Line data Source code
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 0 : start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
74 : {
75 0 : my_post_ptr post = (my_post_ptr) cinfo->post;
76 :
77 0 : switch (pass_mode) {
78 : case JBUF_PASS_THRU:
79 0 : if (cinfo->quantize_colors) {
80 : /* Single-pass processing with color quantization. */
81 0 : 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 0 : if (post->buffer == NULL) {
87 0 : 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 0 : post->pub.post_process_data = cinfo->upsample->upsample;
96 : }
97 0 : break;
98 : #ifdef QUANT_2PASS_SUPPORTED
99 : case JBUF_SAVE_AND_PASS:
100 : /* First pass of 2-pass quantization */
101 0 : if (post->whole_image == NULL)
102 0 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
103 0 : post->pub.post_process_data = post_process_prepass;
104 0 : break;
105 : case JBUF_CRANK_DEST:
106 : /* Second pass of 2-pass quantization */
107 0 : if (post->whole_image == NULL)
108 0 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
109 0 : post->pub.post_process_data = post_process_2pass;
110 0 : break;
111 : #endif /* QUANT_2PASS_SUPPORTED */
112 : default:
113 0 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
114 0 : break;
115 : }
116 0 : post->starting_row = post->next_row = 0;
117 0 : }
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 0 : 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 0 : 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 0 : max_rows = out_rows_avail - *out_row_ctr;
138 0 : if (max_rows > post->strip_height)
139 0 : max_rows = post->strip_height;
140 0 : num_rows = 0;
141 0 : (*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 0 : (*cinfo->cquantize->color_quantize) (cinfo,
146 0 : post->buffer, output_buf + *out_row_ctr, (int) num_rows);
147 0 : *out_row_ctr += num_rows;
148 0 : }
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 0 : 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 0 : 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 0 : if (post->next_row == 0) {
169 0 : 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 0 : old_next_row = post->next_row;
176 0 : (*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 0 : if (post->next_row > old_next_row) {
183 0 : num_rows = post->next_row - old_next_row;
184 0 : (*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
185 : (JSAMPARRAY) NULL, (int) num_rows);
186 0 : *out_row_ctr += num_rows;
187 : }
188 :
189 : /* Advance if we filled the strip. */
190 0 : if (post->next_row >= post->strip_height) {
191 0 : post->starting_row += post->strip_height;
192 0 : post->next_row = 0;
193 : }
194 0 : }
195 :
196 :
197 : /*
198 : * Process some data in the second pass of 2-pass quantization.
199 : */
200 :
201 : METHODDEF(void)
202 0 : 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 0 : 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 0 : if (post->next_row == 0) {
213 0 : 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 0 : num_rows = post->strip_height - post->next_row; /* available in strip */
220 0 : max_rows = out_rows_avail - *out_row_ctr; /* available in output area */
221 0 : if (num_rows > max_rows)
222 0 : num_rows = max_rows;
223 : /* We have to check bottom of image here, can't depend on upsampler. */
224 0 : max_rows = cinfo->output_height - post->starting_row;
225 0 : if (num_rows > max_rows)
226 0 : num_rows = max_rows;
227 :
228 : /* Quantize and emit data. */
229 0 : (*cinfo->cquantize->color_quantize) (cinfo,
230 0 : post->buffer + post->next_row, output_buf + *out_row_ctr,
231 : (int) num_rows);
232 0 : *out_row_ctr += num_rows;
233 :
234 : /* Advance if we filled the strip. */
235 0 : post->next_row += num_rows;
236 0 : if (post->next_row >= post->strip_height) {
237 0 : post->starting_row += post->strip_height;
238 0 : post->next_row = 0;
239 : }
240 0 : }
241 :
242 : #endif /* QUANT_2PASS_SUPPORTED */
243 :
244 :
245 : /*
246 : * Initialize postprocessing controller.
247 : */
248 :
249 : GLOBAL(void)
250 0 : jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
251 : {
252 : my_post_ptr post;
253 :
254 0 : post = (my_post_ptr)
255 0 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
256 : sizeof(my_post_controller));
257 0 : cinfo->post = (struct jpeg_d_post_controller *) post;
258 0 : post->pub.start_pass = start_pass_dpost;
259 0 : post->whole_image = NULL; /* flag for no virtual arrays */
260 0 : post->buffer = NULL; /* flag for no strip buffer */
261 :
262 : /* Create the quantization buffer, if needed */
263 0 : 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 0 : post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
269 0 : 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 0 : post->whole_image = (*cinfo->mem->request_virt_sarray)
274 : ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
275 0 : cinfo->output_width * cinfo->out_color_components,
276 0 : (JDIMENSION) jround_up((long) cinfo->output_height,
277 0 : (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 0 : post->buffer = (*cinfo->mem->alloc_sarray)
285 : ((j_common_ptr) cinfo, JPOOL_IMAGE,
286 0 : cinfo->output_width * cinfo->out_color_components,
287 : post->strip_height);
288 : }
289 : }
290 0 : }
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