont.get_child(0).scroll_to_view(lv.ANIM.OFF)

Widgets

Base object

Base objects with custom styles

#include "../../lv_examples.h"
#if LV_BUILD_EXAMPLES

void lv_example_obj_1(void)
{
    lv_obj_t * obj1;
    obj1 = lv_obj_create(lv_scr_act());
    lv_obj_set_size(obj1, 100, 50);
    lv_obj_align(obj1, LV_ALIGN_CENTER, -60, -30);

    static lv_style_t style_shadow;
    lv_style_init(&style_shadow);
    lv_style_set_shadow_width(&style_shadow, 10);
    lv_style_set_shadow_spread(&style_shadow, 5);
    lv_style_set_shadow_color(&style_shadow, lv_palette_main(LV_PALETTE_BLUE));

    lv_obj_t * obj2;
    obj2 = lv_obj_create(lv_scr_act());
    lv_obj_add_style(obj2, &style_shadow, 0);
    lv_obj_align(obj2, LV_ALIGN_CENTER, 60, 30);
}
#endif

obj1 = lv.obj(lv.scr_act())
obj1.set_size(100, 50)
obj1.align(lv.ALIGN.CENTER, -60, -30)

style_shadow = lv.style_t()
style_shadow.init()
style_shadow.set_shadow_width(10)
style_shadow.set_shadow_spread(5)
style_shadow.set_shadow_color(lv.palette_main(lv.PALETTE.BLUE))

obj2 = lv.obj(lv.scr_act())
obj2.add_style(style_shadow, 0)
obj2.align(lv.ALIGN.CENTER, 60, 30)

Make an object draggable

#include "../../lv_examples.h"
#if LV_BUILD_EXAMPLES

static void drag_event_handler(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);

    lv_indev_t * indev = lv_indev_get_act();
    if(indev == NULL)  return;

    lv_point_t vect;
    lv_indev_get_vect(indev, &vect);

    lv_coord_t x = lv_obj_get_x(obj) + vect.x;
    lv_coord_t y = lv_obj_get_y(obj) + vect.y;
    lv_obj_set_pos(obj, x, y);
}


/**
 * Make an object dragable.
 */
void lv_example_obj_2(void)
{
    lv_obj_t * obj;
    obj = lv_obj_create(lv_scr_act());
    lv_obj_set_size(obj, 150, 100);
    lv_obj_add_event(obj, drag_event_handler, LV_EVENT_PRESSING, NULL);

    lv_obj_t * label = lv_label_create(obj);
    lv_label_set_text(label, "Drag me");
    lv_obj_center(label);

}
#endif

def drag_event_handler(e):

    obj = e.get_target_obj()

    indev = lv.indev_get_act()

    vect = lv.point_t()
    indev.get_vect(vect)
    x = obj.get_x() + vect.x
    y = obj.get_y() + vect.y
    obj.set_pos(x, y)


#
# Make an object dragable.
#

obj = lv.obj(lv.scr_act())
obj.set_size(150, 100)
obj.add_event(drag_event_handler, lv.EVENT.PRESSING, None)

label = lv.label(obj)
label.set_text("Drag me")
label.center()

Arc

Simple Arc

#include "../../lv_examples.h"

#if LV_USE_ARC && LV_BUILD_EXAMPLES

static void value_changed_event_cb(lv_event_t * e);

void lv_example_arc_1(void)
{
    lv_obj_t * label = lv_label_create(lv_scr_act());

    /*Create an Arc*/
    lv_obj_t * arc = lv_arc_create(lv_scr_act());
    lv_obj_set_size(arc, 150, 150);
    lv_arc_set_rotation(arc, 135);
    lv_arc_set_bg_angles(arc, 0, 270);
    lv_arc_set_value(arc, 10);
    lv_obj_center(arc);
    lv_obj_add_event(arc, value_changed_event_cb, LV_EVENT_VALUE_CHANGED, label);

    /*Manually update the label for the first time*/
    lv_obj_send_event(arc, LV_EVENT_VALUE_CHANGED, NULL);
}

static void value_changed_event_cb(lv_event_t * e)
{
    lv_obj_t * arc = lv_event_get_target(e);
    lv_obj_t * label = lv_event_get_user_data(e);

    lv_label_set_text_fmt(label, "%d%%", lv_arc_get_value(arc));

