Simplify ObjectPaintInvalidatorW/C::computePaintInvalidationReason()

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

Index: third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
diff --git a/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp b/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
index 910f0acb6335499ff75a55498a92e19851a02341..3f038a5aca64e81064dd9141112a696be001da35 100644
--- a/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
+++ b/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
@@ -429,19 +429,6 @@ ObjectPaintInvalidatorWithContext::computePaintInvalidationReason() {
   if (style.hasOutline())
     return PaintInvalidationOutline;
 
-  bool locationChanged = m_context.newLocation != m_context.oldLocation;
-
-  // If the bounds are the same then we know that none of the statements below
-  // can match, so we can early out. However, we can't return
-  // PaintInvalidationNone even if !locationChagned, but conservatively return
-  // PaintInvalidationIncremental because we are not sure whether paint
-  // invalidation is actually needed just based on information known to
-  // LayoutObject. For example, a LayoutBox may need paint invalidation if
-  // border box changes.
-  if (m_context.oldBounds == m_context.newBounds)
-    return locationChanged ? PaintInvalidationLocationChange
-                           : PaintInvalidationIncremental;
-
   // If the size is zero on one of our bounds then we know we're going to have
   // to do a full invalidation of either old bounds or new bounds.
   if (m_context.oldBounds.isEmpty())
@@ -456,10 +443,19 @@ ObjectPaintInvalidatorWithContext::computePaintInvalidationReason() {
   if (m_context.newBounds.location() != m_context.oldBounds.location())
     return PaintInvalidationBoundsChange;
 
-  if (locationChanged)
+  if (m_context.newLocation != m_context.oldLocation)
     return PaintInvalidationLocationChange;
 
-  return PaintInvalidationIncremental;
+  // Incremental invalidation is only applicable to LayoutBoxes. Return
+  // PaintInvalidationIncremental no matter if oldBounds and newBounds are equal
+  // because a LayoutBox may need paint invalidation if its border box changes.
+  if (m_object.isBox())
+    return PaintInvalidationIncremental;
+
+  if (m_context.oldBounds != m_context.newBounds)
+    return PaintInvalidationBoundsChange;
+
+  return PaintInvalidationNone;
 }
 
 void ObjectPaintInvalidatorWithContext::invalidateSelectionIfNeeded(
@@ -499,11 +495,6 @@ ObjectPaintInvalidatorWithContext::invalidatePaintIfNeededWithComputedReason(
   // selection rect regardless.
   invalidateSelectionIfNeeded(reason);
 
-  if (reason == PaintInvalidationIncremental) {
-    reason = m_context.oldBounds == m_context.newBounds ? PaintInvalidationNone
-                                                        : PaintInvalidationFull;
-  }
-

[Xianzhu, 2016/10/24 18:23:49]

There would be no change of test results and this CL would be a pure refactor if
I had put the above lines to above invalidateSelectionIfNeeded() and used
PaintInvalidationBoundsChanged instead of PaintInvalidationFull in
https://codereview.chromium.org/2423513002/.

   switch (reason) {
     case PaintInvalidationNone:
       // TODO(trchen): Currently we don't keep track of paint offset of layout