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1 | /* |
2 | * jdpostct.c | |
3 | * | |
4 | * Copyright (C) 1994-1996, 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 | /* 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 | } |