Visualization Library 2.0.0-b5

A lightweight C++ OpenGL middleware for 2D/3D graphics

VL     Star     Watch     Fork     Issue

[Download] [Tutorials] [All Classes] [Grouped Classes]
jccoefct.c
Go to the documentation of this file.
1 /*
2  * jccoefct.c
3  *
4  * Copyright (C) 1994-1997, 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.
7  *
8  * This file contains the coefficient buffer controller for compression.
9  * This controller is the top level of the JPEG compressor proper.
10  * The coefficient buffer lies between forward-DCT and entropy encoding steps.
11  */
12 
13 #define JPEG_INTERNALS
14 #include "jinclude.h"
15 #include "jpeglib.h"
16 
17 
18 /* We use a full-image coefficient buffer when doing Huffman optimization,
19  * and also for writing multiple-scan JPEG files. In all cases, the DCT
20  * step is run during the first pass, and subsequent passes need only read
21  * the buffered coefficients.
22  */
23 #ifdef ENTROPY_OPT_SUPPORTED
24 #define FULL_COEF_BUFFER_SUPPORTED
25 #else
26 #ifdef C_MULTISCAN_FILES_SUPPORTED
27 #define FULL_COEF_BUFFER_SUPPORTED
28 #endif
29 #endif
30 
31 
32 /* Private buffer controller object */
33 
34 typedef struct {
35  struct jpeg_c_coef_controller pub; /* public fields */
36 
37  JDIMENSION iMCU_row_num; /* iMCU row # within image */
38  JDIMENSION mcu_ctr; /* counts MCUs processed in current row */
39  int MCU_vert_offset; /* counts MCU rows within iMCU row */
40  int MCU_rows_per_iMCU_row; /* number of such rows needed */
41 
42  /* For single-pass compression, it's sufficient to buffer just one MCU
43  * (although this may prove a bit slow in practice). We allocate a
44  * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each
45  * MCU constructed and sent. (On 80x86, the workspace is FAR even though
46  * it's not really very big; this is to keep the module interfaces unchanged
47  * when a large coefficient buffer is necessary.)
48  * In multi-pass modes, this array points to the current MCU's blocks
49  * within the virtual arrays.
50  */
51  JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
52 
53  /* In multi-pass modes, we need a virtual block array for each component. */
54  jvirt_barray_ptr whole_image[MAX_COMPONENTS];
55 } my_coef_controller;
56 
57 typedef my_coef_controller * my_coef_ptr;
58 
59 
60 /* Forward declarations */
62  JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
63 #ifdef FULL_COEF_BUFFER_SUPPORTED
65  JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
67  JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
68 #endif
69 
70 
71 LOCAL(void)
73 /* Reset within-iMCU-row counters for a new row */
74 {
75  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
76 
77  /* In an interleaved scan, an MCU row is the same as an iMCU row.
78  * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
79  * But at the bottom of the image, process only what's left.
80  */
81  if (cinfo->comps_in_scan > 1) {
82  coef->MCU_rows_per_iMCU_row = 1;
83  } else {
84  if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))
85  coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
86  else
87  coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
88  }
89 
90  coef->mcu_ctr = 0;
91  coef->MCU_vert_offset = 0;
92 }
93 
94 
95 /*
96  * Initialize for a processing pass.
97  */
98 
99 METHODDEF(void)
101 {
102  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
103 
104  coef->iMCU_row_num = 0;
105  start_iMCU_row(cinfo);
106 
107  switch (pass_mode) {
108  case JBUF_PASS_THRU:
109  if (coef->whole_image[0] != NULL)
110  ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
111  coef->pub.compress_data = compress_data;
112  break;
113 #ifdef FULL_COEF_BUFFER_SUPPORTED
114  case JBUF_SAVE_AND_PASS:
115  if (coef->whole_image[0] == NULL)
116  ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
117  coef->pub.compress_data = compress_first_pass;
118  break;
119  case JBUF_CRANK_DEST:
120  if (coef->whole_image[0] == NULL)
121  ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
122  coef->pub.compress_data = compress_output;
123  break;
124 #endif
125  default:
126  ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
127  break;
128  }
129 }
130 
131 
132 /*
133  * Process some data in the single-pass case.
