I try to rotate an image on a transparent canvas(cf=TRUE_COLOR_ALPHA).
If I want to change the angle, I need to fill background to transparent to clean the old image first.
lvgl.canvas.fill_bg() won’t fill the alpha channel.
Currently I use
cbuf[:] = bytes(4*w*h) to clean the canvas background to transparent and eventually it will need a gc to collect memory.
Use for loop to assign alpha channel of a buffer will not consume memory but is much slower.
Is there any other way to fill the alpha channel of the background of a canvas?