1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/images/SkDecodingImageGenerator.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,140 @@
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 SkDecodingImageGenerator_DEFINED
1.12 +#define SkDecodingImageGenerator_DEFINED
1.13 +
1.14 +#include "SkBitmap.h"
1.15 +#include "SkImageGenerator.h"
1.16 +
1.17 +class SkData;
1.18 +class SkStreamRewindable;
1.19 +
1.20 +/**
1.21 + * An implementation of SkImageGenerator that calls into
1.22 + * SkImageDecoder.
1.23 + */
1.24 +class SkDecodingImageGenerator : public SkImageGenerator {
1.25 +public:
1.26 + virtual ~SkDecodingImageGenerator();
1.27 + virtual SkData* refEncodedData() SK_OVERRIDE;
1.28 + // This implementaion of getInfo() always returns true.
1.29 + virtual bool getInfo(SkImageInfo* info) SK_OVERRIDE;
1.30 + virtual bool getPixels(const SkImageInfo& info,
1.31 + void* pixels,
1.32 + size_t rowBytes) SK_OVERRIDE;
1.33 + /**
1.34 + * These options will be passed on to the image decoder. The
1.35 + * defaults are sensible.
1.36 + *
1.37 + * @param fSampleSize If set to > 1, tells the decoder to return a
1.38 + * smaller than original bitmap, sampling 1 pixel for
1.39 + * every size pixels. e.g. if sample size is set to 3,
1.40 + * then the returned bitmap will be 1/3 as wide and high,
1.41 + * and will contain 1/9 as many pixels as the original.
1.42 + * Note: this is a hint, and the codec may choose to
1.43 + * ignore this, or only approximate the sample size.
1.44 + *
1.45 + * @param fDitherImage Set to true if the the decoder should try to
1.46 + * dither the resulting image when decoding to a smaller
1.47 + * color-space. The default is true.
1.48 + *
1.49 + * @param fRequestedColorType If not given, then use whichever
1.50 + * config the decoder wants. Else try to use this color
1.51 + * type. If the decoder won't support this color type,
1.52 + * SkDecodingImageGenerator::Create will return
1.53 + * NULL. kIndex_8_SkColorType is not supported.
1.54 + */
1.55 + struct Options {
1.56 + Options()
1.57 + : fSampleSize(1)
1.58 + , fDitherImage(true)
1.59 + , fUseRequestedColorType(false)
1.60 + , fRequestedColorType() { }
1.61 + Options(int sampleSize, bool dither)
1.62 + : fSampleSize(sampleSize)
1.63 + , fDitherImage(dither)
1.64 + , fUseRequestedColorType(false)
1.65 + , fRequestedColorType() { }
1.66 + Options(int sampleSize, bool dither, SkColorType colorType)
1.67 + : fSampleSize(sampleSize)
1.68 + , fDitherImage(dither)
1.69 + , fUseRequestedColorType(true)
1.70 + , fRequestedColorType(colorType) { }
1.71 + const int fSampleSize;
1.72 + const bool fDitherImage;
1.73 + const bool fUseRequestedColorType;
1.74 + const SkColorType fRequestedColorType;
1.75 + };
1.76 +
1.77 + /**
1.78 + * These two functions return a SkImageGenerator that calls into
1.79 + * SkImageDecoder. They return NULL on failure.
1.80 + *
1.81 + * The SkData version of this function is preferred. If the stream
1.82 + * has an underlying SkData (such as a SkMemoryStream) pass that in.
1.83 + *
1.84 + * This object will unref the stream when done or on failure. Since
1.85 + * streams have internal state (position), the caller should not pass
1.86 + * a shared stream in. Pass either a new duplicated stream in or
1.87 + * transfer ownership of the stream. This factory asserts
1.88 + * stream->unique().
1.89 + *
1.90 + * For example:
1.91 + * SkStreamRewindable* stream;
1.92 + * ...
1.93 + * SkImageGenerator* gen
1.94 + * = SkDecodingImageGenerator::Create(
1.95 + * stream->duplicate(), SkDecodingImageGenerator::Options());
1.96 + * ...
1.97 + * SkDELETE(gen);
1.98 + *
1.99 + * @param Options (see above)
1.100 + *
1.101 + * @return NULL on failure, a new SkImageGenerator on success.
1.102 + */
1.103 + static SkImageGenerator* Create(SkStreamRewindable* stream,
1.104 + const Options& opt);
1.105 +
1.106 + /**
1.107 + * @param data Contains the encoded image data that will be used by
1.108 + * the SkDecodingImageGenerator. Will be ref()ed by the
1.109 + * SkImageGenerator constructor and and unref()ed on deletion.
1.110 + */
1.111 + static SkImageGenerator* Create(SkData* data, const Options& opt);
1.112 +
1.113 +private:
1.114 + SkData* fData;
1.115 + SkStreamRewindable* fStream;
1.116 + const SkImageInfo fInfo;
1.117 + const int fSampleSize;
1.118 + const bool fDitherImage;
1.119 +
1.120 + SkDecodingImageGenerator(SkData* data,
1.121 + SkStreamRewindable* stream,
1.122 + const SkImageInfo& info,
1.123 + int sampleSize,
1.124 + bool ditherImage);
1.125 + static SkImageGenerator* Create(SkData*, SkStreamRewindable*,
1.126 + const Options&);
1.127 + typedef SkImageGenerator INHERITED;
1.128 +};
1.129 +
1.130 +// // Example of most basic use case:
1.131 +//
1.132 +// bool install_data(SkData* data, SkBitmap* dst) {
1.133 +// return SkInstallDiscardablePixelRef(
1.134 +// SkDecodingImageGenerator::Create(
1.135 +// data, SkDecodingImageGenerator::Options()), dst, NULL);
1.136 +// }
1.137 +// bool install_stream(SkStreamRewindable* stream, SkBitmap* dst) {
1.138 +// return SkInstallDiscardablePixelRef(
1.139 +// SkDecodingImageGenerator::Create(
1.140 +// stream, SkDecodingImageGenerator::Options()), dst, NULL);
1.141 +// }
1.142 +
1.143 +#endif // SkDecodingImageGenerator_DEFINED
