[Qt][WK2] Fix painting on Mac with retina display

https://bugs.webkit.org/show_bug.cgi?id=104574

Reviewed by Kenneth Rohde Christiansen.

Since HiDPI support has been added and enabled in Qt we ended up
painting incorrectly scaled content on high-resolution screens.
Because the intrinsic device pixel ratio is always taken into
account by Qt when painting to high-resolution screens we should
automatically obtain the scale ratio from the window in which the
item is rendered instead of setting it in QML.

Qt does not make it possible to override the device pixel ratio
of the native window, therefore our experimental QML API for setting
a custom value is of no use any more and should be removed.

This patch fixes the scaling issue on Mac retina display by querying
the underlying window for the device scale factor and applying it to
the backing store and the scene-graph rendering of the content node.
Additionally removes the experimental API and related API tests.

Change-Id: I04f23059147773ca279a89ae8976ccd3d9bef292
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@137597 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

10 files changed, 111 insertions, 134 deletions

diff --git a/Source/WebKit2/ChangeLog b/Source/WebKit2/ChangeLog
index afbaeec1a..64e7283e3 100644
--- a/Source/WebKit2/ChangeLog
+++ b/Source/WebKit2/ChangeLog
@@ -1,3 +1,52 @@
+2012-12-13  Andras Becsi  <andras.becsi@digia.com>
+
+        [Qt][WK2] Fix painting on Mac with retina display
+        https://bugs.webkit.org/show_bug.cgi?id=104574
+
+        Reviewed by Kenneth Rohde Christiansen.
+
+        Since HiDPI support has been added and enabled in Qt we ended up
+        painting incorrectly scaled content on high-resolution screens.
+        Because the intrinsic device pixel ratio is always taken into
+        account by Qt when painting to high-resolution screens we should
+        automatically obtain the scale ratio from the window in which the
+        item is rendered instead of setting it in QML.
+
+        Qt does not make it possible to override the device pixel ratio
+        of the native window, therefore our experimental QML API for setting
+        a custom value is of no use any more and should be removed.
+
+        This patch fixes the scaling issue on Mac retina display by querying
+        the underlying window for the device scale factor and applying it to
+        the backing store and the scene-graph rendering of the content node.
+        Additionally removes the experimental API and related API tests.
+
+        * UIProcess/API/qt/qquickwebpage.cpp:
+        (QQuickWebPage::updatePaintNode):
+        * UIProcess/API/qt/qquickwebview.cpp:
+        (QQuickWebViewPrivate::QQuickWebViewPrivate):
+        (QQuickWebViewLegacyPrivate::updateViewportSize):
+        (QQuickWebViewFlickablePrivate::onComponentComplete):
+        * UIProcess/API/qt/qquickwebview_p.h:
+        * UIProcess/API/qt/tests/qquickwebview/tst_qquickwebview.cpp:
+        (tst_QQuickWebView::newWebView):
+        * UIProcess/CoordinatedGraphics/CoordinatedLayerTreeHostProxy.cpp:
+        (WebKit::CoordinatedLayerTreeHostProxy::setVisibleContentsRect):
+        (WebKit::CoordinatedLayerTreeHostProxy::deviceScaleFactor):
+        * UIProcess/CoordinatedGraphics/CoordinatedLayerTreeHostProxy.h:
+        (CoordinatedLayerTreeHostProxy):
+        * UIProcess/qt/QtWebPageSGNode.cpp:
+        (WebKit::ContentsSGNode::ContentsSGNode):
+        (WebKit::ContentsSGNode::render):
+        (WebKit::ContentsSGNode::clipRect):
+        (ContentsSGNode):
+        (WebKit::QtWebPageSGNode::QtWebPageSGNode):
+        (WebKit::QtWebPageSGNode::devicePixelRatio):
+        (WebKit):
+        (WebKit::QtWebPageSGNode::setRenderer):
+        * UIProcess/qt/QtWebPageSGNode.h:
+        (QtWebPageSGNode):
+
 2012-12-10  Simon Hausmann  <simon.hausmann@digia.com>
 
