Consolidate FilterOperation and FilterEffect mapRect implementations

third_party/WebKit/Source/core/style/FilterOperation.cpp

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 #include "core/style/FilterOperation.h"
 
 #include "platform/LengthFunctions.h"
 #include "platform/animation/AnimationUtilities.h"
+#include "platform/graphics/filters/FEDropShadow.h"
 #include "platform/graphics/filters/FEGaussianBlur.h"
 #include "platform/graphics/filters/FilterEffect.h"
-#include "platform/graphics/filters/SkiaImageFilterBuilder.h"
 
 namespace blink {
 
-static inline FloatSize outsetSizeForBlur(float stdDeviation) {
-  IntSize kernelSize = FEGaussianBlur::calculateUnscaledKernelSize(
-      FloatPoint(stdDeviation, stdDeviation));
-  FloatSize outset;
-  // We take the half kernel size and multiply it with three, because we run box
-  // blur three times.
-  outset.setWidth(3.0f * kernelSize.width() * 0.5f);
-  outset.setHeight(3.0f * kernelSize.height() * 0.5f);
-  return outset;
-}
-
 FilterOperation* FilterOperation::blend(const FilterOperation* from,
                                         const FilterOperation* to,
                                         double progress) {
   DCHECK(from || to);
   if (to)
     return to->blend(from, progress);
   return from->blend(0, 1 - progress);
 }
 
 DEFINE_TRACE(ReferenceFilterOperation) {
@@ skipping 81 matching lines @@
     case OPACITY:
       result = clampTo<double>(result, 0, 1);
       break;
     default:
       NOTREACHED();
   }
   return BasicComponentTransferFilterOperation::create(result, m_type);
 }
 
 FloatRect BlurFilterOperation::mapRect(const FloatRect& rect) const {
-  // Matches FEGaussianBlur::mapRect.
   float stdDeviation = floatValueForLength(m_stdDeviation, 0);
-  FloatSize outsetSize = outsetSizeForBlur(stdDeviation);
-  FloatRect mappedRect = rect;
-  mappedRect.inflateX(outsetSize.width());
-  mappedRect.inflateY(outsetSize.height());
-  return mappedRect;
+  return FEGaussianBlur::mapEffect(FloatSize(stdDeviation, stdDeviation), rect);
 }
 
 FilterOperation* BlurFilterOperation::blend(const FilterOperation* from,
                                             double progress) const {
   LengthType lengthType = m_stdDeviation.type();
   if (!from)
     return BlurFilterOperation::create(m_stdDeviation.blend(
         Length(lengthType), progress, ValueRangeNonNegative));
 
   const BlurFilterOperation* fromOp = toBlurFilterOperation(from);
   return BlurFilterOperation::create(m_stdDeviation.blend(
       fromOp->m_stdDeviation, progress, ValueRangeNonNegative));
 }
 
 FloatRect DropShadowFilterOperation::mapRect(const FloatRect& rect) const {
-  FloatSize outsetSize = outsetSizeForBlur(m_stdDeviation);
-  FloatRect mappedRect = rect;
-  mappedRect.inflateX(outsetSize.width());
-  mappedRect.inflateY(outsetSize.height());
-  mappedRect.moveBy(m_location);
-  mappedRect.unite(rect);
-  return mappedRect;
+  float stdDeviation = m_stdDeviation;

[Stephen Chennney, 2016/10/10 19:43:25]

Why does this not do the floatValueForLength that the blur effect does?

[fs, 2016/10/10 20:40:03]

This caught me by surprise too, but it turns out that this m_stdDeviation -
unlike the one in BlurFilterOperation - is a plain 'int'. It'd probably make
sense to "upgrade" it to a Length (like in Blur...) Similarly with m_location.
That's best left to a separate CL though I think.

+  return FEDropShadow::mapEffect(FloatSize(stdDeviation, stdDeviation),
+                                 FloatPoint(m_location), rect);
 }
 
 FilterOperation* DropShadowFilterOperation::blend(const FilterOperation* from,
                                                   double progress) const {
   if (!from) {
     return DropShadowFilterOperation::create(
         blink::blend(IntPoint(), m_location, progress),
         blink::blend(0, m_stdDeviation, progress),
         blink::blend(Color(Color::transparent), m_color, progress));
   }
@@ skipping 16 matching lines @@
 }
 
 bool BoxReflectFilterOperation::operator==(const FilterOperation& o) const {
   if (!isSameType(o))
     return false;
   const auto& other = static_cast<const BoxReflectFilterOperation&>(o);
   return m_reflection == other.m_reflection;
 }
 
 }  // namespace blink