1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
|
#include "mupdf/fitz.h"
/* TODO: check if this works with 16bpp images */
typedef struct fz_predict_s fz_predict;
struct fz_predict_s
{
fz_stream *chain;
int predictor;
int columns;
int colors;
int bpc;
int stride;
int bpp;
unsigned char *in;
unsigned char *out;
unsigned char *ref;
unsigned char *rp, *wp;
unsigned char buffer[4096];
};
static inline int getcomponent(unsigned char *line, int x, int bpc)
{
switch (bpc)
{
case 1: return (line[x >> 3] >> ( 7 - (x & 7) ) ) & 1;
case 2: return (line[x >> 2] >> ( ( 3 - (x & 3) ) << 1 ) ) & 3;
case 4: return (line[x >> 1] >> ( ( 1 - (x & 1) ) << 2 ) ) & 15;
case 8: return line[x];
case 16: return (line[x<<1]<<8)+line[(x<<1)+1];
}
return 0;
}
static inline void putcomponent(unsigned char *buf, int x, int bpc, int value)
{
switch (bpc)
{
case 1: buf[x >> 3] |= value << (7 - (x & 7)); break;
case 2: buf[x >> 2] |= value << ((3 - (x & 3)) << 1); break;
case 4: buf[x >> 1] |= value << ((1 - (x & 1)) << 2); break;
case 8: buf[x] = value; break;
case 16: buf[x<<1] = value>>8; buf[(x<<1)+1] = value; break;
}
}
static inline int paeth(int a, int b, int c)
{
/* The definitions of ac and bc are correct, not a typo. */
int ac = b - c, bc = a - c, abcc = ac + bc;
int pa = fz_absi(ac);
int pb = fz_absi(bc);
int pc = fz_absi(abcc);
return pa <= pb && pa <= pc ? a : pb <= pc ? b : c;
}
static void
fz_predict_tiff(fz_predict *state, unsigned char *out, unsigned char *in)
{
int left[FZ_MAX_COLORS];
int i, k;
const int mask = (1 << state->bpc)-1;
for (k = 0; k < state->colors; k++)
left[k] = 0;
/* special fast case */
if (state->bpc == 8)
{
for (i = 0; i < state->columns; i++)
for (k = 0; k < state->colors; k++)
*out++ = left[k] = (*in++ + left[k]) & 0xFF;
return;
}
/* putcomponent assumes zeroed memory for bpc < 8 */
if (state->bpc < 8)
memset(out, 0, state->stride);
for (i = 0; i < state->columns; i++)
{
for (k = 0; k < state->colors; k++)
{
int a = getcomponent(in, i * state->colors + k, state->bpc);
int b = a + left[k];
int c = b & mask;
putcomponent(out, i * state->colors + k, state->bpc, c);
left[k] = c;
}
}
}
static void
fz_predict_png(fz_predict *state, unsigned char *out, unsigned char *in, size_t len, int predictor)
{
int bpp = state->bpp;
size_t i;
unsigned char *ref = state->ref;
if ((size_t)bpp > len)
bpp = (int)len;
switch (predictor)
{
case 0:
memcpy(out, in, len);
break;
case 1:
for (i = bpp; i > 0; i--)
{
*out++ = *in++;
}
for (i = len - bpp; i > 0; i--)
{
*out = *in++ + out[-bpp];
out++;
}
break;
case 2:
for (i = bpp; i > 0; i--)
{
*out++ = *in++ + *ref++;
}
for (i = len - bpp; i > 0; i--)
{
*out++ = *in++ + *ref++;
}
break;
case 3:
for (i = bpp; i > 0; i--)
{
*out++ = *in++ + (*ref++) / 2;
}
for (i = len - bpp; i > 0; i--)
{
*out = *in++ + (out[-bpp] + *ref++) / 2;
out++;
}
break;
case 4:
for (i = bpp; i > 0; i--)
{
*out++ = *in++ + paeth(0, *ref++, 0);
}
for (i = len - bpp; i > 0; i --)
{
*out = *in++ + paeth(out[-bpp], *ref, ref[-bpp]);
ref++;
out++;
}
break;