134  * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
135  * per call, ie, v_samp_factor block rows for each component in the image.
136  * Returns TRUE if the iMCU row is completed, FALSE if suspended.
137  *
138  * NB: input_buf contains a plane for each component in image,
139  * which we index according to the component's SOF position.
140  */
141 
142 METHODDEF(boolean)
144 {
145  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
146  JDIMENSION MCU_col_num; /* index of current MCU within row */
147  JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
148  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
149  int blkn, bi, ci, yindex, yoffset, blockcnt;
150  JDIMENSION ypos, xpos;
152 
153  /* Loop to write as much as one whole iMCU row */
154  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
155  yoffset++) {
156  for (MCU_col_num = coef->mcu_ctr; MCU_col_num <= last_MCU_col;
157  MCU_col_num++) {
158  /* Determine where data comes from in input_buf and do the DCT thing.
159  * Each call on forward_DCT processes a horizontal row of DCT blocks
160  * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks
161  * sequentially. Dummy blocks at the right or bottom edge are filled in
162  * specially. The data in them does not matter for image reconstruction,
163  * so we fill them with values that will encode to the smallest amount of
164  * data, viz: all zeroes in the AC entries, DC entries equal to previous
165  * block's DC value. (Thanks to Thomas Kinsman for this idea.)
166  */
167  blkn = 0;
168  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
169  compptr = cinfo->cur_comp_info[ci];
170  blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
172  xpos = MCU_col_num * compptr->MCU_sample_width;
173  ypos = yoffset * DCTSIZE; /* ypos == (yoffset+yindex) * DCTSIZE */
174  for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
175  if (coef->iMCU_row_num < last_iMCU_row ||
176  yoffset+yindex < compptr->last_row_height) {
177  (*cinfo->fdct->forward_DCT) (cinfo, compptr,
178  input_buf[compptr->component_index],
179  coef->MCU_buffer[blkn],
180  ypos, xpos, (JDIMENSION) blockcnt);
181  if (blockcnt < compptr->MCU_width) {
182  /* Create some dummy blocks at the right edge of the image. */
183  jzero_far((void FAR *) coef->MCU_buffer[blkn + blockcnt],
184  (compptr->MCU_width - blockcnt) * SIZEOF(JBLOCK));
185  for (bi = blockcnt; bi < compptr->MCU_width; bi++) {
186  coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn+bi-1][0][0];
187  }
188  }
189  } else {
190  /* Create a row of dummy blocks at the bottom of the image. */
191  jzero_far((void FAR *) coef->MCU_buffer[blkn],
193  for (bi = 0; bi < compptr->MCU_width; bi++) {
194  coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn-1][0][0];
195  }
196  }
197  blkn += compptr->MCU_width;
198  ypos += DCTSIZE;
199  }
200  }
201  /* Try to write the MCU. In event of a suspension failure, we will
202  * re-DCT the MCU on restart (a bit inefficient, could be fixed...)
203  */
204  if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {
205  /* Suspension forced; update state counters and exit */
206  coef->MCU_vert_offset = yoffset;
207  coef->mcu_ctr = MCU_col_num;
208  return FALSE;
209  }
210  }
211  /* Completed an MCU row, but perhaps not an iMCU row */
212  coef->mcu_ctr = 0;
213  }
214  /* Completed the iMCU row, advance counters for next one */
215  coef->iMCU_row_num++;
216  start_iMCU_row(cinfo);
217  return TRUE;
218 }
219 
220 
221 #ifdef FULL_COEF_BUFFER_SUPPORTED
222 
223 /*
224  * Process some data in the first pass of a multi-pass case.
225  * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
226  * per call, ie, v_samp_factor block rows for each component in the image.
