Scale the ALPHA_THRESHOLD filter's region based on the device scale factor.

cc/output/filter_operation.h

 // Copyright 2013 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.
 
 #ifndef CC_OUTPUT_FILTER_OPERATION_H_
 #define CC_OUTPUT_FILTER_OPERATION_H_
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
@@ skipping 71 matching lines @@
   int zoom_inset() const {
     DCHECK_EQ(type_, ZOOM);
     return zoom_inset_;
   }
 
   const SkRegion& region() const {
     DCHECK_EQ(type_, ALPHA_THRESHOLD);
     return region_;
   }
 
+  float device_scale_factor() const {
+    DCHECK_EQ(type_, ALPHA_THRESHOLD);
+    return device_scale_factor_;
+  }
+
   static FilterOperation CreateGrayscaleFilter(float amount) {
     return FilterOperation(GRAYSCALE, amount);
   }
 
   static FilterOperation CreateSepiaFilter(float amount) {
     return FilterOperation(SEPIA, amount);
   }
 
   static FilterOperation CreateSaturateFilter(float amount) {
     return FilterOperation(SATURATE, amount);
@@ skipping 40 matching lines @@
   static FilterOperation CreateReferenceFilter(
       const skia::RefPtr<SkImageFilter>& image_filter) {
     return FilterOperation(REFERENCE, image_filter);
   }
 
   static FilterOperation CreateSaturatingBrightnessFilter(float amount) {
     return FilterOperation(SATURATING_BRIGHTNESS, amount);
   }
 
   static FilterOperation CreateAlphaThresholdFilter(const SkRegion& region,
+                                                    float device_scale_factor,

[danakj, 2014/06/17 21:35:28]

The fact that you're setting this to the DSF doesn't seem relevant to the
FilterOperation, it's just a scale that will be applied to the alpha filter.
Let's just call it a general "scale factor" in this code.

[garykac, 2014/07/10 23:02:24]

Acknowledged.

                                                     float inner_threshold,
                                                     float outer_threshold) {
-    return FilterOperation(ALPHA_THRESHOLD, region,
-                           inner_threshold, outer_threshold);
+    return FilterOperation(ALPHA_THRESHOLD,
+                           region,
+                           device_scale_factor,
+                           inner_threshold,
+                           outer_threshold);
   }
 
   bool operator==(const FilterOperation& other) const;
 
   bool operator!=(const FilterOperation& other) const {
     return !(*this == other);
   }
 
   // Methods for restoring a FilterOperation.
   static FilterOperation CreateEmptyFilter() {
@@ skipping 37 matching lines @@
   void set_zoom_inset(int inset) {
     DCHECK_EQ(type_, ZOOM);
     zoom_inset_ = inset;
   }
 
   void set_region(const SkRegion& region) {
     DCHECK_EQ(type_, ALPHA_THRESHOLD);
     region_ = region;
   }
 
+  void set_device_scale_factor(float scale) {
+    DCHECK_EQ(type_, ALPHA_THRESHOLD);
+    device_scale_factor_ = scale;
+  }
+
   // Given two filters of the same type, returns a filter operation created by
   // linearly interpolating a |progress| fraction from |from| to |to|. If either
   // |from| or |to| (but not both) is null, it is treated as a no-op filter of
   // the same type as the other given filter. If both |from| and |to| are null,
   // or if |from| and |to| are non-null but of different types, returns a
   // no-op filter.
   static FilterOperation Blend(const FilterOperation* from,
                                const FilterOperation* to,
                                double progress);
 
   scoped_ptr<base::Value> AsValue() const;
 
  private:
   FilterOperation(FilterType type, float amount);
 
   FilterOperation(FilterType type,
                   const gfx::Point& offset,
                   float stdDeviation,
                   SkColor color);
 
   FilterOperation(FilterType, SkScalar matrix[20]);
 
   FilterOperation(FilterType type, float amount, int inset);
 
   FilterOperation(FilterType type,
                   const skia::RefPtr<SkImageFilter>& image_filter);
 
   FilterOperation(FilterType type,
                   const SkRegion& region,
+                  float device_scale_factor,
                   float inner_threshold,
                   float outer_threshold);
 
   FilterType type_;
   float amount_;
   float outer_threshold_;
   gfx::Point drop_shadow_offset_;
   SkColor drop_shadow_color_;
   skia::RefPtr<SkImageFilter> image_filter_;
   SkScalar matrix_[20];
   int zoom_inset_;
   SkRegion region_;
+  float device_scale_factor_;
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_FILTER_OPERATION_H_