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/src/FreeImage/Source/LibJPEG/jdpostct.c

https://bitbucket.org/cabalistic/ogredeps/
C | 290 lines | 181 code | 37 blank | 72 comment | 22 complexity | 73bad6582af500b1b146ac08e0d23844 MD5 | raw file
  1/*
  2 * jdpostct.c
  3 *
  4 * Copyright (C) 1994-1996, 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 decompression postprocessing controller.
  9 * This controller manages the upsampling, color conversion, and color
 10 * quantization/reduction steps; specifically, it controls the buffering
 11 * between upsample/color conversion and color quantization/reduction.
 12 *
 13 * If no color quantization/reduction is required, then this module has no
 14 * work to do, and it just hands off to the upsample/color conversion code.
 15 * An integrated upsample/convert/quantize process would replace this module
 16 * entirely.
 17 */
 18
 19#define JPEG_INTERNALS
 20#include "jinclude.h"
 21#include "jpeglib.h"
 22
 23
 24/* Private buffer controller object */
 25
 26typedef struct {
 27  struct jpeg_d_post_controller pub; /* public fields */
 28
 29  /* Color quantization source buffer: this holds output data from
 30   * the upsample/color conversion step to be passed to the quantizer.
 31   * For two-pass color quantization, we need a full-image buffer;
 32   * for one-pass operation, a strip buffer is sufficient.
 33   */
 34  jvirt_sarray_ptr whole_image;	/* virtual array, or NULL if one-pass */
 35  JSAMPARRAY buffer;		/* strip buffer, or current strip of virtual */
 36  JDIMENSION strip_height;	/* buffer size in rows */
 37  /* for two-pass mode only: */
 38  JDIMENSION starting_row;	/* row # of first row in current strip */
 39  JDIMENSION next_row;		/* index of next row to fill/empty in strip */
 40} my_post_controller;
 41
 42typedef my_post_controller * my_post_ptr;
 43
 44
 45/* Forward declarations */
 46METHODDEF(void) post_process_1pass
 47	JPP((j_decompress_ptr cinfo,
 48	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 49	     JDIMENSION in_row_groups_avail,
 50	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 51	     JDIMENSION out_rows_avail));
 52#ifdef QUANT_2PASS_SUPPORTED
 53METHODDEF(void) post_process_prepass
 54	JPP((j_decompress_ptr cinfo,
 55	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 56	     JDIMENSION in_row_groups_avail,
 57	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 58	     JDIMENSION out_rows_avail));
 59METHODDEF(void) post_process_2pass
 60	JPP((j_decompress_ptr cinfo,
 61	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 62	     JDIMENSION in_row_groups_avail,
 63	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 64	     JDIMENSION out_rows_avail));
 65#endif
 66
 67
 68/*
 69 * Initialize for a processing pass.
 70 */
 71
 72METHODDEF(void)
 73start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
 74{
 75  my_post_ptr post = (my_post_ptr) cinfo->post;
 76
 77  switch (pass_mode) {
 78  case JBUF_PASS_THRU:
 79    if (cinfo->quantize_colors) {
 80      /* Single-pass processing with color quantization. */
 81      post->pub.post_process_data = post_process_1pass;
 82      /* We could be doing buffered-image output before starting a 2-pass
 83       * color quantization; in that case, jinit_d_post_controller did not
 84       * allocate a strip buffer.  Use the virtual-array buffer as workspace.
 85       */
 86      if (post->buffer == NULL) {
 87	post->buffer = (*cinfo->mem->access_virt_sarray)
 88	  ((j_common_ptr) cinfo, post->whole_image,
 89	   (JDIMENSION) 0, post->strip_height, TRUE);
 90      }
 91    } else {
 92      /* For single-pass processing without color quantization,
 93       * I have no work to do; just call the upsampler directly.
 94       */
 95      post->pub.post_process_data = cinfo->upsample->upsample;
 96    }
 97    break;
 98#ifdef QUANT_2PASS_SUPPORTED
 99  case JBUF_SAVE_AND_PASS:
100    /* First pass of 2-pass quantization */
101    if (post->whole_image == NULL)
102      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
103    post->pub.post_process_data = post_process_prepass;
104    break;
105  case JBUF_CRANK_DEST:
106    /* Second pass of 2-pass quantization */
107    if (post->whole_image == NULL)
108      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
109    post->pub.post_process_data = post_process_2pass;
110    break;
111#endif /* QUANT_2PASS_SUPPORTED */
112  default:
113    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
114    break;
115  }
116  post->starting_row = post->next_row = 0;
117}
118
119
120/*
121 * Process some data in the one-pass (strip buffer) case.
122 * This is used for color precision reduction as well as one-pass quantization.
123 */
124
125METHODDEF(void)
126post_process_1pass (j_decompress_ptr cinfo,
127		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
128		    JDIMENSION in_row_groups_avail,
129		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
130		    JDIMENSION out_rows_avail)
131{
132  my_post_ptr post = (my_post_ptr) cinfo->post;
133  JDIMENSION num_rows, max_rows;
134
135  /* Fill the buffer, but not more than what we can dump out in one go. */
136  /* Note we rely on the upsampler to detect bottom of image. */
137  max_rows = out_rows_avail - *out_row_ctr;
138  if (max_rows > post->strip_height)
139    max_rows = post->strip_height;
140  num_rows = 0;
141  (*cinfo->upsample->upsample) (cinfo,
142		input_buf, in_row_group_ctr, in_row_groups_avail,
143		post->buffer, &num_rows, max_rows);
144  /* Quantize and emit data. */
145  (*cinfo->cquantize->color_quantize) (cinfo,
146		post->buffer, output_buf + *out_row_ctr, (int) num_rows);
147  *out_row_ctr += num_rows;
148}
149
150
151#ifdef QUANT_2PASS_SUPPORTED
152
153/*
154 * Process some data in the first pass of 2-pass quantization.
