[Qt] Possibility to reduce extra SmoothPixMapTransform during image drawing

[chunrong]

I see that current Webkit performs quite a few of SmoothPixmapTransform during image drawing. Some of them might be optimizable.
  Attach patch wants to disable the transform in drawing images which are scaled to smaller size without rotation.
I also attached a simple test webpage which can shows 6X~8X performance difference in my testing.

--- qt.old/ImageQt.cpp	2010-12-08 15:26:15.237726493 +0800
+++ qt/ImageQt.cpp	2010-12-09 18:22:20.817755997 +0800
@@ -189,6 +189,13 @@
 
     // Test using example site at
     // http://www.meyerweb.com/eric/css/edge/complexspiral/demo.html
+    float tsw = src.width();
+    float tsh = src.height();
+    float tw = dst.width();
+    float th = dst.height();
+    if( tw <= tsw && th <= tsh && ctxt->platformContext()->combinedTransform().type() <= QTransform::TxScale){
+        painter->setRenderHint(QPainter::SmoothPixmapTransform, false);
+    }
     painter->drawPixmap(dst, *image, src);
 
     ctxt->restore();

[chunrong]

Created attachment 76181 [details]
A simple test page

[chunrong]

Created attachment 76182 [details]
The tested image for the test page

[chunrong]

Created attachment 76183 [details]
The proposed simple patch

[Benjamin Poulain]

Please follow http://trac.webkit.org/wiki/QtWebKitBugs when reporing bug here.

Closing as invalid, this ha already been discussed on the mailing list. Note that when you include a patch, you should set the review flag (r?) and include a changelog. See https://trac.webkit.org/wiki/QtWebKitContrib.