Split out the style-determined direct compositing reasons

Source/core/rendering/compositing/CompositingReasonFinder.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/rendering/compositing/CompositingReasonFinder.h"
 
 #include "CSSPropertyNames.h"
 #include "HTMLNames.h"
 #include "core/animation/ActiveAnimations.h"
@@ skipping 41 matching lines @@
 {
     return m_compositingTriggers & AnimationTrigger;
 }
 
 bool CompositingReasonFinder::isMainFrame() const
 {
     // FIXME: LocalFrame::isMainFrame() is probably better.
     return !m_renderView.document().ownerElement();
 }
 
-CompositingReasons CompositingReasonFinder::directReasons(const RenderLayer* layer, bool* needToRecomputeCompositingRequirements) const
+CompositingReasons CompositingReasonFinder::styleDeterminedDirectReasons(RenderObject* renderer) const
 {
-    RenderObject* renderer = layer->renderer();
     CompositingReasons directReasons = CompositingReasonNone;
 
     if (requiresCompositingForTransform(renderer))
         directReasons |= CompositingReason3DTransform;
 
     if (requiresCompositingForBackfaceVisibilityHidden(renderer))
         directReasons |= CompositingReasonBackfaceVisibilityHidden;
 
     if (requiresCompositingForAnimation(renderer))
         directReasons |= CompositingReasonActiveAnimation;
 
     if (requiresCompositingForFilters(renderer))
         directReasons |= CompositingReasonFilters;
 
-    if (requiresCompositingForPosition(renderer, layer, 0, needToRecomputeCompositingRequirements))
-        directReasons |= renderer->style()->position() == FixedPosition ? CompositingReasonPositionFixed : CompositingReasonPositionSticky;
+    if (requiresCompositingForWillChange(renderer))
+        directReasons |= CompositingReasonWillChange;
+
+    directReasons |= renderer->additionalCompositingReasons(m_compositingTriggers);
+
+    ASSERT(!(directReasons & ~CompositingReasonComboAllStyleDeterminedDirectReasons));
+    return directReasons;
+}
+
+CompositingReasons CompositingReasonFinder::nonStyleDeterminedDirectReasons(const RenderLayer* layer, bool* needToRecomputeCompositingRequirements) const
+{
+    CompositingReasons directReasons = CompositingReasonNone;
+
+    if (requiresCompositingForOutOfFlowClipping(layer))
+        directReasons |= CompositingReasonOutOfFlowClipping;
 
     if (requiresCompositingForOverflowScrolling(layer))
         directReasons |= CompositingReasonOverflowScrollingTouch;
 
     if (requiresCompositingForOverflowScrollingParent(layer))
         directReasons |= CompositingReasonOverflowScrollingParent;
 
-    if (requiresCompositingForOutOfFlowClipping(layer))
-        directReasons |= CompositingReasonOutOfFlowClipping;
+    RenderObject* renderer = layer->renderer();
+    if (requiresCompositingForPosition(renderer, layer, 0, needToRecomputeCompositingRequirements))
+        directReasons |= renderer->style()->position() == FixedPosition ? CompositingReasonPositionFixed : CompositingReasonPositionSticky;
 
-    if (requiresCompositingForWillChange(renderer))
-        directReasons |= CompositingReasonWillChange;
+    ASSERT(!(directReasons & CompositingReasonComboAllStyleDeterminedDirectReasons));
+    return directReasons;
+}
 
-    directReasons |= renderer->additionalCompositingReasons(m_compositingTriggers);
-
-    return directReasons;
+CompositingReasons CompositingReasonFinder::directReasons(const RenderLayer* layer, bool* needToRecomputeCompositingRequirements) const
+{
+    return styleDeterminedDirectReasons(layer->renderer()) | nonStyleDeterminedDirectReasons(layer, needToRecomputeCompositingRequirements);
 }
 
 bool CompositingReasonFinder::requiresCompositingForScrollableFrame() const
 {
     // Need this done first to determine overflow.
     ASSERT(!m_renderView.needsLayout());
     if (isMainFrame())
         return false;
 
     if (!(m_compositingTriggers & ScrollableInnerFrameTrigger))
@@ skipping 177 matching lines @@
 
     return true;
 }
 
 bool CompositingReasonFinder::requiresCompositingForOverflowScrolling(const RenderLayer* layer) const
 {
     return layer->needsCompositedScrolling();
 }
 
 }