Bug 42771 – Composited layers don't scroll in WebKit2

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKit2

[Simon Fraser (smfr)]

In WebKit2, composited layers don't scroll with the rest of the page.

[Simon Fraser (smfr)]

Created attachment 62217 [details]
Patch for some prep work

[Simon Fraser (smfr)]

Comment on attachment 62217 [details]
Patch for some prep work

http://trac.webkit.org/changeset/63856

[James Robinson]

I tried the patch at http://pastie.org/1054420 in a Chromium mac build and it appears to work fine - the scrolling repaint pixel tests all pass and the scrolling behavior appears correct when manually tested as well.

[Simon Fraser (smfr)]

Created attachment 62322 [details]
More prep work: single bottleneck method

[Simon Fraser (smfr)]

Comment on attachment 62322 [details]
More prep work: single bottleneck method

http://trac.webkit.org/changeset/63907

[Simon Fraser (smfr)]

Created attachment 62365 [details]
Patch

[Eric Seidel (no email)]

Comment on attachment 62217 [details]
Patch for some prep work

Cleared Anders Carlsson's review+ from obsolete attachment 62217 [details] so that this bug does not appear in http://webkit.org/pending-commit.

[Eric Seidel (no email)]

Comment on attachment 62322 [details]
More prep work: single bottleneck method

Cleared Darin Adler's review+ from obsolete attachment 62322 [details] so that this bug does not appear in http://webkit.org/pending-commit.

[Anders Carlsson]

Comment on attachment 62365 [details]
Patch

> diff --git a/WebCore/rendering/RenderLayerCompositor.cpp b/WebCore/rendering/RenderLayerCompositor.cpp
> index 234ad7f270191ef8a7ba5870b072d875bf6f7423..14d45927b3ca31cce19bce537343bbd90ccf8553 100644
> --- a/WebCore/rendering/RenderLayerCompositor.cpp
> +++ b/WebCore/rendering/RenderLayerCompositor.cpp
> -void RenderLayerCompositor::updateContentLayerScrollPosition(const IntPoint& scrollPosition)
> +void RenderLayerCompositor::frameViewDidScroll(const IntPoint& scrollPosition)
>  {
>      if (m_scrollLayer)
>          m_scrollLayer->setPosition(FloatPoint(-scrollPosition.x(), -scrollPosition.y()));
> @@ -1039,6 +1039,9 @@ bool RenderLayerCompositor::shouldPropagateCompositingToEnclosingIFrame() const
>      // On non-Mac platforms, let compositing propagate for all iframes.
>      return true;
>  #else
> +    if (!m_renderView->frameView()->platformWidget())
> +        return true;
> +
Could you add a comment about why we check for a null platform widget here?

Looks fine otherwise!

[Simon Fraser (smfr)]

http://trac.webkit.org/changeset/64054

[WebKit Review Bot]

http://trac.webkit.org/changeset/64054 might have broken Leopard Intel Debug (Tests)
The following changes are on the blame list:
http://trac.webkit.org/changeset/64053
http://trac.webkit.org/changeset/64054

[Darin Fisher (:fishd, Google)]

This patch broke scrolling in Chromium when there is a fixed position element.

Chromium bug:
http://code.google.com/p/chromium/issues/detail?id=52332

It seems like we end up missing some invalidates after scrolling.

[Simon Fraser (smfr)]

(In reply to comment #12)
> This patch broke scrolling in Chromium when there is a fixed position element.
> 
> Chromium bug:
> http://code.google.com/p/chromium/issues/detail?id=52332
> 
> It seems like we end up missing some invalidates after scrolling.

Sounds like bug 42949.