[Mesa-dev] [PATCH] egl_dri2: Allow both 24 and 32 bit X visuals for RGBA configs

[Emil Velikov]

From: Sjoerd Simons <sjoerd.simons at collabora.co.uk>

When using RGBA EGLConfigs allow both RGB and RGBA X visuals, such that
application can decide whether they want to use RGBA (and have the
compositor blend their windows).

On my system with this change EGLConfigs with a 24 bit visual comes up
first, as such applications blindly picking the first EGLConfig will
still get an RGB X visual.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67676
---

Hello gents,

This patch has been stuck in bugzilla since February this year. Bringing 
it around here to gather greater exposure and perhaps some 
comments/reviews.

-Emil

 src/egl/drivers/dri2/egl_dri2.c     |  5 +++++
 src/egl/drivers/dri2/platform_x11.c | 17 +++++++++--------
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
index 20a7243..2ed90a7 100644
--- a/src/egl/drivers/dri2/egl_dri2.c
+++ b/src/egl/drivers/dri2/egl_dri2.c
@@ -110,6 +110,11 @@ EGLint dri2_to_egl_attribute_map[] = {
 static EGLBoolean
 dri2_match_config(const _EGLConfig *conf, const _EGLConfig *criteria)
 {
+
+   if (criteria->NativeVisualID != EGL_DONT_CARE &&
+        conf->NativeVisualID != criteria->NativeVisualID)
+      return EGL_FALSE;
+
    if (_eglCompareConfigs(conf, criteria, NULL, EGL_FALSE) != 0)
       return EGL_FALSE;
 
diff --git a/src/egl/drivers/dri2/platform_x11.c b/src/egl/drivers/dri2/platform_x11.c
index a7a7338..3395fb7 100644
--- a/src/egl/drivers/dri2/platform_x11.c
+++ b/src/egl/drivers/dri2/platform_x11.c
@@ -672,14 +672,15 @@ dri2_x11_add_configs_for_visuals(struct dri2_egl_display *dri2_dpy,
 	    dri2_add_config(disp, dri2_dpy->driver_configs[j], id++,
 			    surface_type, config_attrs, rgba_masks);
 
-            /* 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 (d.data->depth == 24) {
+            /* Allow both 24-bit RGB visual and 32 bit RGBA 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!
+             * Allowing both allows applications to make the decision whether
+             * 32 bit visuals are intended */
+            if (d.data->depth == 24 || d.data->depth == 32) {
                rgba_masks[3] =
                   ~(rgba_masks[0] | rgba_masks[1] | rgba_masks[2]);
                dri2_add_config(disp, dri2_dpy->driver_configs[j], id++,
-- 
2.1.0