         [Qt] Fix QtWebProcess discovery on Windows
diff --git a/Source/WebKit2/UIProcess/API/qt/qquickwebpage.cpp b/Source/WebKit2/UIProcess/API/qt/qquickwebpage.cpp
index e5f3d3ed4..a1f35ae47 100644
--- a/Source/WebKit2/UIProcess/API/qt/qquickwebpage.cpp
+++ b/Source/WebKit2/UIProcess/API/qt/qquickwebpage.cpp
@@ -30,6 +30,7 @@
 #include "qquickwebpage_p_p.h"
 #include "qquickwebview_p.h"
 #include "qwebkittest_p.h"
+#include <QQuickWindow>
 
 using namespace WebKit;
 
@@ -84,8 +85,18 @@ QSGNode* QQuickWebPage::updatePaintNode(QSGNode* oldNode, UpdatePaintNodeData*)
     LayerTreeRenderer* renderer = layerTreeCoordinatorProxy->layerTreeRenderer();
 
     QtWebPageSGNode* node = static_cast<QtWebPageSGNode*>(oldNode);
+
+    const QWindow* window = this->window();
+    ASSERT(window);
+
+    if (window && d->webPageProxy->deviceScaleFactor() != window->devicePixelRatio()) {
+        d->webPageProxy->setIntrinsicDeviceScaleFactor(window->devicePixelRatio());
+        d->viewportItem->experimental()->test()->devicePixelRatioChanged();
+    }
+
     if (!node)
-        node = new QtWebPageSGNode();
+        node = new QtWebPageSGNode(this);
+
     node->setRenderer(renderer);
 
     node->setScale(d->contentsScale);
diff --git a/Source/WebKit2/UIProcess/API/qt/qquickwebview.cpp b/Source/WebKit2/UIProcess/API/qt/qquickwebview.cpp
index 0e33f116f..437d08b94 100644
--- a/Source/WebKit2/UIProcess/API/qt/qquickwebview.cpp
+++ b/Source/WebKit2/UIProcess/API/qt/qquickwebview.cpp
@@ -826,16 +826,15 @@ void QQuickWebViewLegacyPrivate::updateViewportSize()
     if (viewportSize.isEmpty())
         return;
 
-    float devicePixelRatio = webPageProxy->deviceScaleFactor();
     pageView->setContentsSize(viewportSize);
-    // Make sure that our scale matches the one passed to setVisibleContentsRect.
-    pageView->setContentsScale(devicePixelRatio);
 
     // The fixed layout is handled by the FrameView and the drawing area doesn't behave differently
     // whether its fixed or not. We still need to tell the drawing area which part of it
     // has to be rendered on tiles, and in desktop mode it's all of it.
-    webPageProxy->drawingArea()->setSize((viewportSize / devicePixelRatio).toSize(), IntSize());
-    webPageProxy->drawingArea()->setVisibleContentsRect(FloatRect(FloatPoint(), FloatSize(viewportSize / devicePixelRatio)), devicePixelRatio, FloatPoint());
+    webPageProxy->drawingArea()->setSize(viewportSize.toSize(), IntSize());
+    // The backing store scale factor should already be set to the device pixel ratio
+    // of the underlying window, thus we set the effective scale to 1 here.
+    webPageProxy->drawingArea()->setVisibleContentsRect(FloatRect(FloatPoint(), FloatSize(viewportSize)), 1, FloatPoint());
 }
 
 qreal QQuickWebViewLegacyPrivate::zoomFactor() const
@@ -1194,59 +1193,6 @@ void QQuickWebViewExperimental::setUserAgent(const QString& userAgent)
 /*!
     \internal
 
