Fix matching semi-transparent formats

For some reason some Visuals with semi-transparency incorrectly reports
a depth of 24.

Change-Id: If41ba1032fbe7d248f53f735cb84e61038b3300a
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

1 files changed, 8 insertions, 7 deletions

diff --git a/src/platformsupport/glxconvenience/qglxconvenience.cpp b/src/platformsupport/glxconvenience/qglxconvenience.cpp
index d7cc36627a..99ae2671dd 100644
--- a/src/platformsupport/glxconvenience/qglxconvenience.cpp
+++ b/src/platformsupport/glxconvenience/qglxconvenience.cpp
@@ -223,14 +223,15 @@ GLXFBConfig qglx_findConfig(Display *display, int screen , QSurfaceFormat format
                     continue;
             }
 
-            QXlibPointer<XVisualInfo> visual(glXGetVisualFromFBConfig(display, candidate));
-            if (visual.isNull())
-                continue;
+            int actualRed;
+            int actualGreen;
+            int actualBlue;
+            int actualAlpha;
+            glXGetFBConfigAttrib(display, candidate, GLX_RED_SIZE, &actualRed);
+            glXGetFBConfigAttrib(display, candidate, GLX_GREEN_SIZE, &actualGreen);
+            glXGetFBConfigAttrib(display, candidate, GLX_BLUE_SIZE, &actualBlue);
+            glXGetFBConfigAttrib(display, candidate, GLX_ALPHA_SIZE, &actualAlpha);
 
-            const int actualRed = qPopulationCount(visual->red_mask);
-            const int actualGreen = qPopulationCount(visual->green_mask);
-            const int actualBlue = qPopulationCount(visual->blue_mask);
-            const int actualAlpha = visual->depth - actualRed - actualGreen - actualBlue;
 
             if (requestedRed && actualRed < requestedRed)
                 continue;