1#include "mupdf/fitz.h"
2#include "fitz-imp.h"
3
4#include <assert.h>
5
6struct fz_halftone_s
7{
8 int refs;
9 int n;
10 fz_pixmap *comp[1];
11};
12
13static fz_halftone *
14fz_new_halftone(fz_context *ctx, int comps)
15{
16 fz_halftone *ht;
17 int i;
18
19 ht = fz_malloc(ctx, sizeof(fz_halftone) + (comps-1)*sizeof(fz_pixmap *));
20 ht->refs = 1;
21 ht->n = comps;
22 for (i = 0; i < comps; i++)
23 ht->comp[i] = NULL;
24
25 return ht;
26}
27
28fz_halftone *
29fz_keep_halftone(fz_context *ctx, fz_halftone *ht)
30{
31 return fz_keep_imp(ctx, ht, &ht->refs);
32}
33
34void
35fz_drop_halftone(fz_context *ctx, fz_halftone *ht)
36{
37 int i;
38 if (fz_drop_imp(ctx, ht, &ht->refs))
39 {
40 for (i = 0; i < ht->n; i++)
41 fz_drop_pixmap(ctx, ht->comp[i]);
42 fz_free(ctx, ht);
43 }
44}
45
46/* Default mono halftone, lifted from Ghostscript. */
47/* The 0x00 entry has been changed to 0x01 to avoid problems with white
48 * pixels appearing in the output; as we use < 0 should not appear in the
49 * array. I think that gs scales this slightly and hence never actually uses
50 * the raw values here. */
51static unsigned char mono_ht[] =
52{
53 0x0E, 0x8E, 0x2E, 0xAE, 0x06, 0x86, 0x26, 0xA6, 0x0C, 0x8C, 0x2C, 0xAC, 0x04, 0x84, 0x24, 0xA4,
54 0xCE, 0x4E, 0xEE, 0x6E, 0xC6, 0x46, 0xE6, 0x66, 0xCC, 0x4C, 0xEC, 0x6C, 0xC4, 0x44, 0xE4, 0x64,
55 0x3E, 0xBE, 0x1E, 0x9E, 0x36, 0xB6, 0x16, 0x96, 0x3C, 0xBC, 0x1C, 0x9C, 0x34, 0xB4, 0x14, 0x94,
56 0xFE, 0x7E, 0xDE, 0x5E, 0xF6, 0x76, 0xD6, 0x56, 0xFC, 0x7C, 0xDC, 0x5C, 0xF4, 0x74, 0xD4, 0x54,
57 0x01, 0x81, 0x21, 0xA1, 0x09, 0x89, 0x29, 0xA9, 0x03, 0x83, 0x23, 0xA3, 0x0B, 0x8B, 0x2B, 0xAB,
58 0xC1, 0x41, 0xE1, 0x61, 0xC9, 0x49, 0xE9, 0x69, 0xC3, 0x43, 0xE3, 0x63, 0xCB, 0x4B, 0xEB, 0x6B,
59 0x31, 0xB1, 0x11, 0x91, 0x39, 0xB9, 0x19, 0x99, 0x33, 0xB3, 0x13, 0x93, 0x3B, 0xBB, 0x1B, 0x9B,
60 0xF1, 0x71, 0xD1, 0x51, 0xF9, 0x79, 0xD9, 0x59, 0xF3, 0x73, 0xD3, 0x53, 0xFB, 0x7B, 0xDB, 0x5B,
61 0x0D, 0x8D, 0x2D, 0xAD, 0x05, 0x85, 0x25, 0xA5, 0x0F, 0x8F, 0x2F, 0xAF, 0x07, 0x87, 0x27, 0xA7,
62 0xCD, 0x4D, 0xED, 0x6D, 0xC5, 0x45, 0xE5, 0x65, 0xCF, 0x4F, 0xEF, 0x6F, 0xC7, 0x47, 0xE7, 0x67,
63 0x3D, 0xBD, 0x1D, 0x9D, 0x35, 0xB5, 0x15, 0x95, 0x3F, 0xBF, 0x1F, 0x9F, 0x37, 0xB7, 0x17, 0x97,
64 0xFD, 0x7D, 0xDD, 0x5D, 0xF5, 0x75, 0xD5, 0x55, 0xFF, 0x7F, 0xDF, 0x5F, 0xF7, 0x77, 0xD7, 0x57,
65 0x02, 0x82, 0x22, 0xA2, 0x0A, 0x8A, 0x2A, 0xAA, 0x01 /*0x00*/, 0x80, 0x20, 0xA0, 0x08, 0x88, 0x28, 0xA8,
66 0xC2, 0x42, 0xE2, 0x62, 0xCA, 0x4A, 0xEA, 0x6A, 0xC0, 0x40, 0xE0, 0x60, 0xC8, 0x48, 0xE8, 0x68,
67 0x32, 0xB2, 0x12, 0x92, 0x3A, 0xBA, 0x1A, 0x9A, 0x30, 0xB0, 0x10, 0x90, 0x38, 0xB8, 0x18, 0x98,
68 0xF2, 0x72, 0xD2, 0x52, 0xFA, 0x7A, 0xDA, 0x5A, 0xF0, 0x70, 0xD0, 0x50, 0xF8, 0x78, 0xD8, 0x58
69};
70
71/*
72 Create a 'default' halftone structure
73 for the given number of components.
