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

3 files changed, 8 insertions, 2 deletions

diff --git a/src/openvg/qpixmapdata_vg.cpp b/src/openvg/qpixmapdata_vg.cpp
index a5d156d..1231abf 100644
--- a/src/openvg/qpixmapdata_vg.cpp
+++ b/src/openvg/qpixmapdata_vg.cpp
@@ -248,9 +248,10 @@ void QVGPixmapData::createPixmapForImage(QImage &image, Qt::ImageConversionFlags
         // same. Detaching is needed to prevent issues with painting
         // onto this QPixmap later on.
         convertedImage.detach();
+        if (convertedImage.isNull())
+            qWarning("QVGPixmapData: Failed to convert image data (out of memory? try increasing heap size)");
         source = QVolatileImage(convertedImage);
     }
-
     recreate = true;
 }
 
diff --git a/src/openvg/qpixmapdata_vg_p.h b/src/openvg/qpixmapdata_vg_p.h
index 18846f3..4a969c0 100644
--- a/src/openvg/qpixmapdata_vg_p.h
+++ b/src/openvg/qpixmapdata_vg_p.h
@@ -138,7 +138,7 @@ public:
     QSize size() const { return QSize(w, h); }
 
 #if defined(Q_OS_SYMBIAN)
-    QVolatileImage toVolatileImage() const { return source; }
+    QVolatileImage toVolatileImage() const;
     void* toNativeType(NativeType type);
     void fromNativeType(void* pixmap, NativeType type);
     bool initFromNativeImageHandle(void *handle, const QString &type);
diff --git a/src/openvg/qvg_symbian.cpp b/src/openvg/qvg_symbian.cpp
index 249b053..98a5869 100644
--- a/src/openvg/qvg_symbian.cpp
+++ b/src/openvg/qvg_symbian.cpp
@@ -288,6 +288,11 @@ void* QVGPixmapData::toNativeType(NativeType type)
     return 0;
 }
 
+QVolatileImage QVGPixmapData::toVolatileImage() const
+{
+    return source;
+}
+
 QSymbianVGFontGlyphCache::QSymbianVGFontGlyphCache() : QVGFontGlyphCache()
 {
 #ifdef QT_SYMBIAN_HARDWARE_GLYPH_CACHE