Enable QX11GLWindowSurface using "-graphicssystem x11gl" option

When the OpenGL graphics system is in X11GL mode, it will use the
QX11GLWindowSurface for all widgets except QGraphicsViews with the
FullViewportUpdate update mode set, where it will use the regular
QGLWindowSurface, as this is probabbly faster.

QX11GLWindowSurface differs from QGLWindowSurface because it allows
accelerated scrolling and partial updates, while still being using
opengl to do rendering.

Task-number: QT-280
Task-number: QT-2625
Reviewed-By: Trond

5 files changed, 37 insertions, 23 deletions

diff --git a/src/opengl/qgraphicssystem_gl.cpp b/src/opengl/qgraphicssystem_gl.cpp
index a282e4c..58cc28a 100644
--- a/src/opengl/qgraphicssystem_gl.cpp
+++ b/src/opengl/qgraphicssystem_gl.cpp
@@ -40,6 +40,7 @@
 ****************************************************************************/
 
 #include "qgraphicssystem_gl_p.h"
+#include <QGraphicsView>
 
 #include "private/qpixmap_raster_p.h"
 #include "private/qpixmapdata_gl_p.h"
@@ -47,7 +48,7 @@
 #include "private/qgl_p.h"
 #include <private/qwindowsurface_raster_p.h>
 
-#if defined(Q_WS_X11) && defined(QT_OPENGL_ES)
+#if defined(Q_WS_X11) && !defined(QT_NO_EGL)
 #include "private/qpixmapdata_x11gl_p.h"
 #include "private/qwindowsurface_x11gl_p.h"
 #endif
@@ -58,10 +59,6 @@ extern QGLWidget *qt_gl_getShareWidget();
 
 QPixmapData *QGLGraphicsSystem::createPixmapData(QPixmapData::PixelType type) const
 {
-#if defined(Q_WS_X11) && defined(QT_OPENGL_ES)
-    if (type == QPixmapData::PixmapType && QX11GLPixmapData::hasX11GLPixmaps())
-        return new QX11GLPixmapData();
-#endif
     return new QGLPixmapData(type);
 }
 
@@ -75,9 +72,18 @@ QWindowSurface *QGLGraphicsSystem::createWindowSurface(QWidget *widget) const
         return new QRasterWindowSurface(widget);
 #endif
 
-#if defined(Q_WS_X11) && defined(QT_OPENGL_ES)
-    if (QX11GLPixmapData::hasX11GLPixmaps())
-        return new QX11GLWindowSurface(widget);
+#if defined(Q_WS_X11) && !defined(QT_NO_EGL)
+    if (m_useX11GL && QX11GLPixmapData::hasX11GLPixmaps()) {
+        // If the widget is a QGraphicsView which will be re-drawing the entire
+        // scene each frame anyway, we should use QGLWindowSurface as this may
+        // provide proper buffer flipping, which should be faster than QX11GL's
+        // blitting approach:
+        QGraphicsView* qgv = qobject_cast<QGraphicsView*>(widget);
+        if (qgv && qgv->viewportUpdateMode() == QGraphicsView::FullViewportUpdate)
+            return new QGLWindowSurface(widget);
+        else
+            return new QX11GLWindowSurface(widget);
+    }
 #endif
 
     return new QGLWindowSurface(widget);
diff --git a/src/opengl/qgraphicssystem_gl_p.h b/src/opengl/qgraphicssystem_gl_p.h
index ff47854..9d2d506 100644
--- a/src/opengl/qgraphicssystem_gl_p.h
+++ b/src/opengl/qgraphicssystem_gl_p.h
@@ -62,10 +62,12 @@ QT_BEGIN_NAMESPACE
 class Q_OPENGL_EXPORT QGLGraphicsSystem : public QGraphicsSystem
 {
 public:
-    QGLGraphicsSystem();
+    QGLGraphicsSystem(bool useX11GL);
 
     QPixmapData *createPixmapData(QPixmapData::PixelType type) const;
     QWindowSurface *createWindowSurface(QWidget *widget) const;
+private:
+    bool m_useX11GL;
 };
 
