4 * Copyright (C) 1991-1998, Thomas G. Lane.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
8 * This file defines the application interface for the JPEG library.
9 * Most applications using the library need only include this file,
10 * and perhaps jerror.h if they want to know the exact error codes.
17 * First we include the configuration files that record how this
18 * installation of the JPEG library is set up. jconfig.h can be
19 * generated automatically for many systems. jmorecfg.h contains
20 * manual configuration options that most people need not worry about.
23 #ifndef JCONFIG_INCLUDED /* in case jinclude.h already did */
24 #include "jconfig.h" /* widely used configuration options */
26 #include "jmorecfg.h" /* seldom changed options */
32 /* Version ID for the JPEG library.
33 * Might be useful for tests like "#if JPEG_LIB_VERSION >= 60".
36 #define JPEG_LIB_VERSION 62 /* Version 6b */
39 /* Various constants determining the sizes of things.
40 * All of these are specified by the JPEG standard, so don't change them
41 * if you want to be compatible.
44 #define DCTSIZE 8 /* The basic DCT block is 8x8 samples */
45 #define DCTSIZE2 64 /* DCTSIZE squared; # of elements in a block */
46 #define NUM_QUANT_TBLS 4 /* Quantization tables are numbered 0..3 */
47 #define NUM_HUFF_TBLS 4 /* Huffman tables are numbered 0..3 */
48 #define NUM_ARITH_TBLS 16 /* Arith-coding tables are numbered 0..15 */
49 #define MAX_COMPS_IN_SCAN 4 /* JPEG limit on # of components in one scan */
50 #define MAX_SAMP_FACTOR 4 /* JPEG limit on sampling factors */
51 /* Unfortunately, some bozo at Adobe saw no reason to be bound by the standard;
52 * the PostScript DCT filter can emit files with many more than 10 blocks/MCU.
53 * If you happen to run across such a file, you can up D_MAX_BLOCKS_IN_MCU
54 * to handle it. We even let you do this from the jconfig.h file. However,
55 * we strongly discourage changing C_MAX_BLOCKS_IN_MCU; just because Adobe
56 * sometimes emits noncompliant files doesn't mean you should too.
58 #define C_MAX_BLOCKS_IN_MCU 10 /* compressor's limit on blocks per MCU */
59 #ifndef D_MAX_BLOCKS_IN_MCU
60 #define D_MAX_BLOCKS_IN_MCU 10 /* decompressor's limit on blocks per MCU */
64 /* Data structures for images (arrays of samples and of DCT coefficients).
65 * On 80x86 machines, the image arrays are too big for near pointers,
66 * but the pointer arrays can fit in near memory.
69 typedef JSAMPLE FAR *JSAMPROW; /* ptr to one image row of pixel samples. */
70 typedef JSAMPROW *JSAMPARRAY; /* ptr to some rows (a 2-D sample array) */
71 typedef JSAMPARRAY *JSAMPIMAGE; /* a 3-D sample array: top index is color */
73 typedef JCOEF JBLOCK[DCTSIZE2]; /* one block of coefficients */
74 typedef JBLOCK FAR *JBLOCKROW; /* pointer to one row of coefficient blocks */
75 typedef JBLOCKROW *JBLOCKARRAY; /* a 2-D array of coefficient blocks */
76 typedef JBLOCKARRAY *JBLOCKIMAGE; /* a 3-D array of coefficient blocks */
78 typedef JCOEF FAR *JCOEFPTR; /* useful in a couple of places */
81 /* Types for JPEG compression parameters and working tables. */
84 /* DCT coefficient quantization tables. */
87 /* This array gives the coefficient quantizers in natural array order
88 * (not the zigzag order in which they are stored in a JPEG DQT marker).
89 * CAUTION: IJG versions prior to v6a kept this array in zigzag order.
91 UINT16 quantval[DCTSIZE2]; /* quantization step for each coefficient */
92 /* This field is used only during compression. It's initialized FALSE when
93 * the table is created, and set TRUE when it's been output to the file.
94 * You could suppress output of a table by setting this to TRUE.
95 * (See jpeg_suppress_tables for an example.)
97 boolean sent_table; /* TRUE when table has been output */
101 /* Huffman coding tables. */
104 /* These two fields directly represent the contents of a JPEG DHT marker */
105 UINT8 bits[17]; /* bits[k] = # of symbols with codes of */
106 /* length k bits; bits[0] is unused */
107 UINT8 huffval[256]; /* The symbols, in order of incr code length */
108 /* This field is used only during compression. It's initialized FALSE when
109 * the table is created, and set TRUE when it's been output to the file.
110 * You could suppress output of a table by setting this to TRUE.
111 * (See jpeg_suppress_tables for an example.)
113 boolean sent_table; /* TRUE when table has been output */
117 /* Basic info about one component (color channel). */
120 /* These values are fixed over the whole image. */
121 /* For compression, they must be supplied by parameter setup; */
122 /* for decompression, they are read from the SOF marker. */
123 int component_id; /* identifier for this component (0..255) */
124 int component_index; /* its index in SOF or cinfo->comp_info[] */
125 int h_samp_factor; /* horizontal sampling factor (1..4) */
126 int v_samp_factor; /* vertical sampling factor (1..4) */
127 int quant_tbl_no; /* quantization table selector (0..3) */
128 /* These values may vary between scans. */
129 /* For compression, they must be supplied by parameter setup; */
130 /* for decompression, they are read from the SOS marker. */
131 /* The decompressor output side may not use these variables. */
132 int dc_tbl_no; /* DC entropy table selector (0..3) */
133 int ac_tbl_no; /* AC entropy table selector (0..3) */
135 /* Remaining fields should be treated as private by applications. */
137 /* These values are computed during compression or decompression startup: */
138 /* Component's size in DCT blocks.
139 * Any dummy blocks added to complete an MCU are not counted; therefore
140 * these values do not depend on whether a scan is interleaved or not.
142 JDIMENSION width_in_blocks;
143 JDIMENSION height_in_blocks;
144 /* Size of a DCT block in samples. Always DCTSIZE for compression.
145 * For decompression this is the size of the output from one DCT block,
146 * reflecting any scaling we choose to apply during the IDCT step.
