зеркало из https://github.com/mozilla/gecko-dev.git
Bug 1738781 - Invalidate anchor after layout if we can find a better one. r=dholbert
This is _very_ similar to code Blink has dealing with content-visibility: auto: https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/layout/scroll_anchor.cc;l=658-659;drc=fd8802b593110ea18a97ef044f8a40dd24a622ec They don't have this problem on the original test-case because they incorrectly invalidate the anchor when focus changes regardless of whether the focus is a "priority element" per spec. So I think this is a better, more consistent behavior over all. Differential Revision: https://phabricator.services.mozilla.com/D130130
This commit is contained in:
Emilio Cobos Álvarez
Родитель
3f2c1a3ad6
Коммит
d0295b6c6f
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@ -7,6 +7,7 @@
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#include "ScrollAnchorContainer.h"
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#include "mozilla/dom/Text.h"
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#include "mozilla/ScopeExit.h"
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#include "mozilla/PresShell.h"
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#include "mozilla/ProfilerLabels.h"
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#include "mozilla/StaticPrefs_layout.h"
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@ -45,6 +46,7 @@ ScrollAnchorContainer::ScrollAnchorContainer(ScrollFrameHelper* aScrollFrame)
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mAnchorNode(nullptr),
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mLastAnchorOffset(0),
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mDisabled(false),
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mAnchorMightBeSubOptimal(false),
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mAnchorNodeIsDirty(true),
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mApplyingAnchorAdjustment(false),
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mSuppressAnchorAdjustment(false) {}
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@ -263,6 +265,8 @@ void ScrollAnchorContainer::SelectAnchor() {
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ANCHOR_LOG("Skipping selection, doesn't maintain a scroll anchor.\n");
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mAnchorNode = nullptr;
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}
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mAnchorMightBeSubOptimal =
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mAnchorNode && mAnchorNode->HasAnyStateBits(NS_FRAME_HAS_DIRTY_CHILDREN);
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// Update the anchor flags if needed
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if (oldAnchor != mAnchorNode) {
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@ -400,6 +404,7 @@ void ScrollAnchorContainer::InvalidateAnchor(ScheduleSelection aSchedule) {
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FindFor(Frame())->InvalidateAnchor();
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}
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mAnchorNode = nullptr;
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mAnchorMightBeSubOptimal = false;
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mAnchorNodeIsDirty = true;
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mLastAnchorOffset = 0;
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@ -445,6 +450,16 @@ void ScrollAnchorContainer::ApplyAdjustments() {
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ANCHOR_LOG("Anchor has moved from %d to %d.\n", mLastAnchorOffset, current);
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auto maybeInvalidate = MakeScopeExit([&] {
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if (mAnchorMightBeSubOptimal &&
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StaticPrefs::layout_css_scroll_anchoring_reselect_if_suboptimal()) {
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ANCHOR_LOG(
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"Anchor might be suboptimal, invalidating to try finding a better "
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"one\n");
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InvalidateAnchor();
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}
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});
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if (logicalAdjustment == 0) {
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ANCHOR_LOG("Ignoring zero delta anchor adjustment for %p.\n", this);
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mSuppressAnchorAdjustment = false;
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@ -167,6 +167,9 @@ class ScrollAnchorContainer final {
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// layout.css.scroll-anchoring.min-adjustment-threshold.
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bool mDisabled : 1;
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// True if when we selected the current scroll anchor, there were unlaid out
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// children that could be better anchor nodes after layout.
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bool mAnchorMightBeSubOptimal : 1;
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// True if we should recalculate our anchor node at the next chance
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bool mAnchorNodeIsDirty : 1;
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// True if we are applying a scroll anchor adjustment
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@ -7596,6 +7596,14 @@
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value: false
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mirror: always
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# Pref to control whether we reselect scroll anchors if sub-optimal
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#
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# See https://github.com/w3c/csswg-drafts/issues/6787
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- name: layout.css.scroll-anchoring.reselect-if-suboptimal
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type: bool
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value: true
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mirror: always
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# Are shared memory User Agent style sheets enabled?
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- name: layout.css.shared-memory-ua-sheets.enabled
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type: bool
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@ -0,0 +1,54 @@
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<!doctype html>
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<meta charset=utf-8>
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<link rel=help href="https://bugzilla.mozilla.org/show_bug.cgi?id=1738781">
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<link rel=help href="https://github.com/w3c/csswg-drafts/issues/6787">
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<script src="/resources/testharness.js"></script>
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<script src="/resources/testharnessreport.js"></script>
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<style>
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.padding {
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background: grey;
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border: 1px dashed black;
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margin: 5px;
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height: 200vh;
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}
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</style>
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<div id="content"></div>
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<script>
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const content = document.getElementById("content");
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const t = async_test("Scroll anchor is re-selected after adjustment if there are dirty descendants at selection time");
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function replaceAllContent() {
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content.innerHTML = `
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<div class="padding"></div>
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<button id="target">Scroll target</button>
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<div class="padding"></div>
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`;
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}
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function insertContent() {
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let inserted = document.createElement("div");
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inserted.className = "padding inserted";
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content.insertBefore(inserted, content.firstChild);
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}
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// Set the content, and scroll #target into view.
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replaceAllContent();
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document.getElementById("target").scrollIntoView();
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t.step(function() {
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assert_not_equals(window.scrollY, 0, "Should've scrolled");
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});
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// Save the target scroll position, which shouldn't change.
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const oldTargetTop = document.getElementById("target").getBoundingClientRect().top;
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// Replace all the content, then insert content at the top afterwards.
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replaceAllContent();
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requestAnimationFrame(() => requestAnimationFrame(t.step_func_done(function() {
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insertContent();
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const newTargetTop = document.getElementById("target").getBoundingClientRect().top;
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assert_equals(oldTargetTop, newTargetTop, "Scroll position should've been preserved");
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})));
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</script>
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<style>
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