 QT_END_NAMESPACE
diff --git a/src/opengl/qpixmapdata_x11gl_egl.cpp b/src/opengl/qpixmapdata_x11gl_egl.cpp
index 58d34fc..e0c274a 100644
--- a/src/opengl/qpixmapdata_x11gl_egl.cpp
+++ b/src/opengl/qpixmapdata_x11gl_egl.cpp
@@ -216,18 +216,16 @@ QX11GLSharedContexts* QX11GLPixmapData::sharedContexts()
 
 bool QX11GLPixmapData::hasX11GLPixmaps()
 {
-    static bool checkedForX11Pixmaps = false;
-    static bool haveX11Pixmaps = false;
+    static bool checkedForX11GLPixmaps = false;
+    static bool haveX11GLPixmaps = false;
 
-    if (checkedForX11Pixmaps)
-        return haveX11Pixmaps;
+    if (checkedForX11GLPixmaps)
+        return haveX11GLPixmaps;
 
-    checkedForX11Pixmaps = true;
+    checkedForX11GLPixmaps = true;
+    haveX11GLPixmaps = sharedContexts()->isValid();
 
-    if (!qgetenv("QT_USE_X11GL_PIXMAPS").isEmpty() && sharedContexts()->isValid())
-        haveX11Pixmaps = true;
-
-    return haveX11Pixmaps;
+    return haveX11GLPixmaps;
 }
 
 QX11GLPixmapData::QX11GLPixmapData()
diff --git a/src/opengl/qwindowsurface_gl.cpp b/src/opengl/qwindowsurface_gl.cpp
index bcb96fa..92a347b 100644
--- a/src/opengl/qwindowsurface_gl.cpp
+++ b/src/opengl/qwindowsurface_gl.cpp
@@ -94,8 +94,8 @@ QT_BEGIN_NAMESPACE
 #ifdef Q_WS_WIN
 extern Q_GUI_EXPORT bool qt_win_owndc_required;
 #endif
-QGLGraphicsSystem::QGLGraphicsSystem()
-    : QGraphicsSystem()
+QGLGraphicsSystem::QGLGraphicsSystem(bool useX11GL)
+    : QGraphicsSystem(), m_useX11GL(useX11GL)
 {
     QGLWindowSurface::surfaceFormat.setSampleBuffers(true);
 #if defined(Q_WS_X11) && !defined(QT_OPENGL_ES)
diff --git a/src/plugins/graphicssystems/opengl/main.cpp b/src/plugins/graphicssystems/opengl/main.cpp
index abcfb7f..4c740ca 100644
--- a/src/plugins/graphicssystems/opengl/main.cpp
+++ b/src/plugins/graphicssystems/opengl/main.cpp
@@ -59,6 +59,9 @@ QStringList QGLGraphicsSystemPlugin::keys() const
 #if !defined(QT_OPENGL_ES_1)
     list << QLatin1String("OpenGL2");
 #endif
+#if defined(Q_WS_X11) && !defined(QT_NO_EGL)
+    list << QLatin1String("X11GL");
+#endif
     return list;
 }
 
@@ -66,18 +69,23 @@ QGraphicsSystem* QGLGraphicsSystemPlugin::create(const QString& system)
 {
     if (system.toLower() == QLatin1String("opengl1")) {
         QGL::setPreferredPaintEngine(QPaintEngine::OpenGL);
-        return new QGLGraphicsSystem;
+        return new QGLGraphicsSystem(false);
     }
 
 #if !defined(QT_OPENGL_ES_1)
     if (system.toLower() == QLatin1String("opengl2")) {
         QGL::setPreferredPaintEngine(QPaintEngine::OpenGL2);
-        return new QGLGraphicsSystem;
+        return new QGLGraphicsSystem(false);
     }
 #endif
 
+#if defined(Q_WS_X11) && !defined(QT_NO_EGL)
+    if (system.toLower() == QLatin1String("x11gl"))
+        return new QGLGraphicsSystem(true);
+#endif
+
     if (system.toLower() == QLatin1String("opengl"))
-        return new QGLGraphicsSystem;
+        return new QGLGraphicsSystem(false);
 
     return 0;
 }