74
75 num_comps: The number of components to use.
76
77 Returns a simple default halftone. The default halftone uses
78 the same halftone tile for each plane, which may not be ideal
79 for all purposes.
80*/
81fz_halftone *fz_default_halftone(fz_context *ctx, int num_comps)
82{
83 fz_halftone *ht = fz_new_halftone(ctx, num_comps);
84
85 fz_try(ctx)
86 {
87 int i;
88 for (i = 0; i < num_comps; i++)
89 ht->comp[i] = fz_new_pixmap_with_data(ctx, NULL, 16, 16, NULL, 1, 16, mono_ht);
90 }
91 fz_catch(ctx)
92 {
93 fz_drop_halftone(ctx, ht);
94 fz_rethrow(ctx);
95 }
96
97 return ht;
98}
99
100/* Finally, code to actually perform halftoning. */
101static void make_ht_line(unsigned char *buf, fz_halftone *ht, int x, int y, int w)
102{
103 int k, n;
104 n = ht->n;
105 for (k = 0; k < n; k++)
106 {
107 fz_pixmap *tile = ht->comp[k];
108 unsigned char *b = buf++;
109 unsigned char *t;
110 unsigned char *tbase;
111 int px = x + tile->x;
112 int py = y + tile->y;
113 int tw = tile->w;
114 int th = tile->h;
115 int w2 = w;
116 int len;
117 px = px % tw;
118 if (px < 0)
119 px += tw;
120 py = py % th;
121 if (py < 0)
122 py += th;
123
124 assert(tile->n == 1);
125
126 /* Left hand section; from x to tile width */
127 tbase = tile->samples + (unsigned int)(py * tw);
128 t = tbase + px;
129 len = tw - px;
130 if (len > w2)
131 len = w2;
132 w2 -= len;
133 while (len--)
134 {
135 *b = *t++;
136 b += n;
137 }
138
139 /* Centre section - complete copies */
140 w2 -= tw;
141 while (w2 >= 0)
142 {
143 len = tw;
144 t = tbase;
145 while (len--)
146 {
147 *b = *t++;
148 b += n;
149 }
150 w2 -= tw;
151 }
152 w2 += tw;
153
154 /* Right hand section - stragglers */
155 t = tbase;
156 while (w2--)
157 {
158 *b = *t++;
159 b += n;
160 }
161 }
162}
163
164/* Inner mono thresholding code */
165typedef void (threshold_fn)(const unsigned char *ht_line, const unsigned char *pixmap, unsigned char *out, int w, int ht_len);
166
167#ifdef ARCH_ARM
168static void
169do_threshold_1(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)
170__attribute__((naked));
171
172static void
173do_threshold_1(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)
174{
175 asm volatile(
176 ENTER_ARM
177 // Store one more reg that required to keep double stack alignment
178 ".syntax unified\n"
179 "stmfd r13!,{r4-r7,r9,r14} \n"
180 "@ r0 = ht_line \n"
181 "@ r1 = pixmap \n"
182 "@ r2 = out \n"
183 "@ r3 = w \n"
184 "@ <> = ht_len \n"
185 "ldr r9, [r13,#6*4] @ r9 = ht_len \n"
