Replace filter outsets with bounds mapping in Blink.

third_party/WebKit/Source/core/paint/PaintLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 308 matching lines @@
     // Do *not* call this method unless you know what you are dooing. You probably want to call enclosingCompositingLayerForPaintInvalidation() instead.
     // If includeSelf is true, may return this.
     PaintLayer* enclosingLayerWithCompositedLayerMapping(IncludeSelfOrNot) const;
 
     // Returns the enclosing layer root into which this layer paints, inclusive of this one. Note that the enclosing layer may or may not have its own
     // GraphicsLayer backing, but is nevertheless the root for a call to the Layer::paint*() methods.
     PaintLayer* enclosingLayerForPaintInvalidation() const;
 
     PaintLayer* enclosingLayerForPaintInvalidationCrossingFrameBoundaries() const;
 
-    bool hasAncestorWithFilterOutsets() const;
+    bool hasAncestorWithFilterThatMovesPixels() const;
 
     bool canUseConvertToLayerCoords() const
     {
         // These LayoutObjects have an impact on their layers without the layoutObjects knowing about it.
         return !layoutObject()->hasTransformRelatedProperty() && !layoutObject()->isSVGRoot();
     }
 
     void convertToLayerCoords(const PaintLayer* ancestorLayer, LayoutPoint&) const;
     void convertToLayerCoords(const PaintLayer* ancestorLayer, LayoutRect&) const;
 
@@ skipping 122 matching lines @@
     bool backgroundIsKnownToBeOpaqueInRect(const LayoutRect&) const;
 
     bool containsDirtyOverlayScrollbars() const { return m_containsDirtyOverlayScrollbars; }
     void setContainsDirtyOverlayScrollbars(bool dirtyScrollbars) { m_containsDirtyOverlayScrollbars = dirtyScrollbars; }
 
     FilterOperations computeFilterOperations(const ComputedStyle&) const;
     FilterOperations computeBackdropFilterOperations(const ComputedStyle&) const;
     bool paintsWithFilters() const;
     bool paintsWithBackdropFilters() const;
     FilterEffect* lastFilterEffect() const;
-    bool hasFilterOutsets() const;
-    FilterOutsets filterOutsets() const;
+
+    // Can map "forward" to determine which pixels in a destination rect are
+    // affected by pixels in the source rect, or "backward" to determine which
+    // pixels in the source rect are required for a destination rect.
+    // See also FilterEffect::mapRect.
+    FloatRect mapRectForFilter(const FloatRect&, bool forward = true) const;

[Stephen White, 2016/04/06 20:44:11]

I couldn't find any callsites that use forward "false". If so, could you remove
the param? If you really think you'll need it, you can always add it later.

[jbroman, 2016/04/06 21:51:41]

Alright, done.

+
+    // Calls the above, rounding outwards.
+    LayoutRect mapRectForFilter(const LayoutRect&, bool forward = true) const;

[Stephen White, 2016/04/06 20:44:11]

Naming nit: could we call this one mapLayoutRectForFilter(), just to be clear?

[jbroman, 2016/04/06 21:51:41]

Done.

+
+    bool hasFilterThatMovesPixels() const;
 
     PaintLayerFilterInfo* filterInfo() const { return m_rareData ? m_rareData->filterInfo.get() : nullptr; }
     PaintLayerFilterInfo& ensureFilterInfo();
 
     void updateFilters(const ComputedStyle* oldStyle, const ComputedStyle& newStyle);
 
     Node* enclosingNode() const;
 
     bool isInTopLayer() const;
 
@@ skipping 379 matching lines @@
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const blink::PaintLayer*);
 void showLayerTree(const blink::LayoutObject*);
 #endif
 
 #endif // Layer_h