155 */
156
157METHODDEF(void)
158post_process_prepass (j_decompress_ptr cinfo,
159		      JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
160		      JDIMENSION in_row_groups_avail,
161		      JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
162		      JDIMENSION out_rows_avail)
163{
164  my_post_ptr post = (my_post_ptr) cinfo->post;
165  JDIMENSION old_next_row, num_rows;
166
167  /* Reposition virtual buffer if at start of strip. */
168  if (post->next_row == 0) {
169    post->buffer = (*cinfo->mem->access_virt_sarray)
170	((j_common_ptr) cinfo, post->whole_image,
171	 post->starting_row, post->strip_height, TRUE);
172  }
173
174  /* Upsample some data (up to a strip height's worth). */
175  old_next_row = post->next_row;
176  (*cinfo->upsample->upsample) (cinfo,
177		input_buf, in_row_group_ctr, in_row_groups_avail,
178		post->buffer, &post->next_row, post->strip_height);
179
180  /* Allow quantizer to scan new data.  No data is emitted, */
181  /* but we advance out_row_ctr so outer loop can tell when we're done. */
182  if (post->next_row > old_next_row) {
183    num_rows = post->next_row - old_next_row;
184    (*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
185					 (JSAMPARRAY) NULL, (int) num_rows);
186    *out_row_ctr += num_rows;
187  }
188
189  /* Advance if we filled the strip. */
190  if (post->next_row >= post->strip_height) {
191    post->starting_row += post->strip_height;
192    post->next_row = 0;
193  }
194}
195
196
197/*
198 * Process some data in the second pass of 2-pass quantization.
199 */
200
201METHODDEF(void)
202post_process_2pass (j_decompress_ptr cinfo,
203		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
204		    JDIMENSION in_row_groups_avail,
205		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
206		    JDIMENSION out_rows_avail)
207{
208  my_post_ptr post = (my_post_ptr) cinfo->post;
209  JDIMENSION num_rows, max_rows;
210
211  /* Reposition virtual buffer if at start of strip. */
212  if (post->next_row == 0) {
213    post->buffer = (*cinfo->mem->access_virt_sarray)
214	((j_common_ptr) cinfo, post->whole_image,
215	 post->starting_row, post->strip_height, FALSE);
216  }
217
218  /* Determine number of rows to emit. */
219  num_rows = post->strip_height - post->next_row; /* available in strip */
220  max_rows = out_rows_avail - *out_row_ctr; /* available in output area */
221  if (num_rows > max_rows)
222    num_rows = max_rows;
223  /* We have to check bottom of image here, can't depend on upsampler. */
224  max_rows = cinfo->output_height - post->starting_row;
225  if (num_rows > max_rows)
226    num_rows = max_rows;
227
228  /* Quantize and emit data. */
229  (*cinfo->cquantize->color_quantize) (cinfo,
230		post->buffer + post->next_row, output_buf + *out_row_ctr,
231		(int) num_rows);
232  *out_row_ctr += num_rows;
233
234  /* Advance if we filled the strip. */
235  post->next_row += num_rows;
236  if (post->next_row >= post->strip_height) {
237    post->starting_row += post->strip_height;
238    post->next_row = 0;
239  }
240}
241
242#endif /* QUANT_2PASS_SUPPORTED */
243
244
245/*
246 * Initialize postprocessing controller.
247 */
248
249GLOBAL(void)
250jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
251{
252  my_post_ptr post;
253
254  post = (my_post_ptr)
255    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
256				SIZEOF(my_post_controller));
257  cinfo->post = (struct jpeg_d_post_controller *) post;
258  post->pub.start_pass = start_pass_dpost;
259  post->whole_image = NULL;	/* flag for no virtual arrays */
260  post->buffer = NULL;		/* flag for no strip buffer */
261
262  /* Create the quantization buffer, if needed */
263  if (cinfo->quantize_colors) {
264    /* The buffer strip height is max_v_samp_factor, which is typically
265     * an efficient number of rows for upsampling to return.
266     * (In the presence of output rescaling, we might want to be smarter?)
267     */
268    post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
269    if (need_full_buffer) {
270      /* Two-pass color quantization: need full-image storage. */
271      /* We round up the number of rows to a multiple of the strip height. */
272#ifdef QUANT_2PASS_SUPPORTED
273      post->whole_image = (*cinfo->mem->request_virt_sarray)
274	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
275	 cinfo->output_width * cinfo->out_color_components,
276	 (JDIMENSION) jround_up((long) cinfo->output_height,
277				(long) post->strip_height),
278	 post->strip_height);
279#else
280      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
281#endif /* QUANT_2PASS_SUPPORTED */
282    } else {
283      /* One-pass color quantization: just make a strip buffer. */
284      post->buffer = (*cinfo->mem->alloc_sarray)
285	((j_common_ptr) cinfo, JPOOL_IMAGE,
286	 cinfo->output_width * cinfo->out_color_components,
287	 post->strip_height);
288    }
289  }
290}