147 * Values of 1,2,4,8 are likely to be supported. Note that different
148 * components may receive different IDCT scalings.
151 /* The downsampled dimensions are the component's actual, unpadded number
152 * of samples at the main buffer (preprocessing/compression interface), thus
153 * downsampled_width = ceil(image_width * Hi/Hmax)
154 * and similarly for height. For decompression, IDCT scaling is included, so
155 * downsampled_width = ceil(image_width * Hi/Hmax * DCT_scaled_size/DCTSIZE)
157 JDIMENSION downsampled_width; /* actual width in samples */
158 JDIMENSION downsampled_height; /* actual height in samples */
159 /* This flag is used only for decompression. In cases where some of the
160 * components will be ignored (eg grayscale output from YCbCr image),
161 * we can skip most computations for the unused components.
163 boolean component_needed; /* do we need the value of this component? */
165 /* These values are computed before starting a scan of the component. */
166 /* The decompressor output side may not use these variables. */
167 int MCU_width; /* number of blocks per MCU, horizontally */
168 int MCU_height; /* number of blocks per MCU, vertically */
169 int MCU_blocks; /* MCU_width * MCU_height */
170 int MCU_sample_width; /* MCU width in samples, MCU_width*DCT_scaled_size */
171 int last_col_width; /* # of non-dummy blocks across in last MCU */
172 int last_row_height; /* # of non-dummy blocks down in last MCU */
174 /* Saved quantization table for component; NULL if none yet saved.
175 * See jdinput.c comments about the need for this information.
176 * This field is currently used only for decompression.
178 JQUANT_TBL * quant_table;
180 /* Private per-component storage for DCT or IDCT subsystem. */
182 } jpeg_component_info;
185 /* The script for encoding a multiple-scan file is an array of these: */
188 int comps_in_scan; /* number of components encoded in this scan */
189 int component_index[MAX_COMPS_IN_SCAN]; /* their SOF/comp_info[] indexes */
190 int Ss, Se; /* progressive JPEG spectral selection parms */
191 int Ah, Al; /* progressive JPEG successive approx. parms */
194 /* The decompressor can save APPn and COM markers in a list of these: */
196 typedef struct jpeg_marker_struct FAR * jpeg_saved_marker_ptr;
198 struct jpeg_marker_struct {
199 jpeg_saved_marker_ptr next; /* next in list, or NULL */
200 UINT8 marker; /* marker code: JPEG_COM, or JPEG_APP0+n */
201 unsigned int original_length; /* # bytes of data in the file */
202 unsigned int data_length; /* # bytes of data saved at data[] */
203 JOCTET FAR * data; /* the data contained in the marker */
204 /* the marker length word is not counted in data_length or original_length */
207 /* Known color spaces. */
210 JCS_UNKNOWN, /* error/unspecified */
211 JCS_GRAYSCALE, /* monochrome */
212 JCS_RGB, /* red/green/blue */
213 JCS_YCbCr, /* Y/Cb/Cr (also known as YUV) */
214 JCS_CMYK, /* C/M/Y/K */
215 JCS_YCCK /* Y/Cb/Cr/K */
218 /* DCT/IDCT algorithm options. */
221 JDCT_ISLOW, /* slow but accurate integer algorithm */
222 JDCT_IFAST, /* faster, less accurate integer method */
223 JDCT_FLOAT /* floating-point: accurate, fast on fast HW */
226 #ifndef JDCT_DEFAULT /* may be overridden in jconfig.h */
227 #define JDCT_DEFAULT JDCT_ISLOW
229 #ifndef JDCT_FASTEST /* may be overridden in jconfig.h */
230 #define JDCT_FASTEST JDCT_IFAST
233 /* Dithering options for decompression. */
236 JDITHER_NONE, /* no dithering */
237 JDITHER_ORDERED, /* simple ordered dither */
238 JDITHER_FS /* Floyd-Steinberg error diffusion dither */
242 /* Common fields between JPEG compression and decompression master structs. */
244 #define jpeg_common_fields \
245 struct jpeg_error_mgr * err; /* Error handler module */\
246 struct jpeg_memory_mgr * mem; /* Memory manager module */\
247 struct jpeg_progress_mgr * progress; /* Progress monitor, or NULL if none */\
248 void * client_data; /* Available for use by application */\
249 boolean is_decompressor; /* So common code can tell which is which */\
250 int global_state /* For checking call sequence validity */
252 /* Routines that are to be used by both halves of the library are declared
253 * to receive a pointer to this structure. There are no actual instances of
254 * jpeg_common_struct, only of jpeg_compress_struct and jpeg_decompress_struct.
256 struct jpeg_common_struct {
257 jpeg_common_fields; /* Fields common to both master struct types */
258 /* Additional fields follow in an actual jpeg_compress_struct or
259 * jpeg_decompress_struct. All three structs must agree on these
260 * initial fields! (This would be a lot cleaner in C++.)
264 typedef struct jpeg_common_struct * j_common_ptr;
265 typedef struct jpeg_compress_struct * j_compress_ptr;
266 typedef struct jpeg_decompress_struct * j_decompress_ptr;
269 /* Master record for a compression instance */
271 struct jpeg_compress_struct {
272 jpeg_common_fields; /* Fields shared with jpeg_decompress_struct */
274 /* Destination for compressed data */
275 struct jpeg_destination_mgr * dest;
277 /* Description of source image --- these fields must be filled in by
278 * outer application before starting compression. in_color_space must
279 * be correct before you can even call jpeg_set_defaults().
282 JDIMENSION image_width; /* input image width */
283 JDIMENSION image_height; /* input image height */
284 int input_components; /* # of color components in input image */
285 J_COLOR_SPACE in_color_space; /* colorspace of input image */
287 double input_gamma; /* image gamma of input image */
289 /* Compression parameters --- these fields must be set before calling
290 * jpeg_start_compress(). We recommend calling jpeg_set_defaults() to
291 * initialize everything to reasonable defaults, then changing anything
292 * the application specifically wants to change. That way you won't get
293 * burnt when new parameters are added. Also note that there are several
294 * helper routines to simplify changing parameters.
