LODEPNG decoder
Allow the use of PNG images in LVGL. This implementation uses lodepng library.
If enabled in lv_conf.h by LV_USE_LODEPNG LVGL will register a new
image decoder automatically so PNG files can be directly used as any
other image sources.
Note that, a file system driver needs to registered to open images from
files. Read more about it File system or just
enable one in lv_conf.h with LV_USE_FS_...
The whole PNG image is decoded so during decoding RAM equals to
image width x image height x 4 bytes are required.
As it might take significant time to decode PNG images LVGL's Image caching feature can be useful.