-    \qmlproperty real WebViewExperimental::devicePixelRatio
-    \brief The ratio between the CSS units and device pixels when the content is unscaled.
-
-    When designing touch-friendly contents, knowing the approximated target size on a device
-    is important for contents providers in order to get the intented layout and element
-    sizes.
-
-    As most first generation touch devices had a PPI of approximately 160, this became a
-    de-facto value, when used in conjunction with the viewport meta tag.
-
-    Devices with a higher PPI learning towards 240 or 320, applies a pre-scaling on all
-    content, of either 1.5 or 2.0, not affecting the CSS scale or pinch zooming.
-
-    This value can be set using this property and it is exposed to CSS media queries using
-    the -webkit-device-pixel-ratio query.
-
-    For instance, if you want to load an image without having it upscaled on a web view
-    using a device pixel ratio of 2.0 it can be done by loading an image of say 100x100
-    pixels but showing it at half the size.
-
-    FIXME: Move documentation example out in separate files
-
-    @media (-webkit-min-device-pixel-ratio: 1.5) {
-        .icon {
-            width: 50px;
-            height: 50px;
-            url: "/images/icon@2x.png"; // This is actually a 100x100 image
-        }
-    }
-
-    If the above is used on a device with device pixel ratio of 1.5, it will be scaled
-    down but still provide a better looking image.
-*/
-
-qreal QQuickWebViewExperimental::devicePixelRatio() const
-{
-    Q_D(const QQuickWebView);
-    return d->webPageProxy->deviceScaleFactor();
-}
-
-void QQuickWebViewExperimental::setDevicePixelRatio(qreal devicePixelRatio)
-{
-    Q_D(QQuickWebView);
-    if (0 >= devicePixelRatio || devicePixelRatio == this->devicePixelRatio())
-        return;
-
-    d->webPageProxy->setIntrinsicDeviceScaleFactor(devicePixelRatio);
-    emit devicePixelRatioChanged();
-}
-
-/*!
-    \internal
-
     \qmlproperty int WebViewExperimental::deviceWidth
     \brief The device width used by the viewport calculations.
 
diff --git a/Source/WebKit2/UIProcess/API/qt/qquickwebview_p.h b/Source/WebKit2/UIProcess/API/qt/qquickwebview_p.h
index dfe7ad88e..1b372fa40 100644
--- a/Source/WebKit2/UIProcess/API/qt/qquickwebview_p.h
+++ b/Source/WebKit2/UIProcess/API/qt/qquickwebview_p.h
@@ -256,7 +256,6 @@ class QWEBKIT_EXPORT QQuickWebViewExperimental : public QObject {
     Q_PROPERTY(int preferredMinimumContentsWidth WRITE setPreferredMinimumContentsWidth READ preferredMinimumContentsWidth NOTIFY preferredMinimumContentsWidthChanged)
     Q_PROPERTY(int deviceWidth WRITE setDeviceWidth READ deviceWidth NOTIFY deviceWidthChanged)
     Q_PROPERTY(int deviceHeight WRITE setDeviceHeight READ deviceHeight NOTIFY deviceHeightChanged)
-    Q_PROPERTY(qreal devicePixelRatio READ devicePixelRatio WRITE setDevicePixelRatio NOTIFY devicePixelRatioChanged)
 
     Q_PROPERTY(QWebNavigationHistory* navigationHistory READ navigationHistory CONSTANT FINAL)
 