297 int data_precision; /* bits of precision in image data */
299 int num_components; /* # of color components in JPEG image */
300 J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */
302 jpeg_component_info * comp_info;
303 /* comp_info[i] describes component that appears i'th in SOF */
305 JQUANT_TBL * quant_tbl_ptrs[NUM_QUANT_TBLS];
306 /* ptrs to coefficient quantization tables, or NULL if not defined */
308 JHUFF_TBL * dc_huff_tbl_ptrs[NUM_HUFF_TBLS];
309 JHUFF_TBL * ac_huff_tbl_ptrs[NUM_HUFF_TBLS];
310 /* ptrs to Huffman coding tables, or NULL if not defined */
312 UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */
313 UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */
314 UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */
316 int num_scans; /* # of entries in scan_info array */
317 const jpeg_scan_info * scan_info; /* script for multi-scan file, or NULL */
318 /* The default value of scan_info is NULL, which causes a single-scan
319 * sequential JPEG file to be emitted. To create a multi-scan file,
320 * set num_scans and scan_info to point to an array of scan definitions.
323 boolean raw_data_in; /* TRUE=caller supplies downsampled data */
324 boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */
325 boolean optimize_coding; /* TRUE=optimize entropy encoding parms */
326 boolean CCIR601_sampling; /* TRUE=first samples are cosited */
327 int smoothing_factor; /* 1..100, or 0 for no input smoothing */
328 J_DCT_METHOD dct_method; /* DCT algorithm selector */
330 /* The restart interval can be specified in absolute MCUs by setting
331 * restart_interval, or in MCU rows by setting restart_in_rows
332 * (in which case the correct restart_interval will be figured
335 unsigned int restart_interval; /* MCUs per restart, or 0 for no restart */
336 int restart_in_rows; /* if > 0, MCU rows per restart interval */
338 /* Parameters controlling emission of special markers. */
340 boolean write_JFIF_header; /* should a JFIF marker be written? */
341 UINT8 JFIF_major_version; /* What to write for the JFIF version number */
342 UINT8 JFIF_minor_version;
343 /* These three values are not used by the JPEG code, merely copied */
344 /* into the JFIF APP0 marker. density_unit can be 0 for unknown, */
345 /* 1 for dots/inch, or 2 for dots/cm. Note that the pixel aspect */
346 /* ratio is defined by X_density/Y_density even when density_unit=0. */
347 UINT8 density_unit; /* JFIF code for pixel size units */
348 UINT16 X_density; /* Horizontal pixel density */
349 UINT16 Y_density; /* Vertical pixel density */
350 boolean write_Adobe_marker; /* should an Adobe marker be written? */
352 /* State variable: index of next scanline to be written to
353 * jpeg_write_scanlines(). Application may use this to control its
354 * processing loop, e.g., "while (next_scanline < image_height)".
357 JDIMENSION next_scanline; /* 0 .. image_height-1 */
359 /* Remaining fields are known throughout compressor, but generally
360 * should not be touched by a surrounding application.
364 * These fields are computed during compression startup
366 boolean progressive_mode; /* TRUE if scan script uses progressive mode */
367 int max_h_samp_factor; /* largest h_samp_factor */
368 int max_v_samp_factor; /* largest v_samp_factor */
370 JDIMENSION total_iMCU_rows; /* # of iMCU rows to be input to coef ctlr */
371 /* The coefficient controller receives data in units of MCU rows as defined
372 * for fully interleaved scans (whether the JPEG file is interleaved or not).
373 * There are v_samp_factor * DCTSIZE sample rows of each component in an
374 * "iMCU" (interleaved MCU) row.
378 * These fields are valid during any one scan.
379 * They describe the components and MCUs actually appearing in the scan.
381 int comps_in_scan; /* # of JPEG components in this scan */
382 jpeg_component_info * cur_comp_info[MAX_COMPS_IN_SCAN];
383 /* *cur_comp_info[i] describes component that appears i'th in SOS */
385 JDIMENSION MCUs_per_row; /* # of MCUs across the image */
386 JDIMENSION MCU_rows_in_scan; /* # of MCU rows in the image */
388 int blocks_in_MCU; /* # of DCT blocks per MCU */
389 int MCU_membership[C_MAX_BLOCKS_IN_MCU];
390 /* MCU_membership[i] is index in cur_comp_info of component owning */
391 /* i'th block in an MCU */
393 int Ss, Se, Ah, Al; /* progressive JPEG parameters for scan */
396 * Links to compression subobjects (methods and private variables of modules)
398 struct jpeg_comp_master * master;
399 struct jpeg_c_main_controller * main;
400 struct jpeg_c_prep_controller * prep;
401 struct jpeg_c_coef_controller * coef;
402 struct jpeg_marker_writer * marker;
403 struct jpeg_color_converter * cconvert;
404 struct jpeg_downsampler * downsample;
405 struct jpeg_forward_dct * fdct;
406 struct jpeg_entropy_encoder * entropy;
407 jpeg_scan_info * script_space; /* workspace for jpeg_simple_progression */
408 int script_space_size;
412 /* Master record for a decompression instance */
414 struct jpeg_decompress_struct {
415 jpeg_common_fields; /* Fields shared with jpeg_compress_struct */
417 /* Source of compressed data */
418 struct jpeg_source_mgr * src;
420 /* Basic description of image --- filled in by jpeg_read_header(). */
421 /* Application may inspect these values to decide how to process image. */
423 JDIMENSION image_width; /* nominal image width (from SOF marker) */
424 JDIMENSION image_height; /* nominal image height */
425 int num_components; /* # of color components in JPEG image */
426 J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */
428 /* Decompression processing parameters --- these fields must be set before
429 * calling jpeg_start_decompress(). Note that jpeg_read_header() initializes
430 * them to default values.
