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.
43class SkLibGifCodec;
44
45#include "include/codec/SkCodec.h"
46#include "include/codec/SkCodecAnimation.h"
47#include "include/core/SkData.h"
48#include "include/core/SkImageInfo.h"
49#include "include/private/SkTArray.h"
50#include "src/codec/SkCodecPriv.h"
51#include "src/codec/SkColorTable.h"
52#include "src/codec/SkFrameHolder.h"
53#include "src/codec/SkStreamBuffer.h"
54
55#include <array>
56#include <memory>
57
58typedef SkTArray<unsigned char, true> SkGIFRow;
59
60
61#define SK_MAX_DICTIONARY_ENTRY_BITS 12
62#define SK_MAX_DICTIONARY_ENTRIES 4096 // 2^SK_MAX_DICTIONARY_ENTRY_BITS
63#define SK_MAX_COLORS 256
64#define SK_BYTES_PER_COLORMAP_ENTRY 3
65#define SK_DICTIONARY_WORD_SIZE 8
66
67// List of possible parsing states.
68enum SkGIFState {
69 SkGIFType,
70 SkGIFGlobalHeader,
71 SkGIFGlobalColormap,
72 SkGIFImageStart,
73 SkGIFImageHeader,
74 SkGIFImageColormap,
75 SkGIFImageBody,
76 SkGIFLZWStart,
77 SkGIFLZW,
78 SkGIFSubBlock,
79 SkGIFExtension,
80 SkGIFControlExtension,
81 SkGIFConsumeBlock,
82 SkGIFSkipBlock,
83 SkGIFDone,
84 SkGIFCommentExtension,
85 SkGIFApplicationExtension,
86 SkGIFNetscapeExtensionBlock,
87 SkGIFConsumeNetscapeExtension,
88 SkGIFConsumeComment
89};
90
91class SkGIFFrameContext;
92class SkGIFColorMap;
93
94// LZW decoder state machine.
95class SkGIFLZWContext final : public SkNoncopyable {
96public:
97 SkGIFLZWContext(SkLibGifCodec* client, const SkGIFFrameContext* frameContext)
98 : codesize(0)
99 , codemask(0)
100 , clearCode(0)
101 , avail(0)
102 , oldcode(0)
103 , bits(0)
104 , datum(0)
105 , ipass(0)
106 , irow(0)
107 , rowsRemaining(0)
108 , rowIter(nullptr)
109 , m_client(client)
110 , m_frameContext(frameContext)
111 { }
112
113 bool prepareToDecode();
114 void outputRow(const unsigned char* rowBegin);
115 bool doLZW(const unsigned char* block, size_t bytesInBlock);
116 bool hasRemainingRows() { return SkToBool(rowsRemaining); }
117
118private:
119 // LZW decoding states and output states.
120 int codesize;
121 int codemask;
122 int clearCode; // Codeword used to trigger dictionary reset.
123 int avail; // Index of next available slot in dictionary.
124 int oldcode;
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 std::array<std::array<unsigned char, SK_DICTIONARY_WORD_SIZE>,
133 SK_MAX_DICTIONARY_ENTRIES> suffix;
134 unsigned short suffixLength[SK_MAX_DICTIONARY_ENTRIES];
135 SkGIFRow rowBuffer; // Single scanline temporary buffer.
136 unsigned char* rowIter;
137
138 SkLibGifCodec* const m_client;
139 const SkGIFFrameContext* m_frameContext;
140};
141
142struct SkGIFLZWBlock {
143 public:
144 SkGIFLZWBlock(size_t position, size_t size)
145 : blockPosition(position), blockSize(size) {}
146
147 size_t blockPosition;
148 size_t blockSize;
149};
150
151class SkGIFColorMap final {
152public:
153 static constexpr int kNotFound = -1;
154
155 SkGIFColorMap()
156 : m_isDefined(false)
157 , m_position(0)
158 , m_colors(0)
159 , m_transPixel(kNotFound)
160 , m_packColorProc(nullptr)
161 {
162 }
163
164 void setNumColors(int colors) {
165 SkASSERT(!m_colors);
166 SkASSERT(!m_position);
167
168 m_colors = colors;
169 }
170
171 void setTablePosition(size_t position) {
172 SkASSERT(!m_isDefined);
173
174 m_position = position;
175 m_isDefined = true;
176 }
177
178 int numColors() const { return m_colors; }
179
180 bool isDefined() const { return m_isDefined; }
181
182 // Build RGBA table using the data stream.
