REGRESSION (r294902): Content with continuation leaves decoration bit…

…s behind when removed

https://bugs.webkit.org/show_bug.cgi?id=241734
<rdar://95308322>

Reviewed by Simon Fraser.

This patch ensures that when a renderer is removed we always issue a repaint regardless of what the associated layer's repaint bit says.

1. after r294902, repaint is not issued anymore if either the associated or an ancestor layer have the "full repaint" bit set.
2. such layer-driven repaints happen after layout.

In some dynamic content cases, the layer may be removed before layout happens. This patch ensures that we preemptively issue such repaints.

* LayoutTests/fast/repaint/force-repaint-when-layer-is-destroyed-expected.txt: Added.
* LayoutTests/fast/repaint/force-repaint-when-layer-is-destroyed.html: Added.

* Source/WebCore/rendering/RenderLayerModelObject.cpp: Force (full) repaint when the renderer is being destroyed (detached -> non-internal move).
(WebCore::RenderLayerModelObject::willBeRemovedFromTree):
* Source/WebCore/rendering/RenderLayerModelObject.h:
* Source/WebCore/rendering/RenderObject.cpp: move duplicated code from repaint() and repaintRectangle() to issueRepaint().

Canonical link: https://commits.webkit.org/251670@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@295665 268f45cc-cd09-0410-ab3c-d52691b4dbfc

LayoutTests/fast/repaint/force-repaint-when-layer-is-destroyed-expected.txt

@@ -0,0 +1 @@
+PASS

LayoutTests/fast/repaint/force-repaint-when-layer-is-destroyed.html

@@ -0,0 +1,36 @@
+<style>
+.content {
+  transform: translateX(0px);
+  border: 10px solid red;
+  width: 120px;
+}
+
+.continuation {
+  width: 100px;
+  height: 100px;
+  background-color: green;
+  border: solid blue;
+}
+</style><div id=hide_this class=content><span><div class=continuation></div></span></div>
+<pre id=result></pre>
+<script>
+if (window.testRunner) {
+  testRunner.dumpAsText();
+  testRunner.waitUntilDone();
+}
+
+setTimeout(function() {
+  if (window.internals)
+    internals.startTrackingRepaints();
+
+  hide_this.style.display = "none";
+
+  if (window.internals) {
+    result.innerText = internals.repaintRectsAsText().indexOf("8 8 140 126") != -1 ? "PASS" : "FAIL";
+    internals.stopTrackingRepaints();
+  }
+
+  if (window.testRunner)
+    testRunner.notifyDone();
+}, 10);
+</script>

Source/WebCore/rendering/RenderLayerModelObject.cpp

@@ -77,6 +77,14 @@ void RenderLayerModelObject::willBeDestroyed()
     RenderElement::willBeDestroyed();
 }
 
+void RenderLayerModelObject::willBeRemovedFromTree(IsInternalMove isInternalMove)
+{
+    if (auto* layer = this->layer(); layer && layer->needsFullRepaint() && isInternalMove == IsInternalMove::No)
+        issueRepaint(std::nullopt, ClipRepaintToLayer::No, ForceRepaint::Yes);
+
+    RenderElement::willBeRemovedFromTree(isInternalMove);
+}
+
 void RenderLayerModelObject::destroyLayer()
 {
     ASSERT(!hasLayer());

Source/WebCore/rendering/RenderLayerModelObject.h

@@ -95,6 +95,7 @@ class RenderLayerModelObject : public RenderElement {
 
     void createLayer();
     void willBeDestroyed() override;
+    void willBeRemovedFromTree(IsInternalMove) override;
 
 private:
     std::unique_ptr<RenderLayer> m_layer;

Source/WebCore/rendering/RenderObject.cpp

@@ -977,45 +977,37 @@ static inline bool fullRepaintIsScheduled(const RenderObject& renderer)
     return false;
 }
 
-void RenderObject::repaint() const
+void RenderObject::issueRepaint(std::optional<LayoutRect> partialRepaintRect, ClipRepaintToLayer clipRepaintToLayer, ForceRepaint forceRepaint) const
 {
-    // Don't repaint if we're unrooted (note that view() still returns the view when unrooted)
-    if (!isRooted())
-        return;
-
-    const RenderView& view = this->view();
-    if (view.printing())
-        return;
-
     auto repaintContainer = containerForRepaint();
     if (!repaintContainer.renderer)
-        repaintContainer = { fullRepaintIsScheduled(*this), &view };
+        repaintContainer = { fullRepaintIsScheduled(*this), &view() };
 
-    if (!repaintContainer.fullRepaintIsScheduled)
-        repaintUsingContainer(repaintContainer.renderer, clippedOverflowRectForRepaint(repaintContainer.renderer));
+    if (repaintContainer.fullRepaintIsScheduled && forceRepaint == ForceRepaint::No)
+        return;
+
+    auto repaintRect = partialRepaintRect ? computeRectForRepaint(*partialRepaintRect, repaintContainer.renderer) : clippedOverflowRectForRepaint(repaintContainer.renderer);
+    repaintUsingContainer(repaintContainer.renderer, repaintRect, clipRepaintToLayer == ClipRepaintToLayer::Yes);
 }
 
-void RenderObject::repaintRectangle(const LayoutRect& r, bool shouldClipToLayer) const
+void RenderObject::repaint() const
 {
     // Don't repaint if we're unrooted (note that view() still returns the view when unrooted)
-    if (!isRooted())
+    if (!isRooted() || view().printing())
         return;
+    issueRepaint();
+}
 
-    const RenderView& view = this->view();
-    if (view.printing())
+void RenderObject::repaintRectangle(const LayoutRect& repaintRect, bool shouldClipToLayer) const
+{
+    // Don't repaint if we're unrooted (note that view() still returns the view when unrooted)
+    if (!isRooted() || view().printing())
         return;
-
-    LayoutRect dirtyRect(r);
     // FIXME: layoutDelta needs to be applied in parts before/after transforms and
     // repaint containers. https://bugs.webkit.org/show_bug.cgi?id=23308
-    dirtyRect.move(view.frameView().layoutContext().layoutDelta());
-
-    auto repaintContainer = containerForRepaint();
-    if (!repaintContainer.renderer)
-        repaintContainer = { fullRepaintIsScheduled(*this), &view };
-
-    if (!repaintContainer.fullRepaintIsScheduled)
-        repaintUsingContainer(repaintContainer.renderer, computeRectForRepaint(dirtyRect, repaintContainer.renderer), shouldClipToLayer);
+    auto dirtyRect = repaintRect;
+    dirtyRect.move(view().frameView().layoutContext().layoutDelta());
+    issueRepaint(dirtyRect, shouldClipToLayer ? ClipRepaintToLayer::Yes : ClipRepaintToLayer::No);
 }
 
 void RenderObject::repaintSlowRepaintObject() const

Source/WebCore/rendering/RenderObject.h

@@ -803,6 +803,10 @@ class RenderObject : public CachedImageClient {
 
     bool isSetNeedsLayoutForbidden() const;
 
+    enum class ClipRepaintToLayer : uint8_t { No, Yes };
+    enum class ForceRepaint : uint8_t { No, Yes };
+    void issueRepaint(std::optional<LayoutRect> partialRepaintRect = std::nullopt, ClipRepaintToLayer = ClipRepaintToLayer::No, ForceRepaint = ForceRepaint::No) const;
+
 private:
     void addAbsoluteRectForLayer(LayoutRect& result);
     void setLayerNeedsFullRepaint();