[webkit-reviews] review denied: [Bug 93292] [Chromium] Pinch Zoom prototype tracking issue. : [Attachment 160035] Apply scale to root scrolling layer.

[bugzilla-daemon at webkit.org]

Jeff Timanus <twiz at chromium.org> has denied  review:
Bug 93292: [Chromium] Pinch Zoom prototype tracking issue.
https://bugs.webkit.org/show_bug.cgi?id=93292

Attachment 160035: Apply scale to root scrolling layer.
https://bugs.webkit.org/attachment.cgi?id=160035&action=review

------- Additional Comments from Jeff Timanus <twiz at chromium.org>
This patch finally gets a basic pinch-zoom working without using a CSS-scale.

 - The LayerChromium::contentsScale is assigned for all layer descendents of
the root scroll layer, so that the tiles are painted at the proper scale.
 - The page-scale-factor is installed as a transform on the root scrolling
layer in the main thread, just before calculating the drawing transforms.  The
previous approach of applying the scale to the entire tree was the root cause
of the viewport snapping to a smaller size on pinch-zoom release.

This is still a prototyping patch, but demonstrates that a non-CSS zoom is
possible.

Glaring problems that still need correction:
 - How to separate this zooming behaviour from the old zoom?  Some ports likely
want to preserve frameScale, etc.  
 - LCD text is used when the page is rendered during the interactive zoom -
this can cause colour sparkling.  LCD text needs to be disabled when zoom
starts.
 - The scroll position is totally broken after a pinch release, and needs to be
corrected.