433 J_COLOR_SPACE out_color_space; /* colorspace for output */
435 unsigned int scale_num, scale_denom; /* fraction by which to scale image */
437 double output_gamma; /* image gamma wanted in output */
439 boolean buffered_image; /* TRUE=multiple output passes */
440 boolean raw_data_out; /* TRUE=downsampled data wanted */
442 J_DCT_METHOD dct_method; /* IDCT algorithm selector */
443 boolean do_fancy_upsampling; /* TRUE=apply fancy upsampling */
444 boolean do_block_smoothing; /* TRUE=apply interblock smoothing */
446 boolean quantize_colors; /* TRUE=colormapped output wanted */
447 /* the following are ignored if not quantize_colors: */
448 J_DITHER_MODE dither_mode; /* type of color dithering to use */
449 boolean two_pass_quantize; /* TRUE=use two-pass color quantization */
450 int desired_number_of_colors; /* max # colors to use in created colormap */
451 /* these are significant only in buffered-image mode: */
452 boolean enable_1pass_quant; /* enable future use of 1-pass quantizer */
453 boolean enable_external_quant;/* enable future use of external colormap */
454 boolean enable_2pass_quant; /* enable future use of 2-pass quantizer */
456 /* Description of actual output image that will be returned to application.
457 * These fields are computed by jpeg_start_decompress().
458 * You can also use jpeg_calc_output_dimensions() to determine these values
459 * in advance of calling jpeg_start_decompress().
462 JDIMENSION output_width; /* scaled image width */
463 JDIMENSION output_height; /* scaled image height */
464 int out_color_components; /* # of color components in out_color_space */
465 int output_components; /* # of color components returned */
466 /* output_components is 1 (a colormap index) when quantizing colors;
467 * otherwise it equals out_color_components.
469 int rec_outbuf_height; /* min recommended height of scanline buffer */
470 /* If the buffer passed to jpeg_read_scanlines() is less than this many rows
471 * high, space and time will be wasted due to unnecessary data copying.
472 * Usually rec_outbuf_height will be 1 or 2, at most 4.
475 /* When quantizing colors, the output colormap is described by these fields.
476 * The application can supply a colormap by setting colormap non-NULL before
477 * calling jpeg_start_decompress; otherwise a colormap is created during
478 * jpeg_start_decompress or jpeg_start_output.
479 * The map has out_color_components rows and actual_number_of_colors columns.
481 int actual_number_of_colors; /* number of entries in use */
482 JSAMPARRAY colormap; /* The color map as a 2-D pixel array */
484 /* State variables: these variables indicate the progress of decompression.
485 * The application may examine these but must not modify them.
488 /* Row index of next scanline to be read from jpeg_read_scanlines().
489 * Application may use this to control its processing loop, e.g.,
490 * "while (output_scanline < output_height)".
492 JDIMENSION output_scanline; /* 0 .. output_height-1 */
494 /* Current input scan number and number of iMCU rows completed in scan.
495 * These indicate the progress of the decompressor input side.
497 int input_scan_number; /* Number of SOS markers seen so far */
498 JDIMENSION input_iMCU_row; /* Number of iMCU rows completed */
500 /* The "output scan number" is the notional scan being displayed by the
501 * output side. The decompressor will not allow output scan/row number
502 * to get ahead of input scan/row, but it can fall arbitrarily far behind.
504 int output_scan_number; /* Nominal scan number being displayed */
505 JDIMENSION output_iMCU_row; /* Number of iMCU rows read */
507 /* Current progression status. coef_bits[c][i] indicates the precision
508 * with which component c's DCT coefficient i (in zigzag order) is known.
509 * It is -1 when no data has yet been received, otherwise it is the point
510 * transform (shift) value for the most recent scan of the coefficient
511 * (thus, 0 at completion of the progression).
512 * This pointer is NULL when reading a non-progressive file.
514 int (*coef_bits)[DCTSIZE2]; /* -1 or current Al value for each coef */
516 /* Internal JPEG parameters --- the application usually need not look at
517 * these fields. Note that the decompressor output side may not use
518 * any parameters that can change between scans.
521 /* Quantization and Huffman tables are carried forward across input
522 * datastreams when processing abbreviated JPEG datastreams.
525 JQUANT_TBL * quant_tbl_ptrs[NUM_QUANT_TBLS];
526 /* ptrs to coefficient quantization tables, or NULL if not defined */
528 JHUFF_TBL * dc_huff_tbl_ptrs[NUM_HUFF_TBLS];
529 JHUFF_TBL * ac_huff_tbl_ptrs[NUM_HUFF_TBLS];
530 /* ptrs to Huffman coding tables, or NULL if not defined */
532 /* These parameters are never carried across datastreams, since they
533 * are given in SOF/SOS markers or defined to be reset by SOI.
536 int data_precision; /* bits of precision in image data */
538 jpeg_component_info * comp_info;
539 /* comp_info[i] describes component that appears i'th in SOF */
541 boolean progressive_mode; /* TRUE if SOFn specifies progressive mode */
542 boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */
544 UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */
545 UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */
546 UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */
548 unsigned int restart_interval; /* MCUs per restart interval, or 0 for no restart */
550 /* These fields record data obtained from optional markers recognized by
553 boolean saw_JFIF_marker; /* TRUE iff a JFIF APP0 marker was found */
554 /* Data copied from JFIF marker; only valid if saw_JFIF_marker is TRUE: */
555 UINT8 JFIF_major_version; /* JFIF version number */
556 UINT8 JFIF_minor_version;
557 UINT8 density_unit; /* JFIF code for pixel size units */
558 UINT16 X_density; /* Horizontal pixel density */
559 UINT16 Y_density; /* Vertical pixel density */
560 boolean saw_Adobe_marker; /* TRUE iff an Adobe APP14 marker was found */
561 UINT8 Adobe_transform; /* Color transform code from Adobe marker */
563 boolean CCIR601_sampling; /* TRUE=first samples are cosited */
565 /* Aside from the specific data retained from APPn markers known to the
566 * library, the uninterpreted contents of any or all APPn and COM markers
567 * can be saved in a list for examination by the application.
569 jpeg_saved_marker_ptr marker_list; /* Head of list of saved markers */
571 /* Remaining fields are known throughout decompressor, but generally
572 * should not be touched by a surrounding application.
