compiler/libjpeg/main/jdpostct.c

   1 /*
   2     $Id$
   3 */
   4
   5 /*
   6  * jdpostct.c
   7  *
   8  * Copyright (C) 1994-1996, Thomas G. Lane.
   9  * This file is part of the Independent JPEG Group's software.
  10  * For conditions of distribution and use, see the accompanying README file.
  11  *
  12  * This file contains the decompression postprocessing controller.
  13  * This controller manages the upsampling, color conversion, and color
  14  * quantization/reduction steps; specifically, it controls the buffering
  15  * between upsample/color conversion and color quantization/reduction.
  16  *
  17  * If no color quantization/reduction is required, then this module has no
  18  * work to do, and it just hands off to the upsample/color conversion code.
  19  * An integrated upsample/convert/quantize process would replace this module
  20  * entirely.
  21  */
  22
  23 #define JPEG_INTERNALS
  24 #include "jinclude.h"
  25 #include "jpeglib.h"
  26
  27
  28 /* Private buffer controller object */
  29
  30 typedef struct {
  31   struct jpeg_d_post_controller pub; /* public fields */
  32
  33   /* Color quantization source buffer: this holds output data from
  34    * the upsample/color conversion step to be passed to the quantizer.
  35    * For two-pass color quantization, we need a full-image buffer;
  36    * for one-pass operation, a strip buffer is sufficient.
  37    */
  38   jvirt_sarray_ptr whole_image; /* virtual array, or NULL if one-pass */
  39   JSAMPARRAY buffer;            /* strip buffer, or current strip of virtual */
  40   JDIMENSION strip_height;      /* buffer size in rows */
  41   /* for two-pass mode only: */
  42   JDIMENSION starting_row;      /* row # of first row in current strip */
  43   JDIMENSION next_row;          /* index of next row to fill/empty in strip */
  44 } my_post_controller;
  45
  46 typedef my_post_controller * my_post_ptr;
  47
  48
  49 /* Forward declarations */
  50 METHODDEF(void) post_process_1pass
  51         JPP((j_decompress_ptr cinfo,
  52              JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
  53              JDIMENSION in_row_groups_avail,
  54              JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
  55              JDIMENSION out_rows_avail));
  56 #ifdef QUANT_2PASS_SUPPORTED
  57 METHODDEF(void) post_process_prepass
  58         JPP((j_decompress_ptr cinfo,
  59              JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
  60              JDIMENSION in_row_groups_avail,
  61              JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
  62              JDIMENSION out_rows_avail));
  63 METHODDEF(void) post_process_2pass
  64         JPP((j_decompress_ptr cinfo,
  65              JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
  66              JDIMENSION in_row_groups_avail,
  67              JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
  68              JDIMENSION out_rows_avail));
  69 #endif
  70
  71
  72 /*
  73  * Initialize for a processing pass.
  74  */
  75
  76 METHODDEF(void)
  77 start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
  78 {
  79   my_post_ptr post = (my_post_ptr) cinfo->post;
  80
  81   switch (pass_mode) {
  82   case JBUF_PASS_THRU:
  83     if (cinfo->quantize_colors) {
  84       /* Single-pass processing with color quantization. */
  85       post->pub.post_process_data = post_process_1pass;
  86       /* We could be doing buffered-image output before starting a 2-pass
  87        * color quantization; in that case, jinit_d_post_controller did not
  88        * allocate a strip buffer.  Use the virtual-array buffer as workspace.
  89        */
  90       if (post->buffer == NULL) {
  91         post->buffer = (*cinfo->mem->access_virt_sarray)
  92           ((j_common_ptr) cinfo, post->whole_image,
  93            (JDIMENSION) 0, post->strip_height, TRUE);
  94       }
  95     } else {
  96       /* For single-pass processing without color quantization,
  97        * I have no work to do; just call the upsampler directly.
  98        */
  99       post->pub.post_process_data = cinfo->upsample->upsample;
 100     }
 101     break;
 102 #ifdef QUANT_2PASS_SUPPORTED
 103   case JBUF_SAVE_AND_PASS:
 104     /* First pass of 2-pass quantization */
 105     if (post->whole_image == NULL)
 106       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
 107     post->pub.post_process_data = post_process_prepass;
 108     break;
 109   case JBUF_CRANK_DEST:
 110     /* Second pass of 2-pass quantization */
 111     if (post->whole_image == NULL)
 112       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
 113     post->pub.post_process_data = post_process_2pass;
 114     break;
 115 #endif /* QUANT_2PASS_SUPPORTED */
 116   default:
 117     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
 118     break;
 119   }
 120   post->starting_row = post->next_row = 0;
 121 }
 122
 123
 124 /*
 125  * Process some data in the one-pass (strip buffer) case.
 126  * This is used for color precision reduction as well as one-pass quantization.
 127  */
 128
 129 METHODDEF(void)
 130 post_process_1pass (j_decompress_ptr cinfo,
 131                     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 132                     JDIMENSION in_row_groups_avail,
 133                     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 134                     JDIMENSION out_rows_avail)
 135 {
 136   my_post_ptr post = (my_post_ptr) cinfo->post;
 137   JDIMENSION num_rows, max_rows;
 138
 139   /* Fill the buffer, but not more than what we can dump out in one go. */
 140   /* Note we rely on the upsampler to detect bottom of image. */
 141   max_rows = out_rows_avail - *out_row_ctr;
 142   if (max_rows > post->strip_height)
 143     max_rows = post->strip_height;
 144   num_rows = 0;
 145   (*cinfo->upsample->upsample) (cinfo,
 146                 input_buf, in_row_group_ctr, in_row_groups_avail,
 147                 post->buffer, &num_rows, max_rows);
 148   /* Quantize and emit data. */
 149   (*cinfo->cquantize->color_quantize) (cinfo,
 150                 post->buffer, output_buf + *out_row_ctr, (int) num_rows);
 151   *out_row_ctr += num_rows;
 152 }
 153
 154
 155 #ifdef QUANT_2PASS_SUPPORTED
 156
 157 /*
 158  * Process some data in the first pass of 2-pass quantization.
