Toggling visibility:hidden on the parent of a <canvas> can cause the …

…previous frame's contents to be shown. https://bugs.webkit.org/show_bug.cgi?id=274262 <rdar://128226178> Reviewed by Simon Fraser. We should only try to use 'copy' compositing mode to transfer the canvas buffer into the layer (and thus omit any pixel clearing) if there is visible content to copy. * LayoutTests/compositing/canvas/copy-backing-store-visibility-hidden-expected.html: Added. * LayoutTests/compositing/canvas/copy-backing-store-visibility-hidden.html: Added. * Source/WebCore/rendering/RenderLayerBacking.cpp: (WebCore::RenderLayerBacking::updateConfiguration): Canonical link: https://commits.webkit.org/279302@main
WebKit · May 25, 2024 · d611425 · d611425
1 parent be37d4d
commit d611425
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Showing 3 changed files with 52 additions and 1 deletion.
diff --git a/LayoutTests/compositing/canvas/copy-backing-store-visibility-hidden-expected.html b/LayoutTests/compositing/canvas/copy-backing-store-visibility-hidden-expected.html
@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta name="viewport" content="width=device-width, initial-scale=1">
+</head>
+<body>
+</body>
+</html>
diff --git a/LayoutTests/compositing/canvas/copy-backing-store-visibility-hidden.html b/LayoutTests/compositing/canvas/copy-backing-store-visibility-hidden.html
@@ -0,0 +1,43 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<script>
+
+if (window.testRunner) {
+  testRunner.waitUntilDone();
+}
+
+async function doTest() {
+  var canvasElement = document.getElementById("canvas");
+
+  let ctx = canvas.getContext('2d');
+
+  ctx.fillStyle = 'green';
+  ctx.fillRect(0, 0, 100, 100);
+
+  await new Promise(resolve => requestAnimationFrame(resolve));
+
+  ctx.fillStyle = 'green';
+  ctx.fillRect(0, 0, 100, 100);
+
+  await new Promise(resolve => requestAnimationFrame(resolve));
+
+  document.getElementById("parent").style.visibility = "hidden";
+
+  if (window.testRunner) {
+    testRunner.notifyDone();
+  }
+}
+
+window.addEventListener('load', doTest, false);
+</script>
+</head>
+
+<body>
+<div id="parent">
+  <canvas id="canvas"></canvas>
+</div>
+</body>
+
+</html>
diff --git a/Source/WebCore/rendering/RenderLayerBacking.cpp b/Source/WebCore/rendering/RenderLayerBacking.cpp
@@ -1155,7 +1155,7 @@ bool RenderLayerBacking::updateConfiguration(const RenderLayer* compositingAnces
         layerConfigChanged = true;
     }
 
-    bool shouldPaintUsingCompositeCopy = unscaledBitmap && is<RenderHTMLCanvas>(renderer());
+    bool shouldPaintUsingCompositeCopy = unscaledBitmap && is<RenderHTMLCanvas>(renderer()) && m_owningLayer.hasVisibleContent();
     if (shouldPaintUsingCompositeCopy != m_shouldPaintUsingCompositeCopy) {
         m_shouldPaintUsingCompositeCopy = shouldPaintUsingCompositeCopy;
         m_graphicsLayer->setShouldPaintUsingCompositeCopy(shouldPaintUsingCompositeCopy);