WebSVN – Kolibri OS – Diff – /programs/develop/libraries/cairo/src/cairo-image-info.c


/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2008 Adrian Johnson
 *
 * This library is free software; you can redistribute it and/or
 * modify it either under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation
 * (the "LGPL") or, at your option, under the terms of the Mozilla
 * Public License Version 1.1 (the "MPL"). If you do not alter this
 * notice, a recipient may use your version of this file under either
 * the MPL or the LGPL.
 *
 * You should have received a copy of the LGPL along with this library
 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
 * You should have received a copy of the MPL along with this library
 * in the file COPYING-MPL-1.1
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
 * the specific language governing rights and limitations.
 *
 * The Original Code is the cairo graphics library.
 *
 * The Initial Developer of the Original Code is Adrian Johnson.
 *
 * Contributor(s):
 *	Adrian Johnson 
 */
 
#include "cairoint.h"
 
#include "cairo-error-private.h"
#include "cairo-image-info-private.h"
 
static uint32_t
_get_be32 (const unsigned char *p)
{
    return p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3];
}
 
/* JPEG (image/jpeg)
 *
 * http://www.w3.org/Graphics/JPEG/itu-t81.pdf
 */
 
/* Markers with no parameters. All other markers are followed by a two
 * byte length of the parameters. */
#define TEM       0x01
#define RST_begin 0xd0
#define RST_end   0xd7
#define SOI       0xd8
#define EOI       0xd9
 
/* Start of frame markers. */
#define SOF0  0xc0
#define SOF1  0xc1
#define SOF2  0xc2
#define SOF3  0xc3
#define SOF5  0xc5
#define SOF6  0xc6
#define SOF7  0xc7
#define SOF9  0xc9
#define SOF10 0xca
#define SOF11 0xcb
#define SOF13 0xcd
#define SOF14 0xce
#define SOF15 0xcf
 
static const unsigned char *
_jpeg_skip_segment (const unsigned char *p)
{
    int len;
 
    p++;
    len = (p[0] << 8) | p[1];
 
    return p + len;
}
 
static void
_jpeg_extract_info (cairo_image_info_t *info, const unsigned char *p)
{
    info->width = (p[6] << 8) + p[7];
    info->height = (p[4] << 8) + p[5];
    info->num_components = p[8];
    info->bits_per_component = p[3];
}
 
cairo_int_status_t
_cairo_image_info_get_jpeg_info (cairo_image_info_t	*info,
				 const unsigned char	*data,
				 long			 length)
{
    const unsigned char *p = data;
 
    while (p + 1 < data + length) {
	if (*p != 0xff)
	    return CAIRO_INT_STATUS_UNSUPPORTED;
	p++;
 
	switch (*p) {
	    /* skip fill bytes */
	case 0xff:
	    p++;
	    break;
 
	case TEM:
	case SOI:
	case EOI:
	    p++;
	    break;
 
	case SOF0:
	case SOF1:
	case SOF2:
	case SOF3:
	case SOF5:
	case SOF6:
	case SOF7:
	case SOF9:
	case SOF10:
	case SOF11:
	case SOF13:
	case SOF14:
	case SOF15:
	    /* Start of frame found. Extract the image parameters. */
	    if (p + 8 > data + length)
		return CAIRO_INT_STATUS_UNSUPPORTED;
 
	    _jpeg_extract_info (info, p);
	    return CAIRO_STATUS_SUCCESS;
 
	default:
	    if (*p >= RST_begin && *p <= RST_end) {
		p++;
		break;
	    }
 
	    if (p + 2 > data + length)
		return CAIRO_INT_STATUS_UNSUPPORTED;
 
	    p = _jpeg_skip_segment (p);
	    break;
	}
    }
 
    return CAIRO_STATUS_SUCCESS;
}
 
/* JPEG 2000 (image/jp2)
 *
 * http://www.jpeg.org/public/15444-1annexi.pdf
 */
 
#define JPX_FILETYPE 0x66747970
#define JPX_JP2_HEADER 0x6A703268
#define JPX_IMAGE_HEADER 0x69686472
 
static const unsigned char _jpx_signature[] = {
    0x00, 0x00, 0x00, 0x0c, 0x6a, 0x50, 0x20, 0x20, 0x0d, 0x0a, 0x87, 0x0a
};
 