    /*Rotate the label to the current position of the arc*/
    lv_arc_rotate_obj_to_angle(arc, label, 25);
}

#endif

def value_changed_event_cb(e,label):
    arc = e.get_target_obj()

    txt = "{:d}%".format(arc.get_value())
    label.set_text(txt)

    # Rotate the label to the current position of the arc
    arc.rotate_obj_to_angle(label, 25)

label = lv.label(lv.scr_act())

# Create an Arc
arc = lv.arc(lv.scr_act())
arc.set_size(150, 150)
arc.set_rotation(135)
arc.set_bg_angles(0, 270)
arc.set_value(10)
arc.center()
arc.add_event(lambda e: value_changed_event_cb(e,label),lv.EVENT.VALUE_CHANGED, None)

# Manually update the label for the first time
arc.send_event(lv.EVENT.VALUE_CHANGED, None)

Loader with Arc

#include "../../lv_examples.h"

#if LV_USE_ARC && LV_BUILD_EXAMPLES

static void set_angle(void * obj, int32_t v)
{
    lv_arc_set_value(obj, v);
}

/**
 * Create an arc which acts as a loader.
 */
void lv_example_arc_2(void)
{
    /*Create an Arc*/
    lv_obj_t * arc = lv_arc_create(lv_scr_act());
    lv_arc_set_rotation(arc, 270);
    lv_arc_set_bg_angles(arc, 0, 360);
    lv_obj_remove_style(arc, NULL, LV_PART_KNOB);   /*Be sure the knob is not displayed*/
    lv_obj_clear_flag(arc, LV_OBJ_FLAG_CLICKABLE);  /*To not allow adjusting by click*/
    lv_obj_center(arc);

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, arc);
    lv_anim_set_exec_cb(&a, set_angle);
    lv_anim_set_time(&a, 1000);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);    /*Just for the demo*/
    lv_anim_set_repeat_delay(&a, 500);
    lv_anim_set_values(&a, 0, 100);
    lv_anim_start(&a);



}

#endif

def set_angle(obj, v):
    obj.set_value(v)

#
# Create an arc which acts as a loader.
#
# Create an Arc
arc = lv.arc(lv.scr_act())
arc.set_rotation(270)
arc.set_bg_angles(0, 360)
arc.remove_style(None, lv.PART.KNOB)   # Be sure the knob is not displayed
arc.clear_flag(lv.obj.FLAG.CLICKABLE)  #To not allow adjusting by click
arc.center()

a = lv.anim_t()
a.init()
a.set_var(arc)
a.set_time(1000)
a.set_repeat_count(lv.ANIM_REPEAT_INFINITE)    #Just for the demo
a.set_repeat_delay(500)
a.set_values(0, 100)
a.set_custom_exec_cb(lambda a,val: set_angle(arc,val))
lv.anim_t.start(a)

Bar

Simple Bar

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

void lv_example_bar_1(void)
{
    lv_obj_t * bar1 = lv_bar_create(lv_scr_act());
    lv_obj_set_size(bar1, 200, 20);
    lv_obj_center(bar1);
    lv_bar_set_value(bar1, 70, LV_ANIM_OFF);
}

#endif

bar1 = lv.bar(lv.scr_act())
bar1.set_size(200, 20)
bar1.center()
bar1.set_value(70, lv.ANIM.OFF)

Styling a bar

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

/**
 * Example of styling the bar
 */
void lv_example_bar_2(void)
{
    static lv_style_t style_bg;
    static lv_style_t style_indic;

    lv_style_init(&style_bg);
    lv_style_set_border_color(&style_bg, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_border_width(&style_bg, 2);
    lv_style_set_pad_all(&style_bg, 6); /*To make the indicator smaller*/
    lv_style_set_radius(&style_bg, 6);
    lv_style_set_anim_time(&style_bg, 1000);

    lv_style_init(&style_indic);
    lv_style_set_bg_opa(&style_indic, LV_OPA_COVER);
    lv_style_set_bg_color(&style_indic, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_radius(&style_indic, 3);

    lv_obj_t * bar = lv_bar_create(lv_scr_act());
    lv_obj_remove_style_all(bar);  /*To have a clean start*/
    lv_obj_add_style(bar, &style_bg, 0);
    lv_obj_add_style(bar, &style_indic, LV_PART_INDICATOR);

    lv_obj_set_size(bar, 200, 20);
    lv_obj_center(bar);
    lv_bar_set_value(bar, 100, LV_ANIM_ON);
}