183 sk_sp<SkColorTable> buildTable(SkStreamBuffer*, SkColorType dstColorType,
184 int transparentPixel) const;
185
186private:
187 bool m_isDefined;
188 size_t m_position;
189 int m_colors;
190 // Cached values. If these match on a new request, we can reuse m_table.
191 mutable int m_transPixel;
192 mutable PackColorProc m_packColorProc;
193 mutable sk_sp<SkColorTable> m_table;
194};
195
196class SkGifImageReader;
197
198// LocalFrame output state machine.
199class SkGIFFrameContext : public SkFrame {
200public:
201 SkGIFFrameContext(int id)
202 : INHERITED(id)
203 , m_transparentPixel(SkGIFColorMap::kNotFound)
204 , m_dataSize(0)
205 , m_progressiveDisplay(false)
206 , m_interlaced(false)
207 , m_currentLzwBlock(0)
208 , m_isComplete(false)
209 , m_isHeaderDefined(false)
210 , m_isDataSizeDefined(false)
211 {
212 }
213
214 ~SkGIFFrameContext() override
215 {
216 }
217
218 void addLzwBlock(size_t position, size_t size)
219 {
220 m_lzwBlocks.emplace_back(position, size);
221 }
222
223 bool decode(SkStreamBuffer*, SkLibGifCodec* client, bool* frameDecoded);
224
225 int transparentPixel() const { return m_transparentPixel; }
226 void setTransparentPixel(int pixel) { m_transparentPixel = pixel; }
227
228 bool isComplete() const { return m_isComplete; }
229 void setComplete() { m_isComplete = true; }
230 bool isHeaderDefined() const { return m_isHeaderDefined; }
231 void setHeaderDefined() { m_isHeaderDefined = true; }
232 bool isDataSizeDefined() const { return m_isDataSizeDefined; }
233 int dataSize() const { return m_dataSize; }
234 void setDataSize(int size)
235 {
236 m_dataSize = size;
237 m_isDataSizeDefined = true;
238 }
239 bool progressiveDisplay() const { return m_progressiveDisplay; }
240 void setProgressiveDisplay(bool progressiveDisplay) { m_progressiveDisplay = progressiveDisplay; }
241 bool interlaced() const { return m_interlaced; }
242 void setInterlaced(bool interlaced) { m_interlaced = interlaced; }
243
244 void clearDecodeState() { m_lzwContext.reset(); }
245 const SkGIFColorMap& localColorMap() const { return m_localColorMap; }
246 SkGIFColorMap& localColorMap() { return m_localColorMap; }
247
248protected:
249 SkEncodedInfo::Alpha onReportedAlpha() const override;
250
251private:
252 int m_transparentPixel; // Index of transparent pixel. Value is kNotFound if there is no transparent pixel.
253 int m_dataSize;
254
255 bool m_progressiveDisplay; // If true, do Haeberli interlace hack.
256 bool m_interlaced; // True, if scanlines arrive interlaced order.
257
258 std::unique_ptr<SkGIFLZWContext> m_lzwContext;
259 // LZW blocks for this frame.
260 SkTArray<SkGIFLZWBlock> m_lzwBlocks;
261
262 SkGIFColorMap m_localColorMap;
263
264 int m_currentLzwBlock;
265 bool m_isComplete;
266 bool m_isHeaderDefined;
267 bool m_isDataSizeDefined;
268
269 typedef SkFrame INHERITED;
270};
271
272class SkGifImageReader final : public SkFrameHolder {
273public:
274 // This takes ownership of stream.
275 SkGifImageReader(std::unique_ptr<SkStream> stream)
276 : m_client(nullptr)
277 , m_state(SkGIFType)
278 , m_bytesToConsume(6) // Number of bytes for GIF type, either "GIF87a" or "GIF89a".
