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annotate libs/libjpeg/jdpostct.c @ 39:ff055bff6a15

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author John Tsiombikas <nuclear@mutantstargoat.com>
date Sun, 11 Sep 2011 09:03:18 +0300
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nuclear@26 1 /*
nuclear@26 2 * jdpostct.c
nuclear@26 3 *
nuclear@26 4 * Copyright (C) 1994-1996, Thomas G. Lane.
nuclear@26 5 * This file is part of the Independent JPEG Group's software.
nuclear@26 6 * For conditions of distribution and use, see the accompanying README file.
nuclear@26 7 *
nuclear@26 8 * This file contains the decompression postprocessing controller.
nuclear@26 9 * This controller manages the upsampling, color conversion, and color
nuclear@26 10 * quantization/reduction steps; specifically, it controls the buffering
nuclear@26 11 * between upsample/color conversion and color quantization/reduction.
nuclear@26 12 *
nuclear@26 13 * If no color quantization/reduction is required, then this module has no
nuclear@26 14 * work to do, and it just hands off to the upsample/color conversion code.
nuclear@26 15 * An integrated upsample/convert/quantize process would replace this module
nuclear@26 16 * entirely.
nuclear@26 17 */
nuclear@26 18
nuclear@26 19 #define JPEG_INTERNALS
nuclear@26 20 #include "jinclude.h"
nuclear@26 21 #include "jpeglib.h"
nuclear@26 22
nuclear@26 23
nuclear@26 24 /* Private buffer controller object */
nuclear@26 25
nuclear@26 26 typedef struct {
nuclear@26 27 struct jpeg_d_post_controller pub; /* public fields */
nuclear@26 28
nuclear@26 29 /* Color quantization source buffer: this holds output data from
nuclear@26 30 * the upsample/color conversion step to be passed to the quantizer.
nuclear@26 31 * For two-pass color quantization, we need a full-image buffer;
nuclear@26 32 * for one-pass operation, a strip buffer is sufficient.
nuclear@26 33 */
nuclear@26 34 jvirt_sarray_ptr whole_image; /* virtual array, or NULL if one-pass */
nuclear@26 35 JSAMPARRAY buffer; /* strip buffer, or current strip of virtual */
nuclear@26 36 JDIMENSION strip_height; /* buffer size in rows */
nuclear@26 37 /* for two-pass mode only: */
nuclear@26 38 JDIMENSION starting_row; /* row # of first row in current strip */
nuclear@26 39 JDIMENSION next_row; /* index of next row to fill/empty in strip */
nuclear@26 40 } my_post_controller;
nuclear@26 41
nuclear@26 42 typedef my_post_controller * my_post_ptr;
nuclear@26 43
nuclear@26 44
nuclear@26 45 /* Forward declarations */
nuclear@26 46 METHODDEF(void) post_process_1pass
nuclear@26 47 JPP((j_decompress_ptr cinfo,
nuclear@26 48 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@26 49 JDIMENSION in_row_groups_avail,
nuclear@26 50 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 51 JDIMENSION out_rows_avail));
nuclear@26 52 #ifdef QUANT_2PASS_SUPPORTED
nuclear@26 53 METHODDEF(void) post_process_prepass
nuclear@26 54 JPP((j_decompress_ptr cinfo,
nuclear@26 55 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@26 56 JDIMENSION in_row_groups_avail,
nuclear@26 57 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 58 JDIMENSION out_rows_avail));
nuclear@26 59 METHODDEF(void) post_process_2pass
nuclear@26 60 JPP((j_decompress_ptr cinfo,
nuclear@26 61 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@26 62 JDIMENSION in_row_groups_avail,
nuclear@26 63 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 64 JDIMENSION out_rows_avail));
nuclear@26 65 #endif
nuclear@26 66
nuclear@26 67
nuclear@26 68 /*
nuclear@26 69 * Initialize for a processing pass.