#endif

#
# Example of styling the bar
#
style_bg = lv.style_t()
style_indic = lv.style_t()

style_bg.init()
style_bg.set_border_color(lv.palette_main(lv.PALETTE.BLUE))
style_bg.set_border_width(2)
style_bg.set_pad_all(6)            # To make the indicator smaller
style_bg.set_radius(6)
style_bg.set_anim_time(1000)

style_indic.init()
style_indic.set_bg_opa(lv.OPA.COVER)
style_indic.set_bg_color(lv.palette_main(lv.PALETTE.BLUE))
style_indic.set_radius(3)

bar = lv.bar(lv.scr_act())
bar.remove_style_all()   # To have a clean start
bar.add_style(style_bg, 0)
bar.add_style(style_indic, lv.PART.INDICATOR)

bar.set_size(200, 20)
bar.center()
bar.set_value(100, lv.ANIM.ON)

Temperature meter

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

static void set_temp(void * bar, int32_t temp)
{
    lv_bar_set_value(bar, temp, LV_ANIM_ON);
}

/**
 * A temperature meter example
 */
void lv_example_bar_3(void)
{
    static lv_style_t style_indic;

    lv_style_init(&style_indic);
    lv_style_set_bg_opa(&style_indic, LV_OPA_COVER);
    lv_style_set_bg_color(&style_indic, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_bg_grad_color(&style_indic, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_bg_grad_dir(&style_indic, LV_GRAD_DIR_VER);

    lv_obj_t * bar = lv_bar_create(lv_scr_act());
    lv_obj_add_style(bar, &style_indic, LV_PART_INDICATOR);
    lv_obj_set_size(bar, 20, 200);
    lv_obj_center(bar);
    lv_bar_set_range(bar, -20, 40);

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_exec_cb(&a, set_temp);
    lv_anim_set_time(&a, 3000);
    lv_anim_set_playback_time(&a, 3000);
    lv_anim_set_var(&a, bar);
    lv_anim_set_values(&a, -20, 40);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);
    lv_anim_start(&a);
}


#endif

def set_temp(bar, temp):
    bar.set_value(temp, lv.ANIM.ON)

#
# A temperature meter example
#


style_indic = lv.style_t()

style_indic.init()
style_indic.set_bg_opa(lv.OPA.COVER)
style_indic.set_bg_color(lv.palette_main(lv.PALETTE.RED))
style_indic.set_bg_grad_color(lv.palette_main(lv.PALETTE.BLUE))
style_indic.set_bg_grad_dir(lv.GRAD_DIR.VER)

bar = lv.bar(lv.scr_act())
bar.add_style(style_indic, lv.PART.INDICATOR)
bar.set_size(20, 200)
bar.center()
bar.set_range(-20, 40)

a = lv.anim_t()
a.init()
a.set_time(3000)
a.set_playback_time(3000)
a.set_var(bar)
a.set_values(-20, 40)
a.set_repeat_count(lv.ANIM_REPEAT_INFINITE)
a.set_custom_exec_cb(lambda a, val: set_temp(bar,val))
lv.anim_t.start(a)

Stripe pattern and range value

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

/**
 * Bar with stripe pattern and ranged value
 */
void lv_example_bar_4(void)
{
    LV_IMG_DECLARE(img_skew_strip);
    static lv_style_t style_indic;

    lv_style_init(&style_indic);
    lv_style_set_bg_img_src(&style_indic, &img_skew_strip);
    lv_style_set_bg_img_tiled(&style_indic, true);
    lv_style_set_bg_img_opa(&style_indic, LV_OPA_30);

    lv_obj_t * bar = lv_bar_create(lv_scr_act());
    lv_obj_add_style(bar, &style_indic, LV_PART_INDICATOR);

    lv_obj_set_size(bar, 260, 20);
    lv_obj_center(bar);
    lv_bar_set_mode(bar, LV_BAR_MODE_RANGE);
    lv_bar_set_value(bar, 90, LV_ANIM_OFF);
    lv_bar_set_start_value(bar, 20, LV_ANIM_OFF);
}

