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

11 files changed, 62 insertions, 32 deletions

diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index 65793af..d7156a7 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -62,7 +62,11 @@
 
 #include <qhash.h>
 
+#if defined(Q_OS_SYMBIAN)
+#include <private/qpaintengine_s60_p.h>
+#else
 #include <private/qpaintengine_raster_p.h>
+#endif
 
 #include <private/qimage_p.h>
 
@@ -5706,7 +5710,11 @@ QPaintEngine *QImage::paintEngine() const
         return 0;
 
     if (!d->paintEngine) {
+#ifdef Q_OS_SYMBIAN
+        d->paintEngine = new QS60PaintEngine(const_cast<QImage *>(this));
+#else
         d->paintEngine = new QRasterPaintEngine(const_cast<QImage *>(this));
+#endif
     }
 
     return d->paintEngine;
diff --git a/src/gui/image/qpixmapdata.cpp b/src/gui/image/qpixmapdata.cpp
index c46429c..934dbb8 100644
--- a/src/gui/image/qpixmapdata.cpp
+++ b/src/gui/image/qpixmapdata.cpp
@@ -276,6 +276,11 @@ QImage* QPixmapData::buffer()
 }
 
 #if defined(Q_OS_SYMBIAN)
+QVolatileImage QPixmapData::toVolatileImage() const
+{
+    return QVolatileImage();
+}
+
 void* QPixmapData::toNativeType(NativeType /* type */)
 {
     return 0;
diff --git a/src/gui/image/qpixmapdata_p.h b/src/gui/image/qpixmapdata_p.h
index 099c61c..cf089fb 100644
--- a/src/gui/image/qpixmapdata_p.h
+++ b/src/gui/image/qpixmapdata_p.h
@@ -138,7 +138,7 @@ public:
     }
 
 #if defined(Q_OS_SYMBIAN)
-    virtual QVolatileImage toVolatileImage() const { return QVolatileImage(); }
+    virtual QVolatileImage toVolatileImage() const;
     virtual void* toNativeType(NativeType type);
     virtual void fromNativeType(void* pixmap, NativeType type);
 #endif
diff --git a/src/gui/image/qvolatileimage.cpp b/src/gui/image/qvolatileimage.cpp
index b8612b1..9734c82 100644
--- a/src/gui/image/qvolatileimage.cpp
+++ b/src/gui/image/qvolatileimage.cpp
@@ -200,6 +200,16 @@ QImage &QVolatileImage::imageRef() // non-const, in order to cause a detach
     return d->image;
 }
 
+/*!
+  Non-detaching version, for read-only access only.
+  Must be guarded by begin/endDataAccess().
+ */
+const QImage &QVolatileImage::constImageRef() const
+{
+    const_cast<QVolatileImageData *>(d.data())->ensureImage();
+    return d->image;
+}
+
 void *QVolatileImage::duplicateNativeImage() const
 {
     return d->duplicateNativeImage();
@@ -289,12 +299,14 @@ bool QVolatileImagePaintEngine::end()
 void QVolatileImagePaintEngine::drawPixmap(const QPointF &p, const QPixmap &pm)
 {
 #ifdef Q_OS_SYMBIAN
-    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);
     }
@@ -306,12 +318,11 @@ void QVolatileImagePaintEngine::drawPixmap(const QPointF &p, const QPixmap &pm)
 void QVolatileImagePaintEngine::drawPixmap(const QRectF &r, const QPixmap &pm, const QRectF &sr)
 {
 #ifdef Q_OS_SYMBIAN
-    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/image/qvolatileimage_p.h b/src/gui/image/qvolatileimage_p.h
index 97d6ea6..bed2e91 100644
--- a/src/gui/image/qvolatileimage_p.h
+++ b/src/gui/image/qvolatileimage_p.h
@@ -87,6 +87,7 @@ public:
     bool ensureFormat(QImage::Format format);
     QImage toImage() const;
     QImage &imageRef();
+    const QImage &constImageRef() const;
     QPaintEngine *paintEngine();
     void setAlphaChannel(const QPixmap &alphaChannel);
     void fill(uint pixelValue);
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();
 
diff --git a/src/opengl/qgl_symbian.cpp b/src/opengl/qgl_symbian.cpp
index 86176c9..20c2170 100644
--- a/src/opengl/qgl_symbian.cpp
+++ b/src/opengl/qgl_symbian.cpp
@@ -437,7 +437,6 @@ void* QGLPixmapData::toNativeType(NativeType type)
             m_source = QVolatileImage(w, h, QImage::Format_ARGB32_Premultiplied);
         return m_source.duplicateNativeImage();
     }
-
     return 0;
 }
 
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