nuclear@26 70 */
nuclear@26 71
nuclear@26 72 METHODDEF(void)
nuclear@26 73 start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
nuclear@26 74 {
nuclear@26 75 my_post_ptr post = (my_post_ptr) cinfo->post;
nuclear@26 76
nuclear@26 77 switch (pass_mode) {
nuclear@26 78 case JBUF_PASS_THRU:
nuclear@26 79 if (cinfo->quantize_colors) {
nuclear@26 80 /* Single-pass processing with color quantization. */
nuclear@26 81 post->pub.post_process_data = post_process_1pass;
nuclear@26 82 /* We could be doing buffered-image output before starting a 2-pass
nuclear@26 83 * color quantization; in that case, jinit_d_post_controller did not
nuclear@26 84 * allocate a strip buffer. Use the virtual-array buffer as workspace.
nuclear@26 85 */
nuclear@26 86 if (post->buffer == NULL) {
nuclear@26 87 post->buffer = (*cinfo->mem->access_virt_sarray)
nuclear@26 88 ((j_common_ptr) cinfo, post->whole_image,
nuclear@26 89 (JDIMENSION) 0, post->strip_height, TRUE);
nuclear@26 90 }
nuclear@26 91 } else {
nuclear@26 92 /* For single-pass processing without color quantization,
nuclear@26 93 * I have no work to do; just call the upsampler directly.
nuclear@26 94 */
nuclear@26 95 post->pub.post_process_data = cinfo->upsample->upsample;
nuclear@26 96 }
nuclear@26 97 break;
nuclear@26 98 #ifdef QUANT_2PASS_SUPPORTED
nuclear@26 99 case JBUF_SAVE_AND_PASS:
nuclear@26 100 /* First pass of 2-pass quantization */
nuclear@26 101 if (post->whole_image == NULL)
nuclear@26 102 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
nuclear@26 103 post->pub.post_process_data = post_process_prepass;
nuclear@26 104 break;
nuclear@26 105 case JBUF_CRANK_DEST:
nuclear@26 106 /* Second pass of 2-pass quantization */
nuclear@26 107 if (post->whole_image == NULL)
nuclear@26 108 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
nuclear@26 109 post->pub.post_process_data = post_process_2pass;
nuclear@26 110 break;
nuclear@26 111 #endif /* QUANT_2PASS_SUPPORTED */
nuclear@26 112 default:
nuclear@26 113 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
nuclear@26 114 break;
nuclear@26 115 }
nuclear@26 116 post->starting_row = post->next_row = 0;
nuclear@26 117 }
nuclear@26 118
nuclear@26 119
nuclear@26 120 /*
nuclear@26 121 * Process some data in the one-pass (strip buffer) case.
nuclear@26 122 * This is used for color precision reduction as well as one-pass quantization.
nuclear@26 123 */
nuclear@26 124
nuclear@26 125 METHODDEF(void)
nuclear@26 126 post_process_1pass (j_decompress_ptr cinfo,
nuclear@26 127 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@26 128 JDIMENSION in_row_groups_avail,
nuclear@26 129 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 130 JDIMENSION out_rows_avail)
nuclear@26 131 {
nuclear@26 132 my_post_ptr post = (my_post_ptr) cinfo->post;
nuclear@26 133 JDIMENSION num_rows, max_rows;
nuclear@26 134
nuclear@26 135 /* Fill the buffer, but not more than what we can dump out in one go. */
nuclear@26 136 /* Note we rely on the upsampler to detect bottom of image. */
nuclear@26 137 max_rows = out_rows_avail - *out_row_ctr;
nuclear@26 138 if (max_rows > post->strip_height)
nuclear@26 139 max_rows = post->strip_height;
nuclear@26 140 num_rows = 0;
nuclear@26 141 (*cinfo->upsample->upsample) (cinfo,
nuclear@26 142 input_buf, in_row_group_ctr, in_row_groups_avail,
nuclear@26 143 post->buffer, &num_rows, max_rows);
nuclear@26 144 /* Quantize and emit data. */
nuclear@26 145 (*cinfo->cquantize->color_quantize) (cinfo,
nuclear@26 146 post->buffer, output_buf + *out_row_ctr, (int) num_rows);
nuclear@26 147 *out_row_ctr += num_rows;
nuclear@26 148 }
nuclear@26 149
nuclear@26 150
nuclear@26 151 #ifdef QUANT_2PASS_SUPPORTED
nuclear@26 152
nuclear@26 153 /*
nuclear@26 154 * Process some data in the first pass of 2-pass quantization.
