1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/core/SkBitmapScaler.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,108 @@
1.4 +/*
1.5 + * Copyright 2013 Google Inc.
1.6 + *
1.7 + * Use of this source code is governed by a BSD-style license that can be
1.8 + * found in the LICENSE file.
1.9 + */
1.10 +
1.11 +#ifndef SkBitmapScaler_DEFINED
1.12 +#define SkBitmapScaler_DEFINED
1.13 +
1.14 +#include "SkBitmap.h"
1.15 +#include "SkConvolver.h"
1.16 +
1.17 +/** \class SkBitmapScaler
1.18 +
1.19 + Provides the interface for high quality image resampling.
1.20 + */
1.21 +
1.22 +class SK_API SkBitmapScaler {
1.23 +public:
1.24 + enum ResizeMethod {
1.25 + // Quality Methods
1.26 + //
1.27 + // Those enumeration values express a desired quality/speed tradeoff.
1.28 + // They are translated into an algorithm-specific method that depends
1.29 + // on the capabilities (CPU, GPU) of the underlying platform.
1.30 + // It is possible for all three methods to be mapped to the same
1.31 + // algorithm on a given platform.
1.32 +
1.33 + // Good quality resizing. Fastest resizing with acceptable visual quality.
1.34 + // This is typically intended for use during interactive layouts
1.35 + // where slower platforms may want to trade image quality for large
1.36 + // increase in resizing performance.
1.37 + //
1.38 + // For example the resizing implementation may devolve to linear
1.39 + // filtering if this enables GPU acceleration to be used.
1.40 + //
1.41 + // Note that the underlying resizing method may be determined
1.42 + // on the fly based on the parameters for a given resize call.
1.43 + // For example an implementation using a GPU-based linear filter
1.44 + // in the common case may still use a higher-quality software-based
1.45 + // filter in cases where using the GPU would actually be slower - due
1.46 + // to too much latency - or impossible - due to image format or size
1.47 + // constraints.
1.48 + RESIZE_GOOD,
1.49 +
1.50 + // Medium quality resizing. Close to high quality resizing (better
1.51 + // than linear interpolation) with potentially some quality being
1.52 + // traded-off for additional speed compared to RESIZE_BEST.
1.53 + //
1.54 + // This is intended, for example, for generation of large thumbnails
1.55 + // (hundreds of pixels in each dimension) from large sources, where
1.56 + // a linear filter would produce too many artifacts but where
1.57 + // a RESIZE_HIGH might be too costly time-wise.
1.58 + RESIZE_BETTER,
1.59 +
1.60 + // High quality resizing. The algorithm is picked to favor image quality.
1.61 + RESIZE_BEST,
1.62 +
1.63 + //
1.64 + // Algorithm-specific enumerations
1.65 + //
1.66 +
1.67 + // Box filter. This is a weighted average of all of the pixels touching
1.68 + // the destination pixel. For enlargement, this is nearest neighbor.
1.69 + //
1.70 + // You probably don't want this, it is here for testing since it is easy to
1.71 + // compute. Use RESIZE_LANCZOS3 instead.
1.72 + RESIZE_BOX,
1.73 + RESIZE_TRIANGLE,
1.74 + RESIZE_LANCZOS3,
1.75 + RESIZE_HAMMING,
1.76 + RESIZE_MITCHELL,
1.77 +
1.78 + // enum aliases for first and last methods by algorithm or by quality.
1.79 + RESIZE_FIRST_QUALITY_METHOD = RESIZE_GOOD,
1.80 + RESIZE_LAST_QUALITY_METHOD = RESIZE_BEST,
1.81 + RESIZE_FIRST_ALGORITHM_METHOD = RESIZE_BOX,
1.82 + RESIZE_LAST_ALGORITHM_METHOD = RESIZE_MITCHELL,
1.83 + };
1.84 +
1.85 + // Resizes the given source bitmap using the specified resize method, so that
1.86 + // the entire image is (dest_size) big. The dest_subset is the rectangle in
1.87 + // this destination image that should actually be returned.
1.88 + //
1.89 + // The output image will be (dest_subset.width(), dest_subset.height()). This
1.90 + // will save work if you do not need the entire bitmap.
1.91 + //
1.92 + // The destination subset must be smaller than the destination image.
1.93 + static bool Resize(SkBitmap* result,
1.94 + const SkBitmap& source,
1.95 + ResizeMethod method,
1.96 + int dest_width, int dest_height,
1.97 + const SkIRect& dest_subset,
1.98 + const SkConvolutionProcs&,
1.99 + SkBitmap::Allocator* allocator = NULL);
1.100 +
1.101 + // Alternate version for resizing and returning the entire bitmap rather than
1.102 + // a subset.
1.103 + static bool Resize(SkBitmap* result,
1.104 + const SkBitmap& source,
1.105 + ResizeMethod method,
1.106 + int dest_width, int dest_height,
1.107 + const SkConvolutionProcs&,
1.108 + SkBitmap::Allocator* allocator = NULL);
1.109 +};
1.110 +
1.111 +#endif
