/[pcsx2_0.9.7]/trunk/3rdparty/libjpeg/jcprepct.c
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Contents of /trunk/3rdparty/libjpeg/jcprepct.c

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Revision 31 - (show annotations) (download)
Tue Sep 7 03:24:11 2010 UTC (9 years, 11 months ago) by william
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committing r3113 initial commit again...
1 /*
2 * jcprepct.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 compression preprocessing controller.
9 * This controller manages the color conversion, downsampling,
10 * and edge expansion steps.
11 *
12 * Most of the complexity here is associated with buffering input rows
13 * as required by the downsampler. See the comments at the head of
14 * jcsample.c for the downsampler's needs.
15 */
16
17 #define JPEG_INTERNALS
18 #include "jinclude.h"
19 #include "jpeglib.h"
20
21
22 /* At present, jcsample.c can request context rows only for smoothing.
23 * In the future, we might also need context rows for CCIR601 sampling
24 * or other more-complex downsampling procedures. The code to support
25 * context rows should be compiled only if needed.
26 */
27 #ifdef INPUT_SMOOTHING_SUPPORTED
28 #define CONTEXT_ROWS_SUPPORTED
29 #endif
30
31
32 /*
33 * For the simple (no-context-row) case, we just need to buffer one
34 * row group's worth of pixels for the downsampling step. At the bottom of
35 * the image, we pad to a full row group by replicating the last pixel row.
36 * The downsampler's last output row is then replicated if needed to pad
37 * out to a full iMCU row.
38 *
39 * When providing context rows, we must buffer three row groups' worth of
40 * pixels. Three row groups are physically allocated, but the row pointer
41 * arrays are made five row groups high, with the extra pointers above and
42 * below "wrapping around" to point to the last and first real row groups.
43 * This allows the downsampler to access the proper context rows.
44 * At the top and bottom of the image, we create dummy context rows by
45 * copying the first or last real pixel row. This copying could be avoided
46 * by pointer hacking as is done in jdmainct.c, but it doesn't seem worth the
47 * trouble on the compression side.
48 */
49
50
51 /* Private buffer controller object */
52
53 typedef struct {
54 struct jpeg_c_prep_controller pub; /* public fields */
55
56 /* Downsampling input buffer. This buffer holds color-converted data
57 * until we have enough to do a downsample step.
58 */
59 JSAMPARRAY color_buf[MAX_COMPONENTS];
60
61 JDIMENSION rows_to_go; /* counts rows remaining in source image */
62 int next_buf_row; /* index of next row to store in color_buf */
63
64 #ifdef CONTEXT_ROWS_SUPPORTED /* only needed for context case */
65 int this_row_group; /* starting row index of group to process */
66 int next_buf_stop; /* downsample when we reach this index */
67 #endif
68 } my_prep_controller;
69
70 typedef my_prep_controller * my_prep_ptr;
71
72
73 /*
74 * Initialize for a processing pass.
75 */
76
77 METHODDEF(void)
78 start_pass_prep (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
79 {
80 my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
81
82 if (pass_mode != JBUF_PASS_THRU)
83 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
84
85 /* Initialize total-height counter for detecting bottom of image */
86 prep->rows_to_go = cinfo->image_height;
87 /* Mark the conversion buffer empty */
88 prep->next_buf_row = 0;
89 #ifdef CONTEXT_ROWS_SUPPORTED
90 /* Preset additional state variables for context mode.
91 * These aren't used in non-context mode, so we needn't test which mode.
92 */
93 prep->this_row_group = 0;
94 /* Set next_buf_stop to stop after two row groups have been read in. */
95 prep->next_buf_stop = 2 * cinfo->max_v_samp_factor;
96 #endif
97 }
98
99
100 /*
101 * Expand an image vertically from height input_rows to height output_rows,
102 * by duplicating the bottom row.
103 */
104
105 LOCAL(void)
106 expand_bottom_edge (JSAMPARRAY image_data, JDIMENSION num_cols,
107 int input_rows, int output_rows)
108 {
109 register int row;
110
111 for (row = input_rows; row < output_rows; row++) {
112 jcopy_sample_rows(image_data, input_rows-1, image_data, row,
113 1, num_cols);
114 }
115 }
116
117
118 /*
119 * Process some data in the simple no-context case.
120 *
121 * Preprocessor output data is counted in "row groups". A row group
122 * is defined to be v_samp_factor sample rows of each component.
123 * Downsampling will produce this much data from each max_v_samp_factor
124 * input rows.
