1 /* 2 * Copyright 2006 The Android Open Source Project 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 SkImageDecoder_DEFINED 9 #define SkImageDecoder_DEFINED 10 11 #include "SkBitmap.h" 12 #include "SkImage.h" 13 #include "SkRect.h" 14 #include "SkRefCnt.h" 15 #include "SkTRegistry.h" 16 #include "SkTypes.h" 17 18 class SkStream; 19 class SkStreamRewindable; 20 21 /** \class SkImageDecoder 22 23 Base class for decoding compressed images into a SkBitmap 24 */ 25 class SkImageDecoder : SkNoncopyable { 26 public: 27 virtual ~SkImageDecoder(); 28 29 enum Format { 30 kUnknown_Format, 31 kBMP_Format, 32 kGIF_Format, 33 kICO_Format, 34 kJPEG_Format, 35 kPNG_Format, 36 kWBMP_Format, 37 kWEBP_Format, 38 kPKM_Format, 39 kKTX_Format, 40 41 kLastKnownFormat = kKTX_Format, 42 }; 43 44 /** Return the format of image this decoder can decode. If this decoder can decode multiple 45 formats, kUnknown_Format will be returned. 46 */ 47 virtual Format getFormat() const; 48 49 /** Return the format of the SkStreamRewindable or kUnknown_Format if it cannot be determined. 50 Rewinds the stream before returning. 51 */ 52 static Format GetStreamFormat(SkStreamRewindable*); 53 54 /** Return a readable string of the Format provided. 55 */ 56 static const char* GetFormatName(Format); 57 58 /** Return a readable string of the value returned by getFormat(). 59 */ 60 const char* getFormatName() const; 61 62 /** Whether the decoder should skip writing zeroes to output if possible. 63 */ 64 bool getSkipWritingZeroes() const { return fSkipWritingZeroes; } 65 66 /** Set to true if the decoder should skip writing any zeroes when 67 creating the output image. 68 This is a hint that may not be respected by the decoder. 69 It should only be used if it is known that the memory to write 70 to has already been set to 0; otherwise the resulting image will 71 have garbage. 72 This is ideal for images that contain a lot of completely transparent 73 pixels, but may be a performance hit for an image that has only a 74 few transparent pixels. 75 The default is false. 76 */ 77 void setSkipWritingZeroes(bool skip) { fSkipWritingZeroes = skip; } 78 79 /** Returns true if the decoder should try to dither the resulting image. 80 The default setting is true. 81 */ 82 bool getDitherImage() const { return fDitherImage; } 83 84 /** Set to true if the the decoder should try to dither the resulting image. 85 The default setting is true. 86 */ 87 void setDitherImage(bool dither) { fDitherImage = dither; } 88 89 /** Returns true if the decoder should try to decode the 90 resulting image to a higher quality even at the expense of 91 the decoding speed. 92 */ 93 bool getPreferQualityOverSpeed() const { return fPreferQualityOverSpeed; } 94 95 /** Set to true if the the decoder should try to decode the 96 resulting image to a higher quality even at the expense of 97 the decoding speed. 98 */ 99 void setPreferQualityOverSpeed(bool qualityOverSpeed) { 100 fPreferQualityOverSpeed = qualityOverSpeed; 101 } 102 103 /** Set to true to require the decoder to return a bitmap with unpremultiplied 104 colors. The default is false, meaning the resulting bitmap will have its 105 colors premultiplied. 106 NOTE: Passing true to this function may result in a bitmap which cannot 107 be properly used by Skia. 108 */ 109 void setRequireUnpremultipliedColors(bool request) { 110 fRequireUnpremultipliedColors = request; 111 } 112 113 /** Returns true if the decoder will only return bitmaps with unpremultiplied 114 colors. 115 */ 116 bool getRequireUnpremultipliedColors() const { return fRequireUnpremultipliedColors; } 117 118 /** \class Peeker 119 120 Base class for optional callbacks to retrieve meta/chunk data out of 121 an image as it is being decoded. 122 */ 123 class Peeker : public SkRefCnt { 124 public: 125 SK_DECLARE_INST_COUNT(Peeker) 126 127 /** Return true to continue decoding, or false to indicate an error, which 128 will cause the decoder to not return the image. 