186 "subs r3, r3, #7 @ r3 = w -= 7 \n"
187 "ble 2f @ while (w > 0) { \n"
188 "mov r12,r9 @ r12= l = ht_len \n"
189 "b 1f \n"
190 "9: \n"
191 "strb r14,[r2], #1 @ *out++ = 0 \n"
192 "subs r12,r12,#8 @ r12 = l -= 8 \n"
193 "moveq r12,r9 @ if(l==0) l = ht_len \n"
194 "subeq r0, r0, r9 @ ht_line -= l \n"
195 "subs r3, r3, #8 @ w -= 8 \n"
196 "ble 2f @ } \n"
197 "1: \n"
198 "ldr r14,[r1], #4 @ r14= pixmap[0..3] \n"
199 "ldr r5, [r1], #4 @ r5 = pixmap[4..7] \n"
200 "ldrb r4, [r0], #8 @ r0 = ht_line += 8 \n"
201 "adds r14,r14,#1 @ set eq iff r14=-1 \n"
202 "addseq r5, r5, #1 @ set eq iff r14=r5=-1 \n"
203 "beq 9b @ white \n"
204 "ldrb r5, [r1, #-8] @ r5 = pixmap[0] \n"
205 "ldrb r6, [r0, #-7] @ r6 = ht_line[1] \n"
206 "ldrb r7, [r1, #-7] @ r7 = pixmap[1] \n"
207 "mov r14,#0 @ r14= h = 0 \n"
208 "cmp r5, r4 @ if (r5 < r4) \n"
209 "orrlt r14,r14,#0x80 @ h |= 0x80 \n"
210 "ldrb r4, [r0, #-6] @ r4 = ht_line[2] \n"
211 "ldrb r5, [r1, #-6] @ r5 = pixmap[2] \n"
212 "cmp r7, r6 @ if (r7 < r6) \n"
213 "orrlt r14,r14,#0x40 @ h |= 0x40 \n"
214 "ldrb r6, [r0, #-5] @ r6 = ht_line[3] \n"
215 "ldrb r7, [r1, #-5] @ r7 = pixmap[3] \n"
216 "cmp r5, r4 @ if (r5 < r4) \n"
217 "orrlt r14,r14,#0x20 @ h |= 0x20 \n"
218 "ldrb r4, [r0, #-4] @ r4 = ht_line[4] \n"
219 "ldrb r5, [r1, #-4] @ r5 = pixmap[4] \n"
220 "cmp r7, r6 @ if (r7 < r6) \n"
221 "orrlt r14,r14,#0x10 @ h |= 0x10 \n"
222 "ldrb r6, [r0, #-3] @ r6 = ht_line[5] \n"
223 "ldrb r7, [r1, #-3] @ r7 = pixmap[5] \n"
224 "cmp r5, r4 @ if (r5 < r4) \n"
225 "orrlt r14,r14,#0x08 @ h |= 0x08 \n"
226 "ldrb r4, [r0, #-2] @ r4 = ht_line[6] \n"
227 "ldrb r5, [r1, #-2] @ r5 = pixmap[6] \n"
228 "cmp r7, r6 @ if (r7 < r6) \n"
229 "orrlt r14,r14,#0x04 @ h |= 0x04 \n"
230 "ldrb r6, [r0, #-1] @ r6 = ht_line[7] \n"
231 "ldrb r7, [r1, #-1] @ r7 = pixmap[7] \n"
232 "cmp r5, r4 @ if (r5 < r4) \n"
233 "orrlt r14,r14,#0x02 @ h |= 0x02 \n"
234 "cmp r7, r6 @ if (r7 < r6) \n"
235 "orrlt r14,r14,#0x01 @ h |= 0x01 \n"
236 "subs r12,r12,#8 @ r12 = l -= 8 \n"
237 "strb r14,[r2], #1 @ *out++ = h \n"
238 "moveq r12,r9 @ if(l==0) l = ht_len \n"
239 "subeq r0, r0, r9 @ ht_line -= l \n"
240 "subs r3, r3, #8 @ w -= 8 \n"
241 "bgt 1b @ } \n"
242 "2: \n"
243 "adds r3, r3, #7 @ w += 7 \n"
244 "ble 4f @ if (w >= 0) { \n"
245 "ldrb r4, [r0], #1 @ r4 = ht_line[0] \n"
246 "ldrb r5, [r1], #1 @ r5 = pixmap[0] \n"
247 "mov r14, #0 @ r14= h = 0 \n"
248 "cmp r5, r4 @ if (r5 < r4) \n"
249 "orrlt r14,r14,#0x80 @ h |= 0x80 \n"
250 "cmp r3, #1 @ \n"
251 "ldrbgt r4, [r0], #1 @ r6 = ht_line[1] \n"
