gfx/skbitmap_operations.h

   1 // Copyright (c) 2009 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 APP_GFX_SKBITMAP_OPERATIONS_H_
   6 #define APP_GFX_SKBITMAP_OPERATIONS_H_
   7
   8 #include "gfx/color_utils.h"
   9 #include "testing/gtest/include/gtest/gtest_prod.h"
  10
  11 class SkBitmap;
  12
  13 class SkBitmapOperations {
  14  public:
  15   // Create a bitmap that is an inverted image of the passed in image.
  16   // Each color becomes its inverse in the color wheel. So (255, 15, 0) becomes
  17   // (0, 240, 255). The alpha value is not inverted.
  18   static SkBitmap CreateInvertedBitmap(const SkBitmap& image);
  19
  20   // Create a bitmap that is a superimposition of the second bitmap on top of
  21   // the first. The provided bitmaps must use have the kARGB_8888_Config config
  22   // and be of equal dimensions.
  23   static SkBitmap CreateSuperimposedBitmap(const SkBitmap& first,
  24                                            const SkBitmap& second);
  25
  26   // Create a bitmap that is a blend of two others. The alpha argument
  27   // specifies the opacity of the second bitmap. The provided bitmaps must
  28   // use have the kARGB_8888_Config config and be of equal dimensions.
  29   static SkBitmap CreateBlendedBitmap(const SkBitmap& first,
  30                                       const SkBitmap& second,
  31                                       double alpha);
  32
  33   // Create a bitmap that is the original bitmap masked out by the mask defined
  34   // in the alpha bitmap. The images must use the kARGB_8888_Config config and
  35   // be of equal dimensions.
  36   static SkBitmap CreateMaskedBitmap(const SkBitmap& first,
  37                                      const SkBitmap& alpha);
  38
  39   // We create a button background image by compositing the color and image
  40   // together, then applying the mask. This is a highly specialized composite
  41   // operation that is the equivalent of drawing a background in |color|,
  42   // tiling |image| over the top, and then masking the result out with |mask|.
  43   // The images must use kARGB_8888_Config config.
  44   static SkBitmap CreateButtonBackground(SkColor color,
  45                                          const SkBitmap& image,
  46                                          const SkBitmap& mask);
  47
  48   // Shift a bitmap's HSL values. The shift values are in the range of 0-1,
  49   // with the option to specify -1 for 'no change'. The shift values are
  50   // defined as:
  51   // hsl_shift[0] (hue): The absolute hue value for the image - 0 and 1 map
  52   //    to 0 and 360 on the hue color wheel (red).
  53   // hsl_shift[1] (saturation): A saturation shift for the image, with the
  54   //    following key values:
  55   //    0 = remove all color.
  56   //    0.5 = leave unchanged.
  57   //    1 = fully saturate the image.
  58   // hsl_shift[2] (lightness): A lightness shift for the image, with the
  59   //    following key values:
  60   //    0 = remove all lightness (make all pixels black).
  61   //    0.5 = leave unchanged.
  62   //    1 = full lightness (make all pixels white).
  63   static SkBitmap CreateHSLShiftedBitmap(const SkBitmap& bitmap,
  64                                          color_utils::HSL hsl_shift);
  65
  66   // Create a bitmap that is cropped from another bitmap. This is special
  67   // because it tiles the original bitmap, so your coordinates can extend
  68   // outside the bounds of the original image.
  69   static SkBitmap CreateTiledBitmap(const SkBitmap& bitmap,
  70                                     int src_x, int src_y,
  71                                     int dst_w, int dst_h);
  72
  73   // Iteratively downsamples by 2 until the bitmap is no smaller than the
  74   // input size. The normal use of this is to downsample the bitmap "close" to
  75   // the final size, and then use traditional resampling on the result.
  76   // Because the bitmap will be closer to the final size, it will be faster,
  77   // and linear interpolation will generally work well as a second step.
  78   static SkBitmap DownsampleByTwoUntilSize(const SkBitmap& bitmap,
  79                                            int min_w, int min_h);
  80
  81   // Makes a bitmap half has large in each direction by averaging groups of
  82   // 4 pixels. This is one step in generating a mipmap.
  83   static SkBitmap DownsampleByTwo(const SkBitmap& bitmap);
  84  private:
  85   SkBitmapOperations();  // Class for scoping only.
  86
  87   FRIEND_TEST(SkBitmapOperationsTest, DownsampleByTwo);
  88   FRIEND_TEST(SkBitmapOperationsTest, DownsampleByTwoSmall);
  89 };
  90
  91 #endif  // APP_GFX_SKBITMAP_OPERATIONS_H_