nuclear@26 155 */
nuclear@26 156
nuclear@26 157 METHODDEF(void)
nuclear@26 158 post_process_prepass (j_decompress_ptr cinfo,
nuclear@26 159 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@26 160 JDIMENSION in_row_groups_avail,
nuclear@26 161 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 162 JDIMENSION out_rows_avail)
nuclear@26 163 {
nuclear@26 164 my_post_ptr post = (my_post_ptr) cinfo->post;
nuclear@26 165 JDIMENSION old_next_row, num_rows;
nuclear@26 166
nuclear@26 167 /* Reposition virtual buffer if at start of strip. */
nuclear@26 168 if (post->next_row == 0) {
nuclear@26 169 post->buffer = (*cinfo->mem->access_virt_sarray)
nuclear@26 170 ((j_common_ptr) cinfo, post->whole_image,
nuclear@26 171 post->starting_row, post->strip_height, TRUE);
nuclear@26 172 }
nuclear@26 173
nuclear@26 174 /* Upsample some data (up to a strip height's worth). */
nuclear@26 175 old_next_row = post->next_row;
nuclear@26 176 (*cinfo->upsample->upsample) (cinfo,
nuclear@26 177 input_buf, in_row_group_ctr, in_row_groups_avail,
nuclear@26 178 post->buffer, &post->next_row, post->strip_height);
nuclear@26 179
nuclear@26 180 /* Allow quantizer to scan new data. No data is emitted, */
nuclear@26 181 /* but we advance out_row_ctr so outer loop can tell when we're done. */
nuclear@26 182 if (post->next_row > old_next_row) {
nuclear@26 183 num_rows = post->next_row - old_next_row;
nuclear@26 184 (*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
nuclear@26 185 (JSAMPARRAY) NULL, (int) num_rows);
nuclear@26 186 *out_row_ctr += num_rows;
nuclear@26 187 }
nuclear@26 188
nuclear@26 189 /* Advance if we filled the strip. */
nuclear@26 190 if (post->next_row >= post->strip_height) {
nuclear@26 191 post->starting_row += post->strip_height;
nuclear@26 192 post->next_row = 0;
nuclear@26 193 }
nuclear@26 194 }
nuclear@26 195
nuclear@26 196
nuclear@26 197 /*
nuclear@26 198 * Process some data in the second pass of 2-pass quantization.