@@ -312,8 +311,6 @@ public:
     void setDeviceWidth(int);
     int deviceHeight() const;
     void setDeviceHeight(int);
-    qreal devicePixelRatio() const;
-    void setDevicePixelRatio(qreal);
     QList<QUrl> userScripts() const;
     void setUserScripts(const QList<QUrl>& userScripts);
     QUrl remoteInspectorUrl() const;
@@ -371,7 +368,6 @@ Q_SIGNALS:
     void userAgentChanged();
     void deviceWidthChanged();
     void deviceHeightChanged();
-    void devicePixelRatioChanged();
     void enterFullScreenRequested();
     void exitFullScreenRequested();
     void userScriptsChanged();
diff --git a/Source/WebKit2/UIProcess/API/qt/tests/qmltests/WebView/tst_devicePixelRatio.qml b/Source/WebKit2/UIProcess/API/qt/tests/qmltests/WebView/tst_devicePixelRatio.qml
deleted file mode 100644
index 0442b53c9..000000000
--- a/Source/WebKit2/UIProcess/API/qt/tests/qmltests/WebView/tst_devicePixelRatio.qml
+++ /dev/null
@@ -1,62 +0,0 @@
-import QtQuick 2.0
-import QtTest 1.0
-import QtWebKit 3.0
-import QtWebKit.experimental 1.0
-import "../common"
-
-
-TestWebView {
-    id: webView
-    property variant lastResult
-    width: 400
-    height: 300
-    focus: true
-
-    SignalSpy {
-        id: resultSpy
-        target: webView
-        signalName: "lastResultChanged"
-    }
-
-    TestCase {
-        name: "DevicePixelRatio"
-
-        function init() {
-            resultSpy.clear()
-            webView.lastResult = null
-        }
-
-        function test_devicePixelRatio() {
-            resultSpy.clear()
-            webView.url = Qt.resolvedUrl("../common/test1.html");
-            webView.experimental.devicePixelRatio = 2.0
-            verify(webView.waitForLoadSucceeded())
-
-            webView.experimental.evaluateJavaScript(
-                "(function() { return window.devicePixelRatio })()",
-                function(result) {
-                    webView.lastResult = result
-                })
-
-            resultSpy.wait()
-            compare(webView.lastResult, 2.0)
-            compare(webView.lastResult, webView.experimental.devicePixelRatio)
-        }
-
-        function test_devicePixelRatioMediaQuery() {
-            resultSpy.clear()
-            webView.url = Qt.resolvedUrl("../common/test2.html");
-            webView.experimental.devicePixelRatio = 2.0
-            verify(webView.waitForLoadSucceeded())
-
-            webView.experimental.evaluateJavaScript(
-                "(function() { return window.matchMedia(\"(-webkit-device-pixel-ratio: 2)\").matches })()",
-                function(result) {
-                    webView.lastResult = result
-                })
-
-            resultSpy.wait()
-            verify(webView.lastResult)
-        }
-    }
-}
diff --git a/Source/WebKit2/UIProcess/API/qt/tests/qquickwebview/tst_qquickwebview.cpp b/Source/WebKit2/UIProcess/API/qt/tests/qquickwebview/tst_qquickwebview.cpp
index 6e2c342cb..7cf1ddb72 100644
--- a/Source/WebKit2/UIProcess/API/qt/tests/qquickwebview/tst_qquickwebview.cpp
+++ b/Source/WebKit2/UIProcess/API/qt/tests/qquickwebview/tst_qquickwebview.cpp
@@ -93,7 +93,6 @@ QQuickWebView* tst_QQuickWebView::newWebView()
 {
     QObject* viewInstance = m_component->create();
     QQuickWebView* webView = qobject_cast<QQuickWebView*>(viewInstance);
-    webView->experimental()->setDevicePixelRatio(1.5);
     return webView;
 }
 
diff --git a/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeCoordinatorProxy.cpp b/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeCoordinatorProxy.cpp
index 8fb12b902..9cb2c1bc5 100644
--- a/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeCoordinatorProxy.cpp
+++ b/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeCoordinatorProxy.cpp
@@ -56,6 +56,11 @@ void LayerTreeCoordinatorProxy::updateViewport()
     m_drawingAreaProxy->updateViewport();
 }
 
+float LayerTreeCoordinatorProxy::deviceScaleFactor() const
+{
+    return m_drawingAreaProxy->page()->deviceScaleFactor();
+}
+
 void LayerTreeCoordinatorProxy::dispatchUpdate(const Function<void()>& function)
 {
     m_renderer->appendUpdate(function);
@@ -178,19 +183,20 @@ void LayerTreeCoordinatorProxy::setAnimationsLocked(bool locked)
     dispatchUpdate(bind(&LayerTreeRenderer::setAnimationsLocked, m_renderer.get(), locked));
 }
 
