egl: Allow 24-bit visuals for 32-bit RGBA8888 configs

Previously only the 32-bit X visual would match the 32-bit RGBA8888
configs.  This resulted in every config with alpha getting the "magic"
visual whose alpha is used by the compositor.  This also resulted in no
multisample visuals being advertised.  How many ways could we lose?

This patch inverts the problem... now you can't get the visual with
alpha used by the compositor even if you want it.  I think we need to
invent a new value for EGL_TRANSPARENT_TYPE that apps can use to get
this.  I'm surprised that there isn't already a choice for
EGL_TRANSPARENT_ALPHA.

NOTE: This is a candidate for the 9.1 branch.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Tested-by: Tian Ye <yex.tian@intel.com>
Acked-by: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59783

diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
index ae842d7a1bb5a7f9bd63943495bb6b36959de8c3..b7749196c5d20e1fd19b89f118ec88026f97e7b2 100644 (file)
--- a/src/egl/drivers/dri2/egl_dri2.c
+++ b/src/egl/drivers/dri2/egl_dri2.c
@@ -195,7 +195,14 @@ dri2_add_config(_EGLDisplay *disp, const __DRIconfig *dri_config, int id,
       for (i = 0; attr_list[i] != EGL_NONE; i += 2)
          _eglSetConfigKey(&base, attr_list[i], attr_list[i+1]);
 
-   if (depth > 0 && depth != base.BufferSize)
+   /* Allow a 24-bit RGB visual to match a 32-bit RGBA EGLConfig.  Otherwise
+    * it will only match a 32-bit RGBA visual.  On a composited window manager
+    * on X11, this will make all of the EGLConfigs with destination alpha get
+    * blended by the compositor.  This is probably not what the application
+    * wants... especially on drivers that only have 32-bit RGBA EGLConfigs!
+    */
+   if (depth > 0 && depth != base.BufferSize
+       && !(depth == 24 && base.BufferSize == 32))
       return NULL;
 
    if (rgba_masks && memcmp(rgba_masks, dri_masks, sizeof(dri_masks)))