nuclear@26 199 */
nuclear@26 200
nuclear@26 201 METHODDEF(void)
nuclear@26 202 post_process_2pass (j_decompress_ptr cinfo,
nuclear@26 203 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@26 204 JDIMENSION in_row_groups_avail,
nuclear@26 205 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 206 JDIMENSION out_rows_avail)
nuclear@26 207 {
nuclear@26 208 my_post_ptr post = (my_post_ptr) cinfo->post;
nuclear@26 209 JDIMENSION num_rows, max_rows;
nuclear@26 210
nuclear@26 211 /* Reposition virtual buffer if at start of strip. */
nuclear@26 212 if (post->next_row == 0) {
nuclear@26 213 post->buffer = (*cinfo->mem->access_virt_sarray)
nuclear@26 214 ((j_common_ptr) cinfo, post->whole_image,
nuclear@26 215 post->starting_row, post->strip_height, FALSE);
nuclear@26 216 }
nuclear@26 217
nuclear@26 218 /* Determine number of rows to emit. */
nuclear@26 219 num_rows = post->strip_height - post->next_row; /* available in strip */
nuclear@26 220 max_rows = out_rows_avail - *out_row_ctr; /* available in output area */
nuclear@26 221 if (num_rows > max_rows)
nuclear@26 222 num_rows = max_rows;
nuclear@26 223 /* We have to check bottom of image here, can't depend on upsampler. */
nuclear@26 224 max_rows = cinfo->output_height - post->starting_row;
nuclear@26 225 if (num_rows > max_rows)
nuclear@26 226 num_rows = max_rows;
nuclear@26 227
nuclear@26 228 /* Quantize and emit data. */
nuclear@26 229 (*cinfo->cquantize->color_quantize) (cinfo,
nuclear@26 230 post->buffer + post->next_row, output_buf + *out_row_ctr,
nuclear@26 231 (int) num_rows);
nuclear@26 232 *out_row_ctr += num_rows;
nuclear@26 233
nuclear@26 234 /* Advance if we filled the strip. */
nuclear@26 235 post->next_row += num_rows;
nuclear@26 236 if (post->next_row >= post->strip_height) {
nuclear@26 237 post->starting_row += post->strip_height;
nuclear@26 238 post->next_row = 0;
nuclear@26 239 }
nuclear@26 240 }
nuclear@26 241
nuclear@26 242 #endif /* QUANT_2PASS_SUPPORTED */
nuclear@26 243
nuclear@26 244
nuclear@26 245 /*
nuclear@26 246 * Initialize postprocessing controller.
nuclear@26 247 */
nuclear@26 248
nuclear@26 249 GLOBAL(void)
nuclear@26 250 jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
nuclear@26 251 {
nuclear@26 252 my_post_ptr post;
nuclear@26 253
nuclear@26 254 post = (my_post_ptr)
nuclear@26 255 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26 256 SIZEOF(my_post_controller));
nuclear@26 257 cinfo->post = (struct jpeg_d_post_controller *) post;
nuclear@26 258 post->pub.start_pass = start_pass_dpost;
nuclear@26 259 post->whole_image = NULL; /* flag for no virtual arrays */
nuclear@26 260 post->buffer = NULL; /* flag for no strip buffer */
nuclear@26 261
nuclear@26 262 /* Create the quantization buffer, if needed */
nuclear@26 263 if (cinfo->quantize_colors) {
nuclear@26 264 /* The buffer strip height is max_v_samp_factor, which is typically
nuclear@26 265 * an efficient number of rows for upsampling to return.
nuclear@26 266 * (In the presence of output rescaling, we might want to be smarter?)
nuclear@26 267 */
nuclear@26 268 post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
nuclear@26 269 if (need_full_buffer) {
nuclear@26 270 /* Two-pass color quantization: need full-image storage. */
nuclear@26 271 /* We round up the number of rows to a multiple of the strip height. */
nuclear@26 272 #ifdef QUANT_2PASS_SUPPORTED
nuclear@26 273 post->whole_image = (*cinfo->mem->request_virt_sarray)
nuclear@26 274 ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
nuclear@26 275 cinfo->output_width * cinfo->out_color_components,
nuclear@26 276 (JDIMENSION) jround_up((long) cinfo->output_height,
nuclear@26 277 (long) post->strip_height),
nuclear@26 278 post->strip_height);
nuclear@26 279 #else
nuclear@26 280 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
nuclear@26 281 #endif /* QUANT_2PASS_SUPPORTED */
nuclear@26 282 } else {
nuclear@26 283 /* One-pass color quantization: just make a strip buffer. */
nuclear@26 284 post->buffer = (*cinfo->mem->alloc_sarray)
nuclear@26 285 ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26 286 cinfo->output_width * cinfo->out_color_components,
nuclear@26 287 post->strip_height);
nuclear@26 288 }
nuclear@26 289 }
nuclear@26 290 }