[IFC][Integration][Line clamp] LineClamp.currentLineCount should be…

… propagated to the parent layoutState. https://bugs.webkit.org/show_bug.cgi?id=255487 Reviewed by Alan Baradlay. Since multiple children share the same parent context for line clamp, `LineClamp.currentLineCount` set to the individual child should be propagated to their parent layoutState. Otherwise, subsequent children may not see the current state of this value during layout, causing incorrect line clamp results. * LayoutTests/fast/block/line-clamp-nested-blocks-with-layout-state-expected.html: Added. * LayoutTests/fast/block/line-clamp-nested-blocks-with-layout-state.html: Added. * Source/WebCore/page/LocalFrameViewLayoutContext.cpp: (WebCore::LocalFrameViewLayoutContext::popLayoutState): Canonical link: https://commits.webkit.org/263360@main
WebKit · Apr 25, 2023 · 59088ba · 59088ba
1 parent f6cad2b
commit 59088ba
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diff --git a/LayoutTests/fast/block/line-clamp-nested-blocks-with-layout-state-expected.html b/LayoutTests/fast/block/line-clamp-nested-blocks-with-layout-state-expected.html
@@ -0,0 +1,15 @@
+<style>
+  .clamped {
+    font-family: Ahem;
+    display: -webkit-box;
+    -webkit-box-orient: vertical;
+    -webkit-line-clamp: 2;
+    overflow: hidden;
+  }
+</style>
+<body>
+  <div class="clamped">
+    <span>TEST<br />CASE</span>
+    <div>FAIL</div>
+  </div>
+</body>
diff --git a/LayoutTests/fast/block/line-clamp-nested-blocks-with-layout-state.html b/LayoutTests/fast/block/line-clamp-nested-blocks-with-layout-state.html
@@ -0,0 +1,22 @@
+<style>
+  .clamped {
+    font-family: Ahem;
+    display: -webkit-box;
+    -webkit-box-orient: vertical;
+    -webkit-line-clamp: 2;
+    overflow: hidden;
+  }
+</style>
+<body>
+  <div class="clamped">
+    <span id="test">TEST</span>
+    <div>FAIL</div>
+  </div>
+</body>
+<script>
+  if (window.testRunner) testRunner.waitUntilDone();
+  setTimeout(() => {
+    document.getElementById("test").innerHTML = "TEST<br />CASE";
+    if (window.testRunner) testRunner.notifyDone();
+  }, 0);
+</script>
diff --git a/Source/WebCore/page/LocalFrameViewLayoutContext.cpp b/Source/WebCore/page/LocalFrameViewLayoutContext.cpp
@@ -621,7 +621,20 @@ bool LocalFrameViewLayoutContext::pushLayoutState(RenderBox& renderer, const Lay
 
 void LocalFrameViewLayoutContext::popLayoutState()
 {
+    if (!layoutState())
+        return;
+
+    auto currentLineClamp = layoutState()->lineClamp();
+
     m_layoutStateStack.removeLast();
+
+    if (currentLineClamp) {
+        // Propagates the current line clamp state to the parent.
+        if (auto* layoutState = this->layoutState(); layoutState && layoutState->lineClamp()) {
+            ASSERT(layoutState->lineClamp()->maximumLineCount == currentLineClamp->maximumLineCount);
+            layoutState->setLineClamp(currentLineClamp);
+        }
+    }
 }
 
 #ifndef NDEBUG