129 */ 130 virtual bool peek(const char tag[], const void* data, size_t length) = 0; 131 private: 132 typedef SkRefCnt INHERITED; 133 }; 134 135 Peeker* getPeeker() const { return fPeeker; } 136 Peeker* setPeeker(Peeker*); 137 138 #ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER 139 /** \class Chooser 140 141 Base class for optional callbacks to choose an image from a format that 142 contains multiple images. 143 */ 144 class Chooser : public SkRefCnt { 145 public: 146 SK_DECLARE_INST_COUNT(Chooser) 147 148 virtual void begin(int count) {} 149 virtual void inspect(int index, SkBitmap::Config config, int width, int height) {} 150 /** Return the index of the subimage you want, or -1 to choose none of them. 151 */ 152 virtual int choose() = 0; 153 154 private: 155 typedef SkRefCnt INHERITED; 156 }; 157 158 Chooser* getChooser() const { return fChooser; } 159 Chooser* setChooser(Chooser*); 160 #endif 161 162 #ifdef SK_SUPPORT_LEGACY_BITMAP_CONFIG 163 /** 164 * Optional table describing the caller's preferred config based on 165 * information about the src data. Each field should be set to the 166 * preferred config for a src described in the name of the field. The 167 * src attributes are described in terms of depth (8-index, 168 * 8bit-grayscale, or 8-bits/component) and whether there is per-pixel 169 * alpha (does not apply to grayscale). If the caller has no preference 170 * for a particular src type, its slot should be set to kNo_Config. 171 * 172 * NOTE ABOUT PREFERRED CONFIGS: 173 * If a config is preferred, either using a pref table or as a parameter 174 * to some flavor of decode, it is still at the discretion of the codec 175 * as to what output config is actually returned, as it may not be able 176 * to support the caller's preference. 177 * 178 * If a bitmap is decoded into SkBitmap::A8_Config, the resulting bitmap 179 * will either be a conversion of the grayscale in the case of a 180 * grayscale source or the alpha channel in the case of a source with 181 * an alpha channel. 182 */ 183 struct PrefConfigTable { 184 SkBitmap::Config fPrefFor_8Index_NoAlpha_src; 185 SkBitmap::Config fPrefFor_8Index_YesAlpha_src; 186 SkBitmap::Config fPrefFor_8Gray_src; 187 SkBitmap::Config fPrefFor_8bpc_NoAlpha_src; 188 SkBitmap::Config fPrefFor_8bpc_YesAlpha_src; 189 }; 190 191 /** 192 * Set an optional table for specifying the caller's preferred config 193 * based on information about the src data. 194 * 195 * The default is no preference, which will assume the config set by 196 * decode is preferred. 197 */ 198 void setPrefConfigTable(const PrefConfigTable&); 199 200 /** 201 * Do not use a PrefConfigTable to determine the output config. This 202 * is the default, so there is no need to call unless a PrefConfigTable 203 * was previously set. 204 */ 205 void resetPrefConfigTable() { fUsePrefTable = false; } 206 #endif 207 208 SkBitmap::Allocator* getAllocator() const { return fAllocator; } 209 SkBitmap::Allocator* setAllocator(SkBitmap::Allocator*); 210 211 // sample-size, if set to > 1, tells the decoder to return a smaller than 212 // original bitmap, sampling 1 pixel for every size pixels. e.g. if sample 213 // size is set to 3, then the returned bitmap will be 1/3 as wide and high, 214 // and will contain 1/9 as many pixels as the original. 215 // Note: this is a hint, and the codec may choose to ignore this, or only 216 // approximate the sample size. 217 int getSampleSize() const { return fSampleSize; } 218 void setSampleSize(int size); 219 220 /** Reset the sampleSize to its default of 1 221 */ 222 void resetSampleSize() { this->setSampleSize(1); } 223 224 /** Decoding is synchronous, but for long decodes, a different thread can 225 call this method safely. This sets a state that the decoders will 226 periodically check, and if they see it changed to cancel, they will 227 cancel. This will result in decode() returning false. However, there is 228 no guarantee that the decoder will see the state change in time, so 229 it is possible that cancelDecode() will be called, but will be ignored 230 and decode() will return true (assuming no other problems were 231 encountered). 232 233 This state is automatically reset at the beginning of decode(). 