279 , m_version(0)
280 , m_loopCount(cLoopCountNotSeen)
281 , m_streamBuffer(std::move(stream))
282 , m_parseCompleted(false)
283 , m_firstFrameHasAlpha(false)
284 {
285 }
286
287 ~SkGifImageReader() override
288 {
289 }
290
291 void setClient(SkLibGifCodec* client) { m_client = client; }
292
293 // Option to pass to parse(). All enums are negative, because a non-negative value is used to
294 // indicate that the Reader should parse up to and including the frame indicated.
295 enum SkGIFParseQuery {
296 // Parse enough to determine the size. Note that this parses the first frame's header,
297 // since we may decide to expand based on the frame's dimensions.
298 SkGIFSizeQuery = -1,
299 // Parse to the end, so we know about all frames.
300 SkGIFFrameCountQuery = -2,
301 // Parse until we see the loop count.
302 SkGIFLoopCountQuery = -3,
303 };
304
305 // Parse incoming GIF data stream into internal data structures.
306 // Non-negative values are used to indicate to parse through that frame.
307 SkCodec::Result parse(SkGIFParseQuery);
308
309 // Decode the frame indicated by frameIndex.
310 // frameComplete will be set to true if the frame is completely decoded.
311 // The method returns false if there is an error.
312 bool decode(int frameIndex, bool* frameComplete);
313
314 int imagesCount() const
315 {
316 const int frames = m_frames.count();
317 if (!frames) {
318 return 0;
319 }
320
321 // This avoids counting an empty frame when the file is truncated (or
322 // simply not yet complete) after receiving SkGIFControlExtension (and
323 // possibly SkGIFImageHeader) but before reading the color table. This
324 // ensures that we do not count a frame before we know its required
325 // frame.
326 return m_frames.back()->reachedStartOfData() ? frames : frames - 1;
327 }
328 int loopCount() const {
329 if (cLoopCountNotSeen == m_loopCount) {
330 return 0;
331 }
332 return m_loopCount;
333 }
334
335 const SkGIFColorMap& globalColorMap() const
336 {
337 return m_globalColorMap;
338 }
339
340 const SkGIFFrameContext* frameContext(int index) const
341 {
342 return index >= 0 && index < m_frames.count()
343 ? m_frames[index].get() : nullptr;
344 }
345
346 void clearDecodeState() {
347 for (int index = 0; index < m_frames.count(); index++) {
348 m_frames[index]->clearDecodeState();
349 }
350 }
351
352 // Return the color table for frame index (which may be the global color table).
353 sk_sp<SkColorTable> getColorTable(SkColorType dstColorType, int index);
354
355 bool firstFrameHasAlpha() const { return m_firstFrameHasAlpha; }
356
357protected:
358 const SkFrame* onGetFrame(int i) const override {
359 return static_cast<const SkFrame*>(this->frameContext(i));
360 }
361
362private:
363 // Requires that one byte has been buffered into m_streamBuffer.
364 unsigned char getOneByte() const {
365 return reinterpret_cast<const unsigned char*>(m_streamBuffer.get())[0];
366 }
367
368 void addFrameIfNecessary();
369 bool currentFrameIsFirstFrame() const
370 {
371 return m_frames.empty() || (m_frames.count() == 1 && !m_frames[0]->isComplete());
372 }
373
374 // Unowned pointer
375 SkLibGifCodec* m_client;
376
377 // Parsing state machine.
378 SkGIFState m_state; // Current decoder master state.
379 size_t m_bytesToConsume; // Number of bytes to consume for next stage of parsing.
380
381 // Global (multi-image) state.
382 int m_version; // Either 89 for GIF89 or 87 for GIF87.
383 SkGIFColorMap m_globalColorMap;
384
385 static constexpr int cLoopCountNotSeen = -2;
386 int m_loopCount; // Netscape specific extension block to control the number of animation loops a GIF renders.
387
388 SkTArray<std::unique_ptr<SkGIFFrameContext>> m_frames;
389
390 SkStreamBuffer m_streamBuffer;
391 bool m_parseCompleted;
392
393 // This value can be computed before we create a SkGIFFrameContext, so we
394 // store it here instead of on m_frames[0].
395 bool m_firstFrameHasAlpha;
396};
397
398#endif
399