252 "ldrbgt r5, [r1], #1 @ r7 = pixmap[1] \n"
253 "ble 3f @ \n"
254 "cmp r5, r4 @ if (r5 < r4) \n"
255 "orrlt r14,r14,#0x40 @ h |= 0x40 \n"
256 "cmp r3, #2 @ \n"
257 "ldrbgt r4, [r0], #1 @ r6 = ht_line[2] \n"
258 "ldrbgt r5, [r1], #1 @ r7 = pixmap[2] \n"
259 "ble 3f @ \n"
260 "cmp r5, r4 @ if (r5 < r4) \n"
261 "orrlt r14,r14,#0x20 @ h |= 0x20 \n"
262 "cmp r3, #3 @ \n"
263 "ldrbgt r4, [r0], #1 @ r6 = ht_line[3] \n"
264 "ldrbgt r5, [r1], #1 @ r7 = pixmap[3] \n"
265 "ble 3f @ \n"
266 "cmp r5, r4 @ if (r5 < r4) \n"
267 "orrlt r14,r14,#0x10 @ h |= 0x10 \n"
268 "cmp r3, #4 @ \n"
269 "ldrbgt r4, [r0], #1 @ r6 = ht_line[4] \n"
270 "ldrbgt r5, [r1], #1 @ r7 = pixmap[4] \n"
271 "ble 3f @ \n"
272 "cmp r5, r4 @ if (r5 < r4) \n"
273 "orrlt r14,r14,#0x08 @ h |= 0x08 \n"
274 "cmp r3, #5 @ \n"
275 "ldrbgt r4, [r0], #1 @ r6 = ht_line[5] \n"
276 "ldrbgt r5, [r1], #1 @ r7 = pixmap[5] \n"
277 "ble 3f @ \n"
278 "cmp r5, r4 @ if (r5 < r4) \n"
279 "orrlt r14,r14,#0x04 @ h |= 0x04 \n"
280 "cmp r3, #6 @ \n"
281 "ldrbgt r4, [r0], #1 @ r6 = ht_line[6] \n"
282 "ldrbgt r5, [r1], #1 @ r7 = pixmap[6] \n"
283 "ble 3f @ \n"
284 "cmp r5, r4 @ if (r5 < r4) \n"
285 "orrlt r14,r14,#0x02 @ h |= 0x02 \n"
286 "3: \n"
287 "strb r14,[r2] @ *out = h \n"
288 "4: \n"
289 "ldmfd r13!,{r4-r7,r9,PC} @ pop, return to thumb \n"
290 ENTER_THUMB
291 );
292}
293#else
294static void do_threshold_1(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)
295{
296 int h;
297 int l = ht_len;
298
299 w -= 7;
300 while (w > 0)
301 {
302 h = 0;
303 if (pixmap[0] < ht_line[0])
304 h |= 0x80;
305 if (pixmap[1] < ht_line[1])
306 h |= 0x40;
307 if (pixmap[2] < ht_line[2])
308 h |= 0x20;
309 if (pixmap[3] < ht_line[3])
310 h |= 0x10;
311 if (pixmap[4] < ht_line[4])
312 h |= 0x08;
313 if (pixmap[5] < ht_line[5])
314 h |= 0x04;
315 if (pixmap[6] < ht_line[6])
316 h |= 0x02;
317 if (pixmap[7] < ht_line[7])
318 h |= 0x01;
319 pixmap += 8;
320 ht_line += 8;
321 l -= 8;
322 if (l == 0)
323 {
324 l = ht_len;
325 ht_line -= ht_len;
326 }
327 *out++ = h;
328 w -= 8;
329 }
330 if (w > -7)
331 {
332 h = 0;
333 if (pixmap[0] < ht_line[0])
334 h |= 0x80;
335 if (w > -6 && pixmap[1] < ht_line[1])
336 h |= 0x40;
337 if (w > -5 && pixmap[2] < ht_line[2])
338 h |= 0x20;
339 if (w > -4 && pixmap[3] < ht_line[3])
340 h |= 0x10;
341 if (w > -3 && pixmap[4] < ht_line[4])
342 h |= 0x08;
343 if (w > -2 && pixmap[5] < ht_line[5])
344 h |= 0x04;
345 if (w > -1 && pixmap[6] < ht_line[6])
346 h |= 0x02;
347 *out++ = h;
