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| 1 /* |
| 2 * Copyright 2015 Google Inc. |
| 3 * |
| 4 * Use of this source code is governed by a BSD-style license that can be |
| 5 * found in the LICENSE file. |
| 6 */ |
| 7 |
| 8 #ifndef SkAndroidCodec_DEFINED |
| 9 #define SkAndroidCodec_DEFINED |
| 10 |
| 11 #include "SkCodec.h" |
| 12 #include "SkEncodedFormat.h" |
| 13 #include "SkStream.h" |
| 14 #include "SkTypes.h" |
| 15 |
| 16 /** |
| 17 * Abstract interface defining image codec functionality that is necessary for |
| 18 * Android. |
| 19 */ |
| 20 class SkAndroidCodec : SkNoncopyable { |
| 21 public: |
| 22 /** |
| 23 * If this stream represents an encoded image that we know how to decode, |
| 24 * return an SkAndroidCodec that can decode it. Otherwise return NULL. |
| 25 * |
| 26 * If NULL is returned, the stream is deleted immediately. Otherwise, the |
| 27 * SkCodec takes ownership of it, and will delete it when done with it. |
| 28 */ |
| 29 static SkAndroidCodec* NewFromStream(SkStream*); |
| 30 |
| 31 /** |
| 32 * If this data represents an encoded image that we know how to decode, |
| 33 * return an SkAndroidCodec that can decode it. Otherwise return NULL. |
| 34 * |
| 35 * Will take a ref if it returns a codec, else will not affect the data. |
| 36 */ |
| 37 static SkAndroidCodec* NewFromData(SkData*); |
| 38 |
| 39 virtual ~SkAndroidCodec() {} |
| 40 |
| 41 |
| 42 const SkImageInfo& getInfo() const { return fInfo; } |
| 43 |
| 44 /** |
| 45 * Format of the encoded data. |
| 46 */ |
| 47 SkEncodedFormat getEncodedFormat() const { return this->onGetEncodedFormat()
; } |
| 48 |
| 49 /** |
| 50 * Returns the dimensions of the scaled output image, for an input |
| 51 * sampleSize. |
| 52 * |
| 53 * When the sample size divides evenly into the original dimensions, the |
| 54 * scaled output dimensions will simply be equal to the original |
| 55 * dimensions divided by the sample size. |
| 56 * |
| 57 * When the sample size does not divide even into the original |
| 58 * dimensions, the codec may round up or down, depending on what is most |
| 59 * efficient to decode. |
| 60 * |
| 61 * Finally, the codec will always recommend a non-zero output, so the outpu
t |
| 62 * dimension will always be one if the sampleSize is greater than the |
| 63 * original dimension. |
| 64 */ |
| 65 SkISize getSampledDimensions(int sampleSize) const; |
| 66 |
| 67 /** |
| 68 * Return (via desiredSubset) a subset which can decoded from this codec, |
| 69 * or false if the input subset is invalid. |
| 70 * |
| 71 * @param desiredSubset in/out parameter |
| 72 * As input, a desired subset of the original bounds |
| 73 * (as specified by getInfo). |
| 74 * As output, if true is returned, desiredSubset may |
| 75 * have been modified to a subset which is |
| 76 * supported. Although a particular change may have |
| 77 * been made to desiredSubset to create something |
| 78 * supported, it is possible other changes could |
| 79 * result in a valid subset. If false is returned, |
| 80 * desiredSubset's value is undefined. |
| 81 * @return true If the input desiredSubset is valid. |
| 82 * desiredSubset may be modified to a subset |
| 83 * supported by the codec. |
| 84 * false If desiredSubset is invalid (NULL or not fully |
| 85 * contained within the image). |
| 86 */ |
| 87 bool getSupportedSubset(SkIRect* desiredSubset) const; |
| 88 // TODO: Rename SkCodec::getValidSubset() to getSupportedSubset() |
| 89 |
| 90 /** |
| 91 * Returns the dimensions of the scaled, partial output image, for an |
| 92 * input sampleSize and subset. |
| 93 * |
| 94 * @param sampleSize Factor to scale down by. |
| 95 * @param subset Must be a valid subset of the original image |
| 96 * dimensions and a subset supported by SkAndroidCodec. |
| 97 * getSubset() can be used to obtain a subset supported |
| 98 * by SkAndroidCodec. |
| 99 * @return Size of the scaled partial image. Or zero size |
| 100 * if either of the inputs is invalid. |
| 101 */ |
| 102 SkISize getSampledSubsetDimensions(int sampleSize, const SkIRect& subset) co
nst; |
| 103 |
| 104 /** |
| 105 * Additional options to pass to getAndroidPixels(). |
| 106 */ |
| 107 // FIXME: It's a bit redundant to name these AndroidOptions when this class
is already |
| 108 // called SkAndroidCodec. On the other hand, it's may be a bit confu
sing to call |
| 109 // these Options when SkCodec has a slightly different set of Options
. Maybe these |
| 110 // should be DecodeOptions or SamplingOptions? |
| 111 struct AndroidOptions { |
| 112 AndroidOptions() |
| 113 : fZeroInitialized(SkCodec::kNo_ZeroInitialized) |
| 114 , fSubset(nullptr) |
