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