348 }
349}
350#endif
351
352/*
353 Note that the tests in do_threshold_4 are inverted compared to those
354 in do_threshold_1. This is to allow for the fact that the CMYK
355 contone renderings have white = 0, whereas rgb, and greyscale have
356 white = 0xFF. Reversing these tests enables us to maintain that
357 BlackIs1 in bitmaps.
358*/
359#ifdef ARCH_ARM
360static void
361do_threshold_4(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)
362__attribute__((naked));
363
364static void
365do_threshold_4(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)
366{
367 asm volatile(
368 ENTER_ARM
369 // Store one more reg that required to keep double stack alignment
370 "stmfd r13!,{r4-r7,r9,r14} \n"
371 "@ r0 = ht_line \n"
372 "@ r1 = pixmap \n"
373 "@ r2 = out \n"
374 "@ r3 = w \n"
375 "@ <> = ht_len \n"
376 "ldr r9, [r13,#6*4] @ r9 = ht_len \n"
377 "subs r3, r3, #1 @ r3 = w -= 1 \n"
378 "ble 2f @ while (w > 0) { \n"
379 "mov r12,r9 @ r12= l = ht_len \n"
380 "b 1f @ \n"
381 "9: @ \n"
382 "strb r14,[r2], #1 @ *out++ = h \n"
383 "subs r12,r12,#2 @ r12 = l -= 2 \n"
384 "moveq r12,r9 @ if(l==0) l = ht_len \n"
385 "subeq r0, r0, r9, LSL #2 @ ht_line -= l \n"
386 "subs r3, r3, #2 @ w -= 2 \n"
387 "beq 2f @ } \n"
388 "blt 3f @ \n"
389 "1: \n"
390 "ldr r5, [r1], #4 @ r5 = pixmap[0..3] \n"
391 "ldr r7, [r1], #4 @ r7 = pixmap[4..7] \n"
392 "add r0, r0, #8 @ r0 = ht_line += 8 \n"
393 "mov r14,#0 @ r14= h = 0 \n"
394 "orrs r5, r5, r7 @ if (r5 | r7 == 0) \n"
395 "beq 9b @ white \n"
396 "ldrb r4, [r0, #-8] @ r4 = ht_line[0] \n"
397 "ldrb r5, [r1, #-8] @ r5 = pixmap[0] \n"
398 "ldrb r6, [r0, #-7] @ r6 = ht_line[1] \n"
399 "ldrb r7, [r1, #-7] @ r7 = pixmap[1] \n"
400 "cmp r4, r5 @ if (r4 < r5) \n"
401 "orrle r14,r14,#0x80 @ h |= 0x80 \n"
402 "ldrb r4, [r0, #-6] @ r4 = ht_line[2] \n"
403 "ldrb r5, [r1, #-6] @ r5 = pixmap[2] \n"
404 "cmp r6, r7 @ if (r6 < r7) \n"
405 "orrle r14,r14,#0x40 @ h |= 0x40 \n"
406 "ldrb r6, [r0, #-5] @ r6 = ht_line[3] \n"
407 "ldrb r7, [r1, #-5] @ r7 = pixmap[3] \n"
408 "cmp r4, r5 @ if (r4 < r5) \n"
409 "orrle r14,r14,#0x20 @ h |= 0x20 \n"
410 "ldrb r4, [r0, #-4] @ r4 = ht_line[4] \n"
411 "ldrb r5, [r1, #-4] @ r5 = pixmap[4] \n"
412 "cmp r6, r7 @ if (r6 < r7) \n"
413 "orrle r14,r14,#0x10 @ h |= 0x10 \n"
414 "ldrb r6, [r0, #-3] @ r6 = ht_line[5] \n"
415 "ldrb r7, [r1, #-3] @ r7 = pixmap[5] \n"
416 "cmp r4, r5 @ if (r4 < r5) \n"
417 "orrle r14,r14,#0x08 @ h |= 0x08 \n"
418 "ldrb r4, [r0, #-2] @ r4 = ht_line[6] \n"
419 "ldrb r5, [r1, #-2] @ r5 = pixmap[6] \n"
