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