#endif

# Create an image from the png file
try:
    with open('../../assets/img_strip.png','rb') as f:
        png_data = f.read()
except:
    print("Could not find img_strip.png")
    sys.exit()

img_skew_strip_dsc = lv.img_dsc_t({
  'data_size': len(png_data),
  'data': png_data
})

#
# Bar with stripe pattern and ranged value
#

style_indic = lv.style_t()

style_indic.init()
style_indic.set_bg_img_src(img_skew_strip_dsc)
style_indic.set_bg_img_tiled(True)
style_indic.set_bg_img_opa(lv.OPA._30)

bar = lv.bar(lv.scr_act())
bar.add_style(style_indic, lv.PART.INDICATOR)

bar.set_size(260, 20)
bar.center()
bar.set_mode(lv.bar.MODE.RANGE)
bar.set_value(90, lv.ANIM.OFF)
bar.set_start_value(20, lv.ANIM.OFF)

Bar with LTR and RTL base direction

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

/**
 * Bar with LTR and RTL base direction
 */
void lv_example_bar_5(void)
{
    lv_obj_t * label;


    lv_obj_t * bar_ltr = lv_bar_create(lv_scr_act());
    lv_obj_set_size(bar_ltr, 200, 20);
    lv_bar_set_value(bar_ltr, 70, LV_ANIM_OFF);
    lv_obj_align(bar_ltr, LV_ALIGN_CENTER, 0, -30);

    label = lv_label_create(lv_scr_act());
    lv_label_set_text(label, "Left to Right base direction");
    lv_obj_align_to(label, bar_ltr, LV_ALIGN_OUT_TOP_MID, 0, -5);

    lv_obj_t * bar_rtl = lv_bar_create(lv_scr_act());
    lv_obj_set_style_base_dir(bar_rtl, LV_BASE_DIR_RTL, 0);
    lv_obj_set_size(bar_rtl, 200, 20);
    lv_bar_set_value(bar_rtl, 70, LV_ANIM_OFF);
    lv_obj_align(bar_rtl, LV_ALIGN_CENTER, 0, 30);

    label = lv_label_create(lv_scr_act());
    lv_label_set_text(label, "Right to Left base direction");
    lv_obj_align_to(label, bar_rtl, LV_ALIGN_OUT_TOP_MID, 0, -5);
}

#endif

#
# Bar with LTR and RTL base direction
#

bar_ltr = lv.bar(lv.scr_act())
bar_ltr.set_size(200, 20)
bar_ltr.set_value(70, lv.ANIM.OFF)
bar_ltr.align(lv.ALIGN.CENTER, 0, -30)

label = lv.label(lv.scr_act())
label.set_text("Left to Right base direction")
label.align_to(bar_ltr, lv.ALIGN.OUT_TOP_MID, 0, -5)

bar_rtl = lv.bar(lv.scr_act())
bar_rtl.set_style_base_dir(lv.BASE_DIR.RTL,0)
bar_rtl.set_size(200, 20)
bar_rtl.set_value(70, lv.ANIM.OFF)
bar_rtl.align(lv.ALIGN.CENTER, 0, 30)

label = lv.label(lv.scr_act())
label.set_text("Right to Left base direction")
label.align_to(bar_rtl, lv.ALIGN.OUT_TOP_MID, 0, -5)

Custom drawer to show the current value

#include "../../lv_examples.h"
#if LV_USE_BAR && LV_BUILD_EXAMPLES

static void set_value(void * bar, int32_t v)
{
    lv_bar_set_value(bar, v, LV_ANIM_OFF);
}

static void event_cb(lv_event_t * e)
{
    lv_obj_draw_part_dsc_t * dsc = lv_event_get_draw_part_dsc(e);
    if(dsc->part != LV_PART_INDICATOR) return;

    lv_obj_t * obj = lv_event_get_target(e);

    lv_draw_label_dsc_t label_dsc;
    lv_draw_label_dsc_init(&label_dsc);
    label_dsc.font = LV_FONT_DEFAULT;