234 */ 235 void cancelDecode() { 236 // now the subclass must query shouldCancelDecode() to be informed 237 // of the request 238 fShouldCancelDecode = true; 239 } 240 241 /** Passed to the decode method. If kDecodeBounds_Mode is passed, then 242 only the bitmap's info need be set. If kDecodePixels_Mode 243 is passed, then the bitmap must have pixels or a pixelRef. 244 */ 245 enum Mode { 246 kDecodeBounds_Mode, //!< only return info in bitmap 247 kDecodePixels_Mode //!< return entire bitmap (including pixels) 248 }; 249 250 /** Given a stream, decode it into the specified bitmap. 251 If the decoder can decompress the image, it calls bitmap.setInfo(), 252 and then if the Mode is kDecodePixels_Mode, call allocPixelRef(), 253 which will allocated a pixelRef. To access the pixel memory, the codec 254 needs to call lockPixels/unlockPixels on the 255 bitmap. It can then set the pixels with the decompressed image. 256 * If the image cannot be decompressed, return false. After the 257 * decoding, the function converts the decoded colortype in bitmap 258 * to pref if possible. Whether a conversion is feasible is 259 * tested by Bitmap::canCopyTo(pref). 260 261 If an SkBitmap::Allocator is installed via setAllocator, it will be 262 used to allocate the pixel memory. A clever allocator can be used 263 to allocate the memory from a cache, volatile memory, or even from 264 an existing bitmap's memory. 265 266 If a Peeker is installed via setPeeker, it may be used to peek into 267 meta data during the decode. 268 */ 269 bool decode(SkStream*, SkBitmap* bitmap, SkColorType pref, Mode); 270 bool decode(SkStream* stream, SkBitmap* bitmap, Mode mode) { 271 return this->decode(stream, bitmap, kUnknown_SkColorType, mode); 272 } 273 274 /** 275 * Given a stream, build an index for doing tile-based decode. 276 * The built index will be saved in the decoder, and the image size will 277 * be returned in width and height. 278 * 279 * Return true for success or false on failure. 280 */ 281 bool buildTileIndex(SkStreamRewindable*, int *width, int *height); 282 283 /** 284 * Decode a rectangle subset in the image. 285 * The method can only be called after buildTileIndex(). 286 * 287 * Return true for success. 288 * Return false if the index is never built or failing in decoding. 289 */ 290 bool decodeSubset(SkBitmap* bm, const SkIRect& subset, SkColorType pref); 291 292 /** Given a stream, this will try to find an appropriate decoder object. 293 If none is found, the method returns NULL. 294 */ 295 static SkImageDecoder* Factory(SkStreamRewindable*); 296 297 /** Decode the image stored in the specified file, and store the result 298 in bitmap. Return true for success or false on failure. 299 300 @param pref If the PrefConfigTable is not set, prefer this colortype. 301 See NOTE ABOUT PREFERRED CONFIGS. 302 303 @param format On success, if format is non-null, it is set to the format 304 of the decoded file. On failure it is ignored. 305 */ 306 static bool DecodeFile(const char file[], SkBitmap* bitmap, SkColorType pref, Mode, 307 Format* format = NULL); 308 static bool DecodeFile(const char file[], SkBitmap* bitmap) { 309 return DecodeFile(file, bitmap, kUnknown_SkColorType, kDecodePixels_Mode, NULL); 310 } 311 312 /** Decode the image stored in the specified memory buffer, and store the 313 result in bitmap. Return true for success or false on failure. 314 315 @param pref If the PrefConfigTable is not set, prefer this colortype. 316 See NOTE ABOUT PREFERRED CONFIGS. 317 318 @param format On success, if format is non-null, it is set to the format 319 of the decoded buffer. On failure it is ignored. 320 */ 321 static bool DecodeMemory(const void* buffer, size_t size, SkBitmap* bitmap, SkColorType pref, 322 Mode, Format* format = NULL); 323 static bool DecodeMemory(const void* buffer, size_t size, SkBitmap* bitmap){ 324 return DecodeMemory(buffer, size, bitmap, kUnknown_SkColorType, kDecodePixels_Mode, NULL); 325 } 326 327 /** 328 * Struct containing information about a pixel destination. 329 */ 330 struct Target { 331 /** 332 * Pre-allocated memory. 333 */ 334 void* fAddr; 335 336 /** 337 * Rowbytes of the allocated memory. 