ui/gfx/skbitmap_operations.h

   1 // Copyright (c) 2012 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 UI_GFX_SKBITMAP_OPERATIONS_H_
   6 #define UI_GFX_SKBITMAP_OPERATIONS_H_
   7
   8 #include "base/gtest_prod_util.h"
   9 #include "ui/gfx/color_utils.h"
  10 #include "ui/gfx/gfx_export.h"
  11 #include "ui/gfx/shadow_value.h"
  12
  13 namespace gfx {
  14 class Point;
  15 class Size;
  16 }
  17
  18 class SkBitmap;
  19
  20 class GFX_EXPORT SkBitmapOperations {
  21  public:
  22   // Enum for use in rotating images (must be in 90 degree increments),
  23   // see: Rotate.
  24   enum RotationAmount {
  25     ROTATION_90_CW,
  26     ROTATION_180_CW,
  27     ROTATION_270_CW,
  28   };
  29
  30   // Create a bitmap that is an inverted image of the passed in image.
  31   // Each color becomes its inverse in the color wheel. So (255, 15, 0) becomes
  32   // (0, 240, 255). The alpha value is not inverted.
  33   static SkBitmap CreateInvertedBitmap(const SkBitmap& image);
  34
  35   // Create a bitmap that is a superimposition of the second bitmap on top of
  36   // the first. The provided bitmaps must use have the kARGB_8888_Config config
  37   // and be of equal dimensions.
  38   static SkBitmap CreateSuperimposedBitmap(const SkBitmap& first,
  39                                            const SkBitmap& second);
  40
  41   // Create a bitmap that is a blend of two others. The alpha argument
  42   // specifies the opacity of the second bitmap. The provided bitmaps must
  43   // use have the kARGB_8888_Config config and be of equal dimensions.
  44   static SkBitmap CreateBlendedBitmap(const SkBitmap& first,
  45                                       const SkBitmap& second,
  46                                       double alpha);
  47
  48   // Create a bitmap that is the original bitmap masked out by the mask defined
  49   // in the alpha bitmap. The images must use the kARGB_8888_Config config and
  50   // be of equal dimensions.
  51   static SkBitmap CreateMaskedBitmap(const SkBitmap& first,
  52                                      const SkBitmap& alpha);
  53
  54   // We create a button background image by compositing the color and image
  55   // together, then applying the mask. This is a highly specialized composite
  56   // operation that is the equivalent of drawing a background in |color|,
  57   // tiling |image| over the top, and then masking the result out with |mask|.
  58   // The images must use kARGB_8888_Config config.
  59   static SkBitmap CreateButtonBackground(SkColor color,
  60                                          const SkBitmap& image,
  61                                          const SkBitmap& mask);
  62
  63   // Shift a bitmap's HSL values. The shift values are in the range of 0-1,
  64   // with the option to specify -1 for 'no change'. The shift values are
  65   // defined as:
  66   // hsl_shift[0] (hue): The absolute hue value for the image - 0 and 1 map
  67   //    to 0 and 360 on the hue color wheel (red).
  68   // hsl_shift[1] (saturation): A saturation shift for the image, with the
  69   //    following key values:
  70   //    0 = remove all color.
  71   //    0.5 = leave unchanged.
  72   //    1 = fully saturate the image.
  73   // hsl_shift[2] (lightness): A lightness shift for the image, with the
  74   //    following key values:
  75   //    0 = remove all lightness (make all pixels black).
  76   //    0.5 = leave unchanged.
  77   //    1 = full lightness (make all pixels white).
  78   static SkBitmap CreateHSLShiftedBitmap(const SkBitmap& bitmap,
  79                                          const color_utils::HSL& hsl_shift);
  80
  81   // Create a bitmap that is cropped from another bitmap. This is special
  82   // because it tiles the original bitmap, so your coordinates can extend
  83   // outside the bounds of the original image.
  84   static SkBitmap CreateTiledBitmap(const SkBitmap& bitmap,
  85                                     int src_x, int src_y,
  86                                     int dst_w, int dst_h);
  87
  88   // Iteratively downsamples by 2 until the bitmap is no smaller than the
  89   // input size. The normal use of this is to downsample the bitmap "close" to
  90   // the final size, and then use traditional resampling on the result.
  91   // Because the bitmap will be closer to the final size, it will be faster,
  92   // and linear interpolation will generally work well as a second step.
  93   static SkBitmap DownsampleByTwoUntilSize(const SkBitmap& bitmap,
  94                                            int min_w, int min_h);
  95
  96   // Makes a bitmap half has large in each direction by averaging groups of
  97   // 4 pixels. This is one step in generating a mipmap.
  98   static SkBitmap DownsampleByTwo(const SkBitmap& bitmap);
  99
 100   // Unpremultiplies all pixels in |bitmap|. You almost never want to call
 101   // this, as |SkBitmap|s are always premultiplied by conversion. Call this
 102   // only if you will pass the bitmap's data into a system function that
 103   // doesn't expect premultiplied colors.
 104   static SkBitmap UnPreMultiply(const SkBitmap& bitmap);
 105
 106   // Transpose the pixels in |bitmap| by swapping x and y.
 107   static SkBitmap CreateTransposedBitmap(const SkBitmap& bitmap);
 108
 109   // Create a bitmap by combining alpha channel of |bitmap| and color |c|.
 110   // The image must use the kARGB_8888_Config config.
 111   static SkBitmap CreateColorMask(const SkBitmap& bitmap, SkColor c);
 112
 113   // Create a bitmap with drop shadow added to |bitmap|. |shadows| defines
 114   // the shadows to add. The created bitmap would be padded to have enough space
 115   // for shadows and have original bitmap in the center. The image must use the
 116   // kARGB_8888_Config config.
 117   static SkBitmap CreateDropShadow(const SkBitmap& bitmap,
 118                                    const gfx::ShadowValues& shadows);
 119
 120   // Rotates the given source bitmap clockwise by the requested amount.
 121   static SkBitmap Rotate(const SkBitmap& source, RotationAmount rotation);
 122
 123  private:
 124   SkBitmapOperations();  // Class for scoping only.
 125
 126   FRIEND_TEST_ALL_PREFIXES(SkBitmapOperationsTest, DownsampleByTwo);
 127   FRIEND_TEST_ALL_PREFIXES(SkBitmapOperationsTest, DownsampleByTwoSmall);
 128 };
 129
 130 #endif  // UI_GFX_SKBITMAP_OPERATIONS_H_