Fix painting when using clipToImageBuffer()

Reviewed by Simon Hausmann.

When we apply the transform of the parent painter to the painter of
the transparency layer, we adopt its coordinate system, thus offset
should not be in page coordinates, but in the coordinate system of
the parent painter.

* platform/graphics/qt/GraphicsContextQt.cpp:
(WebCore::TransparencyLayer::TransparencyLayer):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@59837 268f45cc-cd09-0410-ab3c-d52691b4dbfc

WebCore/ChangeLog

+2010-05-19  Kenneth Rohde Christiansen  <kenneth@webkit.org>
+
+        Reviewed by Simon Hausmann.
+
+        Fix painting when using clipToImageBuffer()
+
+        When we apply the transform of the parent painter to the painter of
+        the transparency layer, we adopt its coordinate system, thus offset
+        should not be in page coordinates, but in the coordinate system of
+        the parent painter.
+
+        * platform/graphics/qt/GraphicsContextQt.cpp:
+        (WebCore::TransparencyLayer::TransparencyLayer):
+
 2010-05-20  Adam Langley  <agl@chromium.org>
         Reviewed by David Levin.

WebCore/platform/graphics/qt/GraphicsContextQt.cpp

@@ -173,7 +173,7 @@ struct TransparencyLayer : FastAllocBase {
         , alphaMask(alphaMask)
         , saveCounter(1) // see the comment for saveCounter
     {
-        offset = rect.topLeft();
+        offset = p->transform().mapRect(rect).topLeft();
         pixmap.fill(Qt::transparent);
         painter.begin(&pixmap);
         painter.setRenderHint(QPainter::Antialiasing, p->testRenderHint(QPainter::Antialiasing));