-void LayerTreeCoordinatorProxy::setVisibleContentsRect(const FloatRect& rect, float scale, const FloatPoint& trajectoryVector)
+void LayerTreeCoordinatorProxy::setVisibleContentsRect(const FloatRect& rect, float pageScaleFactor, const FloatPoint& trajectoryVector)
 {
     // Inform the renderer to adjust viewport-fixed layers.
     dispatchUpdate(bind(&LayerTreeRenderer::setVisibleContentsRect, m_renderer.get(), rect));
 
     // Round the rect instead of enclosing it to make sure that its size stays the same while panning. This can have nasty effects on layout.
     IntRect roundedRect = roundedIntRect(rect);
-    if (roundedRect == m_lastSentVisibleRect && scale == m_lastSentScale && trajectoryVector == m_lastSentTrajectoryVector)
+    const float effectiveScale = deviceScaleFactor() * pageScaleFactor;
+    if (roundedRect == m_lastSentVisibleRect && effectiveScale == m_lastSentScale && trajectoryVector == m_lastSentTrajectoryVector)
         return;
 
-    m_drawingAreaProxy->page()->process()->send(Messages::LayerTreeCoordinator::SetVisibleContentsRect(roundedRect, scale, trajectoryVector), m_drawingAreaProxy->page()->pageID());
+    m_drawingAreaProxy->page()->process()->send(Messages::LayerTreeCoordinator::SetVisibleContentsRect(roundedRect, effectiveScale, trajectoryVector), m_drawingAreaProxy->page()->pageID());
     m_lastSentVisibleRect = roundedRect;
-    m_lastSentScale = scale;
+    m_lastSentScale = effectiveScale;
     m_lastSentTrajectoryVector = trajectoryVector;
 }
 
diff --git a/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeCoordinatorProxy.h b/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeCoordinatorProxy.h
index fb58b1ae7..a3961ffef 100644
--- a/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeCoordinatorProxy.h
+++ b/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeCoordinatorProxy.h
@@ -64,7 +64,7 @@ public:
     void deleteCompositingLayer(WebLayerID);
     void setRootCompositingLayer(WebLayerID);
     void setContentsSize(const WebCore::FloatSize&);
-    void setVisibleContentsRect(const WebCore::FloatRect&, float scale, const WebCore::FloatPoint& trajectoryVector);
+    void setVisibleContentsRect(const WebCore::FloatRect&, float pageScaleFactor, const WebCore::FloatPoint& trajectoryVector);
     void didRenderFrame(const WebCore::IntSize& contentsSize, const WebCore::IntRect& coveredRect);
     void createTileForLayer(int layerID, int tileID, const WebCore::IntRect&, const SurfaceUpdateInfo&);
     void updateTileForLayer(int layerID, int tileID, const WebCore::IntRect&, const SurfaceUpdateInfo&);
@@ -94,6 +94,8 @@ public:
 #endif
     void setBackgroundColor(const WebCore::Color&);
 
+    float deviceScaleFactor() const;
+
 protected:
     void dispatchUpdate(const Function<void()>&);
 
diff --git a/Source/WebKit2/UIProcess/qt/QtWebPageSGNode.cpp b/Source/WebKit2/UIProcess/qt/QtWebPageSGNode.cpp
index eb7023990..d72980c05 100644
--- a/Source/WebKit2/UIProcess/qt/QtWebPageSGNode.cpp
+++ b/Source/WebKit2/UIProcess/qt/QtWebPageSGNode.cpp
@@ -23,7 +23,10 @@
 
