[中文]

Grid

Overview

The Grid layout is a subset of CSS Grid layout.

It can arrange items (child Widgets) into a 2D "table" that has rows and columns (tracks). An item can span multiple columns or rows. The track's size can be set in pixels, to the largest item (LV_GRID_CONTENT), or to a fraction of the available free space (i.e. Free [FR] Units) to distribute free space proportionally.

To make a Widget a Grid container call lv_obj_set_layout(widget, LV_LAYOUT_GRID).

Note that the Grid layout feature of LVGL needs to be globally enabled with LV_USE_GRID in lv_conf.h.

Terms

• tracks: rows or columns

• free (FR) units: if a track's size is set in FR units it will grow to fill the remaining space in the parent Widget (container), in proportion with other tracks that have non-zero FR-unit values.

• gap: the space between rows and columns or the items on a track

Simple Interface

With the following functions you can cause any parent Widget to have Grid-layout behaviors.

Note

As with Flex containers, the parent Widget must be a Grid container for these styles to take effect. The functions below cause the parent Widget to become a Grid container if it is not already.

Grid descriptors

First you need to describe the size of rows and columns. It can be done by declaring 2 arrays and the track sizes in them. The last element must be LV_GRID_TEMPLATE_LAST.

For example:

static int32_t column_dsc[] = {100, 400, LV_GRID_TEMPLATE_LAST};   /* 2 columns with 100- and 400-px width */
static int32_t row_dsc[] = {100, 100, 100, LV_GRID_TEMPLATE_LAST}; /* 3 100-px tall rows */

To set the descriptors on a parent use lv_obj_set_grid_dsc_array(widget, col_dsc, row_dsc).

Besides settings the sizes in pixels, you can use two special values:

• LV_GRID_CONTENT sets size to fit the largest child on this track

• LV_GRID_FR(X) determines what portion of the remaining space should be used by this track. Larger values means larger space.

Grid items

By default, a Widget's children are not added to the grid. They need to be added manually to a cell.

To do this call lv_obj_set_grid_cell(child, column_align, column_pos, column_span, row_align, row_pos, row_span).

column_align and row_align determine how to align the child Widget in its cell. Possible values are:

• LV_GRID_ALIGN_START: means left when direction is horizontal and top when vertical (default)

• LV_GRID_ALIGN_END: means right when direction is horizontal and bottom when vertical

• LV_GRID_ALIGN_CENTER: simply center column_pos and row_pos means the zero-based index of the cell in which the item should be placed.

column_span and row_span means how many tracks should be occupied from the start cell. Must be >= 1.

Grid align

If there is some empty space, items (Widgets) in Grid tracks can be aligned in several ways:

• LV_GRID_ALIGN_START: means left when direction is horizontal and top when vertical. (default)

• LV_GRID_ALIGN_END: means right when direction is horizontal and bottom when vertical

• LV_GRID_ALIGN_CENTER: simply center

• LV_GRID_ALIGN_SPACE_EVENLY: items are distributed so that the spacing between any two items (and the space to the edges) is equal. Not applies to track_cross_place.

• LV_GRID_ALIGN_SPACE_AROUND: items are evenly distributed in the track with equal space around them. Note that visually the spaces aren't equal, since all the items have equal space on both sides. This makes the space between items double the space between edge items and the container's edge. Does not apply to track_cross_place.

• LV_GRID_ALIGN_SPACE_BETWEEN: items are evenly distributed in the track with first and last items next to container's edges. Does not apply to track_cross_place.

To set the track's alignment use lv_obj_set_grid_align(widget, column_align, row_align).

Sub grid

If you set the column and/or row grid descriptors of a widget to NULL it will use the grid descriptor(s) from it's parent.

For example if you create a grid item that spans columns 2..6 columns and rows 1..3 of the grid, the grid item will occupy 5 columns and 4 rows with the corresponding track size from the parent Grid container.

This way even if a wrapper item is used in the grid, it can be made "transparent" from the grid's point of view.

Limitations:

• The sub-grid is resolved only to a depth of 1 level. That is, a grid can have a sub-grid child, but that sub-grid cannot have another sub-grid.

• LV_GRID_CONTENT tracks on the grid are not handled in the sub-grid, only in its own grid.

The sub-grid feature works the same as in CSS. For further information, see CSS Subgrid.

Style Interface

All the Grid-related values are style properties under the hood so you can use them as you would any other style property.

The following Grid-related style properties exist:

• GRID_COLUMN_DSC_ARRAY

• GRID_ROW_DSC_ARRAY

• GRID_COLUMN_ALIGN

• GRID_ROW_ALIGN

• GRID_CELL_X_ALIGN

• GRID_CELL_COLUMN_POS

• GRID_CELL_COLUMN_SPAN

• GRID_CELL_Y_ALIGN

• GRID_CELL_ROW_POS

• GRID_CELL_ROW_SPAN

Internal padding

To modify the minimum space Grid inserts between Widgets, the following properties can be set on the Grid container style:

• lv_style_set_pad_row() sets padding between rows.

• lv_style_set_pad_column() sets padding between columns.

Other features

RTL

If the base direction of the container is set to LV_BASE_DIR_RTL, the meaning of LV_GRID_ALIGN_START and LV_GRID_ALIGN_END is swapped. I.e. START will mean right-most.

The columns will be placed from right to left.

Further Reading

• Learn more about CSS Grid layout.

• Learn more about CSS Subgrid layout.

Example

[中文]

A simple grid

C code  

 View on GitHub

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

/**
 * A simple grid
 */
void lv_example_grid_1(void)
{
    static int32_t col_dsc[] = {70, 70, 70, LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {50, 50, 50, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    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_button_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

---

Demonstrate cell placement and span

C code  

 View on GitHub

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

/**
 * Demonstrate cell placement and span
 */
void lv_example_grid_2(void)
{
    static int32_t col_dsc[] = {70, 70, 70, LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {50, 50, 50, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    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 grid's -free unit-

C code  

 View on GitHub

#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 int32_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 int32_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_screen_active());
    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 track placement

C code  

 View on GitHub

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

/**
 * Demonstrate track placement
 */
void lv_example_grid_4(void)
{
    static int32_t col_dsc[] = {60, 60, 60, LV_GRID_TEMPLATE_LAST};
    static int32_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_screen_active());
    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 column and row gap

C code  

 View on GitHub

#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 int32_t col_dsc[] = {60, 60, 60, LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {45, 45, 45, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    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_duration(&a, 500);
    lv_anim_set_playback_duration(&a, 500);
    lv_anim_start(&a);

    lv_anim_set_exec_cb(&a, column_gap_anim);
    lv_anim_set_duration(&a, 3000);
    lv_anim_set_playback_duration(&a, 3000);
    lv_anim_start(&a);
}

#endif

---

Demonstrate RTL direction on grid

C code  

 View on GitHub

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

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

    static int32_t col_dsc[] = {60, 60, 60, LV_GRID_TEMPLATE_LAST};
    static int32_t row_dsc[] = {45, 45, 45, LV_GRID_TEMPLATE_LAST};

    /*Create a container with grid*/
    lv_obj_t * cont = lv_obj_create(lv_screen_active());
    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

---

API

lv_grid.h