cc/test/pixel_comparator.h

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CC_TEST_PIXEL_COMPARATOR_H_
   6 #define CC_TEST_PIXEL_COMPARATOR_H_
   7
   8 #include "base/compiler_specific.h"
   9 #include "third_party/skia/include/core/SkBitmap.h"
  10
  11 namespace cc {
  12
  13 // Interface for pixel comparators.
  14 class PixelComparator {
  15  public:
  16   virtual ~PixelComparator() {}
  17
  18   virtual bool Compare(const SkBitmap& actual_bmp,
  19                        const SkBitmap& expected_bmp) const = 0;
  20 };
  21
  22 // Exact pixel comparator. Counts the number of pixel with an error.
  23 class ExactPixelComparator : public PixelComparator {
  24  public:
  25   explicit ExactPixelComparator(const bool discard_alpha);
  26   virtual ~ExactPixelComparator() {}
  27
  28   // Returns true if the two bitmaps are identical. Otherwise, returns false
  29   // and report the number of pixels with an error on LOG(ERROR). Differences
  30   // in the alpha channel are ignored.
  31   virtual bool Compare(const SkBitmap& actual_bmp,
  32                        const SkBitmap& expected_bmp) const override;
  33
  34  private:
  35   // Exclude alpha channel from comparison?
  36   bool discard_alpha_;
  37 };
  38
  39 // Fuzzy pixel comparator. Counts small and arbitrary errors separately and
  40 // computes average and maximum absolute errors per color channel.
  41 class FuzzyPixelComparator : public PixelComparator {
  42  public:
  43   FuzzyPixelComparator(const bool discard_alpha,
  44                        const float error_pixels_percentage_limit,
  45                        const float small_error_pixels_percentage_limit,
  46                        const float avg_abs_error_limit,
  47                        const int max_abs_error_limit,
  48                        const int small_error_threshold);
  49   virtual ~FuzzyPixelComparator() {}
  50
  51   // Computes error metrics and returns true if the errors don't exceed the
  52   // specified limits. Otherwise, returns false and reports the error metrics on
  53   // LOG(ERROR). Differences in the alpha channel are ignored.
  54   virtual bool Compare(const SkBitmap& actual_bmp,
  55                        const SkBitmap& expected_bmp) const override;
  56
  57  private:
  58   // Exclude alpha channel from comparison?
  59   bool discard_alpha_;
  60   // Limit for percentage of pixels with an error.
  61   float error_pixels_percentage_limit_;
  62   // Limit for percentage of pixels with a small error.
  63   float small_error_pixels_percentage_limit_;
  64   // Limit for average absolute error (excluding identical pixels).
  65   float avg_abs_error_limit_;
  66   // Limit for largest absolute error.
  67   int max_abs_error_limit_;
  68   // Threshold for small errors.
  69   int small_error_threshold_;
  70 };
  71
  72 // All pixels can be off by one, but any more than that is an error.
  73 class FuzzyPixelOffByOneComparator : public FuzzyPixelComparator {
  74  public:
  75   explicit FuzzyPixelOffByOneComparator(bool discard_alpha)
  76       : FuzzyPixelComparator(discard_alpha, 100.f, 0.f, 1.f, 1, 0) {}
  77 };
  78
  79 }  // namespace cc
  80
  81 #endif  // CC_TEST_PIXEL_COMPARATOR_H_