 159  */
 160
 161 METHODDEF(void)
 162 post_process_prepass (j_decompress_ptr cinfo,
 163                       JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 164                       JDIMENSION in_row_groups_avail,
 165                       JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 166                       JDIMENSION out_rows_avail)
 167 {
 168   my_post_ptr post = (my_post_ptr) cinfo->post;
 169   JDIMENSION old_next_row, num_rows;
 170
 171   /* Reposition virtual buffer if at start of strip. */
 172   if (post->next_row == 0) {
 173     post->buffer = (*cinfo->mem->access_virt_sarray)
 174         ((j_common_ptr) cinfo, post->whole_image,
 175          post->starting_row, post->strip_height, TRUE);
 176   }
 177
 178   /* Upsample some data (up to a strip height's worth). */
 179   old_next_row = post->next_row;
 180   (*cinfo->upsample->upsample) (cinfo,
 181                 input_buf, in_row_group_ctr, in_row_groups_avail,
 182                 post->buffer, &post->next_row, post->strip_height);
 183
 184   /* Allow quantizer to scan new data.  No data is emitted, */
 185   /* but we advance out_row_ctr so outer loop can tell when we're done. */
 186   if (post->next_row > old_next_row) {
 187     num_rows = post->next_row - old_next_row;
 188     (*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
 189                                          (JSAMPARRAY) NULL, (int) num_rows);
 190     *out_row_ctr += num_rows;
 191   }
 192
 193   /* Advance if we filled the strip. */
 194   if (post->next_row >= post->strip_height) {
 195     post->starting_row += post->strip_height;
 196     post->next_row = 0;
 197   }
 198 }
 199
 200
 201 /*
 202  * Process some data in the second pass of 2-pass quantization.
 203  */
 204
 205 METHODDEF(void)
 206 post_process_2pass (j_decompress_ptr cinfo,
 207                     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 208                     JDIMENSION in_row_groups_avail,
 209                     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 210                     JDIMENSION out_rows_avail)
 211 {
 212   my_post_ptr post = (my_post_ptr) cinfo->post;
 213   JDIMENSION num_rows, max_rows;
 214
 215   /* Reposition virtual buffer if at start of strip. */
 216   if (post->next_row == 0) {
 217     post->buffer = (*cinfo->mem->access_virt_sarray)
 218         ((j_common_ptr) cinfo, post->whole_image,
 219          post->starting_row, post->strip_height, FALSE);
 220   }
 221
 222   /* Determine number of rows to emit. */
 223   num_rows = post->strip_height - post->next_row; /* available in strip */
 224   max_rows = out_rows_avail - *out_row_ctr; /* available in output area */
 225   if (num_rows > max_rows)
 226     num_rows = max_rows;
 227   /* We have to check bottom of image here, can't depend on upsampler. */
 228   max_rows = cinfo->output_height - post->starting_row;
 229   if (num_rows > max_rows)
 230     num_rows = max_rows;
 231
 232   /* Quantize and emit data. */
 233   (*cinfo->cquantize->color_quantize) (cinfo,
 234                 post->buffer + post->next_row, output_buf + *out_row_ctr,
 235                 (int) num_rows);
 236   *out_row_ctr += num_rows;
 237
 238   /* Advance if we filled the strip. */
 239   post->next_row += num_rows;
 240   if (post->next_row >= post->strip_height) {
 241     post->starting_row += post->strip_height;
 242     post->next_row = 0;
 243   }
 244 }
 245
 246 #endif /* QUANT_2PASS_SUPPORTED */
 247
 248
 249 /*
 250  * Initialize postprocessing controller.
 251  */
 252
 253 JGLOBAL(void)
 254 jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
 255 {
 256   my_post_ptr post;
 257
 258   post = (my_post_ptr)
 259     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 260                                 SIZEOF(my_post_controller));
 261   cinfo->post = (struct jpeg_d_post_controller *) post;
 262   post->pub.start_pass = start_pass_dpost;
 263   post->whole_image = NULL;     /* flag for no virtual arrays */
 264   post->buffer = NULL;          /* flag for no strip buffer */
 265
 266   /* Create the quantization buffer, if needed */
 267   if (cinfo->quantize_colors) {
 268     /* The buffer strip height is max_v_samp_factor, which is typically
 269      * an efficient number of rows for upsampling to return.
 270      * (In the presence of output rescaling, we might want to be smarter?)
 271      */
 272     post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
 273     if (need_full_buffer) {
 274       /* Two-pass color quantization: need full-image storage. */
 275       /* We round up the number of rows to a multiple of the strip height. */
 276 #ifdef QUANT_2PASS_SUPPORTED
 277       post->whole_image = (*cinfo->mem->request_virt_sarray)
 278         ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
 279          cinfo->output_width * cinfo->out_color_components,
 280          (JDIMENSION) jround_up((long) cinfo->output_height,
 281                                 (long) post->strip_height),
 282          post->strip_height);
 283 #else
 284       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
 285 #endif /* QUANT_2PASS_SUPPORTED */
 286     } else {
 287       /* One-pass color quantization: just make a strip buffer. */
 288       post->buffer = (*cinfo->mem->alloc_sarray)
 289         ((j_common_ptr) cinfo, JPOOL_IMAGE,
 290          cinfo->output_width * cinfo->out_color_components,
 291          post->strip_height);
 292     }
 293   }
 294 }