From c6c1bbe4abf9e5ce159442be22c1278d39844c08 Mon Sep 17 00:00:00 2001 From: Matt Hoosier Date: Wed, 29 Sep 2021 09:41:34 -0500 Subject: [PATCH] protocol: mention that buffers with alpha are assumed premultiplied This turns out to be the default assumption by compositors, OpenGL, and the DRM framework. Let's say it explicitly to avoid misinterpretation. See https://lists.freedesktop.org/archives/wayland-devel/2021-September/041990.html. Signed-off-by: Matt Hoosier --- protocol/wayland.xml | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/protocol/wayland.xml b/protocol/wayland.xml index 8c31cdc0..029db191 100644 --- a/protocol/wayland.xml +++ b/protocol/wayland.xml @@ -436,6 +436,10 @@ a height and can be attached to a wl_surface, but the mechanism by which a client provides and updates the contents is defined by the buffer factory interface. + + If the buffer uses a format that has an alpha channel, the alpha channel + is assumed to be premultiplied in the color channels unless otherwise + specified.