125 */
126
127 METHODDEF(void)
128 pre_process_data (j_compress_ptr cinfo,
129 JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
130 JDIMENSION in_rows_avail,
131 JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr,
132 JDIMENSION out_row_groups_avail)
133 {
134 my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
135 int numrows, ci;
136 JDIMENSION inrows;
137 jpeg_component_info * compptr;
138
139 while (*in_row_ctr < in_rows_avail &&
140 *out_row_group_ctr < out_row_groups_avail) {
141 /* Do color conversion to fill the conversion buffer. */
142 inrows = in_rows_avail - *in_row_ctr;
143 numrows = cinfo->max_v_samp_factor - prep->next_buf_row;
144 numrows = (int) MIN((JDIMENSION) numrows, inrows);
145 (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr,
146 prep->color_buf,
147 (JDIMENSION) prep->next_buf_row,
148 numrows);
149 *in_row_ctr += numrows;
150 prep->next_buf_row += numrows;
151 prep->rows_to_go -= numrows;
152 /* If at bottom of image, pad to fill the conversion buffer. */
153 if (prep->rows_to_go == 0 &&
154 prep->next_buf_row < cinfo->max_v_samp_factor) {
155 for (ci = 0; ci < cinfo->num_components; ci++) {
156 expand_bottom_edge(prep->color_buf[ci], cinfo->image_width,
157 prep->next_buf_row, cinfo->max_v_samp_factor);
158 }
159 prep->next_buf_row = cinfo->max_v_samp_factor;
160 }
161 /* If we've filled the conversion buffer, empty it. */
162 if (prep->next_buf_row == cinfo->max_v_samp_factor) {
163 (*cinfo->downsample->downsample) (cinfo,
164 prep->color_buf, (JDIMENSION) 0,
165 output_buf, *out_row_group_ctr);
166 prep->next_buf_row = 0;
167 (*out_row_group_ctr)++;
168 }
169 /* If at bottom of image, pad the output to a full iMCU height.
170 * Note we assume the caller is providing a one-iMCU-height output buffer!
171 */
172 if (prep->rows_to_go == 0 &&
173 *out_row_group_ctr < out_row_groups_avail) {
174 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
175 ci++, compptr++) {
176 numrows = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) /
177 cinfo->min_DCT_v_scaled_size;
178 expand_bottom_edge(output_buf[ci],
179 compptr->width_in_blocks * compptr->DCT_h_scaled_size,
180 (int) (*out_row_group_ctr * numrows),
181 (int) (out_row_groups_avail * numrows));
182 }
183 *out_row_group_ctr = out_row_groups_avail;
184 break; /* can exit outer loop without test */
185 }
186 }
187 }
188
189
190 #ifdef CONTEXT_ROWS_SUPPORTED
191
192 /*
193 * Process some data in the context case.
194 */
195
196 METHODDEF(void)
197 pre_process_context (j_compress_ptr cinfo,
198 JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
199 JDIMENSION in_rows_avail,
200 JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr,
201 JDIMENSION out_row_groups_avail)
202 {
203 my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
204 int numrows, ci;
205 int buf_height = cinfo->max_v_samp_factor * 3;
206 JDIMENSION inrows;
207
208 while (*out_row_group_ctr < out_row_groups_avail) {
209 if (*in_row_ctr < in_rows_avail) {
210 /* Do color conversion to fill the conversion buffer. */
211 inrows = in_rows_avail - *in_row_ctr;
212 numrows = prep->next_buf_stop - prep->next_buf_row;
213 numrows = (int) MIN((JDIMENSION) numrows, inrows);
214 (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr,
215 prep->color_buf,
216 (JDIMENSION) prep->next_buf_row,
217 numrows);
218 /* Pad at top of image, if first time through */
219 if (prep->rows_to_go == cinfo->image_height) {
220 for (ci = 0; ci < cinfo->num_components; ci++) {
221 int row;
222 for (row = 1; row <= cinfo->max_v_samp_factor; row++) {
223 jcopy_sample_rows(prep->color_buf[ci], 0,
224 prep->color_buf[ci], -row,
225 1, cinfo->image_width);
226 }
227 }
228 }
229 *in_row_ctr += numrows;
230 prep->next_buf_row += numrows;
231 prep->rows_to_go -= numrows;
232 } else {
233 /* Return for more data, unless we are at the bottom of the image. */
234 if (prep->rows_to_go != 0)
235 break;
236 /* When at bottom of image, pad to fill the conversion buffer. */
237 if (prep->next_buf_row < prep->next_buf_stop) {
238 for (ci = 0; ci < cinfo->num_components; ci++) {
239 expand_bottom_edge(prep->color_buf[ci], cinfo->image_width,
240 prep->next_buf_row, prep->next_buf_stop);
241 }
242 prep->next_buf_row = prep->next_buf_stop;
243 }
244 }
245 /* If we've gotten enough data, downsample a row group. */
246 if (prep->next_buf_row == prep->next_buf_stop) {
247 (*cinfo->downsample->downsample) (cinfo,
248 prep->color_buf,
249 (JDIMENSION) prep->this_row_group,
250 output_buf, *out_row_group_ctr);
251 (*out_row_group_ctr)++;
252 /* Advance pointers with wraparound as necessary. */
253 prep->this_row_group += cinfo->max_v_samp_factor;
254 if (prep->this_row_group >= buf_height)
255 prep->this_row_group = 0;
256 if (prep->next_buf_row >= buf_height)
257 prep->next_buf_row = 0;
258 prep->next_buf_stop = prep->next_buf_row + cinfo->max_v_samp_factor;
259 }
260 }
261 }
262
263
264 /*
265 * Create the wrapped-around downsampling input buffer needed for context mode.
