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