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>

2 files changed, 11 insertions, 0 deletions

diff --git a/src/egl/wayland/wayland-drm/wayland-drm.c b/src/egl/wayland/wayland-drm/wayland-drm.c
index 82ca6aa..43f9169 100644
--- a/src/egl/wayland/wayland-drm/wayland-drm.c
+++ b/src/egl/wayland/wayland-drm/wayland-drm.c
@@ -205,6 +205,14 @@ wayland_buffer_is_drm(struct wl_buffer *buffer)
 		(void (**)(void)) &drm_buffer_interface;
 }
 
+uint32_t
+wayland_drm_buffer_get_format(struct wl_buffer *buffer_base)
+{
+	struct wl_drm_buffer *buffer = (struct wl_drm_buffer *) buffer_base;
+
+	return buffer->format;
+}
+
 void *
 wayland_drm_buffer_get_buffer(struct wl_buffer *buffer_base)
 {
diff --git a/src/egl/wayland/wayland-drm/wayland-drm.h b/src/egl/wayland/wayland-drm/wayland-drm.h
index c9a90ca..bec50a5 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);