Rework how Qt handles GL extensions.

Qt used to store the GL extensions a particular implementation supported
in a global cache, which was initialized once and never updated.
This could cause problems because different types of context might
support different kinds of extensions (e.g. the difference between
sw and hw contexts). With this patch, the GL extensions are cached
and updated within each QGLContext. It also makes the extension
initialization lazy, which saves application initialization costs for
embedded platforms.
The patch introduces a internal cross platform QGLTemporaryContext
class that is used to create a light-weight GL context without going
via QGLWidget and friends (QWS and WinCE still have QGLWidget fallbacks
for now).

Reviewed-by: Kim
Reviewed-by: Samuel

1 files changed, 33 insertions, 13 deletions

diff --git a/src/opengl/qpaintengine_opengl.cpp b/src/opengl/qpaintengine_opengl.cpp
index c823187..57918d0 100644
--- a/src/opengl/qpaintengine_opengl.cpp
+++ b/src/opengl/qpaintengine_opengl.cpp
@@ -108,6 +108,10 @@ static bool DEBUG_TEMP_FLAG;
 #define DEBUG_ONCE_STR(str) DEBUG_ONCE qDebug() << (str);
 #endif
 
+#ifdef Q_WS_X11
+static bool qt_nvidiaFboNeedsFinish = false;
+#endif
+
 static inline void qt_glColor4ubv(unsigned char *col)
 {
     glColor4f(col[0]/255.0f, col[1]/255.0f, col[2]/255.0f, col[3]/255.0f);
@@ -423,7 +427,7 @@ inline void QGLOffscreen::release()
 
 #ifdef Q_WS_X11
     // workaround for bug in nvidia driver versions 9x.xx
-    if (QGLExtensions::nvidiaFboNeedsFinish)
+    if (qt_nvidiaFboNeedsFinish)
         glFinish();
 #endif
 
@@ -477,7 +481,7 @@ inline QGLContext *QGLOffscreen::context() const
 
 bool QGLOffscreen::isSupported()
 {
-    return (QGLExtensions::glExtensions & QGLExtensions::FramebufferObject); // for fbo
+    return (QGLExtensions::glExtensions() & QGLExtensions::FramebufferObject); // for fbo
 }
 
 struct QDrawQueueItem
@@ -1266,7 +1270,7 @@ bool QOpenGLPaintEngine::begin(QPaintDevice *pdev)
         for (int j = 0; j < 4; ++j)
             d->mv_matrix[i][j] = (i == j ? qreal(1) : qreal(0));
 
-    bool has_frag_program = (QGLExtensions::glExtensions & QGLExtensions::FragmentProgram)
+    bool has_frag_program = (QGLExtensions::glExtensions() & QGLExtensions::FragmentProgram)
                             && (pdev->devType() != QInternal::Pixmap);
 
     QGLContext *ctx = const_cast<QGLContext *>(d->device->context());
@@ -1279,11 +1283,27 @@ bool QOpenGLPaintEngine::begin(QPaintDevice *pdev)
         has_frag_program = qt_resolve_frag_program_extensions(ctx) && qt_resolve_version_1_3_functions(ctx);
 
     d->use_stencil_method = d->device->format().stencil()
-                            && (QGLExtensions::glExtensions & QGLExtensions::StencilWrap);
+                            && (QGLExtensions::glExtensions() & QGLExtensions::StencilWrap);
     if (d->device->format().directRendering()
-        && (d->use_stencil_method && QGLExtensions::glExtensions & QGLExtensions::StencilTwoSide))
+        && (d->use_stencil_method && QGLExtensions::glExtensions() & QGLExtensions::StencilTwoSide))
         d->has_stencil_face_ext = qt_resolve_stencil_face_extension(ctx);
 
