kc3-lang/SDL

2021-10-22T16:59:46

wayland: Wayland cursors should use premultiplied alpha It turns out that Wayland's WL_SHM_FORMAT_ARGB8888 format (and, indeed, all wayland RGBA formats) should be treated as premultiplied. SDL surfaces tend not to be premultiplied, and this is assumed by other backends when dealing with cursors. This change premultiplies the cursor surface in Wayland_CreateCursor() using the new SDL_PremultiplySurfaceAlphaToARGB8888(). In so doing, it also adds support for a wider range of input surfaces, including those with non-ARGB8888 pixel formats, and those which don't have pitch==width. This should fix #4856