1 /* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* ***** BEGIN LICENSE BLOCK ***** 3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1 4 * 5 * The contents of this file are subject to the Mozilla Public License Version 6 * 1.1 (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * http://www.mozilla.org/MPL/ 9 * 10 * Software distributed under the License is distributed on an "AS IS" basis, 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License 12 * for the specific language governing rights and limitations under the 13 * License. 14 * 15 * The Original Code is Mozilla Communicator client code. 16 * 17 * The Initial Developer of the Original Code is 18 * Netscape Communications Corporation. 19 * Portions created by the Initial Developer are Copyright (C) 1998 20 * the Initial Developer. All Rights Reserved. 21 * 22 * Contributor(s): 23 * 24 * Alternatively, the contents of this file may be used under the terms of 25 * either the GNU General Public License Version 2 or later (the "GPL"), or 26 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), 27 * in which case the provisions of the GPL or the LGPL are applicable instead 28 * of those above. If you wish to allow use of your version of this file only 29 * under the terms of either the GPL or the LGPL, and not to allow others to 30 * use your version of this file under the terms of the MPL, indicate your 31 * decision by deleting the provisions above and replace them with the notice 32 * and other provisions required by the GPL or the LGPL. If you do not delete 33 * the provisions above, a recipient may use your version of this file under 34 * the terms of any one of the MPL, the GPL or the LGPL. 35 * 36 * ***** END LICENSE BLOCK ***** */ 37 38 #ifndef SkGifImageReader_h 39 #define SkGifImageReader_h 40 41 // Define ourselves as the clientPtr. Mozilla just hacked their C++ callback class into this old C decoder, 42 // so we will too. 43 class SkGifCodec; 44 45 #include "SkCodec.h" 46 #include "SkCodecPriv.h" 47 #include "SkCodecAnimation.h" 48 #include "SkColorTable.h" 49 #include "SkData.h" 50 #include "SkFrameHolder.h" 51 #include "SkImageInfo.h" 52 #include "SkStreamBuffer.h" 53 #include "../private/SkTArray.h" 54 #include <memory> 55 #include <vector> 56 57 typedef SkTArray<unsigned char, true> SkGIFRow; 58 59 60 #define SK_MAX_DICTIONARY_ENTRY_BITS 12 61 #define SK_MAX_DICTIONARY_ENTRIES 4096 // 2^SK_MAX_DICTIONARY_ENTRY_BITS 62 #define SK_MAX_COLORS 256 63 #define SK_BYTES_PER_COLORMAP_ENTRY 3 64 65 // List of possible parsing states. 66 enum SkGIFState { 67 SkGIFType, 68 SkGIFGlobalHeader, 69 SkGIFGlobalColormap, 70 SkGIFImageStart, 71 SkGIFImageHeader, 72 SkGIFImageColormap, 73 SkGIFImageBody, 74 SkGIFLZWStart, 75 SkGIFLZW, 76 SkGIFSubBlock, 77 SkGIFExtension, 78 SkGIFControlExtension, 79 SkGIFConsumeBlock, 80 SkGIFSkipBlock, 81 SkGIFDone, 82 SkGIFCommentExtension, 83 SkGIFApplicationExtension, 84 SkGIFNetscapeExtensionBlock, 85 SkGIFConsumeNetscapeExtension, 86 SkGIFConsumeComment 87 }; 88 89 class SkGIFFrameContext; 90 class SkGIFColorMap; 91 92 // LZW decoder state machine. 93 class SkGIFLZWContext final : public SkNoncopyable { 94 public: 95 SkGIFLZWContext(SkGifCodec* client, const SkGIFFrameContext* frameContext) 96 : codesize(0) 97 , codemask(0) 98 , clearCode(0) 99 , avail(0) 100 , oldcode(0) 101 , firstchar(0) 102 , bits(0) 103 , datum(0) 104 , ipass(0) 105 , irow(0) 106 , rowsRemaining(0) 107 , rowIter(0) 108 , m_client(client) 109 , m_frameContext(frameContext) 110 { } 111 112 bool prepareToDecode(); 113 bool outputRow(const unsigned char* rowBegin); 114 bool doLZW(const unsigned char* block, size_t bytesInBlock); 115 bool hasRemainingRows() { return SkToBool(rowsRemaining); } 116 117 private: 118 // LZW decoding states and output states. 119 int codesize; 120 int codemask; 121 int clearCode; // Codeword used to trigger dictionary reset. 122 int avail; // Index of next available slot in dictionary. 123 int oldcode; 124 unsigned char firstchar; 125 int bits; // Number of unread bits in "datum". 126 int datum; // 32-bit input buffer. 127 int ipass; // Interlace pass; Ranges 1-4 if interlaced. 128 size_t irow; // Current output row, starting at zero. 129 size_t rowsRemaining; // Rows remaining to be output. 130 131 unsigned short prefix[SK_MAX_DICTIONARY_ENTRIES]; 132 unsigned char suffix[SK_MAX_DICTIONARY_ENTRIES]; 133 unsigned short suffixLength[SK_MAX_DICTIONARY_ENTRIES]; 134 SkGIFRow rowBuffer; // Single scanline temporary buffer. 