[webkit-changes] [WebKit/WebKit] 18970a: [UnifiedPDF] Embedded PDFs are blurry when zooming...

[Abrar Rahman Protyasha]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 18970a1eb04af74556cf9413f2363550ac2aee61
      https://github.com/WebKit/WebKit/commit/18970a1eb04af74556cf9413f2363550ac2aee61
  Author: Abrar Rahman Protyasha <a_protyasha at apple.com>
  Date:   2024-05-25 (Sat, 25 May 2024)

  Changed paths:
    A LayoutTests/compositing/plugins/pdf/pdf-in-embed-with-root-page-zoom-expected.txt
    A LayoutTests/compositing/plugins/pdf/pdf-in-embed-with-root-page-zoom.html
    M LayoutTests/platform/mac-wk2/TestExpectations
    A LayoutTests/resources/image.pdf
    M Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp
    M Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/UnifiedPDFPlugin.mm

  Log Message:
  -----------
  [UnifiedPDF] Embedded PDFs are blurry when zooming the containing page
https://bugs.webkit.org/show_bug.cgi?id=274565
rdar://128290750

Reviewed by Simon Fraser.

In 275712 at main, we unconditionally allow the plugin's root layer to
apply page scale. This allows any embed plugin's internal scale change
to be reflected in the tiled backing.

However, that change breaks the assumption in GraphicsLayer that
there's a single layer applying page scale. This assumption meant that
when recursively commiting changes in a layer tree, GraphicsLayer only
selects (and propagates) scale factor from the furthest descendant layer
that applies page scale. We see this aligning with the behavior that
regardless of root page scaling, all painted tiles only reflect the embed
plugin's scale.

To fix this, we move away from our previous assumption of a single layer
applying page scale. Instead, as we traverse the layer tree, we
maintain a combined page scale representing the product of the scale
factor of each layer that applies page scale. This would not only account
for differences between root page scale and embed plugin scale, but also
any intermediate CSS transform scale.

* LayoutTests/compositing/plugins/pdf/pdf-in-embed-with-root-page-zoom-expected.txt: Added.
* LayoutTests/compositing/plugins/pdf/pdf-in-embed-with-root-page-zoom.html: Added.
* LayoutTests/platform/mac-wk2/TestExpectations:
* LayoutTests/resources/image.pdf: Added.
* Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp:
(WebCore::GraphicsLayerCA::computePositionRelativeToBase const):
(WebCore::GraphicsLayerCA::recursiveCommitChanges):
* Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/UnifiedPDFPlugin.mm:
(WebKit::UnifiedPDFPlugin::setPageScaleFactor):

Canonical link: https://commits.webkit.org/279314@main



To unsubscribe from these emails, change your notification settings at https://github.com/WebKit/WebKit/settings/notifications