[SCM] WebKit Debian packaging branch, debian/experimental, updated. upstream/1.3.3-9427-gc2be6fc

[ariya at webkit.org]

The following commit has been merged in the debian/experimental branch:
commit 36eb3343047d9922f87f762a721d8da58bf9ffdd
Author: ariya at webkit.org <ariya at webkit.org@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Date:   Thu Aug 19 05:59:53 2010 +0000

    [Qt] Short lived shadow buffer for blur operation
    https://bugs.webkit.org/show_bug.cgi?id=44094
    
    Patch by Ariya Hidayat <ariya at sencha.com> on 2010-08-18
    Reviewed by Kenneth Rohde Christiansen.
    
    ContextShadow needs a scratch image as the buffer for the blur filter.
    Instead of creating and destroying the buffer for every operation,
    we create a buffer which will be automatically purged via a timer.
    
    * platform/graphics/qt/ContextShadow.cpp:
    (WebCore::):
    (WebCore::ShadowBuffer::ShadowBuffer):
    (WebCore::ShadowBuffer::scratchImage):
    (WebCore::ShadowBuffer::schedulePurge):
    (WebCore::ShadowBuffer::purgeBuffer):
    (WebCore::ContextShadow::drawShadowRect):
    
    git-svn-id: http://svn.webkit.org/repository/webkit/trunk@65654 268f45cc-cd09-0410-ab3c-d52691b4dbfc

diff --git a/WebCore/ChangeLog b/WebCore/ChangeLog
index adc7b9d..9e8d269 100644
--- a/WebCore/ChangeLog
+++ b/WebCore/ChangeLog
@@ -1,3 +1,22 @@
+2010-08-18  Ariya Hidayat  <ariya at sencha.com>
+
+        Reviewed by Kenneth Rohde Christiansen.
+
+        [Qt] Short lived shadow buffer for blur operation
+        https://bugs.webkit.org/show_bug.cgi?id=44094
+
+        ContextShadow needs a scratch image as the buffer for the blur filter.
+        Instead of creating and destroying the buffer for every operation,
+        we create a buffer which will be automatically purged via a timer.
+
+        * platform/graphics/qt/ContextShadow.cpp:
+        (WebCore::):
+        (WebCore::ShadowBuffer::ShadowBuffer):
+        (WebCore::ShadowBuffer::scratchImage):
+        (WebCore::ShadowBuffer::schedulePurge):
+        (WebCore::ShadowBuffer::purgeBuffer):
+        (WebCore::ContextShadow::drawShadowRect):
+
 2010-08-18  Alexey Marinichev  <amarinichev at chromium.org>
 
         Reviewed by Darin Fisher.
diff --git a/WebCore/platform/graphics/qt/ContextShadow.cpp b/WebCore/platform/graphics/qt/ContextShadow.cpp
index 0511218..80b17f9 100644
--- a/WebCore/platform/graphics/qt/ContextShadow.cpp
+++ b/WebCore/platform/graphics/qt/ContextShadow.cpp
@@ -28,8 +28,72 @@
 #include "config.h"
 #include "ContextShadow.h"
 
+#include "Timer.h"
+#include <wtf/Noncopyable.h>
+
 namespace WebCore {
 
+// ContextShadow needs a scratch image as the buffer for the blur filter.
+// Instead of creating and destroying the buffer for every operation,
+// we create a buffer which will be automatically purged via a timer.
+
+class ShadowBuffer: public Noncopyable {
+public:
+    ShadowBuffer();
+
+    QImage* scratchImage(const QSize& size);
+
+    void schedulePurge();
+
+private:
+    QImage image;
+    void purgeBuffer(Timer<ShadowBuffer>*);
+    Timer<ShadowBuffer> purgeTimer;
+};
+
+ShadowBuffer::ShadowBuffer()
+    : purgeTimer(this, &ShadowBuffer::purgeBuffer)
+{
+}
+
+QImage* ShadowBuffer::scratchImage(const QSize& size)
+{
+    int width = size.width();
+    int height = size.height();
+
+    // We do not need to recreate the buffer if the buffer is reasonably
+    // larger than the requested size. However, if the requested size is
+    // much smaller than our buffer, reduce our buffer so that we will not
+    // keep too many allocated pixels for too long.
+    if (!image.isNull() && (image.width() > width) && (image.height() > height))
+        if (((2 * width) > image.width()) && ((2 * height) > image.height())) {
+            image.fill(Qt::transparent);
+            return &image;
+        }
+
+    // Round to the nearest 32 pixels so we do not grow the buffer everytime
+    // there is larger request by 1 pixel.
+    width = (1 + (width >> 5)) << 5;
+    height = (1 + (height >> 5)) << 5;
+
+    image = QImage(width, height, QImage::Format_ARGB32_Premultiplied);
+    image.fill(Qt::transparent);
+    return &image;
+}
+
+void ShadowBuffer::schedulePurge()
+{
+    static const double BufferPurgeDelay = 2; // seconds
+    purgeTimer.startOneShot(BufferPurgeDelay);
+}
+
+void ShadowBuffer::purgeBuffer(Timer<ShadowBuffer>*)
+{
+    image = QImage();
+}
+
+Q_GLOBAL_STATIC(ShadowBuffer, scratchShadowBuffer)
+
 ContextShadow::ContextShadow()
     : type(NoShadow)
     , blurRadius(0)
@@ -235,16 +299,18 @@ void ContextShadow::drawShadowRect(QPainter* p, const QRectF& rect)
             alignedBufferRect.adjust(-extra, -extra, extra, extra);
         }
 
-        QImage shadowImage(alignedBufferRect.size(), QImage::Format_ARGB32_Premultiplied);
-        shadowImage.fill(Qt::transparent);
-        QPainter shadowPainter(&shadowImage);
+        ShadowBuffer* shadowBuffer = scratchShadowBuffer();
+        QImage* shadowImage = shadowBuffer->scratchImage(alignedBufferRect.size());
+        QPainter shadowPainter(shadowImage);
 
         shadowPainter.fillRect(shadowRect.translated(-alignedBufferRect.topLeft()), color);
         shadowPainter.end();
 
-        shadowBlur(shadowImage, blurRadius, color);
+        shadowBlur(*shadowImage, blurRadius, color);
+
+        p->drawImage(alignedBufferRect.topLeft(), *shadowImage);
 
-        p->drawImage(alignedBufferRect.topLeft(), shadowImage);
+        shadowBuffer->schedulePurge();
 
         return;
     }

-- 
WebKit Debian packaging