    char buf[8];
    lv_snprintf(buf, sizeof(buf), "%d", (int)lv_bar_get_value(obj));

    lv_point_t txt_size;
    lv_txt_get_size(&txt_size, buf, label_dsc.font, label_dsc.letter_space, label_dsc.line_space, LV_COORD_MAX,
                    label_dsc.flag);

    lv_area_t txt_area;
    /*If the indicator is long enough put the text inside on the right*/
    if(lv_area_get_width(dsc->draw_area) > txt_size.x + 20) {
        txt_area.x2 = dsc->draw_area->x2 - 5;
        txt_area.x1 = txt_area.x2 - txt_size.x + 1;
        label_dsc.color = lv_color_white();
    }
    /*If the indicator is still short put the text out of it on the right*/
    else {
        txt_area.x1 = dsc->draw_area->x2 + 5;
        txt_area.x2 = txt_area.x1 + txt_size.x - 1;
        label_dsc.color = lv_color_black();
    }

    txt_area.y1 = dsc->draw_area->y1 + (lv_area_get_height(dsc->draw_area) - txt_size.y) / 2;
    txt_area.y2 = txt_area.y1 + txt_size.y - 1;

    lv_draw_label(dsc->draw_ctx, &label_dsc, &txt_area, buf, NULL);
}

/**
 * Custom drawer on the bar to display the current value
 */
void lv_example_bar_6(void)
{
    lv_obj_t * bar = lv_bar_create(lv_scr_act());
    lv_obj_add_event(bar, event_cb, LV_EVENT_DRAW_PART_END, NULL);
    lv_obj_set_size(bar, 200, 20);
    lv_obj_center(bar);

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, bar);
    lv_anim_set_values(&a, 0, 100);
    lv_anim_set_exec_cb(&a, set_value);
    lv_anim_set_time(&a, 2000);
    lv_anim_set_playback_time(&a, 2000);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);
    lv_anim_start(&a);

}

#endif

def set_value(bar, v):
    bar.set_value(v, lv.ANIM.OFF)

def event_cb(e):
    dsc = lv.obj_draw_part_dsc_t.__cast__(e.get_param())
    if dsc.part != lv.PART.INDICATOR:
        return

    obj= e.get_target_obj()

    label_dsc = lv.draw_label_dsc_t()
    label_dsc.init()
    # label_dsc.font = LV_FONT_DEFAULT;

    value_txt = str(obj.get_value())
    txt_size = lv.point_t()
    lv.txt_get_size(txt_size, value_txt, label_dsc.font, label_dsc.letter_space, label_dsc.line_space, lv.COORD.MAX, label_dsc.flag)

    txt_area = lv.area_t()
    # If the indicator is long enough put the text inside on the right
    if dsc.draw_area.get_width() > txt_size.x + 20:
        txt_area.x2 = dsc.draw_area.x2 - 5
        txt_area.x1 = txt_area.x2 - txt_size.x + 1
        label_dsc.color = lv.color_white()
    # If the indicator is still short put the text out of it on the right*/
    else:
        txt_area.x1 = dsc.draw_area.x2 + 5
        txt_area.x2 = txt_area.x1 + txt_size.x - 1
        label_dsc.color = lv.color_black()

    txt_area.y1 = dsc.draw_area.y1 + (dsc.draw_area.get_height() - txt_size.y) // 2
    txt_area.y2 = txt_area.y1 + txt_size.y - 1

    dsc.draw_ctx.label(label_dsc, txt_area, value_txt, None)

#
# Custom drawer on the bar to display the current value
#

bar = lv.bar(lv.scr_act())
bar.add_event(event_cb, lv.EVENT.DRAW_PART_END, None)
bar.set_size(200, 20)
bar.center()

a = lv.anim_t()
a.init()
a.set_var(bar)
a.set_values(0, 100)
a.set_custom_exec_cb(lambda a,val: set_value(bar,val))
a.set_time(2000)
a.set_playback_time(2000)
a.set_repeat_count(lv.ANIM_REPEAT_INFINITE)
lv.anim_t.start(a)