338 */ 339 size_t fRowBytes; 340 }; 341 342 /** Decode the image stored in the specified SkStreamRewindable, and store the result 343 in bitmap. Return true for success or false on failure. 344 345 @param pref If the PrefConfigTable is not set, prefer this colortype. 346 See NOTE ABOUT PREFERRED CONFIGS. 347 348 @param format On success, if format is non-null, it is set to the format 349 of the decoded stream. On failure it is ignored. 350 */ 351 static bool DecodeStream(SkStreamRewindable* stream, SkBitmap* bitmap, SkColorType pref, Mode, 352 Format* format = NULL); 353 static bool DecodeStream(SkStreamRewindable* stream, SkBitmap* bitmap) { 354 return DecodeStream(stream, bitmap, kUnknown_SkColorType, kDecodePixels_Mode, NULL); 355 } 356 357 #ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CONFIG 358 bool decode(SkStream* stream, SkBitmap* bitmap, SkBitmap::Config pref, Mode mode) { 359 return this->decode(stream, bitmap, SkBitmapConfigToColorType(pref), mode); 360 } 361 bool decodeSubset(SkBitmap* bm, const SkIRect& subset, SkBitmap::Config pref) { 362 return this->decodeSubset(bm, subset, SkBitmapConfigToColorType(pref)); 363 } 364 static bool DecodeFile(const char file[], SkBitmap* bitmap, SkBitmap::Config pref, Mode mode, 365 Format* format = NULL) { 366 return DecodeFile(file, bitmap, SkBitmapConfigToColorType(pref), mode, format); 367 } 368 static bool DecodeMemory(const void* buffer, size_t size, SkBitmap* bitmap, 369 SkBitmap::Config pref, Mode mode, Format* format = NULL) { 370 return DecodeMemory(buffer, size, bitmap, SkBitmapConfigToColorType(pref), mode, format); 371 } 372 static bool DecodeStream(SkStreamRewindable* stream, SkBitmap* bitmap, SkBitmap::Config pref, 373 Mode mode, Format* format = NULL) { 374 return DecodeStream(stream, bitmap, SkBitmapConfigToColorType(pref), mode, format); 375 } 376 #endif 377 378 protected: 379 // must be overridden in subclasses. This guy is called by decode(...) 380 virtual bool onDecode(SkStream*, SkBitmap* bitmap, Mode) = 0; 381 382 // If the decoder wants to support tiled based decoding, 383 // this method must be overridden. This guy is called by buildTileIndex(...) 384 virtual bool onBuildTileIndex(SkStreamRewindable*, int *width, int *height) { 385 return false; 386 } 387 388 // If the decoder wants to support tiled based decoding, 389 // this method must be overridden. This guy is called by decodeRegion(...) 390 virtual bool onDecodeSubset(SkBitmap* bitmap, const SkIRect& rect) { 391 return false; 392 } 393 394 /* 395 * Crop a rectangle from the src Bitmap to the dest Bitmap. src and dst are 396 * both sampled by sampleSize from an original Bitmap. 397 * 398 * @param dst the destination bitmap. 399 * @param src the source bitmap that is sampled by sampleSize from the 400 * original bitmap. 401 * @param sampleSize the sample size that src is sampled from the original bitmap. 402 * @param (dstX, dstY) the upper-left point of the dest bitmap in terms of 403 * the coordinate in the original bitmap. 404 * @param (width, height) the width and height of the unsampled dst. 405 * @param (srcX, srcY) the upper-left point of the src bitmap in terms of 406 * the coordinate in the original bitmap. 407 * @return bool Whether or not it succeeded. 408 */ 409 bool cropBitmap(SkBitmap *dst, SkBitmap *src, int sampleSize, 410 int dstX, int dstY, int width, int height, 411 int srcX, int srcY); 412 413 /** 414 * Copy all fields on this decoder to the other decoder. Used by subclasses 415 * to decode a subimage using a different decoder, but with the same settings. 416 */ 417 void copyFieldsToOther(SkImageDecoder* other); 418 419 /** Can be queried from within onDecode, to see if the user (possibly in 420 a different thread) has requested the decode to cancel. If this returns 421 true, your onDecode() should stop and return false. 422 Each subclass needs to decide how often it can query this, to balance 423 responsiveness with performance. 424 425 Calling this outside of onDecode() may return undefined values. 426 */ 427 428 public: 429 bool shouldCancelDecode() const { return fShouldCancelDecode; } 430 431 protected: 432 SkImageDecoder(); 433 434 /** 435 * Return the default preference being used by the current or latest call to decode. 