576 * These fields are computed during decompression startup
578 int max_h_samp_factor; /* largest h_samp_factor */
579 int max_v_samp_factor; /* largest v_samp_factor */
581 int min_DCT_scaled_size; /* smallest DCT_scaled_size of any component */
583 JDIMENSION total_iMCU_rows; /* # of iMCU rows in image */
584 /* The coefficient controller's input and output progress is measured in
585 * units of "iMCU" (interleaved MCU) rows. These are the same as MCU rows
586 * in fully interleaved JPEG scans, but are used whether the scan is
587 * interleaved or not. We define an iMCU row as v_samp_factor DCT block
588 * rows of each component. Therefore, the IDCT output contains
589 * v_samp_factor*DCT_scaled_size sample rows of a component per iMCU row.
592 JSAMPLE * sample_range_limit; /* table for fast range-limiting */
595 * These fields are valid during any one scan.
596 * They describe the components and MCUs actually appearing in the scan.
597 * Note that the decompressor output side must not use these fields.
599 int comps_in_scan; /* # of JPEG components in this scan */
600 jpeg_component_info * cur_comp_info[MAX_COMPS_IN_SCAN];
601 /* *cur_comp_info[i] describes component that appears i'th in SOS */
603 JDIMENSION MCUs_per_row; /* # of MCUs across the image */
604 JDIMENSION MCU_rows_in_scan; /* # of MCU rows in the image */
606 int blocks_in_MCU; /* # of DCT blocks per MCU */
607 int MCU_membership[D_MAX_BLOCKS_IN_MCU];
608 /* MCU_membership[i] is index in cur_comp_info of component owning */
609 /* i'th block in an MCU */
611 int Ss, Se, Ah, Al; /* progressive JPEG parameters for scan */
613 /* This field is shared between entropy decoder and marker parser.
614 * It is either zero or the code of a JPEG marker that has been
615 * read from the data source, but has not yet been processed.
620 * Links to decompression subobjects (methods, private variables of modules)
622 struct jpeg_decomp_master * master;
623 struct jpeg_d_main_controller * main;
624 struct jpeg_d_coef_controller * coef;
625 struct jpeg_d_post_controller * post;
626 struct jpeg_input_controller * inputctl;
627 struct jpeg_marker_reader * marker;
628 struct jpeg_entropy_decoder * entropy;
629 struct jpeg_inverse_dct * idct;
630 struct jpeg_upsampler * upsample;
631 struct jpeg_color_deconverter * cconvert;
632 struct jpeg_color_quantizer * cquantize;
636 /* "Object" declarations for JPEG modules that may be supplied or called
637 * directly by the surrounding application.
638 * As with all objects in the JPEG library, these structs only define the
639 * publicly visible methods and state variables of a module. Additional
640 * private fields may exist after the public ones.
644 /* Error handler object */
646 struct jpeg_error_mgr {
647 /* Error exit handler: does not return to caller */
648 JMETHOD(void, error_exit, (j_common_ptr cinfo));
649 /* Conditionally emit a trace or warning message */
650 JMETHOD(void, emit_message, (j_common_ptr cinfo, int msg_level));
651 /* Routine that actually outputs a trace or error message */
652 JMETHOD(void, output_message, (j_common_ptr cinfo));
653 /* Format a message string for the most recent JPEG error or message */
654 JMETHOD(void, format_message, (j_common_ptr cinfo, char * buffer));
655 #define JMSG_LENGTH_MAX 200 /* recommended size of format_message buffer */
656 /* Reset error state variables at start of a new image */
657 JMETHOD(void, reset_error_mgr, (j_common_ptr cinfo));
659 /* The message ID code and any parameters are saved here.
660 * A message can have one string parameter or up to 8 int parameters.
663 #define JMSG_STR_PARM_MAX 80
666 char s[JMSG_STR_PARM_MAX];
669 /* Standard state variables for error facility */
671 int trace_level; /* max msg_level that will be displayed */
673 /* For recoverable corrupt-data errors, we emit a warning message,
674 * but keep going unless emit_message chooses to abort. emit_message
675 * should count warnings in num_warnings. The surrounding application
676 * can check for bad data by seeing if num_warnings is nonzero at the
679 long num_warnings; /* number of corrupt-data warnings */
681 /* These fields point to the table(s) of error message strings.
682 * An application can change the table pointer to switch to a different
683 * message list (typically, to change the language in which errors are
684 * reported). Some applications may wish to add additional error codes
685 * that will be handled by the JPEG library error mechanism; the second
686 * table pointer is used for this purpose.
688 * First table includes all errors generated by JPEG library itself.
689 * Error code 0 is reserved for a "no such error string" message.
691 const char * const * jpeg_message_table; /* Library errors */
692 int last_jpeg_message; /* Table contains strings 0..last_jpeg_message */
693 /* Second table can be added by application (see cjpeg/djpeg for example).
694 * It contains strings numbered first_addon_message..last_addon_message.
696 const char * const * addon_message_table; /* Non-library errors */
697 int first_addon_message; /* code for first string in addon table */
698 int last_addon_message; /* code for last string in addon table */
702 /* Progress monitor object */
704 struct jpeg_progress_mgr {
705 JMETHOD(void, progress_monitor, (j_common_ptr cinfo));
707 long pass_counter; /* work units completed in this pass */
708 long pass_limit; /* total number of work units in this pass */
709 int completed_passes; /* passes completed so far */
710 int total_passes; /* total number of passes expected */
714 /* Data destination object for compression */
716 struct jpeg_destination_mgr {
717 JOCTET * next_output_byte; /* => next byte to write in buffer */
718 size_t free_in_buffer; /* # of byte spaces remaining in buffer */
720 JMETHOD(void, init_destination, (j_compress_ptr cinfo));
721 JMETHOD(boolean, empty_output_buffer, (j_compress_ptr cinfo));
722 JMETHOD(void, term_destination, (j_compress_ptr cinfo));
726 /* Data source object for decompression */
728 struct jpeg_source_mgr {
729 const JOCTET * next_input_byte; /* => next byte to read from buffer */
730 size_t bytes_in_buffer; /* # of bytes remaining in buffer */
732 JMETHOD(void, init_source, (j_decompress_ptr cinfo));
733 JMETHOD(boolean, fill_input_buffer, (j_decompress_ptr cinfo));
734 JMETHOD(void, skip_input_data, (j_decompress_ptr cinfo, long num_bytes));
735 JMETHOD(boolean, resync_to_restart, (j_decompress_ptr cinfo, int desired));
736 JMETHOD(void, term_source, (j_decompress_ptr cinfo));
740 /* Memory manager object.
