egl_dri2/wayland: handle creating xrgb8888 images

When creating an EGLImage from a struct wl_buffer * this ensures
that we create an XRGB8888 image if the wayland buffer doesn't have an
alpha channel. To determine if a wl_buffer has a valid alpha channel
this patch adds an internal wayland_drm_buffer_has_alpha() function.

It's important to get the internal format for an EGLImage right so that
if a GL texture is later created from the image then the GL driver will
know if it should sample the alpha from the texture or flatten it to
a constant of 1.0.

This avoids needing fragment program workarounds in wayland compositors
to manually ignore the alpha component of textures created from wayland
buffers.

krh: Edited to use wl_buffer_get_format() instead of wl_buffer_has_alpha().

Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/egl/wayland/wayland-drm/wayland-drm.h b/src/egl/wayland/wayland-drm/wayland-drm.h
index c9a90cad1ba..bec50a5539f 100644
--- a/src/egl/wayland/wayland-drm/wayland-drm.h
+++ b/src/egl/wayland/wayland-drm/wayland-drm.h
@@ -29,6 +29,9 @@ wayland_drm_uninit(struct wl_drm *drm);
 int
 wayland_buffer_is_drm(struct wl_buffer *buffer);
 
+uint32_t
+wayland_drm_buffer_get_format(struct wl_buffer *buffer_base);
+
 void *
 wayland_drm_buffer_get_buffer(struct wl_buffer *buffer);