227  * This amount of data is read from the source buffer, DCT'd and quantized,
228  * and saved into the virtual arrays. We also generate suitable dummy blocks
229  * as needed at the right and lower edges. (The dummy blocks are constructed
230  * in the virtual arrays, which have been padded appropriately.) This makes
231  * it possible for subsequent passes not to worry about real vs. dummy blocks.
232  *
233  * We must also emit the data to the entropy encoder. This is conveniently
234  * done by calling compress_output() after we've loaded the current strip
235  * of the virtual arrays.
236  *
237  * NB: input_buf contains a plane for each component in image. All
238  * components are DCT'd and loaded into the virtual arrays in this pass.
239  * However, it may be that only a subset of the components are emitted to
240  * the entropy encoder during this first pass; be careful about looking
241  * at the scan-dependent variables (MCU dimensions, etc).
242  */
243 
244 METHODDEF(boolean)
246 {
247  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
248  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
249  JDIMENSION blocks_across, MCUs_across, MCUindex;
250  int bi, ci, h_samp_factor, block_row, block_rows, ndummy;
251  JCOEF lastDC;
254  JBLOCKROW thisblockrow, lastblockrow;
255 
256  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
257  ci++, compptr++) {
258  /* Align the virtual buffer for this component. */
259  buffer = (*cinfo->mem->access_virt_barray)
260  ((j_common_ptr) cinfo, coef->whole_image[ci],
261  coef->iMCU_row_num * compptr->v_samp_factor,
263  /* Count non-dummy DCT block rows in this iMCU row. */
264  if (coef->iMCU_row_num < last_iMCU_row)
265  block_rows = compptr->v_samp_factor;
266  else {
267  /* NB: can't use last_row_height here, since may not be set! */
268  block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
269  if (block_rows == 0) block_rows = compptr->v_samp_factor;
270  }
271  blocks_across = compptr->width_in_blocks;
272  h_samp_factor = compptr->h_samp_factor;
273  /* Count number of dummy blocks to be added at the right margin. */
274  ndummy = (int) (blocks_across % h_samp_factor);
275  if (ndummy > 0)
276  ndummy = h_samp_factor - ndummy;
277  /* Perform DCT for all non-dummy blocks in this iMCU row. Each call
278  * on forward_DCT processes a complete horizontal row of DCT blocks.
279  */
280  for (block_row = 0; block_row < block_rows; block_row++) {
281  thisblockrow = buffer[block_row];
282  (*cinfo->fdct->forward_DCT) (cinfo, compptr,
283  input_buf[ci], thisblockrow,
284  (JDIMENSION) (block_row * DCTSIZE),
285  (JDIMENSION) 0, blocks_across);
286  if (ndummy > 0) {
287  /* Create dummy blocks at the right edge of the image. */
288  thisblockrow += blocks_across; /* => first dummy block */
289  jzero_far((void FAR *) thisblockrow, ndummy * SIZEOF(JBLOCK));
290  lastDC = thisblockrow[-1][0];
291  for (bi = 0; bi < ndummy; bi++) {
292  thisblockrow[bi][0] = lastDC;
293  }
294  }
295  }
296  /* If at end of image, create dummy block rows as needed.
297  * The tricky part here is that within each MCU, we want the DC values
298  * of the dummy blocks to match the last real block's DC value.
299  * This squeezes a few more bytes out of the resulting file...
300  */
301  if (coef->iMCU_row_num == last_iMCU_row) {
302  blocks_across += ndummy; /* include lower right corner */
303  MCUs_across = blocks_across / h_samp_factor;
304  for (block_row = block_rows; block_row < compptr->v_samp_factor;
305  block_row++) {
306  thisblockrow = buffer[block_row];
307  lastblockrow = buffer[block_row-1];
308  jzero_far((void FAR *) thisblockrow,
309  (size_t) (blocks_across * SIZEOF(JBLOCK)));
310  for (MCUindex = 0; MCUindex < MCUs_across; MCUindex++) {
311  lastDC = lastblockrow[h_samp_factor-1][0];
312  for (bi = 0; bi < h_samp_factor; bi++) {
313  thisblockrow[bi][0] = lastDC;
314  }
315  thisblockrow += h_samp_factor; /* advance to next MCU in row */
316  lastblockrow += h_samp_factor;
317  }
318  }
319  }
320  }
321  /* NB: compress_output will increment iMCU_row_num if successful.
