| /* |
| * Copyright 2013 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkBitmapScaler_DEFINED |
| #define SkBitmapScaler_DEFINED |
| |
| #include "SkBitmap.h" |
| #include "SkConvolver.h" |
| |
| /** \class SkBitmapScaler |
| |
| Provides the interface for high quality image resampling. |
| */ |
| |
| class SK_API SkBitmapScaler { |
| public: |
| enum ResizeMethod { |
| // Quality Methods |
| // |
| // Those enumeration values express a desired quality/speed tradeoff. |
| // They are translated into an algorithm-specific method that depends |
| // on the capabilities (CPU, GPU) of the underlying platform. |
| // It is possible for all three methods to be mapped to the same |
| // algorithm on a given platform. |
| |
| // Good quality resizing. Fastest resizing with acceptable visual quality. |
| // This is typically intended for use during interactive layouts |
| // where slower platforms may want to trade image quality for large |
| // increase in resizing performance. |
| // |
| // For example the resizing implementation may devolve to linear |
| // filtering if this enables GPU acceleration to be used. |
| // |
| // Note that the underlying resizing method may be determined |
| // on the fly based on the parameters for a given resize call. |
| // For example an implementation using a GPU-based linear filter |
| // in the common case may still use a higher-quality software-based |
| // filter in cases where using the GPU would actually be slower - due |
| // to too much latency - or impossible - due to image format or size |
| // constraints. |
| RESIZE_GOOD, |
| |
| // Medium quality resizing. Close to high quality resizing (better |
| // than linear interpolation) with potentially some quality being |
| // traded-off for additional speed compared to RESIZE_BEST. |
| // |
| // This is intended, for example, for generation of large thumbnails |
| // (hundreds of pixels in each dimension) from large sources, where |
| // a linear filter would produce too many artifacts but where |
| // a RESIZE_HIGH might be too costly time-wise. |
| RESIZE_BETTER, |
| |
| // High quality resizing. The algorithm is picked to favor image quality. |
| RESIZE_BEST, |
| |
| // |
| // Algorithm-specific enumerations |
| // |
| |
| // Box filter. This is a weighted average of all of the pixels touching |
| // the destination pixel. For enlargement, this is nearest neighbor. |
| // |
| // You probably don't want this, it is here for testing since it is easy to |
| // compute. Use RESIZE_LANCZOS3 instead. |
| RESIZE_BOX, |
| RESIZE_TRIANGLE, |
| RESIZE_LANCZOS3, |
| RESIZE_HAMMING, |
| RESIZE_MITCHELL, |
| |
| // enum aliases for first and last methods by algorithm or by quality. |
| RESIZE_FIRST_QUALITY_METHOD = RESIZE_GOOD, |
| RESIZE_LAST_QUALITY_METHOD = RESIZE_BEST, |
| RESIZE_FIRST_ALGORITHM_METHOD = RESIZE_BOX, |
| RESIZE_LAST_ALGORITHM_METHOD = RESIZE_MITCHELL, |
| }; |
| |
| static bool Resize(SkBitmap* result, const SkPixmap& src, ResizeMethod method, |
| float dest_width, float dest_height, SkBitmap::Allocator* = nullptr); |
| |
| /** Platforms can also optionally overwrite the convolution functions |
| if we have SIMD versions of them. |
| */ |
| |
| static void PlatformConvolutionProcs(SkConvolutionProcs*); |
| }; |
| |
| #endif |