Bug 63555 – [Qt] GraphicsContext::clipToImageBuffer does not support scale transformation

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Igor Trindade Oliveira]

Qt implementation of GraphicsContext::clipToImageBuffer calls internally ImageBuffer::clip.
ImageBuffer::clip creates a alphaMask and push it in TransparencyLayer. However if GraphicsContext does a scale
transformation the alphaMask is not scaled.

[Igor Trindade Oliveira]

Created attachment 98963 [details]
Patch

Proposed patch.

[Andreas Kling]

Comment on attachment 98963 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=98963&action=review

> Source/WebCore/ChangeLog:10
> +        No new tests. (OOPS!)

Oops indeed! The commit-queue will choke on this line, replace it with one of these three:
1) Tests: list of tests that exercise this change...
2) No new tests because...
3) Awkward silence.

> Source/WebCore/platform/graphics/qt/ImageBufferQt.cpp:167
> +    QRectF deviceClip = context->platformContext()->transform().mapRect(floatRect);
> +    if (alphaMask.width() != deviceClip.width() || alphaMask.height() != deviceClip.height())
> +        alphaMask = alphaMask.scaled(deviceClip.width(), deviceClip.height());

We should do this in GraphicsContext::pushTransparencyLayerInternal() instead, then we avoid doing mapRect() twice, and ImageBuffer doesn't need to know about any painter transforms.

[Igor Trindade Oliveira]

Created attachment 99082 [details]
Patch

Proposed patch. Update ChangeLog and move scale complexity to GraphicsContext::pushTransparencyLayerInternal.

[WebKit Review Bot]

The commit-queue encountered the following flaky tests while processing attachment 99082 [details]:

http/tests/media/video-cancel-load.html bug 56797 (authors: [e-mail], [e-mail], [e-mail], and [e-mail])
The commit-queue is continuing to process your patch.

[WebKit Review Bot]

Comment on attachment 99082 [details]
Patch

Clearing flags on attachment: 99082

Committed r90020: <http://trac.webkit.org/changeset/90020>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.