322  * A suspension return will result in redoing all the work above next time.
323  */
324 
325  /* Emit data to the entropy encoder, sharing code with subsequent passes */
326  return compress_output(cinfo, input_buf);
327 }
328 
329 
330 /*
331  * Process some data in subsequent passes of a multi-pass case.
332  * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
333  * per call, ie, v_samp_factor block rows for each component in the scan.
334  * The data is obtained from the virtual arrays and fed to the entropy coder.
335  * Returns TRUE if the iMCU row is completed, FALSE if suspended.
336  *
337  * NB: input_buf is ignored; it is likely to be a NULL pointer.
338  */
339 
340 METHODDEF(boolean)
342 {
343  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
344  JDIMENSION MCU_col_num; /* index of current MCU within row */
345  int blkn, ci, xindex, yindex, yoffset;
346  JDIMENSION start_col;
348  JBLOCKROW buffer_ptr;
350 
351  /* Align the virtual buffers for the components used in this scan.
352  * NB: during first pass, this is safe only because the buffers will
353  * already be aligned properly, so jmemmgr.c won't need to do any I/O.
354  */
355  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
356  compptr = cinfo->cur_comp_info[ci];
357  buffer[ci] = (*cinfo->mem->access_virt_barray)
358  ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
359  coef->iMCU_row_num * compptr->v_samp_factor,
361  }
362 
363  /* Loop to process one whole iMCU row */
364  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
365  yoffset++) {
366  for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
367  MCU_col_num++) {
368  /* Construct list of pointers to DCT blocks belonging to this MCU */
369  blkn = 0; /* index of current DCT block within MCU */
370  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
371  compptr = cinfo->cur_comp_info[ci];
372  start_col = MCU_col_num * compptr->MCU_width;
373  for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
374  buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
375  for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
376  coef->MCU_buffer[blkn++] = buffer_ptr++;
377  }
378  }
379  }
380  /* Try to write the MCU. */
381  if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {
382  /* Suspension forced; update state counters and exit */
383  coef->MCU_vert_offset = yoffset;
384  coef->mcu_ctr = MCU_col_num;
385  return FALSE;
386  }
387  }
388  /* Completed an MCU row, but perhaps not an iMCU row */
389  coef->mcu_ctr = 0;
390  }
391  /* Completed the iMCU row, advance counters for next one */
392  coef->iMCU_row_num++;
393  start_iMCU_row(cinfo);
394  return TRUE;
395 }
396 
397 #endif /* FULL_COEF_BUFFER_SUPPORTED */
398 
399 
400 /*
401  * Initialize coefficient buffer controller.
