From b1ee2df8d21df5d4d54427c4dc0bcb58613736a3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Toma=C5=BE=20Vajngerl?= <tomaz.vajngerl@collabora.co.uk>
Date: Fri, 3 Jul 2015 14:38:24 +0900
Subject: [PATCH] tdf#88831 fix inverted textures when OpenGL is enabled

GLX returns a wrong value if the y coords are inverted. Most other
programs don't even ask for this (gnome-shell for example) and just
assumes "true" (and this works because most relevant X servers work
like this). We make this more robust and assume true only if the
returned value is GLX_DONT_CARE (-1).

(cherry picked from commit f7f0486376adbabf3ea66bfd8a7b692c335ec3c8)

Change-Id: I4800b3364fd00f5f4a8f5a459472bfa8d97827ba
---
 vcl/source/opengl/OpenGLHelper.cxx | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/vcl/source/opengl/OpenGLHelper.cxx b/vcl/source/opengl/OpenGLHelper.cxx
index c71380e..6387192 100644
--- a/vcl/source/opengl/OpenGLHelper.cxx
+++ b/vcl/source/opengl/OpenGLHelper.cxx
@@ -507,7 +507,11 @@ GLXFBConfig OpenGLHelper::GetPixmapFBConfig( Display* pDisplay, bool& bInverted
         }
 
         glXGetFBConfigAttrib( pDisplay, aFbConfigs[i], GLX_Y_INVERTED_EXT, &nValue );
-        bInverted = (nValue == True) ? true : false;
+
+        // Looks like that X sends GLX_DONT_CARE but this usually means "true" for most
+        // of the X implementations. Investigation on internet pointed that this could be
+        // safely "true" all the time (for example gnome-shell always assumes "true").
+        bInverted = nValue == True || nValue == int(GLX_DONT_CARE);
 
         break;
     }
-- 
2.4.0