Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 618e0c9aab19d67ea3a915dd3fbaa62617004e88
https://github.com/WebKit/WebKit/commit/618e0c9aab19d67ea3a915dd3fbaa62617004e88
Author: Simon Fraser <[email protected]>
Date: 2025-02-03 (Mon, 03 Feb 2025)
Changed paths:
A
LayoutTests/fast/scrolling/mac/unscrollable-root-overflow-hidden-on-one-axis-expected.txt
A
LayoutTests/fast/scrolling/mac/unscrollable-root-overflow-hidden-on-one-axis.html
M Source/WebCore/page/WheelEventTestMonitor.cpp
M Source/WebCore/page/WheelEventTestMonitor.h
M Source/WebCore/page/scrolling/ScrollingTree.cpp
M Source/WebCore/page/scrolling/ScrollingTreeGestureState.cpp
M Source/WebCore/page/scrolling/ScrollingTreeScrollingNode.cpp
M Source/WebCore/page/scrolling/ScrollingTreeScrollingNode.h
M Source/WebCore/page/scrolling/mac/ScrollingTreeScrollingNodeDelegateMac.mm
M Source/WebCore/platform/ScrollingEffectsController.h
M Source/WebCore/platform/graphics/ca/TileController.cpp
M Source/WebCore/platform/mac/ScrollingEffectsController.mm
M Source/WebKit/Shared/WebCoreArgumentCoders.serialization.in
Log Message:
-----------
A page with `overflow-y: hidden` can sometimes still be scrolled
https://bugs.webkit.org/show_bug.cgi?id=286554
rdar://143660753
Reviewed by Matt Woodrow.
A page with `body { overflow-y: hidden; }` can still be partially scrolled
(without
momentum). This happens because the `shouldRubberBand()` logic says that we can
rubberband
vertically, so we allow the event through and apply the scroll delta.
The bug falls out of some complexity around when we actually allow
rubberbanding on the
root, which has some surprising behaviors. We allow rubberbanding on an
unscrollable root
to give the user a feeling of responsiveness, but only "unscrollable" in the
sense of "not
enough content to scroll", not "scrolling disallowed by the web content (i.e.
`overflow:
hidden`). The bug was that we didn't strictly evaluate this per axis, so if the
horizontal
axis allowed rubberbanding, we'd also allow it on the vertical axis.
Fix by expanding out the logic in
`ScrollingTreeScrollingNode::shouldRubberBand()` to
check each axis independently. Also have
`ScrollingTreeScrollingNodeDelegateMac::shouldRubberBandOnSide()` share the
same code.
Fixing `shouldRubberBand()` is not strictly enough though; there are cases
where a
rubberband can be started on the horizontal axis, then, with a circular gesture
on the
trackpad, the vertical axis can be stretched. This PR partially fixes this with
the
changes in ScrollingEffectsController, but a full fix for this rare edge case
requires
more work.
Because `ScrollingTree::handleWheelEventWithNode()` now more accurately
predicts whether
an event will trigger any event handling, some tests[1] timed out because
`WheelEventTestMonitor`
never received any deferral reasons. Rather than require tests to know if an
event will
cause any scrolling, introduce a "None" deferral reason purely to allow a test
that uses
`eventSender.monitorWheelEvents()` to not time out when an event simply doesn't
trigger any
scrolling, for example because of `overscroll-behavior: none`.
[1]
imported/w3c/web-platform-tests/css/css-overscroll-behavior/overscroll-behavior.html
*
LayoutTests/fast/scrolling/mac/unscrollable-root-overflow-hidden-on-one-axis-expected.txt:
Added.
*
LayoutTests/fast/scrolling/mac/unscrollable-root-overflow-hidden-on-one-axis.html:
Added.
* Source/WebCore/page/WheelEventTestMonitor.cpp:
(WebCore::operator<<):
* Source/WebCore/page/WheelEventTestMonitor.h:
* Source/WebCore/page/scrolling/ScrollingTree.cpp:
(WebCore::ScrollingTree::determineWheelEventProcessing):
(WebCore::ScrollingTree::handleWheelEvent):
(WebCore::ScrollingTree::handleWheelEventWithNode):
* Source/WebCore/page/scrolling/ScrollingTreeGestureState.cpp:
(WebCore::ScrollingTreeGestureState::nodeDidHandleEvent):
* Source/WebCore/page/scrolling/ScrollingTreeScrollingNode.cpp:
(WebCore::ScrollingTreeScrollingNode::shouldRubberBandOnSide const):
(WebCore::ScrollingTreeScrollingNode::shouldRubberBand const):
(WebCore::ScrollingTreeScrollingNode::canHandleWheelEvent const):
* Source/WebCore/page/scrolling/ScrollingTreeScrollingNode.h:
* Source/WebCore/page/scrolling/mac/ScrollingTreeScrollingNodeDelegateMac.mm:
(WebCore::ScrollingTreeScrollingNodeDelegateMac::shouldRubberBandOnSide const):
* Source/WebCore/platform/ScrollingEffectsController.h:
* Source/WebCore/platform/graphics/ca/TileController.cpp:
(WebCore::TileController::computeTileSize):
* Source/WebCore/platform/mac/ScrollingEffectsController.mm:
(WebCore::ScrollingEffectsController::clampDeltaForAllowedAxes):
(WebCore::ScrollingEffectsController::modifyScrollDeltaForStretching):
(WebCore::ScrollingEffectsController::applyScrollDeltaWithStretching):
* Source/WebKit/Shared/WebCoreArgumentCoders.serialization.in:
Canonical link: https://commits.webkit.org/289750@main
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