436 */ 437 SkColorType getDefaultPref() { return fDefaultPref; } 438 439 #ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER 440 // helper function for decoders to handle the (common) case where there is only 441 // once choice available in the image file. 442 bool chooseFromOneChoice(SkColorType, int width, int height) const; 443 #endif 444 445 /* Helper for subclasses. Call this to allocate the pixel memory given the bitmap's info. 446 Returns true on success. This method handles checking for an optional Allocator. 447 */ 448 bool allocPixelRef(SkBitmap*, SkColorTable*) const; 449 450 /** 451 * The raw data of the src image. 452 */ 453 enum SrcDepth { 454 // Color-indexed. 455 kIndex_SrcDepth, 456 // Grayscale in 8 bits. 457 k8BitGray_SrcDepth, 458 // 8 bits per component. Used for 24 bit if there is no alpha. 459 k32Bit_SrcDepth, 460 }; 461 /** The subclass, inside onDecode(), calls this to determine the colorType of 462 the returned bitmap. SrcDepth and hasAlpha reflect the raw data of the 463 src image. This routine returns the caller's preference given 464 srcDepth and hasAlpha, or kUnknown_SkColorType if there is no preference. 465 */ 466 SkColorType getPrefColorType(SrcDepth, bool hasAlpha) const; 467 468 private: 469 Peeker* fPeeker; 470 #ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER 471 Chooser* fChooser; 472 #endif 473 SkBitmap::Allocator* fAllocator; 474 int fSampleSize; 475 SkColorType fDefaultPref; // use if fUsePrefTable is false 476 #ifdef SK_SUPPORT_LEGACY_BITMAP_CONFIG 477 PrefConfigTable fPrefTable; // use if fUsePrefTable is true 478 bool fUsePrefTable; 479 #endif 480 bool fDitherImage; 481 bool fSkipWritingZeroes; 482 mutable bool fShouldCancelDecode; 483 bool fPreferQualityOverSpeed; 484 bool fRequireUnpremultipliedColors; 485 }; 486 487 /** Calling newDecoder with a stream returns a new matching imagedecoder 488 instance, or NULL if none can be found. The caller must manage its ownership 489 of the stream as usual, calling unref() when it is done, as the returned 490 decoder may have called ref() (and if so, the decoder is responsible for 491 balancing its ownership when it is destroyed). 492 */ 493 class SkImageDecoderFactory : public SkRefCnt { 494 public: 495 SK_DECLARE_INST_COUNT(SkImageDecoderFactory) 496 497 virtual SkImageDecoder* newDecoder(SkStreamRewindable*) = 0; 498 499 private: 500 typedef SkRefCnt INHERITED; 501 }; 502 503 class SkDefaultImageDecoderFactory : SkImageDecoderFactory { 504 public: 505 // calls SkImageDecoder::Factory(stream) 506 virtual SkImageDecoder* newDecoder(SkStreamRewindable* stream) { 507 return SkImageDecoder::Factory(stream); 508 } 509 }; 510 511 // This macro declares a global (i.e., non-class owned) creation entry point 512 // for each decoder (e.g., CreateJPEGImageDecoder) 513 #define DECLARE_DECODER_CREATOR(codec) \ 514 SkImageDecoder *Create ## codec (); 515 516 // This macro defines the global creation entry point for each decoder. Each 517 // decoder implementation that registers with the decoder factory must call it. 518 #define DEFINE_DECODER_CREATOR(codec) \ 519 SkImageDecoder *Create ## codec () { \ 520 return SkNEW( Sk ## codec ); \ 521 } 522 523 // All the decoders known by Skia. Note that, depending on the compiler settings, 524 // not all of these will be available 525 DECLARE_DECODER_CREATOR(BMPImageDecoder); 526 DECLARE_DECODER_CREATOR(GIFImageDecoder); 527 DECLARE_DECODER_CREATOR(ICOImageDecoder); 528 DECLARE_DECODER_CREATOR(JPEGImageDecoder); 529 DECLARE_DECODER_CREATOR(PNGImageDecoder); 530 DECLARE_DECODER_CREATOR(WBMPImageDecoder); 531 DECLARE_DECODER_CREATOR(WEBPImageDecoder); 532 DECLARE_DECODER_CREATOR(PKMImageDecoder); 533 DECLARE_DECODER_CREATOR(KTXImageDecoder); 534 535 // Typedefs to make registering decoder and formatter callbacks easier. 536 // These have to be defined outside SkImageDecoder. :( 537 typedef SkTRegistry<SkImageDecoder*(*)(SkStreamRewindable*)> SkImageDecoder_DecodeReg; 538 typedef SkTRegistry<SkImageDecoder::Format(*)(SkStreamRewindable*)> SkImageDecoder_FormatReg; 539 540 #endif 541
