Use device pixel ratio scaled backing stores for unscaled bitmap cont…

…ent if the page is downscaling https://bugs.webkit.org/show_bug.cgi?id=242978 Reviewed by Simon Fraser and Dean Jackson. If the page is downscaled, then not including the device pixel ratio in the backing store means that we'll end up downscaling the image/canvas content and then upscaling it again by the device pixel ratio during compositing. This checks if we'd downscaling during painting if we removed the device pixel ratio, and skips the unscaled bitmap optimization if so. * LayoutTests/compositing/canvas/hidpi-canvas-backing-store-invalidation-2-expected.txt: Added. * LayoutTests/compositing/canvas/hidpi-canvas-backing-store-invalidation-2.html: Added. * Source/WebCore/rendering/RenderLayerBacking.cpp: (WebCore::RenderLayerBacking::isUnscaledBitmapOnly const): Canonical link: https://commits.webkit.org/252855@main
WebKit · Jul 27, 2022 · fe12c1c · fe12c1c
1 parent 9b9da1b
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diff --git a/LayoutTests/compositing/canvas/hidpi-canvas-backing-store-invalidation-2-expected.txt b/LayoutTests/compositing/canvas/hidpi-canvas-backing-store-invalidation-2-expected.txt
@@ -0,0 +1,63 @@
+Tests whether we switch back to a hidpi backing store when we zoom out (and would otherwise downscale the content too much).
+
+ (GraphicsLayer
+  (anchor 0.00 0.00)
+  (bounds 2008.00 1141.00)
+  (device scale 2.00)
+  (children 1
+    (GraphicsLayer
+      (bounds 2008.00 1141.00)
+      (contentsOpaque 1)
+      (device scale 2.00)
+      (children 1
+        (GraphicsLayer
+          (position 8.00 68.00)
+          (bounds 2000.00 1004.00)
+          (opacity 0.50)
+          (device scale 2.00)
+          (children 1
+            (GraphicsLayer
+              (anchor 0.00 0.00)
+              (bounds 2000.00 1000.00)
+              (drawsContent 1)
+              (transform [0.50 0.00 0.00 0.00] [0.00 0.50 0.00 0.00] [0.00 0.00 1.00 0.00] [0.00 0.00 0.00 1.00])
+              (device scale 1.00)
+            )
+          )
+        )
+      )
+    )
+  )
+)
+(GraphicsLayer
+  (anchor 0.00 0.00)
+  (bounds 1004.00 780.00)
+  (device scale 2.00)
+  (children 1
+    (GraphicsLayer
+      (anchor 0.00 0.00)
+      (bounds 2008.00 1561.00)
+      (contentsOpaque 1)
+      (transform [0.50 0.00 0.00 0.00] [0.00 0.50 0.00 0.00] [0.00 0.00 1.00 0.00] [0.00 0.00 0.00 1.00])
+      (device scale 2.00)
+      (children 1
+        (GraphicsLayer
+          (position 8.00 68.00)
+          (bounds 2000.00 1004.00)
+          (opacity 0.50)
+          (device scale 2.00)
+          (children 1
+            (GraphicsLayer
+              (anchor 0.00 0.00)
+              (bounds 2000.00 1000.00)
+              (drawsContent 1)
+              (transform [0.50 0.00 0.00 0.00] [0.00 0.50 0.00 0.00] [0.00 0.00 1.00 0.00] [0.00 0.00 0.00 1.00])
+              (device scale 2.00)
+            )
+          )
+        )
+      )
+    )
+  )
+)
+
diff --git a/LayoutTests/compositing/canvas/hidpi-canvas-backing-store-invalidation-2.html b/LayoutTests/compositing/canvas/hidpi-canvas-backing-store-invalidation-2.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta name="viewport" content="initial-scale=1">
+<script>
+
+if (window.testRunner) {
+  testRunner.dumpAsText();
+  testRunner.waitUntilDone();
+}
+
+function doTest() {
+  var canvasElement = document.getElementById("canvas");
+  let dpr = window.devicePixelRatio || 1;
+
+  canvas.width *= dpr;
+  canvas.height *= dpr;
+
+  canvas.style.transform = "scale(" + 1/dpr + ", " + 1/dpr + ")";
+
+  let ctx = canvas.getContext('2d');
+  ctx.scale(dpr, dpr);
+
+  ctx.fillStyle = 'green';
+  ctx.fillRect(0, 0, 1000, 500);
+
+  if (window.testRunner) {
+    document.getElementById('layers-before').innerText = internals.layerTreeAsText(document, internals.LAYER_TREE_INCLUDES_DEVICE_SCALE);
+  }
+
+  requestAnimationFrame(function() {
+    if (window.internals) {
+      window.internals.setPageScaleFactor(0.5, 0, 0);
+    }
+
+    if (window.testRunner) {
+      document.getElementById('layers-after').innerText = internals.layerTreeAsText(document, internals.LAYER_TREE_INCLUDES_DEVICE_SCALE);
+      testRunner.notifyDone();
+    }
+  });
+}
+
+window.addEventListener('load', doTest, false);
+</script>
+</head>
+
+<body>
+<p> Tests whether we switch back to a hidpi backing store when we zoom out (and would otherwise downscale the content too much).</p>
+<div style="opacity:0.5">
+<canvas id="canvas" width="1000" height="500" style="transform-origin:top left"></canvas>
+</div>
+<pre id="layers-before">Initial layer tree goes here in DRT</pre>
+<pre id="layers-after">Mutated layer tree goes here in DRT</pre>
+</body>
+
+</html>
diff --git a/...ts/platform/gtk/compositing/canvas/hidpi-canvas-backing-store-invalidation-2-expected.txt b/...ts/platform/gtk/compositing/canvas/hidpi-canvas-backing-store-invalidation-2-expected.txt
@@ -0,0 +1,3 @@
+Tests whether we switch back to a hidpi backing store when we zoom out (and would otherwise downscale the content too much).
+
+
diff --git a/...latform/ios-wk2/compositing/canvas/hidpi-canvas-backing-store-invalidation-2-expected.txt b/...latform/ios-wk2/compositing/canvas/hidpi-canvas-backing-store-invalidation-2-expected.txt
@@ -0,0 +1,62 @@
+Tests whether we switch back to a hidpi backing store when we zoom out (and would otherwise downscale the content too much).
+
+ (GraphicsLayer
+  (anchor 0.00 0.00)
+  (bounds 2008.00 1144.00)
+  (device scale 2.00)
+  (children 1
+    (GraphicsLayer
+      (bounds 2008.00 1144.00)
+      (contentsOpaque 1)
+      (device scale 2.00)
+      (children 1
+        (GraphicsLayer
+          (position 8.00 72.00)
+          (bounds 2000.00 1005.00)
+          (opacity 0.50)
+          (device scale 2.00)
+          (children 1
+            (GraphicsLayer
+              (anchor 0.00 0.00)
+              (bounds 2000.00 1000.00)
+              (usingTiledLayer 1)
+              (drawsContent 1)
+              (transform [0.50 0.00 0.00 0.00] [0.00 0.50 0.00 0.00] [0.00 0.00 1.00 0.00] [0.00 0.00 0.00 1.00])
+              (device scale 1.00)
+            )
+          )
+        )
+      )
+    )
+  )
+)
+(GraphicsLayer
+  (anchor 0.00 0.00)
+  (bounds 2008.00 1550.00)
+  (device scale 2.00)
+  (children 1
+    (GraphicsLayer
+      (bounds 2008.00 1550.00)
+      (contentsOpaque 1)
+      (device scale 2.00)
+      (children 1
+        (GraphicsLayer
+          (position 8.00 72.00)
+          (bounds 2000.00 1005.00)
+          (opacity 0.50)
+          (device scale 2.00)
+          (children 1
+            (GraphicsLayer
+              (anchor 0.00 0.00)
+              (bounds 2000.00 1000.00)
+              (drawsContent 1)
+              (transform [0.50 0.00 0.00 0.00] [0.00 0.50 0.00 0.00] [0.00 0.00 1.00 0.00] [0.00 0.00 0.00 1.00])
+              (device scale 1.00)
+            )
+          )
+        )
+      )
+    )
+  )
+)
+
diff --git a/Source/WebCore/page/FrameView.cpp b/Source/WebCore/page/FrameView.cpp
@@ -3173,6 +3173,16 @@ void FrameView::setNeedsCompositingGeometryUpdate()
     }
 }
 