 #include "LayerTreeRenderer.h"
 #include <QtGui/QPolygonF>
+#include <QtQuick/QQuickItem>
+#include <QtQuick/QQuickWindow>
 #include <QtQuick/QSGSimpleRectNode>
+#include <WebCore/TransformationMatrix.h>
 #include <private/qsgrendernode_p.h>
 
 using namespace WebCore;
@@ -45,7 +48,13 @@ public:
 
     virtual void render(const RenderState& state)
     {
-        QMatrix4x4 renderMatrix = matrix() ? *matrix() : QMatrix4x4();
+        TransformationMatrix renderMatrix;
+        if (pageNode()->devicePixelRatio() != 1.0) {
+            renderMatrix.scale(pageNode()->devicePixelRatio());
+            if (matrix())
+                renderMatrix.multiply(*matrix());
+        } else if (matrix())
+            renderMatrix = *matrix();
 
         // When rendering to an intermediate surface, Qt will
         // mirror the projection matrix to fit on the destination coordinate system.
@@ -61,6 +70,13 @@ public:
         layerTreeRenderer()->purgeGLResources();
     }
 
+    const QtWebPageSGNode* pageNode() const
+    {
+        const QtWebPageSGNode* parent = static_cast<QtWebPageSGNode*>(this->parent());
+        ASSERT(parent);
+        return parent;
+    }
+
     LayerTreeRenderer* layerTreeRenderer() const { return m_renderer.get(); }
 
 private:
@@ -73,6 +89,8 @@ private:
             QMatrix4x4 clipMatrix;
             if (clip->matrix())
                 clipMatrix = *clip->matrix();
+            clipMatrix.scale(pageNode()->devicePixelRatio());
+
             QRectF currentClip;
 
             if (clip->isRectangular())
@@ -108,9 +126,10 @@ private:
     RefPtr<LayerTreeRenderer> m_renderer;
 };
 
-QtWebPageSGNode::QtWebPageSGNode()
+QtWebPageSGNode::QtWebPageSGNode(const QQuickItem* item)
     : m_contentsNode(0)
     , m_backgroundNode(new QSGSimpleRectNode)
+    , m_item(item)
 {
     appendChildNode(m_backgroundNode);
 }
@@ -128,6 +147,13 @@ void QtWebPageSGNode::setScale(float scale)
     setMatrix(matrix);
 }
 
+qreal QtWebPageSGNode::devicePixelRatio() const
+{
+    if (const QWindow* window = m_item->window())
+        return window->devicePixelRatio();
+    return 1;
+}
+
 void QtWebPageSGNode::setRenderer(PassRefPtr<LayerTreeRenderer> renderer)
 {
     if (m_contentsNode && m_contentsNode->layerTreeRenderer() == renderer)
@@ -135,6 +161,7 @@ void QtWebPageSGNode::setRenderer(PassRefPtr<LayerTreeRenderer> renderer)
 
     delete m_contentsNode;
     m_contentsNode = new ContentsSGNode(renderer);
+    // This sets the parent node of the content to QtWebPageSGNode.
     appendChildNode(m_contentsNode);
 }
 
diff --git a/Source/WebKit2/UIProcess/qt/QtWebPageSGNode.h b/Source/WebKit2/UIProcess/qt/QtWebPageSGNode.h
index 11d18984e..368df704a 100644
--- a/Source/WebKit2/UIProcess/qt/QtWebPageSGNode.h
+++ b/Source/WebKit2/UIProcess/qt/QtWebPageSGNode.h
@@ -25,6 +25,7 @@
 #include <wtf/PassRefPtr.h>
 
 QT_BEGIN_NAMESPACE
+class QQuickItem;
 class QSGSimpleRectNode;
 QT_END_NAMESPACE
 
@@ -35,14 +36,16 @@ class LayerTreeRenderer;
 
 class QtWebPageSGNode : public QSGTransformNode {
     public:
-        QtWebPageSGNode();
+        QtWebPageSGNode(const QQuickItem*);
         void setBackground(const QRectF&, const QColor&);
         void setScale(float);
         void setRenderer(PassRefPtr<LayerTreeRenderer>);
+        qreal devicePixelRatio() const;
 
     private:
         ContentsSGNode* m_contentsNode;
         QSGSimpleRectNode* m_backgroundNode;
+        const QQuickItem* const m_item;
 };
 
 } // namespace WebKit