BMP Decoder

This BMP Decoder utility allows you to use images from .BMP files in LVGL.

Library source: https://github.com/caj-johnson/bmp-decoder

Instead of loading the whole image at once, BMP pixels are read on demand, so using BMP images requires very little RAM.

If enabled in lv_conf.h by setting LV_USE_BMP to 1, LVGL will register a new image decoder automatically so BMP files can be directly used as image sources. Example:

lv_image_set_src(my_img, "S:path/to/picture.bmp");

Note that, a File System (lv_fs_drv) driver needs to registered to open images from files. Follow the instructions in File System (lv_fs_drv).

Limitations

• Only BMP files are supported. BMP images as C arrays (lv_image_dsc_t) are not. This is because there is no practical differences between how the BMP files and LVGL's image format stores the image data.

• BMP files can be loaded only from .BMP files. If you want to store them in flash it's better to convert them to a C array with LVGL's image converter.

• The BMP file's color format needs to match the configured LV_COLOR_DEPTH of the display on which it will be rendered. You can use GIMP to save the image in the required format. Both RGB888 and ARGB888 works with LV_COLOR_DEPTH 32

• Color palettes are not supported.

• Because the whole image is not loaded, it cannot be zoomed or rotated.

Example

Open a BMP image from file

C code  

 View on GitHub

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

/**
 * Open a BMP file from a file
 */
void lv_example_bmp_1(void)
{
    lv_obj_t * img = lv_image_create(lv_screen_active());
    /* Assuming a File system is attached to letter 'A'
     * E.g. set LV_USE_FS_STDIO 'A' in lv_conf.h */
    lv_image_set_src(img, "A:lvgl/examples/libs/bmp/example_32bit.bmp");
    lv_obj_center(img);

}

#endif

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API

lv_bmp.h