Bug 91374 – [chromium] Only apply page scale delta to root scroll layer

• Component: New Bugs
• Status: RESOLVED FIXED

[Sami Kyöstilä]

Only apply page scale delta to root scroll layer

[Sami Kyöstilä]

Created attachment 152508 [details]
Patch

[Adrienne Walker]

Comment on attachment 152508 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=152508&action=review

> Source/WebCore/platform/graphics/chromium/cc/CCLayerTreeHostImpl.cpp:796
> +    if (m_rootScrollLayerImpl)
> +        m_rootScrollLayerImpl->setPageScaleDelta(m_pageScaleDelta);

If page delta is applied recursively through the tree, then I wonder why you're applying it to the scroll layer and not to the root itself.  Is it because you don't want to scale the root scrollbars?

> Source/WebKit/chromium/tests/CCLayerTreeHostImplTest.cpp:1015
> +    // The page scale delta should only be applied to the scrollable root layer.
> +    EXPECT_EQ(root->pageScaleDelta(), newPageScale);
> +    EXPECT_EQ(child->pageScaleDelta(), defaultPageScale);
> +    EXPECT_EQ(grandChild->pageScaleDelta(), defaultPageScale);

If the real bug is that the resulting draw transforms have double scale in them, can you make that assertion here as well?

[Sami Kyöstilä]

(In reply to comment #2)
> If page delta is applied recursively through the tree, then I wonder why you're applying it to the scroll layer and not to the root itself.  Is it because you don't want to scale the root scrollbars?

That's right. The overlay controls should not be scaled when pinch zooming.
 
> > Source/WebKit/chromium/tests/CCLayerTreeHostImplTest.cpp:1015
> > +    // The page scale delta should only be applied to the scrollable root layer.
> > +    EXPECT_EQ(root->pageScaleDelta(), newPageScale);
> > +    EXPECT_EQ(child->pageScaleDelta(), defaultPageScale);
> > +    EXPECT_EQ(grandChild->pageScaleDelta(), defaultPageScale);
> 
> If the real bug is that the resulting draw transforms have double scale in them, can you make that assertion here as well?

Good idea. I don't think we're checking for that anywhere at the moment.

[Sami Kyöstilä]

(In reply to comment #3)
> That's right. The overlay controls should not be scaled when pinch zooming.

Sorry, I meant *overflow* controls.

[Sami Kyöstilä]

Created attachment 152552 [details]
Patch

- Check for correct draw transforms on all layers.

[Alexandre Elias]

Looks good to me, thanks.

[Adrienne Walker]

Comment on attachment 152552 [details]
Patch

R=me.  Thanks for the extra tests.

[WebKit Review Bot]

Comment on attachment 152552 [details]
Patch

Clearing flags on attachment: 152552

Committed r122746: <http://trac.webkit.org/changeset/122746>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.