Button

Simple Buttons

#include "../../lv_examples.h"
#if LV_USE_BTN && LV_BUILD_EXAMPLES

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);

    if(code == LV_EVENT_CLICKED) {
        LV_LOG_USER("Clicked");
    }
    else if(code == LV_EVENT_VALUE_CHANGED) {
        LV_LOG_USER("Toggled");
    }
}

void lv_example_btn_1(void)
{
    lv_obj_t * label;

    lv_obj_t * btn1 = lv_btn_create(lv_scr_act());
    lv_obj_add_event(btn1, event_handler, LV_EVENT_ALL, NULL);
    lv_obj_align(btn1, LV_ALIGN_CENTER, 0, -40);

    label = lv_label_create(btn1);
    lv_label_set_text(label, "Button");
    lv_obj_center(label);

    lv_obj_t * btn2 = lv_btn_create(lv_scr_act());
    lv_obj_add_event(btn2, event_handler, LV_EVENT_ALL, NULL);
    lv_obj_align(btn2, LV_ALIGN_CENTER, 0, 40);
    lv_obj_add_flag(btn2, LV_OBJ_FLAG_CHECKABLE);
    lv_obj_set_height(btn2, LV_SIZE_CONTENT);

    label = lv_label_create(btn2);
    lv_label_set_text(label, "Toggle");
    lv_obj_center(label);
}
#endif

def event_handler(evt):
    code = evt.get_code()

    if code == lv.EVENT.CLICKED:
            print("Clicked event seen")
    elif code == lv.EVENT.VALUE_CHANGED:
        print("Value changed seen")

# create a simple button
btn1 = lv.btn(lv.scr_act())

# attach the callback
btn1.add_event(event_handler,lv.EVENT.ALL, None)

btn1.align(lv.ALIGN.CENTER,0,-40)
label=lv.label(btn1)
label.set_text("Button")

# create a toggle button
btn2 = lv.btn(lv.scr_act())

# attach the callback
#btn2.add_event(event_handler,lv.EVENT.VALUE_CHANGED,None)
btn2.add_event(event_handler,lv.EVENT.ALL, None)

btn2.align(lv.ALIGN.CENTER,0,40)
btn2.add_flag(lv.obj.FLAG.CHECKABLE)
btn2.set_height(lv.SIZE_CONTENT)

label=lv.label(btn2)
label.set_text("Toggle")
label.center()

Styling buttons

#include "../../lv_examples.h"
#if LV_USE_BTN && LV_BUILD_EXAMPLES

/**
 * Style a button from scratch
 */
void lv_example_btn_2(void)
{
    /*Init the style for the default state*/
    static lv_style_t style;
    lv_style_init(&style);

    lv_style_set_radius(&style, 3);

    lv_style_set_bg_opa(&style, LV_OPA_100);
    lv_style_set_bg_color(&style, lv_palette_main(LV_PALETTE_BLUE));
    lv_style_set_bg_grad_color(&style, lv_palette_darken(LV_PALETTE_BLUE, 2));
    lv_style_set_bg_grad_dir(&style, LV_GRAD_DIR_VER);

    lv_style_set_border_opa(&style, LV_OPA_40);
    lv_style_set_border_width(&style, 2);
    lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_GREY));

    lv_style_set_shadow_width(&style, 8);
    lv_style_set_shadow_color(&style, lv_palette_main(LV_PALETTE_GREY));
    lv_style_set_shadow_ofs_y(&style, 8);

    lv_style_set_outline_opa(&style, LV_OPA_COVER);
    lv_style_set_outline_color(&style, lv_palette_main(LV_PALETTE_BLUE));

    lv_style_set_text_color(&style, lv_color_white());
    lv_style_set_pad_all(&style, 10);

    /*Init the pressed style*/
    static lv_style_t style_pr;
    lv_style_init(&style_pr);

    /*Add a large outline when pressed*/
    lv_style_set_outline_width(&style_pr, 30);
    lv_style_set_outline_opa(&style_pr, LV_OPA_TRANSP);

    lv_style_set_translate_y(&style_pr, 5);
    lv_style_set_shadow_ofs_y(&style_pr, 3);
    lv_style_set_bg_color(&style_pr, lv_palette_darken(LV_PALETTE_BLUE, 2));
    lv_style_set_bg_grad_color(&style_pr, lv_palette_darken(LV_PALETTE_BLUE, 4));