266 */
267
268 LOCAL(void)
269 create_context_buffer (j_compress_ptr cinfo)
270 {
271 my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
272 int rgroup_height = cinfo->max_v_samp_factor;
273 int ci, i;
274 jpeg_component_info * compptr;
275 JSAMPARRAY true_buffer, fake_buffer;
276
277 /* Grab enough space for fake row pointers for all the components;
278 * we need five row groups' worth of pointers for each component.
279 */
280 fake_buffer = (JSAMPARRAY)
281 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
282 (cinfo->num_components * 5 * rgroup_height) *
283 SIZEOF(JSAMPROW));
284
285 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
286 ci++, compptr++) {
287 /* Allocate the actual buffer space (3 row groups) for this component.
288 * We make the buffer wide enough to allow the downsampler to edge-expand
289 * horizontally within the buffer, if it so chooses.
290 */
291 true_buffer = (*cinfo->mem->alloc_sarray)
292 ((j_common_ptr) cinfo, JPOOL_IMAGE,
293 (JDIMENSION) (((long) compptr->width_in_blocks *
294 cinfo->min_DCT_h_scaled_size *
295 cinfo->max_h_samp_factor) / compptr->h_samp_factor),
296 (JDIMENSION) (3 * rgroup_height));
297 /* Copy true buffer row pointers into the middle of the fake row array */
298 MEMCOPY(fake_buffer + rgroup_height, true_buffer,
299 3 * rgroup_height * SIZEOF(JSAMPROW));
300 /* Fill in the above and below wraparound pointers */
301 for (i = 0; i < rgroup_height; i++) {
302 fake_buffer[i] = true_buffer[2 * rgroup_height + i];
303 fake_buffer[4 * rgroup_height + i] = true_buffer[i];
304 }
305 prep->color_buf[ci] = fake_buffer + rgroup_height;
306 fake_buffer += 5 * rgroup_height; /* point to space for next component */
307 }
308 }
309
310 #endif /* CONTEXT_ROWS_SUPPORTED */
311
312
313 /*
314 * Initialize preprocessing controller.
315 */
316
317 GLOBAL(void)
318 jinit_c_prep_controller (j_compress_ptr cinfo, boolean need_full_buffer)
319 {
320 my_prep_ptr prep;
321 int ci;
322 jpeg_component_info * compptr;
323
324 if (need_full_buffer) /* safety check */
325 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
326
327 prep = (my_prep_ptr)
328 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
329 SIZEOF(my_prep_controller));
330 cinfo->prep = (struct jpeg_c_prep_controller *) prep;
331 prep->pub.start_pass = start_pass_prep;
332
333 /* Allocate the color conversion buffer.
334 * We make the buffer wide enough to allow the downsampler to edge-expand
335 * horizontally within the buffer, if it so chooses.
336 */
337 if (cinfo->downsample->need_context_rows) {
338 /* Set up to provide context rows */
339 #ifdef CONTEXT_ROWS_SUPPORTED
340 prep->pub.pre_process_data = pre_process_context;
341 create_context_buffer(cinfo);
342 #else
343 ERREXIT(cinfo, JERR_NOT_COMPILED);
344 #endif
345 } else {
346 /* No context, just make it tall enough for one row group */
347 prep->pub.pre_process_data = pre_process_data;
348 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
349 ci++, compptr++) {
350 prep->color_buf[ci] = (*cinfo->mem->alloc_sarray)
351 ((j_common_ptr) cinfo, JPOOL_IMAGE,
352 (JDIMENSION) (((long) compptr->width_in_blocks *
353 cinfo->min_DCT_h_scaled_size *
354 cinfo->max_h_samp_factor) / compptr->h_samp_factor),
355 (JDIMENSION) cinfo->max_v_samp_factor);
356 }
357 }
358 }

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