[Webkit-unassigned] [Bug 100719] New: [Qt] Rendering a scaled canvas with shadowBlur is incorrect and really slow

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=100719

           Summary: [Qt] Rendering a scaled canvas with shadowBlur is
                    incorrect and really slow
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Macintosh
        OS/Version: Mac OS X 10.8
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P3
         Component: WebKit Qt
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: evan.exe at gmail.com


Created an attachment (id=171357)
 --> (https://bugs.webkit.org/attachment.cgi?id=171357&action=review)
Screenshot and demo C++ Qt project

OS X version: 10.8.2
Qt version: 4.8.1

Load shadow-blur-test.html in a QWebView. It renders two identical red squares with a drop shadow. The left square has a scale of 1 and the right square has a scale of 0.01.

Expected:
Both the left and right renderings should look the same.

Instead:
The left rendering is rendered correctly but the right rendering only has a drop shadow along the vertical edges. In addition, rendering the right square takes 13 seconds vs 1 millisecond for the left square. It seems that QtWebKit renders the shadow at a huge resolution and then downsamples afterwards.

Workaround:
Don't use the canvas transform API and do all transforms manually instead.

-- 
Configure bugmail: https://bugs.webkit.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.