    /*Add a transition to the outline*/
    static lv_style_transition_dsc_t trans;
    static lv_style_prop_t props[] = {LV_STYLE_OUTLINE_WIDTH, LV_STYLE_OUTLINE_OPA, 0};
    lv_style_transition_dsc_init(&trans, props, lv_anim_path_linear, 300, 0, NULL);

    lv_style_set_transition(&style_pr, &trans);

    lv_obj_t * btn1 = lv_btn_create(lv_scr_act());
    lv_obj_remove_style_all(btn1);                          /*Remove the style coming from the theme*/
    lv_obj_add_style(btn1, &style, 0);
    lv_obj_add_style(btn1, &style_pr, LV_STATE_PRESSED);
    lv_obj_set_size(btn1, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_obj_center(btn1);

    lv_obj_t * label = lv_label_create(btn1);
    lv_label_set_text(label, "Button");
    lv_obj_center(label);
}
#endif

#
# Style a button from scratch
#

# Init the style for the default state
style = lv.style_t()
style.init()

style.set_radius(3)

style.set_bg_opa(lv.OPA.COVER)
style.set_bg_color(lv.palette_main(lv.PALETTE.BLUE))
style.set_bg_grad_color(lv.palette_darken(lv.PALETTE.BLUE, 2))
style.set_bg_grad_dir(lv.GRAD_DIR.VER)

style.set_border_opa(lv.OPA._40)
style.set_border_width(2)
style.set_border_color(lv.palette_main(lv.PALETTE.GREY))

style.set_shadow_width(8)
style.set_shadow_color(lv.palette_main(lv.PALETTE.GREY))
style.set_shadow_ofs_y(8)

style.set_outline_opa(lv.OPA.COVER)
style.set_outline_color(lv.palette_main(lv.PALETTE.BLUE))

style.set_text_color(lv.color_white())
style.set_pad_all(10)

# Init the pressed style
style_pr = lv.style_t()
style_pr.init()

# Add a large outline when pressed
style_pr.set_outline_width(30)
style_pr.set_outline_opa(lv.OPA.TRANSP)

style_pr.set_translate_y(5)
style_pr.set_shadow_ofs_y(3)
style_pr.set_bg_color(lv.palette_darken(lv.PALETTE.BLUE, 2))
style_pr.set_bg_grad_color(lv.palette_darken(lv.PALETTE.BLUE, 4))

# Add a transition to the outline
trans = lv.style_transition_dsc_t()
props = [lv.STYLE.OUTLINE_WIDTH, lv.STYLE.OUTLINE_OPA, 0]
trans.init(props, lv.anim_t.path_linear, 300, 0, None)

style_pr.set_transition(trans)

btn1 = lv.btn(lv.scr_act())
btn1.remove_style_all()                          # Remove the style coming from the theme
btn1.add_style(style, 0)
btn1.add_style(style_pr, lv.STATE.PRESSED)
btn1.set_size(lv.SIZE_CONTENT, lv.SIZE_CONTENT)
btn1.center()

label = lv.label(btn1)
label.set_text("Button")
label.center()

Gummy button

#include "../../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_BTN

/**
 * Create a style transition on a button to act like a gum when clicked
 */
void lv_example_btn_3(void)
{
    /*Properties to transition*/
    static lv_style_prop_t props[] = {
        LV_STYLE_TRANSFORM_WIDTH, LV_STYLE_TRANSFORM_HEIGHT, LV_STYLE_TEXT_LETTER_SPACE, 0
    };

    /*Transition descriptor when going back to the default state.
     *Add some delay to be sure the press transition is visible even if the press was very short*/
    static lv_style_transition_dsc_t transition_dsc_def;
    lv_style_transition_dsc_init(&transition_dsc_def, props, lv_anim_path_overshoot, 250, 100, NULL);

    /*Transition descriptor when going to pressed state.
     *No delay, go to presses state immediately*/
    static lv_style_transition_dsc_t transition_dsc_pr;
    lv_style_transition_dsc_init(&transition_dsc_pr, props, lv_anim_path_ease_in_out, 250, 0, NULL);

