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.ijg 9 * file. 10 * 11 * This file contains the decompression postprocessing controller. 12 * This controller manages the upsampling, color conversion, and color 13 * quantization/reduction steps; specifically, it controls the buffering 14 * between upsample/color conversion and color quantization/reduction. 15 * 16 * If no color quantization/reduction is required, then this module has no 17 * work to do, and it just hands off to the upsample/color conversion code. 18 * An integrated upsample/convert/quantize process would replace this module 19 * entirely. 20 */ 21 22 #define JPEG_INTERNALS 23 #include "jinclude.h" 24 #include "jpeglib.h" 25 26 27 /* Private buffer controller object */ 28 29 typedef struct { 30 struct jpeg_d_post_controller pub; /* public fields */ 31 32 /* Color quantization source buffer: this holds output data from 33 * the upsample/color conversion step to be passed to the quantizer. 34 * For two-pass color quantization, we need a full-image buffer; 35 * for one-pass operation, a strip buffer is sufficient. 36 */ 37 jvirt_sarray_ptr whole_image; /* virtual array, or NULL if one-pass */ 38 JSAMPARRAY buffer; /* strip buffer, or current strip of virtual */ 39 JDIMENSION strip_height; /* buffer size in rows */ 40 /* for two-pass mode only: */ 41 JDIMENSION starting_row; /* row # of first row in current strip */ 42 JDIMENSION next_row; /* index of next row to fill/empty in strip */ 43 } my_post_controller; 44 45 typedef my_post_controller *my_post_ptr; 46 47 48 /* Forward declarations */ 49 METHODDEF(void) post_process_1pass 50 (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, 51 JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail, 52 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, 53 JDIMENSION out_rows_avail); 54 #ifdef QUANT_2PASS_SUPPORTED 55 METHODDEF(void) post_process_prepass 56 (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, 57 JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail, 58 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, 59 JDIMENSION out_rows_avail); 60 METHODDEF(void) post_process_2pass 61 (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, 62 JDIMENSION *in_row_group_ctr, 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 72 METHODDEF(void) 73 start_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 */ 124 125 METHODDEF(void) 126 post_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 */ 156 157 METHODDEF(void) 158 post_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 */ 200 201 METHODDEF(void) 202 post_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 */ 248 249 GLOBAL(void) 250 jinit_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 } 291