741 * Allocates "small" objects (a few K total), "large" objects (tens of K),
742 * and "really big" objects (virtual arrays with backing store if needed).
743 * The memory manager does not allow individual objects to be freed; rather,
744 * each created object is assigned to a pool, and whole pools can be freed
745 * at once. This is faster and more convenient than remembering exactly what
746 * to free, especially where malloc()/free() are not too speedy.
747 * NB: alloc routines never return NULL. They exit to error_exit if not
751 #define JPOOL_PERMANENT 0 /* lasts until master record is destroyed */
752 #define JPOOL_IMAGE 1 /* lasts until done with image/datastream */
753 #define JPOOL_NUMPOOLS 2
755 typedef struct jvirt_sarray_control * jvirt_sarray_ptr;
756 typedef struct jvirt_barray_control * jvirt_barray_ptr;
759 struct jpeg_memory_mgr {
760 /* Method pointers */
761 JMETHOD(void *, alloc_small, (j_common_ptr cinfo, int pool_id,
762 size_t sizeofobject));
763 JMETHOD(void FAR *, alloc_large, (j_common_ptr cinfo, int pool_id,
764 size_t sizeofobject));
765 JMETHOD(JSAMPARRAY, alloc_sarray, (j_common_ptr cinfo, int pool_id,
766 JDIMENSION samplesperrow,
767 JDIMENSION numrows));
768 JMETHOD(JBLOCKARRAY, alloc_barray, (j_common_ptr cinfo, int pool_id,
769 JDIMENSION blocksperrow,
770 JDIMENSION numrows));
771 JMETHOD(jvirt_sarray_ptr, request_virt_sarray, (j_common_ptr cinfo,
774 JDIMENSION samplesperrow,
776 JDIMENSION maxaccess));
777 JMETHOD(jvirt_barray_ptr, request_virt_barray, (j_common_ptr cinfo,
780 JDIMENSION blocksperrow,
782 JDIMENSION maxaccess));
783 JMETHOD(void, realize_virt_arrays, (j_common_ptr cinfo));
784 JMETHOD(JSAMPARRAY, access_virt_sarray, (j_common_ptr cinfo,
785 jvirt_sarray_ptr ptr,
786 JDIMENSION start_row,
789 JMETHOD(JBLOCKARRAY, access_virt_barray, (j_common_ptr cinfo,
790 jvirt_barray_ptr ptr,
791 JDIMENSION start_row,
794 JMETHOD(void, free_pool, (j_common_ptr cinfo, int pool_id));
795 JMETHOD(void, self_destruct, (j_common_ptr cinfo));
797 /* Limit on memory allocation for this JPEG object. (Note that this is
798 * merely advisory, not a guaranteed maximum; it only affects the space
799 * used for virtual-array buffers.) May be changed by outer application
800 * after creating the JPEG object.
802 long max_memory_to_use;
804 /* Maximum allocation request accepted by alloc_large. */
805 long max_alloc_chunk;
809 /* Routine signature for application-supplied marker processing methods.
810 * Need not pass marker code since it is stored in cinfo->unread_marker.
812 typedef JMETHOD(boolean, jpeg_marker_parser_method, (j_decompress_ptr cinfo));
815 /* Declarations for routines called by application.
816 * The JPP macro hides prototype parameters from compilers that can't cope.
817 * Note JPP requires double parentheses.
820 #ifdef HAVE_PROTOTYPES
821 #define JPP(arglist) arglist
823 #define JPP(arglist) ()
827 /* Short forms of external names for systems with brain-damaged linkers.
828 * We shorten external names to be unique in the first six letters, which
829 * is good enough for all known systems.
830 * (If your compiler itself needs names to be unique in less than 15
831 * characters, you are out of luck. Get a better compiler.)
834 #ifdef NEED_SHORT_EXTERNAL_NAMES
835 #define jpeg_std_error jStdError
836 #define jpeg_CreateCompress jCreaCompress
837 #define jpeg_CreateDecompress jCreaDecompress
838 #define jpeg_destroy_compress jDestCompress
839 #define jpeg_destroy_decompress jDestDecompress
840 #define jpeg_stdio_dest jStdDest
841 #define jpeg_stdio_src jStdSrc
842 #define jpeg_set_defaults jSetDefaults
843 #define jpeg_set_colorspace jSetColorspace
844 #define jpeg_default_colorspace jDefColorspace
845 #define jpeg_set_quality jSetQuality
846 #define jpeg_set_linear_quality jSetLQuality
847 #define jpeg_add_quant_table jAddQuantTable
848 #define jpeg_quality_scaling jQualityScaling
849 #define jpeg_simple_progression jSimProgress
850 #define jpeg_suppress_tables jSuppressTables
851 #define jpeg_alloc_quant_table jAlcQTable
852 #define jpeg_alloc_huff_table jAlcHTable
853 #define jpeg_start_compress jStrtCompress
854 #define jpeg_write_scanlines jWrtScanlines
855 #define jpeg_finish_compress jFinCompress
856 #define jpeg_write_raw_data jWrtRawData
857 #define jpeg_write_marker jWrtMarker
858 #define jpeg_write_m_header jWrtMHeader
859 #define jpeg_write_m_byte jWrtMByte
860 #define jpeg_write_tables jWrtTables
861 #define jpeg_read_header jReadHeader
862 #define jpeg_start_decompress jStrtDecompress
863 #define jpeg_read_scanlines jReadScanlines
864 #define jpeg_finish_decompress jFinDecompress
865 #define jpeg_read_raw_data jReadRawData
866 #define jpeg_has_multiple_scans jHasMultScn
867 #define jpeg_start_output jStrtOutput
868 #define jpeg_finish_output jFinOutput
869 #define jpeg_input_complete jInComplete
870 #define jpeg_new_colormap jNewCMap
871 #define jpeg_consume_input jConsumeInput
872 #define jpeg_calc_output_dimensions jCalcDimensions
873 #define jpeg_save_markers jSaveMarkers
874 #define jpeg_set_marker_processor jSetMarker
875 #define jpeg_read_coefficients jReadCoefs
876 #define jpeg_write_coefficients jWrtCoefs
877 #define jpeg_copy_critical_parameters jCopyCrit
878 #define jpeg_abort_compress jAbrtCompress
879 #define jpeg_abort_decompress jAbrtDecompress
880 #define jpeg_abort jAbort
881 #define jpeg_destroy jDestroy
882 #define jpeg_resync_to_restart jResyncRestart
883 #endif /* NEED_SHORT_EXTERNAL_NAMES */
886 /* Default error-management setup */
887 EXTERN(struct jpeg_error_mgr *) jpeg_std_error
888 JPP((struct jpeg_error_mgr * err));
890 /* Initialization of JPEG compression objects.
