Paint invisible layer content in presence of composited animations.

third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp

Index: third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
index 5063ae67f1e8ecc9aa18f669fb220b2f224ed429..1417a0ad45ece2d1c8019818031935fdabb2bd2e 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
@@ -66,12 +66,25 @@ static ShouldRespectOverflowClipType shouldRespectOverflowClip(
 
 bool PaintLayerPainter::paintedOutputInvisible(
     const PaintLayerPaintingInfo& paintingInfo) {
-  if (m_paintLayer.layoutObject()->hasBackdropFilter())
+  const LayoutObject& layoutObject = *m_paintLayer.layoutObject();
+  if (layoutObject.hasBackdropFilter())
     return false;
 
-  if (RuntimeEnabledFeatures::slimmingPaintV2Enabled() &&
-      m_paintLayer.layoutObject()->styleRef().opacity())
-    return false;
+  if (RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
+    if (layoutObject.styleRef().opacity())

[pdr., 2017/01/26 22:50:38]

Do you need to check opacity > kMinimumVisibleOpacity here?

[wkorman, 2017/01/26 23:09:12]

http://crrev.com/2523103003 added PaintLayerPainterTest.DontPaintWithTinyOpacity
which explicitly checks that for SPv2 any opacity, even one <
kMinimumVisibleOpacity, paints for SPv2. I'm presuming the author had a specific
reason for that, so would like to preserve that logic in this change, though it
does seem like the optimization conceptually should be valid for SPv2 as well.

+      return false;
+
+    const EffectPaintPropertyNode* effect =
+        layoutObject.paintProperties()->effect();
+    const TransformPaintPropertyNode* transform =
+        layoutObject.paintProperties()->transform();
+    if ((effect &&
+         (effect->compositingReasons() & CompositingReasonActiveAnimation)) ||
+        (transform && (transform->compositingReasons() &
+                       CompositingReasonActiveAnimation))) {
+      return false;
+    }
+  }
 
   // 0.0004f < 1/2048. With 10-bit color channels (only available on the
   // newest Macs; otherwise it's 8-bit), we see that an alpha of 1/2048 or
@@ -79,8 +92,7 @@ bool PaintLayerPainter::paintedOutputInvisible(
   // not visible.
   static const float kMinimumVisibleOpacity = 0.0004f;
   if (m_paintLayer.paintsWithTransparency(paintingInfo.getGlobalPaintFlags())) {
-    if (m_paintLayer.layoutObject()->styleRef().opacity() <
-        kMinimumVisibleOpacity) {
+    if (layoutObject.styleRef().opacity() < kMinimumVisibleOpacity) {
       return true;
     }
   }