[Qt] Enable tiled shadow blur for inset box shadows

https://bugs.webkit.org/show_bug.cgi?id=111736

Reviewed by Noam Rosenthal.

Paint inset box-shadows using the optimized tiled shadow blur, instead of
applying shadow blur to the entire painted rect.

This optimizes the default CSS on common pastebin sites.

Tested by existing tests.

* platform/graphics/GraphicsContext.cpp:
* platform/graphics/ShadowBlur.cpp:
(WebCore::ShadowBlur::drawInsetShadowWithTiling):
    Must set fill color before calling clearShadow, as that might clear m_color.
(WebCore::ShadowBlur::drawLayerPieces):
    Ditto.
* platform/graphics/qt/GraphicsContextQt.cpp:
(WebCore::GraphicsContext::fillPath):
(WebCore::GraphicsContext::fillRectWithRoundedHole):

Change-Id: Idc563ff997f8150ef9553d8fe3d164e488f16e9f
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145366 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>

3 files changed, 34 insertions, 3 deletions

diff --git a/Source/WebCore/platform/graphics/GraphicsContext.cpp b/Source/WebCore/platform/graphics/GraphicsContext.cpp
index c21173ae2..4ede7da2e 100644
--- a/Source/WebCore/platform/graphics/GraphicsContext.cpp
+++ b/Source/WebCore/platform/graphics/GraphicsContext.cpp
@@ -671,7 +671,7 @@ void GraphicsContext::fillRoundedRect(const RoundedRect& rect, const Color& colo
     fillRoundedRect(rect.rect(), rect.radii().topLeft(), rect.radii().topRight(), rect.radii().bottomLeft(), rect.radii().bottomRight(), color, colorSpace);
 }
 
-#if !USE(CG)
+#if !USE(CG) && !PLATFORM(QT)
 void GraphicsContext::fillRectWithRoundedHole(const IntRect& rect, const RoundedRect& roundedHoleRect, const Color& color, ColorSpace colorSpace)
 {
     if (paintingDisabled())
diff --git a/Source/WebCore/platform/graphics/ShadowBlur.cpp b/Source/WebCore/platform/graphics/ShadowBlur.cpp
index 335928367..5c92612d2 100644
--- a/Source/WebCore/platform/graphics/ShadowBlur.cpp
+++ b/Source/WebCore/platform/graphics/ShadowBlur.cpp
@@ -696,9 +696,9 @@ void ShadowBlur::drawInsetShadowWithTiling(GraphicsContext* graphicsContext, con
 
     {
         GraphicsContextStateSaver fillStateSaver(*graphicsContext);
-        graphicsContext->clearShadow();
         graphicsContext->setFillRule(RULE_EVENODD);
         graphicsContext->setFillColor(m_color, m_colorSpace);
+        graphicsContext->clearShadow();
         graphicsContext->fillPath(exteriorPath);
     }
     
@@ -772,8 +772,8 @@ void ShadowBlur::drawLayerPieces(GraphicsContext* graphicsContext, const FloatRe
     }
 
     GraphicsContextStateSaver stateSaver(*graphicsContext);
-    graphicsContext->clearShadow();
     graphicsContext->setFillColor(m_color, m_colorSpace);
+    graphicsContext->clearShadow();
 
     // Note that drawing the ImageBuffer is faster than creating a Image and drawing that,
     // because ImageBuffer::draw() knows that it doesn't have to copy the image bits.
diff --git a/Source/WebCore/platform/graphics/qt/GraphicsContextQt.cpp b/Source/WebCore/platform/graphics/qt/GraphicsContextQt.cpp
index e91c2d287..ec992d648 100644
--- a/Source/WebCore/platform/graphics/qt/GraphicsContextQt.cpp
+++ b/Source/WebCore/platform/graphics/qt/GraphicsContextQt.cpp
@@ -791,6 +791,37 @@ void GraphicsContext::fillRoundedRect(const IntRect& rect, const IntSize& topLef
     p->fillPath(path.platformPath(), QColor(color));
 }
 
+void GraphicsContext::fillRectWithRoundedHole(const IntRect& rect, const RoundedRect& roundedHoleRect, const Color& color, ColorSpace colorSpace)
+{
+    if (paintingDisabled() || !color.isValid())
+        return;
+
+    Path path;
+    path.addRect(rect);
+    if (!roundedHoleRect.radii().isZero())
+        path.addRoundedRect(roundedHoleRect);
+    else
+        path.addRect(roundedHoleRect.rect());
+
+    QPainterPath platformPath = path.platformPath();
+    platformPath.setFillRule(Qt::OddEvenFill);
+
+    QPainter* p = m_data->p();
+    if (hasShadow()) {
+        ShadowBlur* shadow = shadowBlur();
+        if (shadow->mustUseShadowBlur(this))
+            shadow->drawInsetShadow(this, rect, roundedHoleRect.rect(), roundedHoleRect.radii());
+        else {
+            const QPointF shadowOffset(m_state.shadowOffset.width(), m_state.shadowOffset.height());
+            p->translate(shadowOffset);
+            p->fillPath(platformPath, QColor(m_state.shadowColor));
+            p->translate(-shadowOffset);
+        }
+    }
+
+    p->fillPath(platformPath, QColor(color));
+}
+
 bool GraphicsContext::isInTransparencyLayer() const
 {
     return m_data->layerCount;