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1 /* | 1 /* |
2 * Copyright 2013 Google Inc. | 2 * Copyright 2013 Google Inc. |
3 * | 3 * |
4 * Use of this source code is governed by a BSD-style license that can be | 4 * Use of this source code is governed by a BSD-style license that can be |
5 * found in the LICENSE file. | 5 * found in the LICENSE file. |
6 */ | 6 */ |
7 | 7 |
8 #ifndef SkBitmapScaler_DEFINED | 8 #ifndef SkBitmapScaler_DEFINED |
9 #define SkBitmapScaler_DEFINED | 9 #define SkBitmapScaler_DEFINED |
10 | 10 |
11 #include "SkBitmap.h" | 11 #include "SkBitmap.h" |
12 #include "SkConvolver.h" | 12 #include "SkConvolver.h" |
13 | 13 |
14 /** \class SkBitmapScaler | 14 /** \class SkBitmapScaler |
15 | 15 |
16 Provides the interface for high quality image resampling. | 16 Provides the interface for high quality image resampling. |
17 */ | 17 */ |
18 | 18 |
19 class SK_API SkBitmapScaler { | 19 class SK_API SkBitmapScaler { |
20 public: | 20 public: |
21 enum ResizeMethod { | 21 enum ResizeMethod { |
22 // Quality Methods | |
23 // | |
24 // Those enumeration values express a desired quality/speed tradeoff. | |
25 // They are translated into an algorithm-specific method that depends | |
26 // on the capabilities (CPU, GPU) of the underlying platform. | |
27 // It is possible for all three methods to be mapped to the same | |
28 // algorithm on a given platform. | |
29 | |
30 // Good quality resizing. Fastest resizing with acceptable visual qualit
y. | |
31 // This is typically intended for use during interactive layouts | |
32 // where slower platforms may want to trade image quality for large | |
33 // increase in resizing performance. | |
34 // | |
35 // For example the resizing implementation may devolve to linear | |
36 // filtering if this enables GPU acceleration to be used. | |
37 // | |
38 // Note that the underlying resizing method may be determined | |
39 // on the fly based on the parameters for a given resize call. | |
40 // For example an implementation using a GPU-based linear filter | |
41 // in the common case may still use a higher-quality software-based | |
42 // filter in cases where using the GPU would actually be slower - due | |
43 // to too much latency - or impossible - due to image format or size | |
44 // constraints. | |
45 RESIZE_GOOD, | |
46 | |
47 // Medium quality resizing. Close to high quality resizing (better | |
48 // than linear interpolation) with potentially some quality being | |
49 // traded-off for additional speed compared to RESIZE_BEST. | |
50 // | |
51 // This is intended, for example, for generation of large thumbnails | |
52 // (hundreds of pixels in each dimension) from large sources, where | |
53 // a linear filter would produce too many artifacts but where | |
54 // a RESIZE_HIGH might be too costly time-wise. | |
55 RESIZE_BETTER, | |
56 | |
57 // High quality resizing. The algorithm is picked to favor image quality
. | |
58 RESIZE_BEST, | |
59 | |
60 // | |
61 // Algorithm-specific enumerations | |
62 // | |
63 | |
64 // Box filter. This is a weighted average of all of the pixels touching | |
65 // the destination pixel. For enlargement, this is nearest neighbor. | |
66 // | |
67 // You probably don't want this, it is here for testing since it is easy
to | |
68 // compute. Use RESIZE_LANCZOS3 instead. | |
69 RESIZE_BOX, | 22 RESIZE_BOX, |
70 RESIZE_TRIANGLE, | 23 RESIZE_TRIANGLE, |
71 RESIZE_LANCZOS3, | 24 RESIZE_LANCZOS3, |
72 RESIZE_HAMMING, | 25 RESIZE_HAMMING, |
73 RESIZE_MITCHELL, | 26 RESIZE_MITCHELL, |
74 | 27 |
75 // enum aliases for first and last methods by algorithm or by quality. | 28 RESIZE_FirstMethod = RESIZE_BOX, |
76 RESIZE_FIRST_QUALITY_METHOD = RESIZE_GOOD, | 29 RESIZE_LastMethod = RESIZE_MITCHELL, |
77 RESIZE_LAST_QUALITY_METHOD = RESIZE_BEST, | |
78 RESIZE_FIRST_ALGORITHM_METHOD = RESIZE_BOX, | |
79 RESIZE_LAST_ALGORITHM_METHOD = RESIZE_MITCHELL, | |
80 }; | 30 }; |
81 | 31 |
82 static bool Resize(SkBitmap* result, const SkPixmap& src, ResizeMethod metho
d, | 32 static bool Resize(SkBitmap* result, const SkPixmap& src, ResizeMethod metho
d, |
83 float dest_width, float dest_height, SkBitmap::Allocator*
= nullptr); | 33 int dest_width, int dest_height, SkBitmap::Allocator* = n
ullptr); |
84 | 34 |
85 /** Platforms can also optionally overwrite the convolution functions | 35 /** Platforms can also optionally overwrite the convolution functions |
86 if we have SIMD versions of them. | 36 if we have SIMD versions of them. |
87 */ | 37 */ |
88 | 38 |
89 static void PlatformConvolutionProcs(SkConvolutionProcs*); | 39 static void PlatformConvolutionProcs(SkConvolutionProcs*); |
90 }; | 40 }; |
91 | 41 |
92 #endif | 42 #endif |
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