402  */
403 
404 GLOBAL(void)
406 {
407  my_coef_ptr coef;
408 
409  coef = (my_coef_ptr)
410  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
411  SIZEOF(my_coef_controller));
412  cinfo->coef = (struct jpeg_c_coef_controller *) coef;
413  coef->pub.start_pass = start_pass_coef;
414 
415  /* Create the coefficient buffer. */
416  if (need_full_buffer) {
417 #ifdef FULL_COEF_BUFFER_SUPPORTED
418  /* Allocate a full-image virtual array for each component, */
419  /* padded to a multiple of samp_factor DCT blocks in each direction. */
420  int ci;
422 
423  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
424  ci++, compptr++) {
425  coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
426  ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
427  (JDIMENSION) jround_up((long) compptr->width_in_blocks,
428  (long) compptr->h_samp_factor),
429  (JDIMENSION) jround_up((long) compptr->height_in_blocks,
430  (long) compptr->v_samp_factor),
431  (JDIMENSION) compptr->v_samp_factor);
432  }
433 #else
434  ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
435 #endif
436  } else {
437  /* We only need a single-MCU buffer. */
439  int i;
440 
441  buffer = (JBLOCKROW)
442  (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
444  for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
445  coef->MCU_buffer[i] = buffer + i;
446  }
447  coef->whole_image[0] = NULL; /* flag for no virtual arrays */
448  }
449 }
for(n=1;n< outline->n_points;n++)
Definition: ftbbox.c:593
#define NULL
Definition: ftobjs.h:61
struct jpeg_common_struct * j_common_ptr
Definition: jpeglib.h:261
JCOEF JBLOCK[DCTSIZE2]
Definition: jpeglib.h:70
compress_data(j_compress_ptr cinfo, JSAMPIMAGE input_buf)
Definition: jccoefct.c:143
JBLOCKROW * JBLOCKARRAY
Definition: jpeglib.h:72
#define MAX_COMPONENTS
Definition: jmorecfg.h:35
#define ERREXIT(cinfo, code)
Definition: jerror.h:205
#define SIZEOF(object)
Definition: jinclude.h:80
boolean need_full_buffer
Definition: jpegint.h:338
short JCOEF
Definition: jmorecfg.h:99
jpeg_component_info * compptr
Definition: jdct.h:102
JDIMENSION width_in_blocks
Definition: jpeglib.h:139
#define JPOOL_IMAGE
Definition: jpeglib.h:749
jround_up(long a, long b)
Definition: jutils.c:81
compress_output(j_compress_ptr cinfo, JSAMPIMAGE input_buf)
Definition: jccoefct.c:341
JDIMENSION height_in_blocks
Definition: jpeglib.h:140
compress_first_pass(j_compress_ptr cinfo, JSAMPIMAGE input_buf)
Definition: jccoefct.c:245
struct jpeg_c_coef_controller * coef
Definition: jpeglib.h:398
my_coef_controller * my_coef_ptr
Definition: jccoefct.c:57
#define LOCAL(type)
Definition: jmorecfg.h:189
JDIMENSION total_iMCU_rows
Definition: jpeglib.h:367
#define C_MAX_BLOCKS_IN_MCU
Definition: jpeglib.h:55
typedef long(ZCALLBACK *tell_file_func) OF((voidpf opaque
JBLOCK FAR * JBLOCKROW
Definition: jpeglib.h:71
GLuint buffer
GLint GLint GLint yoffset
jzero_far(void FAR *target, size_t bytestozero)
Definition: jutils.c:165
#define FAR
Definition: zconf.h:215
#define JPP(arglist)
Definition: jpeglib.h:818
JSAMPARRAY * JSAMPIMAGE
Definition: jpeglib.h:68
#define FALSE
Definition: ftobjs.h:57
METHODDEF(boolean)
Definition: jccoefct.c:61
int i[8]
Definition: jpeglib.h:662
struct jvirt_barray_control * jvirt_barray_ptr
Definition: jpeglib.h:753
if(!abbox) return FT_THROW(Invalid_Argument)
typedef int
Definition: png.h:978
#define GLOBAL(type)
Definition: jmorecfg.h:191
start_pass_coef(j_compress_ptr cinfo, J_BUF_MODE pass_mode)
Definition: jccoefct.c:100
start_iMCU_row(j_compress_ptr cinfo)
Definition: jctrans.c:227
jpeg_component_info * cur_comp_info[MAX_COMPS_IN_SCAN]
Definition: jpeglib.h:379
J_BUF_MODE
Definition: jpegint.h:16
#define DCTSIZE
Definition: jpeglib.h:41
unsigned int JDIMENSION
Definition: jmorecfg.h:174
jinit_c_coef_controller(j_compress_ptr cinfo, boolean need_full_buffer)
Definition: jccoefct.c:405
#define TRUE
Definition: ftobjs.h:53
#define MAX_COMPS_IN_SCAN
Definition: jpeglib.h:46