+void FrameView::setDescendantsNeedUpdateBackingAndHierarchyTraversal()
+{
+    RenderView* renderView = this->renderView();
+    if (renderView->usesCompositing()) {
+        if (auto* rootLayer = renderView->layer())
+            rootLayer->setDescendantsNeedUpdateBackingAndHierarchyTraversal();
+        renderView->compositor().scheduleCompositingLayerUpdate();
+    }
+}
+
 void FrameView::scheduleSelectionUpdate()
 {
     if (needsLayout())

diff --git a/Source/WebCore/page/FrameView.h b/Source/WebCore/page/FrameView.h
@@ -133,6 +133,7 @@ class FrameView final : public ScrollView {
 
     void setNeedsCompositingConfigurationUpdate();
     void setNeedsCompositingGeometryUpdate();
+    void setDescendantsNeedUpdateBackingAndHierarchyTraversal();
 
     WEBCORE_EXPORT void setViewportConstrainedObjectsNeedLayout();
 

diff --git a/Source/WebCore/page/Page.cpp b/Source/WebCore/page/Page.cpp
@@ -1208,6 +1208,7 @@ void Page::setPageScaleFactor(float scale, const IntPoint& origin, bool inStable
         if (view && !delegatesScaling()) {
             view->setNeedsLayoutAfterViewConfigurationChange();
             view->setNeedsCompositingGeometryUpdate();
+            view->setDescendantsNeedUpdateBackingAndHierarchyTraversal();
 
             document->resolveStyle(Document::ResolveStyleType::Rebuild);
 

diff --git a/Source/WebCore/rendering/RenderLayerBacking.cpp b/Source/WebCore/rendering/RenderLayerBacking.cpp
@@ -2900,6 +2900,9 @@ bool RenderLayerBacking::isUnscaledBitmapOnly() const
     if (m_owningLayer.hasVisibleBoxDecorationsOrBackground())
         return false;
 
+    if (pageScaleFactor() < 1.0f)
+        return false;
+
     auto contents = contentsBox();
     if (contents.location() != LayoutPoint(0, 0))
         return false;