[Webkit-unassigned] [Bug 29438] New: [Qt] WebKit: webpage with flash

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=29438

           Summary: [Qt] WebKit: webpage with flash
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Other
        OS/Version: Mac OS X 10.5
            Status: NEW
          Keywords: Qt
          Severity: Normal
          Priority: P2
         Component: New Bugs
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: vestbo at webkit.org


banner uses more CPU time than normal browser.

This bug report originated from issue QTBUG-4251
<http://bugreports.qt.nokia.com/browse/QTBUG-4251>

--- Description ---

Simple test application (source attached) shows webpage with flash 
banner. Unfortunately it uses much more CPU time than normal browser 
which shows same page (Internet Explorer, Mozilla Firefox, Safari).

We analysed application using DevPartner profiler and it shows that 
problem is with QT and WebKit integration.

Application spend lot of time in function QPixmap::fromWinHBITMAP() in 
GraphicsContext::releaseWindowsContext() 
(C:\Qt\4.5.2\src\3rdparty\webkit\WebCore\platform\graphics\GraphicsContext.cpp). 
We analysed releaseWindowsContext() function and think that translation 
from HDC to QPixmap is not optimal solution. Source code below:

GraphicsContext::releaseWindowsContext()
...
  HBITMAP bitmap = static_cast<HBITMAP>(GetCurrentObject(hdc, OBJ_BITMAP));
  BITMAP info;
  GetObject(bitmap, sizeof(info), &info);
  ASSERT(info.bmBitsPixel == 32);

  QPixmap pixmap = QPixmap::fromWinHBITMAP(bitmap, supportAlphaBlend ? 
QPixmap::PremultipliedAlpha : QPixmap::NoAlpha);
  m_data->p()->drawPixmap(dstRect, pixmap);

We think that it will be better to draw HDC directly on the screen 
without translation to QPixmap.

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