Handle QVolatileImage-backed pixmaps optimally in drawPixmap().

When drawing such pixmaps (used by both the openvg and opengl graphics
systems) onto another pixmap or to a QImage, the performance was
sub-optimal due to missing and accidentally disabled support
specific to QVolatileImage. This is now fixed and drawing pixmaps into
a QImage is also made optimal by using the QS60PaintEngine for
QImage too. This will cause a 5-7x (or even up to 12x on certain
hardware and platform) increase in offscreen pixmap drawing
performance.

Task-number: QTBUG-19880
Reviewed-by: Jani Hautakangas

2 files changed, 16 insertions, 16 deletions

diff --git a/src/gui/painting/qpaintengine_s60.cpp b/src/gui/painting/qpaintengine_s60.cpp
index 091e2e6..fd7bea2 100644
--- a/src/gui/painting/qpaintengine_s60.cpp
+++ b/src/gui/painting/qpaintengine_s60.cpp
@@ -60,7 +60,7 @@ bool QS60PaintEngine::begin(QPaintDevice *device)
 {
     Q_D(QS60PaintEngine);
 
-    if (pixmapData->classId() == QPixmapData::RasterClass) {
+    if (pixmapData && pixmapData->classId() == QPixmapData::RasterClass) {
         pixmapData->beginDataAccess();
         bool ret = QRasterPaintEngine::begin(device);
         // Make sure QPaintEngine::paintDevice() returns the proper device.
@@ -69,13 +69,12 @@ bool QS60PaintEngine::begin(QPaintDevice *device)
         d->pdev = device;
         return ret;
     }
-
     return QRasterPaintEngine::begin(device);
 }
 
 bool QS60PaintEngine::end()
 {
-    if (pixmapData->classId() == QPixmapData::RasterClass) {
+    if (pixmapData && pixmapData->classId() == QPixmapData::RasterClass) {
         bool ret = QRasterPaintEngine::end();
         pixmapData->endDataAccess();
         return ret;
@@ -91,12 +90,14 @@ void QS60PaintEngine::drawPixmap(const QPointF &p, const QPixmap &pm)
         QRasterPaintEngine::drawPixmap(p, pm);
         srcData->endDataAccess();
     } else {
-        void *nativeData = pm.pixmapData()->toNativeType(QPixmapData::VolatileImage);
-        if (nativeData) {
-            QVolatileImage *img = static_cast<QVolatileImage *>(nativeData);
-            img->beginDataAccess();
-            QRasterPaintEngine::drawImage(p, img->imageRef());
-            img->endDataAccess(true);
+        QVolatileImage img = pm.pixmapData()->toVolatileImage();
+        if (!img.isNull()) {
+            img.beginDataAccess();
+            // imageRef() would detach and since we received the QVolatileImage
+            // from toVolatileImage() by value, it would cause a copy which
+            // would ruin our goal. So use constImageRef() instead.
+            QRasterPaintEngine::drawImage(p, img.constImageRef());
+            img.endDataAccess(true);
         } else {
             QRasterPaintEngine::drawPixmap(p, pm);
         }
@@ -111,12 +112,11 @@ void QS60PaintEngine::drawPixmap(const QRectF &r, const QPixmap &pm, const QRect
         QRasterPaintEngine::drawPixmap(r, pm, sr);
         srcData->endDataAccess();
     } else {
-        void *nativeData = pm.pixmapData()->toNativeType(QPixmapData::VolatileImage);
-        if (nativeData) {
-            QVolatileImage *img = static_cast<QVolatileImage *>(nativeData);
-            img->beginDataAccess();
-            QRasterPaintEngine::drawImage(r, img->imageRef(), sr);
-            img->endDataAccess(true);
+        QVolatileImage img = pm.pixmapData()->toVolatileImage();
+        if (!img.isNull()) {
+            img.beginDataAccess();
+            QRasterPaintEngine::drawImage(r, img.constImageRef(), sr);
+            img.endDataAccess(true);
         } else {
             QRasterPaintEngine::drawPixmap(r, pm, sr);
         }
diff --git a/src/gui/painting/qpaintengine_s60_p.h b/src/gui/painting/qpaintengine_s60_p.h
index 2a3b443..5535c24 100644
--- a/src/gui/painting/qpaintengine_s60_p.h
+++ b/src/gui/painting/qpaintengine_s60_p.h
@@ -65,7 +65,7 @@ class QS60PaintEngine : public QRasterPaintEngine
     Q_DECLARE_PRIVATE(QS60PaintEngine)
 
 public:
-    QS60PaintEngine(QPaintDevice *device, QS60PixmapData* data);
+    QS60PaintEngine(QPaintDevice *device, QS60PixmapData *data = 0);
     bool begin(QPaintDevice *device);
     bool end();