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msarett8c8f22a2015-04-01 06:58:48 -07001/*
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#include "SkCodec.h"
msarettad8bcfe2016-03-07 07:09:03 -08009#include "SkColorSpace.h"
msarett10522ff2015-09-07 08:54:01 -070010#include "SkColorTable.h"
msarett8c8f22a2015-04-01 06:58:48 -070011#include "SkImageInfo.h"
msarett10522ff2015-09-07 08:54:01 -070012#include "SkSwizzler.h"
msarett8c8f22a2015-04-01 06:58:48 -070013
msarett39b2d5a2016-02-17 08:26:31 -080014struct GifFileType;
15struct SavedImage;
msarett8c8f22a2015-04-01 06:58:48 -070016
17/*
18 *
19 * This class implements the decoding for gif images
20 *
21 */
22class SkGifCodec : public SkCodec {
23public:
scroggodb30be22015-12-08 18:54:13 -080024 static bool IsGif(const void*, size_t);
msarett8c8f22a2015-04-01 06:58:48 -070025
26 /*
27 * Assumes IsGif was called and returned true
28 * Creates a gif decoder
29 * Reads enough of the stream to determine the image format
30 */
31 static SkCodec* NewFromStream(SkStream*);
msarett10522ff2015-09-07 08:54:01 -070032
msarett8c8f22a2015-04-01 06:58:48 -070033protected:
34
35 /*
msarett438b2ad2015-04-09 12:43:10 -070036 * Read enough of the stream to initialize the SkGifCodec.
37 * Returns a bool representing success or failure.
38 *
39 * @param codecOut
halcanary96fcdcc2015-08-27 07:41:13 -070040 * If it returned true, and codecOut was not nullptr,
msarett438b2ad2015-04-09 12:43:10 -070041 * codecOut will be set to a new SkGifCodec.
42 *
43 * @param gifOut
halcanary96fcdcc2015-08-27 07:41:13 -070044 * If it returned true, and codecOut was nullptr,
45 * gifOut must be non-nullptr and gifOut will be set to a new
msarett438b2ad2015-04-09 12:43:10 -070046 * GifFileType pointer.
47 *
48 * @param stream
49 * Deleted on failure.
50 * codecOut will take ownership of it in the case where we created a codec.
51 * Ownership is unchanged when we returned a gifOut.
52 *
53 */
msarett10522ff2015-09-07 08:54:01 -070054 static bool ReadHeader(SkStream* stream, SkCodec** codecOut,
55 GifFileType** gifOut);
msarett438b2ad2015-04-09 12:43:10 -070056
57 /*
msarett10522ff2015-09-07 08:54:01 -070058 * Performs the full gif decode
msarett8c8f22a2015-04-01 06:58:48 -070059 */
60 Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&,
msarette6dd0042015-10-09 11:07:34 -070061 SkPMColor*, int*, int*) override;
msarett8c8f22a2015-04-01 06:58:48 -070062
63 SkEncodedFormat onGetEncodedFormat() const override {
64 return kGIF_SkEncodedFormat;
65 }
66
scroggob427db12015-08-12 07:24:13 -070067 bool onRewind() override;
68
msarettf7eb6fc2016-09-13 09:04:11 -070069 uint64_t onGetFillValue(const SkImageInfo&) const override;
msarette6dd0042015-10-09 11:07:34 -070070
mtkleine9759282015-10-15 08:55:33 -070071 int onOutputScanline(int inputScanline) const override;
msarette6dd0042015-10-09 11:07:34 -070072
msarett8c8f22a2015-04-01 06:58:48 -070073private:
74
75 /*
msarett10522ff2015-09-07 08:54:01 -070076 * A gif can contain multiple image frames. We will only decode the first
77 * frame. This function reads up to the first image frame, processing
78 * transparency and/or animation information that comes before the image
79 * data.
80 *
81 * @param gif Pointer to the library type that manages the gif decode
82 * @param transIndex This call will set the transparent index based on the
83 * extension data.
84 */
scroggo46c57472015-09-30 08:57:13 -070085 static Result ReadUpToFirstImage(GifFileType* gif, uint32_t* transIndex);
msarett10522ff2015-09-07 08:54:01 -070086
87 /*
88 * A gif may contain many image frames, all of different sizes.
msarett4aa02d82015-10-06 07:46:02 -070089 * This function checks if the gif dimensions are valid, based on the frame
90 * dimensions, and corrects the gif dimensions if necessary.
msarett10522ff2015-09-07 08:54:01 -070091 *
msarett4aa02d82015-10-06 07:46:02 -070092 * @param gif Pointer to the library type that manages the gif decode
93 * @param size Size of the image that we will decode.
94 * Will be set by this function if the return value is true.
95 * @param frameRect Contains the dimenions and offset of the first image frame.
96 * Will be set by this function if the return value is true.
97 *
98 * @return true on success, false otherwise
msarett10522ff2015-09-07 08:54:01 -070099 */
msarett4aa02d82015-10-06 07:46:02 -0700100 static bool GetDimensions(GifFileType* gif, SkISize* size, SkIRect* frameRect);
msarett10522ff2015-09-07 08:54:01 -0700101
102 /*
103 * Initializes the color table that we will use for decoding.
104 *
105 * @param dstInfo Contains the requested dst color type.
106 * @param inputColorPtr Copies the encoded color table to the client's
107 * input color table if the client requests kIndex8.
108 * @param inputColorCount If the client requests kIndex8, sets
109 * inputColorCount to 256. Since gifs always
110 * contain 8-bit indices, we need a 256 entry color
111 * table to ensure that indexing is always in
112 * bounds.