135 unsigned char* rowIter; 136 137 SkGifCodec* const m_client; 138 const SkGIFFrameContext* m_frameContext; 139 }; 140 141 struct SkGIFLZWBlock { 142 public: 143 SkGIFLZWBlock(size_t position, size_t size) 144 : blockPosition(position), blockSize(size) {} 145 146 size_t blockPosition; 147 size_t blockSize; 148 }; 149 150 class SkGIFColorMap final { 151 public: 152 static constexpr int kNotFound = -1; 153 154 SkGIFColorMap() 155 : m_isDefined(false) 156 , m_position(0) 157 , m_colors(0) 158 , m_transPixel(kNotFound) 159 , m_packColorProc(nullptr) 160 { 161 } 162 163 void setNumColors(int colors) { 164 SkASSERT(!m_colors); 165 SkASSERT(!m_position); 166 167 m_colors = colors; 168 } 169 170 void setTablePosition(size_t position) { 171 SkASSERT(!m_isDefined); 172 173 m_position = position; 174 m_isDefined = true; 175 } 176 177 int numColors() const { return m_colors; } 178 179 bool isDefined() const { return m_isDefined; } 180 181 // Build RGBA table using the data stream. 182 sk_sp<SkColorTable> buildTable(SkStreamBuffer*, SkColorType dstColorType, 183 int transparentPixel) const; 184 185 private: 186 bool m_isDefined; 187 size_t m_position; 188 int m_colors; 189 // Cached values. If these match on a new request, we can reuse m_table. 190 mutable int m_transPixel; 191 mutable PackColorProc m_packColorProc; 192 mutable sk_sp<SkColorTable> m_table; 193 }; 194 195 class SkGifImageReader; 196 197 // LocalFrame output state machine. 198 class SkGIFFrameContext : public SkFrame { 199 public: 200 SkGIFFrameContext(SkGifImageReader* reader, int id) 201 : INHERITED(id) 202 , m_owner(reader) 203 , m_transparentPixel(SkGIFColorMap::kNotFound) 204 , m_dataSize(0) 205 , m_progressiveDisplay(false) 206 , m_interlaced(false) 207 , m_delayTime(0) 208 , m_currentLzwBlock(0) 209 , m_isComplete(false) 210 , m_isHeaderDefined(false) 211 , m_isDataSizeDefined(false) 212 { 213 } 214 215 ~SkGIFFrameContext() override 216 { 217 } 218 219 void addLzwBlock(size_t position, size_t size) 220 { 221 m_lzwBlocks.push_back(SkGIFLZWBlock(position, size)); 222 } 223 224 bool decode(SkStreamBuffer*, SkGifCodec* client, bool* frameDecoded); 225 226 int transparentPixel() const { return m_transparentPixel; } 227 void setTransparentPixel(int pixel) { m_transparentPixel = pixel; } 228 229 unsigned delayTime() const { return m_delayTime; } 230 void setDelayTime(unsigned delay) { m_delayTime = delay; } 231 bool isComplete() const { return m_isComplete; } 232 void setComplete() { m_isComplete = true; } 233 bool isHeaderDefined() const { return m_isHeaderDefined; } 234 void setHeaderDefined() { m_isHeaderDefined = true; } 235 bool isDataSizeDefined() const { return m_isDataSizeDefined; } 236 int dataSize() const { return m_dataSize; } 237 void setDataSize(int size) 238 { 239 m_dataSize = size; 240 m_isDataSizeDefined = true; 241 } 242 bool progressiveDisplay() const { return m_progressiveDisplay; } 243 void setProgressiveDisplay(bool progressiveDisplay) { m_progressiveDisplay = progressiveDisplay; } 244 bool interlaced() const { return m_interlaced; } 245 void setInterlaced(bool interlaced) { m_interlaced = interlaced; } 246 247 void clearDecodeState() { m_lzwContext.reset(); } 248 const SkGIFColorMap& localColorMap() const { return m_localColorMap; } 249 SkGIFColorMap& localColorMap() { return m_localColorMap; } 250 251 protected: 252 bool onReportsAlpha() const override; 253 254 private: 255 // Unowned pointer to the object that owns this frame. 256 const SkGifImageReader* m_owner; 257 258 int m_transparentPixel; // Index of transparent pixel. Value is kNotFound if there is no transparent pixel. 259 int m_dataSize; 260 261 bool m_progressiveDisplay; // If true, do Haeberli interlace hack. 262 bool m_interlaced; // True, if scanlines arrive interlaced order. 263 264 unsigned m_delayTime; // Display time, in milliseconds, for this image in a multi-image GIF. 265 266 std::unique_ptr<SkGIFLZWContext> m_lzwContext; 267 // LZW blocks for this frame. 268 std::vector<SkGIFLZWBlock> m_lzwBlocks; 269 270 SkGIFColorMap m_localColorMap; 271 272 int m_currentLzwBlock; 273 bool m_isComplete; 274 bool m_isHeaderDefined; 275 bool m_isDataSizeDefined; 276 277 typedef SkFrame INHERITED; 278 }; 279 280 class SkGifImageReader final : public SkFrameHolder { 281 public: 282 // This takes ownership of stream. 