From 14a896cf6b8b67a8d83a6204737249afa9ecd220 Mon Sep 17 00:00:00 2001
From: Trond Kjernaasen <trond@trolltech.com>
Date: Mon, 28 Sep 2009 16:52:04 +0200
Subject: Fixed a crash in the boxes demo when using -graphicssystem opengl.

Several problems:
1. The demo leaked the scene contents, which caused cleanup problems.
2. The QGLContext::currentContext() could be changed behind Qt's back
   under Windows (the temp contexts never reset the current context).
3. QGLFormat::openGLVersionFlags() function would return uninitialized
   flags if the QGLWidget constructor happened to call
   qt_gl_preferGL2Engine().

Reviewed-by: Kim
---
 demos/boxes/main.cpp                                   | 7 ++++---
 src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp | 2 +-
 src/opengl/qgl.cpp                                     | 2 +-
 src/opengl/qgl_win.cpp                                 | 6 ++++++
 4 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/demos/boxes/main.cpp b/demos/boxes/main.cpp
index 557afc9..957f183 100644
--- a/demos/boxes/main.cpp
+++ b/demos/boxes/main.cpp
@@ -68,7 +68,7 @@ protected:
 inline bool matchString(const char *extensionString, const char *subString)
 {
     int subStringLength = strlen(subString);
-    return (strncmp(extensionString, subString, subStringLength) == 0) 
+    return (strncmp(extensionString, subString, subStringLength) == 0)
         && ((extensionString[subStringLength] == ' ') || (extensionString[subStringLength] == '\0'));
 }
 
@@ -137,11 +137,12 @@ int main(int argc, char **argv)
         "This demo can be GPU and CPU intensive and may\n"
         "work poorly or not at all on your system.");
 
+    widget->makeCurrent(); // The current context must be set before calling Scene's constructor
+    Scene scene(1024, 768, maxTextureSize);
     GraphicsView view;
     view.setViewport(widget);
     view.setViewportUpdateMode(QGraphicsView::FullViewportUpdate);
-    widget->makeCurrent(); // The current context must be set before calling Scene's constructor
-    view.setScene(new Scene(1024, 768, maxTextureSize));
+    view.setScene(&scene);
     view.show();
 
     return app.exec();
diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
index 119c89d..7e45fd9 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
@@ -129,7 +129,7 @@ public Q_SLOTS:
                 // since the context holding the texture is shared, and
                 // about to be destroyed, we have to transfer ownership
                 // of the texture to one of the share contexts
-                ctx = const_cast<QGLContext *>(shares.at(0));
+                ctx = const_cast<QGLContext *>((ctx == shares.at(0)) ? shares.at(1) : shares.at(0));
             }
         }
     }
diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index 97a4a73..0ad6772 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -1245,11 +1245,11 @@ QGLFormat::OpenGLVersionFlags QGLFormat::openGLVersionFlags()
         if (cachedDefault) {
             return defaultVersionFlags;
         } else {
-            cachedDefault = true;
             if (!hasOpenGL())
                 return defaultVersionFlags;
             dummy = new QGLWidget;
             dummy->makeCurrent(); // glGetString() needs a current context
+            cachedDefault = true;
         }
     }
 
diff --git a/src/opengl/qgl_win.cpp b/src/opengl/qgl_win.cpp
index 2f9e225..5b5820a 100644
--- a/src/opengl/qgl_win.cpp
+++ b/src/opengl/qgl_win.cpp
@@ -660,6 +660,8 @@ public:
         int dmy_pf = ChoosePixelFormat(dmy_pdc, &dmy_pfd);
         SetPixelFormat(dmy_pdc, dmy_pf, &dmy_pfd);
         dmy_rc = wglCreateContext(dmy_pdc);
+        old_dc = wglGetCurrentDC();
+        old_context = wglGetCurrentContext();
         wglMakeCurrent(dmy_pdc, dmy_rc);
     }
 
@@ -668,10 +670,14 @@ public:
         wglDeleteContext(dmy_rc);
         ReleaseDC(dmy_id, dmy_pdc);
         DestroyWindow(dmy_id);
+        if (old_dc && old_context)
+            wglMakeCurrent(old_dc, old_context);
     }
 
     HDC dmy_pdc;
     HGLRC dmy_rc;
+    HDC old_dc;
+    HGLRC old_context;
     WId dmy_id;
 };
 
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