891 * jpeg_create_compress() and jpeg_create_decompress() are the exported
892 * names that applications should call. These expand to calls on
893 * jpeg_CreateCompress and jpeg_CreateDecompress with additional information
894 * passed for version mismatch checking.
895 * NB: you must set up the error-manager BEFORE calling jpeg_create_xxx.
897 #define jpeg_create_compress(cinfo) \
898 jpeg_CreateCompress((cinfo), JPEG_LIB_VERSION, \
899 (size_t) sizeof(struct jpeg_compress_struct))
900 #define jpeg_create_decompress(cinfo) \
901 jpeg_CreateDecompress((cinfo), JPEG_LIB_VERSION, \
902 (size_t) sizeof(struct jpeg_decompress_struct))
903 EXTERN(void) jpeg_CreateCompress JPP((j_compress_ptr cinfo,
904 int version, size_t structsize));
905 EXTERN(void) jpeg_CreateDecompress JPP((j_decompress_ptr cinfo,
906 int version, size_t structsize));
907 /* Destruction of JPEG compression objects */
908 EXTERN(void) jpeg_destroy_compress JPP((j_compress_ptr cinfo));
909 EXTERN(void) jpeg_destroy_decompress JPP((j_decompress_ptr cinfo));
911 /* Standard data source and destination managers: stdio streams. */
912 /* Caller is responsible for opening the file before and closing after. */
913 EXTERN(void) jpeg_stdio_dest JPP((j_compress_ptr cinfo, FILE * outfile));
914 EXTERN(void) jpeg_stdio_src JPP((j_decompress_ptr cinfo, FILE * infile));
916 /* Default parameter setup for compression */
917 EXTERN(void) jpeg_set_defaults JPP((j_compress_ptr cinfo));
918 /* Compression parameter setup aids */
919 EXTERN(void) jpeg_set_colorspace JPP((j_compress_ptr cinfo,
920 J_COLOR_SPACE colorspace));
921 EXTERN(void) jpeg_default_colorspace JPP((j_compress_ptr cinfo));
922 EXTERN(void) jpeg_set_quality JPP((j_compress_ptr cinfo, int quality,
923 boolean force_baseline));
924 EXTERN(void) jpeg_set_linear_quality JPP((j_compress_ptr cinfo,
926 boolean force_baseline));
927 EXTERN(void) jpeg_add_quant_table JPP((j_compress_ptr cinfo, int which_tbl,
928 const unsigned int *basic_table,
930 boolean force_baseline));
931 EXTERN(int) jpeg_quality_scaling JPP((int quality));
932 EXTERN(void) jpeg_simple_progression JPP((j_compress_ptr cinfo));
933 EXTERN(void) jpeg_suppress_tables JPP((j_compress_ptr cinfo,
935 EXTERN(JQUANT_TBL *) jpeg_alloc_quant_table JPP((j_common_ptr cinfo));
936 EXTERN(JHUFF_TBL *) jpeg_alloc_huff_table JPP((j_common_ptr cinfo));
938 /* Main entry points for compression */
939 EXTERN(void) jpeg_start_compress JPP((j_compress_ptr cinfo,
940 boolean write_all_tables));
941 EXTERN(JDIMENSION) jpeg_write_scanlines JPP((j_compress_ptr cinfo,
942 JSAMPARRAY scanlines,
943 JDIMENSION num_lines));
944 EXTERN(void) jpeg_finish_compress JPP((j_compress_ptr cinfo));
946 /* Replaces jpeg_write_scanlines when writing raw downsampled data. */
947 EXTERN(JDIMENSION) jpeg_write_raw_data JPP((j_compress_ptr cinfo,
949 JDIMENSION num_lines));
951 /* Write a special marker. See libjpeg.doc concerning safe usage. */
952 EXTERN(void) jpeg_write_marker
953 JPP((j_compress_ptr cinfo, int marker,
954 const JOCTET * dataptr, unsigned int datalen));
955 /* Same, but piecemeal. */
956 EXTERN(void) jpeg_write_m_header
957 JPP((j_compress_ptr cinfo, int marker, unsigned int datalen));
958 EXTERN(void) jpeg_write_m_byte
959 JPP((j_compress_ptr cinfo, int val));
961 /* Alternate compression function: just write an abbreviated table file */
962 EXTERN(void) jpeg_write_tables JPP((j_compress_ptr cinfo));
964 /* Decompression startup: read start of JPEG datastream to see what's there */
965 EXTERN(int) jpeg_read_header JPP((j_decompress_ptr cinfo,
966 boolean require_image));
967 /* Return value is one of: */
968 #define JPEG_SUSPENDED 0 /* Suspended due to lack of input data */
969 #define JPEG_HEADER_OK 1 /* Found valid image datastream */
970 #define JPEG_HEADER_TABLES_ONLY 2 /* Found valid table-specs-only datastream */
971 /* If you pass require_image = TRUE (normal case), you need not check for
972 * a TABLES_ONLY return code; an abbreviated file will cause an error exit.
973 * JPEG_SUSPENDED is only possible if you use a data source module that can
974 * give a suspension return (the stdio source module doesn't).
