Prevented infinite recursion in GL graphics system.

If creating a QGLWidget triggers the creation of a QPixmap then we might
end up in an infinite recursion due to QPixmap trying to access
qt_gl_share_widget(). This can happen via setWindowIcon for example.
Adding an initializing flag to QGLGlobalShareWidget and preventing
QGLFramebufferObject::hasOpenGLFramebufferObjects() and
::hasOpenGLFramebufferBlit() from creating a QGLWidget every time they
are called with no active GL context.

Reviewed-by: Trond

3 files changed, 12 insertions, 8 deletions

diff --git a/src/opengl/qglframebufferobject.cpp b/src/opengl/qglframebufferobject.cpp
index 7f229e2..eacf5bb 100644
--- a/src/opengl/qglframebufferobject.cpp
+++ b/src/opengl/qglframebufferobject.cpp
@@ -935,8 +935,7 @@ QPaintEngine *QGLFramebufferObject::paintEngine() const
 */
 bool QGLFramebufferObject::hasOpenGLFramebufferObjects()
 {
-    if (!QGLContext::currentContext())
-        QGLWidget dmy; // needed to detect and init the QGLExtensions object
+    QGLExtensions::init();
     return (QGLExtensions::glExtensions & QGLExtensions::FramebufferObject);
 }
 
@@ -1098,8 +1097,7 @@ bool QGLFramebufferObject::isBound() const
 */
 bool QGLFramebufferObject::hasOpenGLFramebufferBlit()
 {
-    if (!QGLContext::currentContext())
-        QGLWidget dmy; // needed to detect and init the QGLExtensions object
+    QGLExtensions::init();
     return (QGLExtensions::glExtensions & QGLExtensions::FramebufferBlit);
 }
 
diff --git a/src/opengl/qpixmapdata_gl.cpp b/src/opengl/qpixmapdata_gl.cpp
index 5e73ef5..f745aae 100644
--- a/src/opengl/qpixmapdata_gl.cpp
+++ b/src/opengl/qpixmapdata_gl.cpp
@@ -114,8 +114,11 @@ QGLPixmapData::~QGLPixmapData()
     QGLWidget *shareWidget = qt_gl_share_widget();
     if (!shareWidget)
         return;
-    QGLShareContextScope ctx(shareWidget->context());
-    glDeleteTextures(1, &m_textureId);
+
+    if (m_textureId) {
+        QGLShareContextScope ctx(shareWidget->context());
+        glDeleteTextures(1, &m_textureId);
+    }
 }
 
 bool QGLPixmapData::isValid() const
diff --git a/src/opengl/qwindowsurface_gl.cpp b/src/opengl/qwindowsurface_gl.cpp
index 50d0ae7..3a7a07e 100644
--- a/src/opengl/qwindowsurface_gl.cpp
+++ b/src/opengl/qwindowsurface_gl.cpp
@@ -184,11 +184,13 @@ QGLGraphicsSystem::QGLGraphicsSystem()
 class QGLGlobalShareWidget
 {
 public:
-    QGLGlobalShareWidget() : widget(0) {}
+    QGLGlobalShareWidget() : widget(0), initializing(false) {}
 
     QGLWidget *shareWidget() {
-        if (!widget && !cleanedUp) {
+        if (!initializing && !widget && !cleanedUp) {
+            initializing = true;
             widget = new QGLWidget;
+            initializing = false;
         }
         return widget;
     }
@@ -204,6 +206,7 @@ public:
 
 private:
     QGLWidget *widget;
+    bool initializing;
 };
 
 bool QGLGlobalShareWidget::cleanedUp = false;