| 115 , fColorPtr(nullptr) |
| 116 , fColorCount(nullptr) |
| 117 , fSampleSize(1) |
| 118 {} |
| 119 |
| 120 /** |
| 121 * Indicates is destination pixel memory is zero initialized. |
| 122 */ |
| 123 SkCodec::ZeroInitialized fZeroInitialized; |
| 124 |
| 125 /** |
| 126 * If not NULL, represents a subset of the original image to decode. |
| 127 * |
| 128 * Must be within the bounds returned by getInfo(). |
| 129 * |
| 130 * If the EncodedFormat is kWEBP_SkEncodedFormat, the top and left |
| 131 * values must be even. |
| 132 */ |
| 133 SkIRect* fSubset; |
| 134 |
| 135 /** |
| 136 * If the client has requested a decode to kIndex8_SkColorType |
| 137 * (specified in the SkImageInfo), then the caller must provide |
| 138 * storage for up to 256 SkPMColor values in fColorPtr. On success, |
| 139 * the codec must copy N colors into that storage, (where N is the |
| 140 * logical number of table entries) and set fColorCount to N. |
| 141 * |
| 142 * If the client does not request kIndex8_SkColorType, then the last |
| 143 * two parameters may be NULL. If fColorCount is not null, it will be |
| 144 * set to 0. |
| 145 */ |
| 146 SkPMColor* fColorPtr; |
| 147 int* fColorCount; |
| 148 |
| 149 /** |
| 150 * The client may provide an integer downscale factor for the decode. |
| 151 * The codec may implement this downscaling by sampling or another |
| 152 * method if it is more efficient. |
| 153 */ |
| 154 int fSampleSize; |
| 155 }; |
| 156 |
| 157 /** |
| 158 * Decode into the given pixels, a block of memory of size at |
| 159 * least (info.fHeight - 1) * rowBytes + (info.fWidth * |
| 160 * bytesPerPixel) |
| 161 * |
| 162 * Repeated calls to this function should give the same results, |
| 163 * allowing the PixelRef to be immutable. |
| 164 * |
| 165 * @param info A description of the format (config, size) |
| 166 * expected by the caller. This can simply be identical |
| 167 * to the info returned by getInfo(). |
| 168 * |
| 169 * This contract also allows the caller to specify |
| 170 * different output-configs, which the implementation can |
| 171 * decide to support or not. |
| 172 * |
| 173 * A size that does not match getInfo() implies a request |
| 174 * to scale or subset. If the codec cannot perform this |
| 175 * scaling or subsetting, it will return an error code. |
| 176 * |
| 177 * If info is kIndex8_SkColorType, then the caller must provide storage for
up to 256 |
| 178 * SkPMColor values in options->fColorPtr. On success the codec must copy N
colors into |
| 179 * that storage, (where N is the logical number of table entries) and set |
| 180 * options->fColorCount to N. |
| 181 * |
| 182 * If info is not kIndex8_SkColorType, options->fColorPtr and options->fCol
orCount may |
| 183 * be nullptr. |
| 184 * |
| 185 * The AndroidOptions object is also used to specify any requested scaling
or subsetting |
| 186 * using options->fSampleSize and options->fSubset. |
| 187 * |
| 188 * @return Result kSuccess, or another value explaining the type of failure
. |
| 189 */ |
| 190 // FIXME: It's a bit redundant to name this getAndroidPixels() when this cla
ss is already |
| 191 // called SkAndroidCodec. On the other hand, it's may be a bit confu
sing to call |
| 192 // this getPixels() when it is a slightly different API than SkCodec'
s getPixels(). |
| 193 // Maybe this should be decode() or decodeSubset()? |
| 194 SkCodec::Result getAndroidPixels(const SkImageInfo& info, void* pixels, size
_t rowBytes, |
| 195 AndroidOptions* options); |
| 196 |
| 197 /** |
| 198 * Simplified version of getAndroidPixels() where we supply the default And
roidOptions. |
| 199 * |
| 200 * This will return an error if the info is kIndex_8_SkColorType and also w
ill not perform |
| 201 * any scaling or subsetting. |
| 202 */ |
| 203 SkCodec::Result getAndroidPixels(const SkImageInfo& info, void* pixels, size
_t rowBytes); |
| 204 |
| 205 protected: |
| 206 |
| 207 SkAndroidCodec(const SkImageInfo&); |
| 208 |
| 209 virtual SkEncodedFormat onGetEncodedFormat() const = 0; |
| 210 |
| 211 virtual SkISize onGetSampledDimensions(int sampleSize) const = 0; |
| 212 |
| 213 virtual bool onGetSupportedSubset(SkIRect* desiredSubset) const = 0; |
| 214 |
| 215 virtual SkCodec::Result onGetAndroidPixels(const SkImageInfo& info, void* pi
xels, |
| 216 size_t rowBytes, AndroidOptions& options) = 0; |
| 217 |
| 218 private: |
| 219 |
| 220 // This will always be a reference to the info that is contained by the |
| 221 // embedded SkCodec. |
| 222 const SkImageInfo& fInfo; |
| 223 }; |
| 224 #endif // SkAndroidCodec_DEFINED |
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