Friedemann's crash fix

Don't delete the paint device after painting has started.

1 files changed, 26 insertions, 24 deletions

diff --git a/src/gui/painting/qbackingstore.cpp b/src/gui/painting/qbackingstore.cpp
index 65a108f7ee..7b0a4e2ed4 100644
--- a/src/gui/painting/qbackingstore.cpp
+++ b/src/gui/painting/qbackingstore.cpp
@@ -118,31 +118,8 @@ QPaintDevice *QBackingStore::paintDevice()
 {
     QPaintDevice *device = d_ptr->platformBackingStore->paintDevice();
 
-    // When QtGui is applying a high-dpi scale factor the backing store
-    // creates a "large" backing store image. This image needs to be
-    // painted on as a high-dpi image, which is done by setting
-    // devicePixelRatio. Do this on a separate image instance that shares
-    // the image data to avoid having the new devicePxielRatio be propagated
-    // back to the platform plugin.
-    if (QHighDpiScaling::isActive() && device->devType() == QInternal::Image) {
-        QImage *source = reinterpret_cast<QImage *>(device);
-        const bool needsNewImage = d_ptr->highDpiBackingstore.isNull()
-            || source->data_ptr() != d_ptr->highDpiBackingstore->data_ptr()
-            || source->size() != d_ptr->highDpiBackingstore->size()
-            || source->devicePixelRatio() != d_ptr->highDpiBackingstore->devicePixelRatio();
-        if (needsNewImage) {
-            qCDebug(lcScaling) << "QBackingStore::paintDevice new backingstore for" << d_ptr->window;
-            qCDebug(lcScaling) << "  source size" << source->size() << "dpr" << source->devicePixelRatio();
-            d_ptr->highDpiBackingstore.reset(
-                new QImage(source->bits(), source->width(), source->height(), source->format()));
-            qreal targetDevicePixelRatio = d_ptr->window->devicePixelRatio();
-            d_ptr->highDpiBackingstore->setDevicePixelRatio(targetDevicePixelRatio);
-            qCDebug(lcScaling) <<"  destinaion size" << d_ptr->highDpiBackingstore->size()
-                               << "dpr" << targetDevicePixelRatio;
-        }
-
+    if (QHighDpiScaling::isActive() && device->devType() == QInternal::Image)
         return d_ptr->highDpiBackingstore.data();
-    }
 
     return device;
 }
@@ -185,6 +162,31 @@ void QBackingStore::beginPaint(const QRegion &region)
     if (d_ptr->highDpiBackingstore &&
         d_ptr->highDpiBackingstore->devicePixelRatio() != d_ptr->window->devicePixelRatio())
         resize(size());
+
+    // When QtGui is applying a high-dpi scale factor the backing store
+    // creates a "large" backing store image. This image needs to be
+    // painted on as a high-dpi image, which is done by setting
+    // devicePixelRatio. Do this on a separate image instance that shares
+    // the image data to avoid having the new devicePxielRatio be propagated
+    // back to the platform plugin.
+    QPaintDevice *device = d_ptr->platformBackingStore->paintDevice();
+    if (QHighDpiScaling::isActive() && device->devType() == QInternal::Image) {
+        QImage *source = reinterpret_cast<QImage *>(device);
+        const bool needsNewImage = d_ptr->highDpiBackingstore.isNull()
+            || source->data_ptr() != d_ptr->highDpiBackingstore->data_ptr()
+            || source->size() != d_ptr->highDpiBackingstore->size()
+            || source->devicePixelRatio() != d_ptr->highDpiBackingstore->devicePixelRatio();
+        if (needsNewImage) {
+            qCDebug(lcScaling) << "QBackingStore::beginPaint new backingstore for" << d_ptr->window;
+            qCDebug(lcScaling) << "  source size" << source->size() << "dpr" << source->devicePixelRatio();
+            d_ptr->highDpiBackingstore.reset(
+                new QImage(source->bits(), source->width(), source->height(), source->format()));
+            qreal targetDevicePixelRatio = d_ptr->window->devicePixelRatio();
+            d_ptr->highDpiBackingstore->setDevicePixelRatio(targetDevicePixelRatio);
+            qCDebug(lcScaling) <<"  destination size" << d_ptr->highDpiBackingstore->size()
+                               << "dpr" << targetDevicePixelRatio;
+        }
+    }
     d_ptr->platformBackingStore->beginPaint(QHighDpi::toNativeLocalRegion(region, d_ptr->window));
 }