[webkit-changes] [WebKit/WebKit] 38771c: [Remote Inspection] numberOfVisibilityAdjustmentRe...

[Wenson Hsieh]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 38771c35ceb476acc7d75e856add5df546ec8db3
      https://github.com/WebKit/WebKit/commit/38771c35ceb476acc7d75e856add5df546ec8db3
  Author: Wenson Hsieh <wenson_hsieh at apple.com>
  Date:   2024-07-27 (Sat, 27 Jul 2024)

  Changed paths:
    M Source/WebCore/page/ElementTargetingController.cpp
    M Source/WebCore/page/ElementTargetingController.h
    M Source/WebCore/page/LocalFrame.cpp
    M Source/WebCore/page/Page.cpp
    M Source/WebCore/page/Page.h
    M Tools/TestWebKitAPI/Tests/WebKitCocoa/ElementTargetingTests.mm

  Log Message:
  -----------
  [Remote Inspection] numberOfVisibilityAdjustmentRects returns 0 after loading from back/forward cache
https://bugs.webkit.org/show_bug.cgi?id=277187
rdar://132521358

Reviewed by Richard Robinson.

`ElementTargetingController`'s set of `m_adjustedElements` is currently reset whenever a load is
committed. This causes `numberOfVisibilityAdjustmentRects()` to always return 0 when the current
document has been restored from the back/forward cache, since adjustment state persists on the DOM
nodes in the new document, but `m_adjustedElements` is empty.

To address this, we:

1.  Keep track of a `WeakSet` of documents wherein we've previously applied adjustments.

2.  Add plumbing to inform `ElementTargetingController` when the main document will change; if the
    new document is one where we've previously applied adjustments, then set a boolean flag,
    `m_shouldRecomputeAdjustedElements`, to indicate that we need to lazily compute
    `m_adjustedElements` if the client ever asks for the adjusted rect count.

3.  If `m_shouldRecomputeAdjustedElements` is set and

This design ensures that we do no additional work (i.e. the full tree traversal) in the following
scenarios:

(a) No element has ever been adjusted in the document we're loading.
(b) The client never requests the adjustment rect count.

* Source/WebCore/page/ElementTargetingController.cpp:
(WebCore::ElementTargetingController::adjustVisibility):
(WebCore::ElementTargetingController::adjustVisibilityInRepeatedlyTargetedRegions):
(WebCore::ElementTargetingController::applyVisibilityAdjustmentFromSelectors):
(WebCore::ElementTargetingController::didChangeMainDocument):
(WebCore::ElementTargetingController::numberOfVisibilityAdjustmentRects):
(WebCore::ElementTargetingController::recomputeAdjustedElementsIfNeeded):

Collect the set of elements with active visibility adjustments, if necessary. See above for more
details.

(WebCore::ElementTargetingController::numberOfVisibilityAdjustmentRects const): Deleted.

Make this non-const, now that it invokes `recomputeAdjustedElementsIfNeeded`.

* Source/WebCore/page/ElementTargetingController.h:
* Source/WebCore/page/LocalFrame.cpp:
(WebCore::LocalFrame::setDocument):
* Source/WebCore/page/Page.cpp:
(WebCore::Page::didChangeMainDocument):

Additionally plumb the new document through `didChangeMainDocument()`. Perhaps counterintuitively,
`didChangeMainDocument` is invoked *before* the main frame's document has actually changed to the
new value.

* Source/WebCore/page/Page.h:
* Tools/TestWebKitAPI/Tests/WebKitCocoa/ElementTargetingTests.mm:
(TestWebKitAPI::TEST(ElementTargeting, CountVisibilityAdjustmentsAfterNavigatingBack)):

Add a new API test to exercise the change.

Canonical link: https://commits.webkit.org/281452@main



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