420 "cmp r6, r7 @ if (r6 < r7) \n"
421 "orrle r14,r14,#0x04 @ h |= 0x04 \n"
422 "ldrb r6, [r0, #-1] @ r6 = ht_line[7] \n"
423 "ldrb r7, [r1, #-1] @ r7 = pixmap[7] \n"
424 "cmp r4, r5 @ if (r4 < r5) \n"
425 "orrle r14,r14,#0x02 @ h |= 0x02 \n"
426 "cmp r6, r7 @ if (r7 < r6) \n"
427 "orrle r14,r14,#0x01 @ h |= 0x01 \n"
428 "subs r12,r12,#2 @ r12 = l -= 2 \n"
429 "strb r14,[r2], #1 @ *out++ = h \n"
430 "moveq r12,r9 @ if(l==0) l = ht_len \n"
431 "subeq r0, r0, r9, LSL #2 @ ht_line -= l \n"
432 "subs r3, r3, #2 @ w -= 2 \n"
433 "bgt 1b @ } \n"
434 "blt 3f @ \n"
435 "2: \n"
436 "ldrb r4, [r0], #1 @ r4 = ht_line[0] \n"
437 "ldrb r5, [r1], #1 @ r5 = pixmap[0] \n"
438 "mov r14, #0 @ r14= h = 0 \n"
439 "ldrb r6, [r0], #1 @ r6 = ht_line[1] \n"
440 "ldrb r7, [r1], #1 @ r7 = pixmap[1] \n"
441 "cmp r4, r5 @ if (r4 < r5) \n"
442 "orrle r14,r14,#0x80 @ h |= 0x80 \n"
443 "ldrb r4, [r0], #1 @ r6 = ht_line[2] \n"
444 "ldrb r5, [r1], #1 @ r7 = pixmap[2] \n"
445 "cmp r6, r7 @ if (r6 < r7) \n"
446 "orrle r14,r14,#0x40 @ h |= 0x40 \n"
447 "ldrb r6, [r0], #1 @ r6 = ht_line[1] \n"
448 "ldrb r7, [r1], #1 @ r7 = pixmap[3] \n"
449 "cmp r4, r5 @ if (r4 < r5) \n"
450 "orrle r14,r14,#0x20 @ h |= 0x20 \n"
451 "cmp r6, r7 @ if (r6 < r7) \n"
452 "orrle r14,r14,#0x10 @ h |= 0x10 \n"
453 "strb r14,[r2] @ *out = h \n"
454 "3: \n"
455 "ldmfd r13!,{r4-r7,r9,PC} @ pop, return to thumb \n"
456 ENTER_THUMB
457 );
458}
459#else
460static void do_threshold_4(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)
461{
462 int l = ht_len;
463
464 w--;
465 while (w > 0)
466 {
467 int h = 0;
468 if (pixmap[0] >= ht_line[0])
469 h |= 0x80;
470 if (pixmap[1] >= ht_line[1])
471 h |= 0x40;
472 if (pixmap[2] >= ht_line[2])
473 h |= 0x20;
474 if (pixmap[3] >= ht_line[3])
475 h |= 0x10;
476 if (pixmap[4] >= ht_line[4])
477 h |= 0x08;
478 if (pixmap[5] >= ht_line[5])
479 h |= 0x04;
480 if (pixmap[6] >= ht_line[6])
481 h |= 0x02;
482 if (pixmap[7] >= ht_line[7])
483 h |= 0x01;
484 *out++ = h;
485 l -= 2;
486 if (l == 0)
487 {
488 l = ht_len;
489 ht_line -= ht_len<<2;
490 }
491 pixmap += 8;
492 ht_line += 8;
493 w -= 2;
494 }
495 if (w == 0)
496 {
497 int h = 0;
498 if (pixmap[0] >= ht_line[0])
499 h |= 0x80;
500 if (pixmap[1] >= ht_line[1])
501 h |= 0x40;
502 if (pixmap[2] >= ht_line[2])
503 h |= 0x20;
504 if (pixmap[3] >= ht_line[3])
505 h |= 0x10;
506 *out = h;
507 }
508}
509#endif
510
511/*
512 Make a bitmap from a pixmap and a halftone.
513
514 pix: The pixmap to generate from. Currently must be a single color
515 component with no alpha.
