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
|
/*
* Copyright © 2005 Novell, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without
* fee, provided that the above copyright notice appear in all copies
* and that both that copyright notice and this permission notice
* appear in supporting documentation, and that the name of
* Novell, Inc. not be used in advertising or publicity pertaining to
* distribution of the software without specific, written prior permission.
* Novell, Inc. makes no representations about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*
* NOVELL, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
* NO EVENT SHALL NOVELL, INC. BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
* OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Author: David Reveman <davidr@novell.com>
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <png.h>
#include <setjmp.h>
#define FALSE 0
#define TRUE (!FALSE)
static void
premultiplyData (png_structp png,
png_row_infop row_info,
png_bytep data)
{
unsigned int i;
for (i = 0; i < row_info->rowbytes; i += 4)
{
unsigned char *base = &data[i];
unsigned char blue = base[0];
unsigned char green = base[1];
unsigned char red = base[2];
unsigned char alpha = base[3];
int p;
red = (unsigned) red * (unsigned) alpha / 255;
green = (unsigned) green * (unsigned) alpha / 255;
blue = (unsigned) blue * (unsigned) alpha / 255;
p = (alpha << 24) | (red << 16) | (green << 8) | (blue << 0);
memcpy (base, &p, sizeof (int));
}
}
int readPng(const char *filename,
char **data,
unsigned int *width,
unsigned int *height)
{
static const int PNG_SIG_SIZE = 8;
unsigned char png_sig[PNG_SIG_SIZE];
FILE *file;
int sig_bytes;
png_struct *png;
png_info *info;
png_uint_32 png_width, png_height;
int depth, color_type, interlace, i;
unsigned int pixel_size;
png_byte **row_pointers;
file = fopen (filename, "r");
if (!file)
{
fprintf(stderr, "Couldn't open file: '%s'\n", filename);
return FALSE;
}
sig_bytes = fread (png_sig, 1, PNG_SIG_SIZE, file);
if (png_check_sig (png_sig, sig_bytes) == 0)
{
fclose (file);
return FALSE;
}
png = png_create_read_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png)
{
fclose (file);
return FALSE;
}
info = png_create_info_struct (png);
if (info == NULL)
{
fclose (file);
png_destroy_read_struct (&png, NULL, NULL);
return FALSE;
}
png_init_io (png, file);
png_set_sig_bytes (png, sig_bytes);
png_read_info (png, info);
png_get_IHDR (png, info,
&png_width, &png_height, &depth,
&color_type, &interlace, NULL, NULL);
*width = png_width;
*height = png_height;
/* convert palette/gray image to rgb */
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb (png);
/* expand gray bit depth if needed */
if (color_type == PNG_COLOR_TYPE_GRAY && depth < 8)
png_set_expand_gray_1_2_4_to_8 (png);
/* transform transparency to alpha */
if (png_get_valid(png, info, PNG_INFO_tRNS))
png_set_tRNS_to_alpha (png);
if (depth == 16)
png_set_strip_16 (png);
if (depth < 8)
png_set_packing (png);
/* convert grayscale to RGB */
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb (png);
if (interlace != PNG_INTERLACE_NONE)
png_set_interlace_handling (png);
png_set_bgr (png);
png_set_filler (png, 0xff, PNG_FILLER_AFTER);
png_set_read_user_transform_fn (png, premultiplyData);
png_read_update_info (png, info);
pixel_size = 4;
*data = (char *) malloc (png_width * png_height * pixel_size);
if (*data == NULL)
{
fclose (file);
return FALSE;
}
row_pointers = (png_byte **) malloc (png_height * sizeof (char *));
for (i=0; i < png_height; i++)
row_pointers[i] = (png_byte *) (*data + i * png_width * pixel_size);
png_read_image (png, row_pointers);
png_read_end (png, info);
free (row_pointers);
fclose (file);
png_destroy_read_struct (&png, &info, NULL);
return TRUE;
}
|
