1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/2d/image_operations.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,157 @@
1.4 +// Copyright (c) 2006-2011 The Chromium Authors. All rights reserved.
1.5 +//
1.6 +// Redistribution and use in source and binary forms, with or without
1.7 +// modification, are permitted provided that the following conditions
1.8 +// are met:
1.9 +// * Redistributions of source code must retain the above copyright
1.10 +// notice, this list of conditions and the following disclaimer.
1.11 +// * Redistributions in binary form must reproduce the above copyright
1.12 +// notice, this list of conditions and the following disclaimer in
1.13 +// the documentation and/or other materials provided with the
1.14 +// distribution.
1.15 +// * Neither the name of Google, Inc. nor the names of its contributors
1.16 +// may be used to endorse or promote products derived from this
1.17 +// software without specific prior written permission.
1.18 +//
1.19 +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
1.20 +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
1.21 +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
1.22 +// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
1.23 +// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
1.24 +// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
1.25 +// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
1.26 +// OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
1.27 +// AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
1.28 +// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
1.29 +// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
1.30 +// SUCH DAMAGE.
1.31 +
1.32 +#ifndef SKIA_EXT_IMAGE_OPERATIONS_H_
1.33 +#define SKIA_EXT_IMAGE_OPERATIONS_H_
1.34 +
1.35 +#include "skia/SkTypes.h"
1.36 +#include "Types.h"
1.37 +
1.38 +class SkBitmap;
1.39 +struct SkIRect;
1.40 +
1.41 +namespace skia {
1.42 +
1.43 +class ImageOperations {
1.44 + public:
1.45 + enum ResizeMethod {
1.46 + //
1.47 + // Quality Methods
1.48 + //
1.49 + // Those enumeration values express a desired quality/speed tradeoff.
1.50 + // They are translated into an algorithm-specific method that depends
1.51 + // on the capabilities (CPU, GPU) of the underlying platform.
1.52 + // It is possible for all three methods to be mapped to the same
1.53 + // algorithm on a given platform.
1.54 +
1.55 + // Good quality resizing. Fastest resizing with acceptable visual quality.
1.56 + // This is typically intended for use during interactive layouts
1.57 + // where slower platforms may want to trade image quality for large
1.58 + // increase in resizing performance.
1.59 + //
1.60 + // For example the resizing implementation may devolve to linear
1.61 + // filtering if this enables GPU acceleration to be used.
1.62 + //
1.63 + // Note that the underlying resizing method may be determined
1.64 + // on the fly based on the parameters for a given resize call.
1.65 + // For example an implementation using a GPU-based linear filter
1.66 + // in the common case may still use a higher-quality software-based
1.67 + // filter in cases where using the GPU would actually be slower - due
1.68 + // to too much latency - or impossible - due to image format or size
1.69 + // constraints.
1.70 + RESIZE_GOOD,
1.71 +
1.72 + // Medium quality resizing. Close to high quality resizing (better
1.73 + // than linear interpolation) with potentially some quality being
1.74 + // traded-off for additional speed compared to RESIZE_BEST.
1.75 + //
1.76 + // This is intended, for example, for generation of large thumbnails
1.77 + // (hundreds of pixels in each dimension) from large sources, where
1.78 + // a linear filter would produce too many artifacts but where
1.79 + // a RESIZE_HIGH might be too costly time-wise.
1.80 + RESIZE_BETTER,
1.81 +
1.82 + // High quality resizing. The algorithm is picked to favor image quality.
1.83 + RESIZE_BEST,
1.84 +
1.85 + //
1.86 + // Algorithm-specific enumerations
1.87 + //
1.88 +
1.89 + // Box filter. This is a weighted average of all of the pixels touching
1.90 + // the destination pixel. For enlargement, this is nearest neighbor.
1.91 + //
1.92 + // You probably don't want this, it is here for testing since it is easy to
1.93 + // compute. Use RESIZE_LANCZOS3 instead.
1.94 + RESIZE_BOX,
1.95 +
1.96 + // 1-cycle Hamming filter. This is tall is the middle and falls off towards
1.97 + // the window edges but without going to 0. This is about 40% faster than
1.98 + // a 2-cycle Lanczos.
1.99 + RESIZE_HAMMING1,
1.100 +
1.101 + // 2-cycle Lanczos filter. This is tall in the middle, goes negative on
1.102 + // each side, then returns to zero. Does not provide as good a frequency
1.103 + // response as a 3-cycle Lanczos but is roughly 30% faster.
1.104 + RESIZE_LANCZOS2,
1.105 +
1.106 + // 3-cycle Lanczos filter. This is tall in the middle, goes negative on
1.107 + // each side, then oscillates 2 more times. It gives nice sharp edges.
1.108 + RESIZE_LANCZOS3,
1.109 +
1.110 + // Lanczos filter + subpixel interpolation. If subpixel rendering is not
1.111 + // appropriate we automatically fall back to Lanczos.
1.112 + RESIZE_SUBPIXEL,
1.113 +
1.114 + // enum aliases for first and last methods by algorithm or by quality.
1.115 + RESIZE_FIRST_QUALITY_METHOD = RESIZE_GOOD,
1.116 + RESIZE_LAST_QUALITY_METHOD = RESIZE_BEST,
1.117 + RESIZE_FIRST_ALGORITHM_METHOD = RESIZE_BOX,
1.118 + RESIZE_LAST_ALGORITHM_METHOD = RESIZE_SUBPIXEL,
1.119 + };
1.120 +
1.121 + // Resizes the given source bitmap using the specified resize method, so that
1.122 + // the entire image is (dest_size) big. The dest_subset is the rectangle in
1.123 + // this destination image that should actually be returned.
1.124 + //
1.125 + // The output image will be (dest_subset.width(), dest_subset.height()). This
1.126 + // will save work if you do not need the entire bitmap.
1.127 + //
1.128 + // The destination subset must be smaller than the destination image.
1.129 + static SkBitmap Resize(const SkBitmap& source,
1.130 + ResizeMethod method,
1.131 + int dest_width, int dest_height,
1.132 + const SkIRect& dest_subset,
1.133 + void* dest_pixels = nullptr);
1.134 +
1.135 + // Alternate version for resizing and returning the entire bitmap rather than
1.136 + // a subset.
1.137 + static SkBitmap Resize(const SkBitmap& source,
1.138 + ResizeMethod method,
1.139 + int dest_width, int dest_height,
1.140 + void* dest_pixels = nullptr);
1.141 +
1.142 + private:
1.143 + ImageOperations(); // Class for scoping only.
1.144 +
1.145 + // Supports all methods except RESIZE_SUBPIXEL.
1.146 + static SkBitmap ResizeBasic(const SkBitmap& source,
1.147 + ResizeMethod method,
1.148 + int dest_width, int dest_height,
1.149 + const SkIRect& dest_subset,
1.150 + void* dest_pixels = nullptr);
1.151 +
1.152 + // Subpixel renderer.
1.153 + static SkBitmap ResizeSubpixel(const SkBitmap& source,
1.154 + int dest_width, int dest_height,
1.155 + const SkIRect& dest_subset);
1.156 +};
1.157 +
1.158 +} // namespace skia
1.159 +
1.160 +#endif // SKIA_EXT_IMAGE_OPERATIONS_H_
