Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * jdpostct.c |
| 3 | * |
| 4 | * Copyright (C) 1994, 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 | |
| 26 | typedef 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 | |
| 42 | typedef my_post_controller * my_post_ptr; |
| 43 | |
| 44 | |
| 45 | /* Forward declarations */ |
| 46 | METHODDEF 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 |
| 53 | METHODDEF 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)); |
| 59 | METHODDEF 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 | |
| 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 | } else { |
| 83 | /* For single-pass processing without color quantization, |
| 84 | * I have no work to do; just call the upsampler directly. |
| 85 | */ |
| 86 | post->pub.post_process_data = cinfo->upsample->upsample; |
| 87 | } |
| 88 | break; |
| 89 | #ifdef QUANT_2PASS_SUPPORTED |
| 90 | case JBUF_SAVE_AND_PASS: |
| 91 | /* First pass of 2-pass quantization */ |
| 92 | if (post->whole_image == NULL) |
| 93 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| 94 | post->pub.post_process_data = post_process_prepass; |
| 95 | break; |
| 96 | case JBUF_CRANK_DEST: |
| 97 | /* Second pass of 2-pass quantization */ |
| 98 | if (post->whole_image == NULL) |
| 99 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| 100 | post->pub.post_process_data = post_process_2pass; |
| 101 | break; |
| 102 | #endif /* QUANT_2PASS_SUPPORTED */ |
| 103 | default: |
| 104 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| 105 | break; |
| 106 | } |
| 107 | post->starting_row = post->next_row = 0; |
| 108 | } |
| 109 | |
| 110 | |
| 111 | /* |
| 112 | * Process some data in the one-pass (strip buffer) case. |
| 113 | * This is used for color precision reduction as well as one-pass quantization. |
| 114 | */ |
| 115 | |
| 116 | METHODDEF void |
| 117 | post_process_1pass (j_decompress_ptr cinfo, |
| 118 | JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, |
| 119 | JDIMENSION in_row_groups_avail, |
| 120 | JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
| 121 | JDIMENSION out_rows_avail) |
| 122 | { |
| 123 | my_post_ptr post = (my_post_ptr) cinfo->post; |
| 124 | JDIMENSION num_rows, max_rows; |
| 125 | |
| 126 | /* Fill the buffer, but not more than what we can dump out in one go. */ |
| 127 | /* Note we rely on the upsampler to detect bottom of image. */ |
| 128 | max_rows = out_rows_avail - *out_row_ctr; |
| 129 | if (max_rows > post->strip_height) |
| 130 | max_rows = post->strip_height; |
| 131 | num_rows = 0; |
| 132 | (*cinfo->upsample->upsample) (cinfo, |
| 133 | input_buf, in_row_group_ctr, in_row_groups_avail, |
| 134 | post->buffer, &num_rows, max_rows); |
| 135 | /* Quantize and emit data. */ |
| 136 | (*cinfo->cquantize->color_quantize) (cinfo, |
| 137 | post->buffer, output_buf + *out_row_ctr, (int) num_rows); |
| 138 | *out_row_ctr += num_rows; |
| 139 | } |
| 140 | |
| 141 | |
| 142 | #ifdef QUANT_2PASS_SUPPORTED |
| 143 | |
| 144 | /* |
| 145 | * Process some data in the first pass of 2-pass quantization. |
| 146 | */ |
| 147 | |
| 148 | METHODDEF void |
| 149 | post_process_prepass (j_decompress_ptr cinfo, |
| 150 | JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, |
| 151 | JDIMENSION in_row_groups_avail, |
| 152 | JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
| 153 | JDIMENSION out_rows_avail) |
| 154 | { |
| 155 | my_post_ptr post = (my_post_ptr) cinfo->post; |
| 156 | JDIMENSION old_next_row, num_rows; |
| 157 | |
| 158 | /* Reposition virtual buffer if at start of strip. */ |
| 159 | if (post->next_row == 0) { |
| 160 | post->buffer = (*cinfo->mem->access_virt_sarray) |
| 161 | ((j_common_ptr) cinfo, post->whole_image, post->starting_row, TRUE); |
| 162 | } |
| 163 | |
| 164 | /* Upsample some data (up to a strip height's worth). */ |
| 165 | old_next_row = post->next_row; |
| 166 | (*cinfo->upsample->upsample) (cinfo, |
| 167 | input_buf, in_row_group_ctr, in_row_groups_avail, |
| 168 | post->buffer, &post->next_row, post->strip_height); |
| 169 | |
| 170 | /* Allow quantizer to scan new data. No data is emitted, */ |