516
517 ht: The halftone to use. NULL implies the default halftone.
518
519 Returns the resultant bitmap. Throws exceptions in the case of
520 failure to allocate.
521*/
522fz_bitmap *fz_new_bitmap_from_pixmap(fz_context *ctx, fz_pixmap *pix, fz_halftone *ht)
523{
524 return fz_new_bitmap_from_pixmap_band(ctx, pix, ht, 0);
525}
526
527/* TAOCP, vol 2, p337 */
528static int gcd(int u, int v)
529{
530 int r;
531
532 do
533 {
534 if (v == 0)
535 return u;
536 r = u % v;
537 u = v;
538 v = r;
539 }
540 while (1);
541}
542
543/*
544 Make a bitmap from a pixmap and a
545 halftone, allowing for the position of the pixmap within an
546 overall banded rendering.
547
548 pix: The pixmap to generate from. Currently must be a single color
549 component with no alpha.
550
551 ht: The halftone to use. NULL implies the default halftone.
552
553 band_start: Vertical offset within the overall banded rendering
554 (in pixels)
555
556 Returns the resultant bitmap. Throws exceptions in the case of
557 failure to allocate.
558*/
559fz_bitmap *fz_new_bitmap_from_pixmap_band(fz_context *ctx, fz_pixmap *pix, fz_halftone *ht, int band_start)
560{
561 fz_bitmap *out = NULL;
562 unsigned char *ht_line = NULL;
563 unsigned char *o, *p;
564 int w, h, x, y, n, pstride, ostride, lcm, i;
565 fz_halftone *ht_ = NULL;
566 threshold_fn *thresh;
567
568 fz_var(ht_line);
569
570 if (!pix)
571 return NULL;
572
573 if (pix->alpha != 0)
574 fz_throw(ctx, FZ_ERROR_GENERIC, "pixmap may not have alpha channel to convert to bitmap");
575
576 n = pix->n;
577
578 switch(n)
579 {
580 case 1:
581 thresh = do_threshold_1;
582 break;
583 case 4:
584 thresh = do_threshold_4;
585 break;
586 default:
587 fz_throw(ctx, FZ_ERROR_GENERIC, "pixmap must be grayscale or CMYK to convert to bitmap");
588 return NULL;
589 }
590
591 if (ht == NULL)
592 ht_ = ht = fz_default_halftone(ctx, n);
593
594 /* Find the minimum length for the halftone line. This
595 * is the LCM of the halftone lengths and 8. (We need a
596 * multiple of 8 for the unrolled threshold routines - if
597 * we ever use SSE, we may need longer.) We use the fact
598 * that LCM(a,b) = a * b / GCD(a,b) and use euclids
599 * algorithm.
600 */
601 lcm = 8;
602 for (i = 0; i < ht->n; i++)
603 {
604 w = ht->comp[i]->w;
605 lcm = lcm / gcd(lcm, w) * w;
606 }
607
608 fz_try(ctx)
609 {
610 ht_line = fz_malloc(ctx, lcm * n);
611 out = fz_new_bitmap(ctx, pix->w, pix->h, n, pix->xres, pix->yres);
612 o = out->samples;
613 p = pix->samples;
614
615 h = pix->h;
616 x = pix->x;
617 y = pix->y + band_start;
618 w = pix->w;
619 ostride = out->stride;
620 pstride = pix->stride;
621 while (h--)
622 {
623 make_ht_line(ht_line, ht, x, y++, lcm);
624 thresh(ht_line, p, o, w, lcm);
625 o += ostride;
626 p += pstride;
627 }
628 }
629 fz_always(ctx)
630 {
631 fz_drop_halftone(ctx, ht_);
632 fz_free(ctx, ht_line);
633 }
634 fz_catch(ctx)
635 fz_rethrow(ctx);
636
637 return out;
638}
639