+#ifdef Q_WS_X11
+    static bool nvidia_workaround_needs_init = true;
+    if (nvidia_workaround_needs_init) {
+        // nvidia 9x.xx unix drivers contain a bug which requires us to
+        // call glFinish before releasing an fbo to avoid painting
+        // artifacts
+        const QByteArray versionString(reinterpret_cast<const char*>(glGetString(GL_VERSION)));
+        const int pos = versionString.indexOf("NVIDIA");
+        if (pos >= 0) {
+            const float nvidiaDriverVersion = versionString.mid(pos + strlen("NVIDIA")).toFloat();
+            qt_nvidiaFboNeedsFinish = nvidiaDriverVersion >= 90.0 && nvidiaDriverVersion < 100.0;
+        }
+        nvidia_workaround_needs_init = false;
+    }
+#endif
+
 #ifndef QT_OPENGL_ES
     if (!ctx->d_ptr->internal_context) {
         glGetDoublev(GL_PROJECTION_MATRIX, &d->projection_matrix[0][0]);
@@ -1333,10 +1353,10 @@ bool QOpenGLPaintEngine::begin(QPaintDevice *pdev)
         glDisableClientState(GL_TEXTURE_COORD_ARRAY);
         glDisableClientState(GL_VERTEX_ARRAY);
 
-        if (QGLExtensions::glExtensions & QGLExtensions::SampleBuffers)
+        if (QGLExtensions::glExtensions() & QGLExtensions::SampleBuffers)
             glDisable(GL_MULTISAMPLE);
         glDisable(GL_TEXTURE_2D);
-        if (QGLExtensions::glExtensions & QGLExtensions::TextureRectangle)
+        if (QGLExtensions::glExtensions() & QGLExtensions::TextureRectangle)
             glDisable(GL_TEXTURE_RECTANGLE_NV);
         glDisable(GL_STENCIL_TEST);
         glDisable(GL_CULL_FACE);
@@ -1534,7 +1554,7 @@ void QOpenGLPaintEnginePrivate::updateGradient(const QBrush &brush, const QRectF
 #ifdef QT_OPENGL_ES
     Q_UNUSED(brush);
 #else
-    bool has_mirrored_repeat = QGLExtensions::glExtensions & QGLExtensions::MirroredRepeat;
+    bool has_mirrored_repeat = QGLExtensions::glExtensions() & QGLExtensions::MirroredRepeat;
     Qt::BrushStyle style = brush.style();
 
     QTransform m = brush.transform();
@@ -2098,7 +2118,7 @@ static inline bool needsEmulation(Qt::BrushStyle style)
 {
     return !(style == Qt::SolidPattern
              || (style == Qt::LinearGradientPattern
-                 && (QGLExtensions::glExtensions & QGLExtensions::MirroredRepeat)));
+                 && (QGLExtensions::glExtensions() & QGLExtensions::MirroredRepeat)));
 }
 
 void QOpenGLPaintEnginePrivate::updateUseEmulation()
@@ -2420,12 +2440,12 @@ void QOpenGLPaintEngine::updateRenderHints(QPainter::RenderHints hints)
             d->high_quality_antialiasing = true;
         } else {
             d->high_quality_antialiasing = false;
-            if (QGLExtensions::glExtensions & QGLExtensions::SampleBuffers)
+            if (QGLExtensions::glExtensions() & QGLExtensions::SampleBuffers)
                 glEnable(GL_MULTISAMPLE);
         }
     } else {
         d->high_quality_antialiasing = false;
-        if (QGLExtensions::glExtensions & QGLExtensions::SampleBuffers)
+        if (QGLExtensions::glExtensions() & QGLExtensions::SampleBuffers)
             glDisable(GL_MULTISAMPLE);
     }
 
@@ -2435,14 +2455,14 @@ void QOpenGLPaintEngine::updateRenderHints(QPainter::RenderHints hints)
         if (!d->offscreen.isValid()) {
             DEBUG_ONCE_STR("Unable to initialize offscreen, disabling high quality antialiasing");
             d->high_quality_antialiasing = false;
-            if (QGLExtensions::glExtensions & QGLExtensions::SampleBuffers)
+            if (QGLExtensions::glExtensions() & QGLExtensions::SampleBuffers)
                 glEnable(GL_MULTISAMPLE);
         }
     }
 
     d->has_antialiasing = d->high_quality_antialiasing
                           || ((hints & QPainter::Antialiasing)
-                              && (QGLExtensions::glExtensions & QGLExtensions::SampleBuffers));
+                              && (QGLExtensions::glExtensions() & QGLExtensions::SampleBuffers));
 }