977 /* Main entry points for decompression */
978 EXTERN(boolean) jpeg_start_decompress JPP((j_decompress_ptr cinfo));
979 EXTERN(JDIMENSION) jpeg_read_scanlines JPP((j_decompress_ptr cinfo,
980 JSAMPARRAY scanlines,
981 JDIMENSION max_lines));
982 EXTERN(boolean) jpeg_finish_decompress JPP((j_decompress_ptr cinfo));
984 /* Replaces jpeg_read_scanlines when reading raw downsampled data. */
985 EXTERN(JDIMENSION) jpeg_read_raw_data JPP((j_decompress_ptr cinfo,
987 JDIMENSION max_lines));
989 /* Additional entry points for buffered-image mode. */
990 EXTERN(boolean) jpeg_has_multiple_scans JPP((j_decompress_ptr cinfo));
991 EXTERN(boolean) jpeg_start_output JPP((j_decompress_ptr cinfo,
993 EXTERN(boolean) jpeg_finish_output JPP((j_decompress_ptr cinfo));
994 EXTERN(boolean) jpeg_input_complete JPP((j_decompress_ptr cinfo));
995 EXTERN(void) jpeg_new_colormap JPP((j_decompress_ptr cinfo));
996 EXTERN(int) jpeg_consume_input JPP((j_decompress_ptr cinfo));
997 /* Return value is one of: */
998 /* #define JPEG_SUSPENDED 0 Suspended due to lack of input data */
999 #define JPEG_REACHED_SOS 1 /* Reached start of new scan */
1000 #define JPEG_REACHED_EOI 2 /* Reached end of image */
1001 #define JPEG_ROW_COMPLETED 3 /* Completed one iMCU row */
1002 #define JPEG_SCAN_COMPLETED 4 /* Completed last iMCU row of a scan */
1004 /* Precalculate output dimensions for current decompression parameters. */
1005 EXTERN(void) jpeg_calc_output_dimensions JPP((j_decompress_ptr cinfo));
1007 /* Control saving of COM and APPn markers into marker_list. */
1008 EXTERN(void) jpeg_save_markers
1009 JPP((j_decompress_ptr cinfo, int marker_code,
1010 unsigned int length_limit));
1012 /* Install a special processing method for COM or APPn markers. */
1013 EXTERN(void) jpeg_set_marker_processor
1014 JPP((j_decompress_ptr cinfo, int marker_code,
1015 jpeg_marker_parser_method routine));
1017 /* Read or write raw DCT coefficients --- useful for lossless transcoding. */
1018 EXTERN(jvirt_barray_ptr *) jpeg_read_coefficients JPP((j_decompress_ptr cinfo));
1019 EXTERN(void) jpeg_write_coefficients JPP((j_compress_ptr cinfo,
1020 jvirt_barray_ptr * coef_arrays));
1021 EXTERN(void) jpeg_copy_critical_parameters JPP((j_decompress_ptr srcinfo,
1022 j_compress_ptr dstinfo));
1024 /* If you choose to abort compression or decompression before completing
1025 * jpeg_finish_(de)compress, then you need to clean up to release memory,
1026 * temporary files, etc. You can just call jpeg_destroy_(de)compress
1027 * if you're done with the JPEG object, but if you want to clean it up and
1028 * reuse it, call this:
1030 EXTERN(void) jpeg_abort_compress JPP((j_compress_ptr cinfo));
1031 EXTERN(void) jpeg_abort_decompress JPP((j_decompress_ptr cinfo));
1033 /* Generic versions of jpeg_abort and jpeg_destroy that work on either
1034 * flavor of JPEG object. These may be more convenient in some places.
1036 EXTERN(void) jpeg_abort JPP((j_common_ptr cinfo));
1037 EXTERN(void) jpeg_destroy JPP((j_common_ptr cinfo));
1039 /* Default restart-marker-resync procedure for use by data source modules */
1040 EXTERN(boolean) jpeg_resync_to_restart JPP((j_decompress_ptr cinfo,
1044 /* These marker codes are exported since applications and data source modules
1045 * are likely to want to use them.
1048 #define JPEG_RST0 0xD0 /* RST0 marker code */
1049 #define JPEG_EOI 0xD9 /* EOI marker code */
1050 #define JPEG_APP0 0xE0 /* APP0 marker code */
1051 #define JPEG_COM 0xFE /* COM marker code */
1054 /* If we have a brain-damaged compiler that emits warnings (or worse, errors)
1055 * for structure definitions that are never filled in, keep it quiet by
1056 * supplying dummy definitions for the various substructures.
1059 #ifdef INCOMPLETE_TYPES_BROKEN
1060 #ifndef JPEG_INTERNALS /* will be defined in jpegint.h */
1061 struct jvirt_sarray_control { long dummy; };
1062 struct jvirt_barray_control { long dummy; };
1063 struct jpeg_comp_master { long dummy; };
1064 struct jpeg_c_main_controller { long dummy; };
1065 struct jpeg_c_prep_controller { long dummy; };
1066 struct jpeg_c_coef_controller { long dummy; };
1067 struct jpeg_marker_writer { long dummy; };
1068 struct jpeg_color_converter { long dummy; };
1069 struct jpeg_downsampler { long dummy; };
1070 struct jpeg_forward_dct { long dummy; };
1071 struct jpeg_entropy_encoder { long dummy; };
1072 struct jpeg_decomp_master { long dummy; };
1073 struct jpeg_d_main_controller { long dummy; };
1074 struct jpeg_d_coef_controller { long dummy; };
1075 struct jpeg_d_post_controller { long dummy; };
1076 struct jpeg_input_controller { long dummy; };
1077 struct jpeg_marker_reader { long dummy; };
1078 struct jpeg_entropy_decoder { long dummy; };
1079 struct jpeg_inverse_dct { long dummy; };
1080 struct jpeg_upsampler { long dummy; };
1081 struct jpeg_color_deconverter { long dummy; };
1082 struct jpeg_color_quantizer { long dummy; };
1083 #endif /* JPEG_INTERNALS */
1084 #endif /* INCOMPLETE_TYPES_BROKEN */
1088 * The JPEG library modules define JPEG_INTERNALS before including this file.
1089 * The internal structure declarations are read only when that is true.
1090 * Applications using the library should not include jpegint.h, but may wish
1091 * to include jerror.h.
1098 #ifdef JPEG_INTERNALS
1099 #include "jpegint.h" /* fetch private declarations */
1100 #include "jerror.h" /* fetch error codes too */
1103 #endif /* JPEGLIB_H */