BMP decoder

This extension allows the use of BMP images in LVGL.

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

The pixels are read on demand (not the whole image is loaded) so using BMP images requires very little RAM.

If enabled in lv_conf.h by LV_USE_BMP LVGL will register a new image decoder automatically so BMP files can be directly used as image sources. For example:

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

Note that, a file system driver needs to registered to open images from files. Read more about it File System (lv_fs_drv) or just enable one in lv_conf.h with LV_USE_FS_...

Limitations

  • Only BMP files are supported and BMP images as C array (lv_image_dsc_t) are not. It's 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 file. If you want to store them in flash it's better to convert them to C array with LVGL's image converter.

  • The BMP files color format needs to match with LV_COLOR_DEPTH. Use GIMP to save the image in the required format. Both RGB888 and ARGB888 works with LV_COLOR_DEPTH 32

  • Palette is not supported.

  • Because not the whole image is read in 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

API

lv_bmp.h