    /*Add only the new transition to he default state*/
    static lv_style_t style_def;
    lv_style_init(&style_def);
    lv_style_set_transition(&style_def, &transition_dsc_def);

    /*Add the transition and some transformation to the presses state.*/
    static lv_style_t style_pr;
    lv_style_init(&style_pr);
    lv_style_set_transform_width(&style_pr, 10);
    lv_style_set_transform_height(&style_pr, -10);
    lv_style_set_text_letter_space(&style_pr, 10);
    lv_style_set_transition(&style_pr, &transition_dsc_pr);

    lv_obj_t * btn1 = lv_btn_create(lv_scr_act());
    lv_obj_align(btn1, LV_ALIGN_CENTER, 0, -80);
    lv_obj_add_style(btn1, &style_pr, LV_STATE_PRESSED);
    lv_obj_add_style(btn1, &style_def, 0);

    lv_obj_t * label = lv_label_create(btn1);
    lv_label_set_text(label, "Gum");
}
#endif

#
# Create a style transition on a button to act like a gum when clicked
#

# Properties to transition
props = [lv.STYLE.TRANSFORM_WIDTH, lv.STYLE.TRANSFORM_HEIGHT, lv.STYLE.TEXT_LETTER_SPACE, 0]

# Transition descriptor when going back to the default state.
# Add some delay to be sure the press transition is visible even if the press was very short*/
transition_dsc_def = lv.style_transition_dsc_t()
transition_dsc_def.init(props, lv.anim_t.path_overshoot, 250, 100, None)

# Transition descriptor when going to pressed state.
# No delay, go to pressed state immediately
transition_dsc_pr = lv.style_transition_dsc_t()
transition_dsc_pr.init(props, lv.anim_t.path_ease_in_out, 250, 0, None)

# Add only the new transition to the default state
style_def = lv.style_t()
style_def.init()
style_def.set_transition(transition_dsc_def)

# Add the transition and some transformation to the presses state.
style_pr = lv.style_t()
style_pr.init()
style_pr.set_transform_width(10)
style_pr.set_transform_height(-10)
style_pr.set_text_letter_space(10)
style_pr.set_transition(transition_dsc_pr)

btn1 = lv.btn(lv.scr_act())
btn1.align(lv.ALIGN.CENTER, 0, -80)
btn1.add_style(style_pr, lv.STATE.PRESSED)
btn1.add_style(style_def, 0)

label = lv.label(btn1)
label.set_text("Gum")

Button matrix

Simple Button matrix

#include "../../lv_examples.h"
#if LV_USE_BTNMATRIX && LV_BUILD_EXAMPLES

static void event_handler(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);
    if(code == LV_EVENT_VALUE_CHANGED) {
        uint32_t id = lv_btnmatrix_get_selected_btn(obj);
        const char * txt = lv_btnmatrix_get_btn_text(obj, id);
        LV_UNUSED(txt);
        LV_LOG_USER("%s was pressed\n", txt);
    }
}


static const char * btnm_map[] = {"1", "2", "3", "4", "5", "\n",
                                  "6", "7", "8", "9", "0", "\n",
                                  "Action1", "Action2", ""
                                 };

void lv_example_btnmatrix_1(void)
{
    lv_obj_t * btnm1 = lv_btnmatrix_create(lv_scr_act());
    lv_btnmatrix_set_map(btnm1, btnm_map);
    lv_btnmatrix_set_btn_width(btnm1, 10, 2);        /*Make "Action1" twice as wide as "Action2"*/
    lv_btnmatrix_set_btn_ctrl(btnm1, 10, LV_BTNMATRIX_CTRL_CHECKABLE);
    lv_btnmatrix_set_btn_ctrl(btnm1, 11, LV_BTNMATRIX_CTRL_CHECKED);
    lv_obj_align(btnm1, LV_ALIGN_CENTER, 0, 0);
    lv_obj_add_event(btnm1, event_handler, LV_EVENT_ALL, NULL);
}

#endif

def event_handler(e):
    code = e.get_code()
    obj  = e.get_target_obj()

    if code == lv.EVENT.VALUE_CHANGED :
        id = obj.get_selected_btn()
        txt = obj.get_btn_text(id)

        print("%s was pressed"%txt)

btnm_map = ["1", "2", "3", "4", "5", &quo