283 SkGifImageReader(SkStream* stream) 284 : m_client(nullptr) 285 , m_state(SkGIFType) 286 , m_bytesToConsume(6) // Number of bytes for GIF type, either "GIF87a" or "GIF89a". 287 , m_version(0) 288 , m_loopCount(cLoopCountNotSeen) 289 , m_streamBuffer(stream) 290 , m_parseCompleted(false) 291 , m_firstFrameHasAlpha(false) 292 { 293 } 294 295 ~SkGifImageReader() override 296 { 297 } 298 299 void setClient(SkGifCodec* client) { m_client = client; } 300 301 // Option to pass to parse(). All enums are negative, because a non-negative value is used to 302 // indicate that the Reader should parse up to and including the frame indicated. 303 enum SkGIFParseQuery { 304 // Parse enough to determine the size. Note that this parses the first frame's header, 305 // since we may decide to expand based on the frame's dimensions. 306 SkGIFSizeQuery = -1, 307 // Parse to the end, so we know about all frames. 308 SkGIFFrameCountQuery = -2, 309 // Parse until we see the loop count. 310 SkGIFLoopCountQuery = -3, 311 }; 312 313 // Parse incoming GIF data stream into internal data structures. 314 // Non-negative values are used to indicate to parse through that frame. 315 SkCodec::Result parse(SkGIFParseQuery); 316 317 // Decode the frame indicated by frameIndex. 318 // frameComplete will be set to true if the frame is completely decoded. 319 // The method returns false if there is an error. 320 bool decode(int frameIndex, bool* frameComplete); 321 322 int imagesCount() const 323 { 324 const size_t frames = m_frames.size(); 325 if (!frames) { 326 return 0; 327 } 328 329 // This avoids counting an empty frame when the file is truncated (or 330 // simply not yet complete) after receiving SkGIFControlExtension (and 331 // possibly SkGIFImageHeader) but before reading the color table. This 332 // ensures that we do not count a frame before we know its required 333 // frame. 334 return static_cast<int>(m_frames.back()->reachedStartOfData() ? frames : frames - 1); 335 } 336 int loopCount() const { 337 if (cLoopCountNotSeen == m_loopCount) { 338 return 0; 339 } 340 return m_loopCount; 341 } 342 343 const SkGIFColorMap& globalColorMap() const 344 { 345 return m_globalColorMap; 346 } 347 348 const SkGIFFrameContext* frameContext(int index) const 349 { 350 return index >= 0 && index < static_cast<int>(m_frames.size()) 351 ? m_frames[index].get() : 0; 352 } 353 354 void clearDecodeState() { 355 for (size_t index = 0; index < m_frames.size(); index++) { 356 m_frames[index]->clearDecodeState(); 357 } 358 } 359 360 // Return the color table for frame index (which may be the global color table). 361 sk_sp<SkColorTable> getColorTable(SkColorType dstColorType, int index); 362 363 bool firstFrameHasAlpha() const { return m_firstFrameHasAlpha; } 364 365 // Helper function that returns whether an SkGIFFrameContext has transparency. 366 // This method is sometimes called before creating one/parsing its color map, 367 // so it cannot rely on SkGIFFrameContext::transparentPixel or ::localColorMap(). 368 bool hasTransparency(int transPix, bool hasLocalColorMap, int localMapColors) const; 369 370 protected: 371 const SkFrame* onGetFrame(int i) const override { 372 return static_cast<const SkFrame*>(this->frameContext(i)); 373 } 374 375 private: 376 // Requires that one byte has been buffered into m_streamBuffer. 377 unsigned char getOneByte() const { 378 return reinterpret_cast<const unsigned char*>(m_streamBuffer.get())[0]; 379 } 380 381 void addFrameIfNecessary(); 382 bool currentFrameIsFirstFrame() const 383 { 384 return m_frames.empty() || (m_frames.size() == 1u && !m_frames[0]->isComplete()); 385 } 386 387 // Unowned pointer 388 SkGifCodec* m_client; 389 390 // Parsing state machine. 391 SkGIFState m_state; // Current decoder master state. 392 size_t m_bytesToConsume; // Number of bytes to consume for next stage of parsing. 393 394 // Global (multi-image) state. 395 int m_version; // Either 89 for GIF89 or 87 for GIF87. 396 SkGIFColorMap m_globalColorMap; 397 398 static constexpr int cLoopCountNotSeen = -2; 399 int m_loopCount; // Netscape specific extension block to control the number of animation loops a GIF renders. 400 401 std::vector<std::unique_ptr<SkGIFFrameContext>> m_frames; 402 403 SkStreamBuffer m_streamBuffer; 404 bool m_parseCompleted; 405 406 // This value can be computed before we create a SkGIFFrameContext, so we 407 // store it here instead of on m_frames[0]. 408 bool m_firstFrameHasAlpha; 409 }; 410 411 #endif 412