}
}
static int
next_predict(fz_context *ctx, fz_stream *stm, size_t len)
{
fz_predict *state = stm->state;
unsigned char *buf = state->buffer;
unsigned char *p = buf;
unsigned char *ep;
int ispng = state->predictor >= 10;
size_t n;
if (len >= sizeof(state->buffer))
len = sizeof(state->buffer);
ep = buf + len;
while (state->rp < state->wp && p < ep)
*p++ = *state->rp++;
while (p < ep)
{
n = fz_read(ctx, state->chain, state->in, state->stride + ispng);
if (n == 0)
break;
if (state->predictor == 1)
memcpy(state->out, state->in, n);
else if (state->predictor == 2)
fz_predict_tiff(state, state->out, state->in);
else
{
fz_predict_png(state, state->out, state->in + 1, n - 1, state->in[0]);
memcpy(state->ref, state->out, state->stride);
}
state->rp = state->out;
state->wp = state->out + n - ispng;
while (state->rp < state->wp && p < ep)
*p++ = *state->rp++;
}
stm->rp = buf;
stm->wp = p;
if (stm->rp == stm->wp)
return EOF;
stm->pos += p - buf;
return *stm->rp++;
}
static void
close_predict(fz_context *ctx, void *state_)
{
fz_predict *state = (fz_predict *)state_;
fz_drop_stream(ctx, state->chain);
fz_free(ctx, state->in);
fz_free(ctx, state->out);
fz_free(ctx, state->ref);
fz_free(ctx, state);
}
/* Default values: predictor = 1, columns = 1, colors = 1, bpc = 8 */
fz_stream *
fz_open_predict(fz_context *ctx, fz_stream *chain, int predictor, int columns, int colors, int bpc)
{
fz_predict *state = NULL;
fz_var(state);
if (predictor < 1)
predictor = 1;
if (columns < 1)
columns = 1;
if (colors < 1)
colors = 1;
if (bpc < 1)
bpc = 8;
fz_try(ctx)
{
if (bpc != 1 && bpc != 2 && bpc != 4 && bpc != 8 && bpc != 16)
fz_throw(ctx, FZ_ERROR_GENERIC, "invalid number of bits per component: %d", bpc);
if (colors > FZ_MAX_COLORS)
fz_throw(ctx, FZ_ERROR_GENERIC, "too many color components (%d > %d)", colors, FZ_MAX_COLORS);
if (columns >= INT_MAX / (bpc * colors))
fz_throw(ctx, FZ_ERROR_GENERIC, "too many columns lead to an integer overflow (%d)", columns);
state = fz_malloc_struct(ctx, fz_predict);
state->in = NULL;
state->out = NULL;
state->chain = chain;
state->predictor = predictor;
state->columns = columns;
state->colors = colors;
state->bpc = bpc;
if (state->predictor != 1 && state->predictor != 2 &&
state->predictor != 10 && state->predictor != 11 &&
state->predictor != 12 && state->predictor != 13 &&
state->predictor != 14 && state->predictor != 15)
{
fz_warn(ctx, "invalid predictor: %d", state->predictor);
state->predictor = 1;
}
state->stride = (state->bpc * state->colors * state->columns + 7) / 8;
state->bpp = (state->bpc * state->colors + 7) / 8;
state->in = fz_malloc(ctx, state->stride + 1);
state->out = fz_malloc(ctx, state->stride);
state->ref = fz_malloc(ctx, state->stride);
state->rp = state->out;
state->wp = state->out;
memset(state->ref, 0, state->stride);
}
fz_catch(ctx)
{
if (state)
{
fz_free(ctx, state->in);
fz_free(ctx, state->out);
}
fz_free(ctx, state);
fz_drop_stream(ctx, chain);
fz_rethrow(ctx);
}
return fz_new_stream(ctx, state, next_predict, close_predict);
}
|
