Hi everyone,

Recently, I've been reading the code of image.c and wondering how to make
emacs support transparent image. Then I find that a small change on the
src/image.c can make it worked (and wonder why this have not been solved
since the solution is so simple).

This patch can support the transparent png, webp and svg. The core of the
patch is to change the code,

 PUT_PIXEL (mask_img, x, y, *p > 0 ? PIX_MASK_DRAW : PIX_MASK_RETAIN);

to

 PUT_PIXEL (mask_img, x, y, *p > 0 ? *p : PIX_MASK_RETAIN);

Then all worked like a magic.

I have checked my patch in linux by default configure option "../configure"
for dwm and pgtk build for hyprland, both are fine. I don't know whether it
could support other platforms since I don't have them.

Please check my patch and happy to hear comments.

Best regards,
Zhang