Bar (lv_bar)¶
Overview¶
The bar object has a background and an indicator on it. The width of the indicator is set according to the current value of the bar.
Vertical bars can be created if the width of the object is smaller than its height.
Not only the end, but also the start value of the bar can be set, which changes the start position of the indicator.
Parts and Styles¶
LV_PART_MAIN
The background of the bar and it uses the typical background style properties. Adding padding makes the indicator smaller or larger. Theanim_time
style property sets the animation time if the values set withLV_ANIM_ON
.LV_PART_INDICATOR
The indicator itself; also uses all the typical background properties.
Usage¶
Value and range¶
A new value can be set by lv_bar_set_value(bar, new_value, LV_ANIM_ON/OFF)
.
The value is interpreted in a range (minimum and maximum values) which can be modified with lv_bar_set_range(bar, min, max)
.
The default range is 0..100.
The new value in lv_bar_set_value
can be set with or without an animation depending on the last parameter (LV_ANIM_ON/OFF
).
Modes¶
The bar can be one of the following modes:
LV_BAR_MODE_NORMAL
A normal bar as described aboveLV_BAR_MODE_SYMMETRICAL
Draw the indicator from the zero value to current value. Requires a negative minimum range and positive maximum range.LV_BAR_MODE_RANGE
Allows setting the start value too bylv_bar_set_start_value(bar, new_value, LV_ANIM_ON/OFF)
. The start value always has to be smaller than the end value.
Events¶
LV_EVENT_DRAW_PART_BEGIN
andLV_EVENT_DRAW_PART_END
are sent for the following parts:LV_BAR_DRAW_PART_INDICATOR
The indicator of the barpart
:LV_PART_INDICATOR
draw_area
: area of the indicatorrect_dsc
See the events of the Base object too.
Learn more about Events.
Example¶
Simple Bar¶
C code
GitHub#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¶
C code
GitHub#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¶
C code
GitHub#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¶
C code
GitHub#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
#
# get an icon
#
def get_icon(filename,xres,yres):
try:
sdl_filename = "../../assets/" + filename + "_" + str(xres) + "x" + str(yres) + "_argb8888.fnt"
print("file name: ", sdl_filename)
with open(sdl_filename,'rb') as f:
icon_data = f.read()
except:
print("Could not find image file: " + filename)
return None
icon_dsc = lv.img_dsc_t(
{
"header": {"always_zero": 0, "w": xres, "h": yres, "cf": lv.img.CF.TRUE_COLOR_ALPHA},
"data": icon_data,
"data_size": len(icon_data),
}
)
return icon_dsc
#
# Bar with stripe pattern and ranged value
#
img_skew_strip_dsc = get_icon("img_skew_strip",80,20)
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¶
C code
GitHub#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¶
C code
GitHub#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_param(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_cb(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()
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_cb(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)
API¶
Typedefs
-
typedef uint8_t lv_bar_mode_t¶
Enums
Functions
-
lv_obj_t *lv_bar_create(lv_obj_t *parent)¶
Create a bar object
- Parameters
parent -- pointer to an object, it will be the parent of the new bar
- Returns
pointer to the created bar
-
void lv_bar_set_value(lv_obj_t *obj, int32_t value, lv_anim_enable_t anim)¶
Set a new value on the bar
- Parameters
bar -- pointer to a bar object
value -- new value
anim -- LV_ANIM_ON: set the value with an animation; LV_ANIM_OFF: change the value immediately
-
void lv_bar_set_start_value(lv_obj_t *obj, int32_t start_value, lv_anim_enable_t anim)¶
Set a new start value on the bar
- Parameters
obj -- pointer to a bar object
value -- new start value
anim -- LV_ANIM_ON: set the value with an animation; LV_ANIM_OFF: change the value immediately
-
void lv_bar_set_range(lv_obj_t *obj, int32_t min, int32_t max)¶
Set minimum and the maximum values of a bar
- Parameters
obj -- pointer to the bar object
min -- minimum value
max -- maximum value
-
void lv_bar_set_mode(lv_obj_t *obj, lv_bar_mode_t mode)¶
Set the type of bar.
- Parameters
obj -- pointer to bar object
mode -- bar type from ::lv_bar_mode_t
-
int32_t lv_bar_get_value(const lv_obj_t *obj)¶
Get the value of a bar
- Parameters
obj -- pointer to a bar object
- Returns
the value of the bar
-
int32_t lv_bar_get_start_value(const lv_obj_t *obj)¶
Get the start value of a bar
- Parameters
obj -- pointer to a bar object
- Returns
the start value of the bar
-
int32_t lv_bar_get_min_value(const lv_obj_t *obj)¶
Get the minimum value of a bar
- Parameters
obj -- pointer to a bar object
- Returns
the minimum value of the bar
-
int32_t lv_bar_get_max_value(const lv_obj_t *obj)¶
Get the maximum value of a bar
- Parameters
obj -- pointer to a bar object
- Returns
the maximum value of the bar
-
lv_bar_mode_t lv_bar_get_mode(lv_obj_t *obj)¶
Get the type of bar.
- Parameters
obj -- pointer to bar object
- Returns
bar type from ::lv_bar_mode_t
Variables
-
const lv_obj_class_t lv_bar_class¶
-
struct _lv_bar_anim_t¶
-
struct lv_bar_t¶
Public Members
-
int32_t cur_value¶
Current value of the bar
-
int32_t min_value¶
Minimum value of the bar
-
int32_t max_value¶
Maximum value of the bar
-
int32_t start_value¶
Start value of the bar
-
lv_area_t indic_area¶
Save the indicator area. Might be used by derived types
-
_lv_bar_anim_t cur_value_anim¶
-
_lv_bar_anim_t start_value_anim¶
-
lv_bar_mode_t mode¶
Type of bar
-
int32_t cur_value¶