113 */
114 void initializeColorTable(const SkImageInfo& dstInfo, SkPMColor* colorPtr,
115 int* inputColorCount);
116
117 /*
scroggo3a7701c2015-09-30 09:15:14 -0700118 * Checks for invalid inputs and calls setFrameDimensions(), and
msarett10522ff2015-09-07 08:54:01 -0700119 * initializeColorTable() in the proper sequence.
120 */
scroggo46c57472015-09-30 08:57:13 -0700121 Result prepareToDecode(const SkImageInfo& dstInfo, SkPMColor* inputColorPtr,
msarett10522ff2015-09-07 08:54:01 -0700122 int* inputColorCount, const Options& opts);
123
124 /*
125 * Initializes the swizzler.
126 *
127 * @param dstInfo Output image information. Dimensions may have been
128 * adjusted if the image frame size does not match the size
129 * indicated in the header.
msarettfdb47572015-10-13 12:50:14 -0700130 * @param options Informs the swizzler if destination memory is zero initialized.
131 * Contains subset information.
msarett10522ff2015-09-07 08:54:01 -0700132 */
msarettb30d6982016-02-15 10:18:45 -0800133 void initializeSwizzler(const SkImageInfo& dstInfo,
msarettfdb47572015-10-13 12:50:14 -0700134 const Options& options);
msarett10522ff2015-09-07 08:54:01 -0700135
msarette6dd0042015-10-09 11:07:34 -0700136 SkSampler* getSampler(bool createIfNecessary) override {
137 SkASSERT(fSwizzler);
138 return fSwizzler;
139 }
scroggoe7fc14b2015-10-02 13:14:46 -0700140
msarett10522ff2015-09-07 08:54:01 -0700141 /*
msarette6dd0042015-10-09 11:07:34 -0700142 * @return true if the read is successful and false if the read fails.
msarett10522ff2015-09-07 08:54:01 -0700143 */
msarette6dd0042015-10-09 11:07:34 -0700144 bool readRow();
scroggo46c57472015-09-30 08:57:13 -0700145
146 Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& opts,
147 SkPMColor inputColorPtr[], int* inputColorCount) override;
148
msarette6dd0042015-10-09 11:07:34 -0700149 int onGetScanlines(void* dst, int count, size_t rowBytes) override;
scroggo46c57472015-09-30 08:57:13 -0700150
msarett72261c02015-11-19 15:29:26 -0800151 bool onSkipScanlines(int count) override;
152
153 /*
154 * For a scanline decode of "count" lines, this function indicates how
155 * many of the "count" lines should be skipped until we reach the top of
156 * the image frame and how many of the "count" lines are actually inside
157 * the image frame.
158 *
159 * @param count The number of scanlines requested.
160 * @param rowsBeforeFrame Output variable. The number of lines before
161 * we reach the top of the image frame.
162 * @param rowsInFrame Output variable. The number of lines to decode
163 * inside the image frame.
164 */
165 void handleScanlineFrame(int count, int* rowsBeforeFrame, int* rowsInFrame);
166
scroggo46c57472015-09-30 08:57:13 -0700167 SkScanlineOrder onGetScanlineOrder() const override;
168
msarett10522ff2015-09-07 08:54:01 -0700169 /*
msarett8c8f22a2015-04-01 06:58:48 -0700170 * This function cleans up the gif object after the decode completes
171 * It is used in a SkAutoTCallIProc template
172 */
msarett438b2ad2015-04-09 12:43:10 -0700173 static void CloseGif(GifFileType* gif);
msarett8c8f22a2015-04-01 06:58:48 -0700174
175 /*
176 * Frees any extension data used in the decode
177 * Used in a SkAutoTCallVProc
178 */
179 static void FreeExtension(SavedImage* image);
180
181 /*
182 * Creates an instance of the decoder
183 * Called only by NewFromStream
184 *
msarettc30c4182016-04-20 11:53:35 -0700185 * @param info contains properties of the encoded data
msarett8c8f22a2015-04-01 06:58:48 -0700186 * @param stream the stream of image data
187 * @param gif pointer to library type that manages gif decode
188 * takes ownership
msarett10522ff2015-09-07 08:54:01 -0700189 * @param transIndex The transparent index. An invalid value
190 * indicates that there is no transparent index.
msarett8c8f22a2015-04-01 06:58:48 -0700191 */
msarettc30c4182016-04-20 11:53:35 -0700192 SkGifCodec(int width, int height, const SkEncodedInfo& info, SkStream* stream,
193 GifFileType* gif, uint32_t transIndex, const SkIRect& frameRect, bool frameIsSubset);
msarett8c8f22a2015-04-01 06:58:48 -0700194
msarett438b2ad2015-04-09 12:43:10 -0700195 SkAutoTCallVProc<GifFileType, CloseGif> fGif; // owned
msarett10522ff2015-09-07 08:54:01 -0700196 SkAutoTDeleteArray<uint8_t> fSrcBuffer;
msarett4aa02d82015-10-06 07:46:02 -0700197 const SkIRect fFrameRect;
msarett10522ff2015-09-07 08:54:01 -0700198 const uint32_t fTransIndex;
199 uint32_t fFillIndex;
msarett4aa02d82015-10-06 07:46:02 -0700200 const bool fFrameIsSubset;
msarett10522ff2015-09-07 08:54:01 -0700201 SkAutoTDelete<SkSwizzler> fSwizzler;
202 SkAutoTUnref<SkColorTable> fColorTable;
203
msarett8c8f22a2015-04-01 06:58:48 -0700204 typedef SkCodec INHERITED;
205};