| 171 | /* but we advance out_row_ctr so outer loop can tell when we're done. */ |
| 172 | if (post->next_row > old_next_row) { |
| 173 | num_rows = post->next_row - old_next_row; |
| 174 | (*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row, |
| 175 | (JSAMPARRAY) NULL, (int) num_rows); |
| 176 | *out_row_ctr += num_rows; |
| 177 | } |
| 178 | |
| 179 | /* Advance if we filled the strip. */ |
| 180 | if (post->next_row >= post->strip_height) { |
| 181 | post->starting_row += post->strip_height; |
| 182 | post->next_row = 0; |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | |
| 187 | /* |
| 188 | * Process some data in the second pass of 2-pass quantization. |
| 189 | */ |
| 190 | |
| 191 | METHODDEF void |
| 192 | post_process_2pass (j_decompress_ptr cinfo, |
| 193 | JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, |
| 194 | JDIMENSION in_row_groups_avail, |
| 195 | JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
| 196 | JDIMENSION out_rows_avail) |
| 197 | { |
| 198 | my_post_ptr post = (my_post_ptr) cinfo->post; |
| 199 | JDIMENSION num_rows, max_rows; |
| 200 | |
| 201 | /* Reposition virtual buffer if at start of strip. */ |
| 202 | if (post->next_row == 0) { |
| 203 | post->buffer = (*cinfo->mem->access_virt_sarray) |
| 204 | ((j_common_ptr) cinfo, post->whole_image, post->starting_row, FALSE); |
| 205 | } |
| 206 | |
| 207 | /* Determine number of rows to emit. */ |
| 208 | num_rows = post->strip_height - post->next_row; /* available in strip */ |
| 209 | max_rows = out_rows_avail - *out_row_ctr; /* available in output area */ |
| 210 | if (num_rows > max_rows) |
| 211 | num_rows = max_rows; |
| 212 | /* We have to check bottom of image here, can't depend on upsampler. */ |
| 213 | max_rows = cinfo->output_height - post->starting_row; |
| 214 | if (num_rows > max_rows) |
| 215 | num_rows = max_rows; |
| 216 | |
| 217 | /* Quantize and emit data. */ |
| 218 | (*cinfo->cquantize->color_quantize) (cinfo, |
| 219 | post->buffer + post->next_row, output_buf + *out_row_ctr, |
| 220 | (int) num_rows); |
| 221 | *out_row_ctr += num_rows; |
| 222 | |
| 223 | /* Advance if we filled the strip. */ |
| 224 | post->next_row += num_rows; |
| 225 | if (post->next_row >= post->strip_height) { |
| 226 | post->starting_row += post->strip_height; |
| 227 | post->next_row = 0; |
| 228 | } |
| 229 | } |
| 230 | |
| 231 | #endif /* QUANT_2PASS_SUPPORTED */ |
| 232 | |
| 233 | |
| 234 | /* |
| 235 | * Initialize postprocessing controller. |
| 236 | */ |
| 237 | |
| 238 | GLOBAL void |
| 239 | jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer) |
| 240 | { |
| 241 | my_post_ptr post; |
| 242 | |
| 243 | post = (my_post_ptr) |
| 244 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 245 | SIZEOF(my_post_controller)); |
| 246 | cinfo->post = (struct jpeg_d_post_controller *) post; |
| 247 | post->pub.start_pass = start_pass_dpost; |
| 248 | post->whole_image = NULL; /* flag for no virtual arrays */ |
| 249 | |
| 250 | /* Create the quantization buffer, if needed */ |
| 251 | if (cinfo->quantize_colors) { |
| 252 | /* The buffer strip height is max_v_samp_factor, which is typically |
| 253 | * an efficient number of rows for upsampling to return. |
| 254 | * (In the presence of output rescaling, we might want to be smarter?) |
| 255 | */ |
| 256 | post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor; |
| 257 | if (need_full_buffer) { |
| 258 | /* Two-pass color quantization: need full-image storage. */ |
| 259 | #ifdef QUANT_2PASS_SUPPORTED |
| 260 | post->whole_image = (*cinfo->mem->request_virt_sarray) |
| 261 | ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 262 | cinfo->output_width * cinfo->out_color_components, |
| 263 | cinfo->output_height, post->strip_height); |
| 264 | #else |
| 265 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| 266 | #endif /* QUANT_2PASS_SUPPORTED */ |
| 267 | } else { |
| 268 | /* One-pass color quantization: just make a strip buffer. */ |
| 269 | post->buffer = (*cinfo->mem->alloc_sarray) |
| 270 | ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 271 | cinfo->output_width * cinfo->out_color_components, |
| 272 | post->strip_height); |
| 273 | } |
| 274 | } |
| 275 | } |