static const unsigned char *
_jpx_next_box (const unsigned char *p)
{
    return p + _get_be32 (p);
}
 
static const unsigned char *
_jpx_get_box_contents (const unsigned char *p)
{
    return p + 8;
}
 
static cairo_bool_t
_jpx_match_box (const unsigned char *p, const unsigned char *end, uint32_t type)
{
    uint32_t length;
 
    if (p + 8 < end) {
	length = _get_be32 (p);
	if (_get_be32 (p + 4) == type &&  p + length < end)
	    return TRUE;
    }
 
    return FALSE;
}
 
static const unsigned char *
_jpx_find_box (const unsigned char *p, const unsigned char *end, uint32_t type)
{
    while (p < end) {
	if (_jpx_match_box (p, end, type))
	    return p;
	p = _jpx_next_box (p);
    }
 
    return NULL;
}
 
static void
_jpx_extract_info (const unsigned char *p, cairo_image_info_t *info)
{
    info->height = _get_be32 (p);
    info->width = _get_be32 (p + 4);
    info->num_components = (p[8] << 8) + p[9];
    info->bits_per_component = p[10];
}
 
cairo_int_status_t
_cairo_image_info_get_jpx_info (cairo_image_info_t	*info,
				const unsigned char	*data,
				unsigned long		 length)
{
    const unsigned char *p = data;
    const unsigned char *end = data + length;
 
    /* First 12 bytes must be the JPEG 2000 signature box. */
    if (length < ARRAY_LENGTH(_jpx_signature) ||
	memcmp(p, _jpx_signature, ARRAY_LENGTH(_jpx_signature)) != 0)
	return CAIRO_INT_STATUS_UNSUPPORTED;
 
    p += ARRAY_LENGTH(_jpx_signature);
 
    /* Next box must be a File Type Box */
    if (! _jpx_match_box (p, end, JPX_FILETYPE))
	return CAIRO_INT_STATUS_UNSUPPORTED;
 
    p = _jpx_next_box (p);
 
    /* Locate the JP2 header box. */
    p = _jpx_find_box (p, end, JPX_JP2_HEADER);
    if (!p)
	return CAIRO_INT_STATUS_UNSUPPORTED;
 
    /* Step into the JP2 header box. First box must be the Image
     * Header */
    p = _jpx_get_box_contents (p);
    if (! _jpx_match_box (p, end, JPX_IMAGE_HEADER))
	return CAIRO_INT_STATUS_UNSUPPORTED;
 
    /* Get the image info */
    p = _jpx_get_box_contents (p);
    _jpx_extract_info (p, info);
 
    return CAIRO_STATUS_SUCCESS;
}
 
/* PNG (image/png)
 *
 * http://www.w3.org/TR/2003/REC-PNG-20031110/
 */
 
#define PNG_IHDR 0x49484452
 
static const unsigned char _png_magic[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
 
cairo_int_status_t
_cairo_image_info_get_png_info (cairo_image_info_t     *info,
                               const unsigned char     *data,
                               unsigned long            length)
{
    const unsigned char *p = data;
    const unsigned char *end = data + length;
 
    if (length < 8 || memcmp (data, _png_magic, 8) != 0)
       return CAIRO_INT_STATUS_UNSUPPORTED;
 
    p += 8;
 
    /* The first chunk must be IDHR. IDHR has 13 bytes of data plus
     * the 12 bytes of overhead for the chunk. */
    if (p + 13 + 12 > end)
       return CAIRO_INT_STATUS_UNSUPPORTED;
 
    p += 4;
    if (_get_be32 (p) != PNG_IHDR)
       return CAIRO_INT_STATUS_UNSUPPORTED;
 
    p += 4;
    info->width = _get_be32 (p);
    p += 4;
    info->height = _get_be32 (p);
 
    return CAIRO_STATUS_SUCCESS;
}

Rev 1892	Rev 3959
1	/* cairo - a vector graphics library with display and print output	1	/* cairo - a vector graphics library with display and print output
2	*	2	*
3	* Copyright © 2008 Adrian Johnson	3	* Copyright © 2008 Adrian Johnson
4	*	4	*
5	* This library is free software; you can redistribute it and/or	5	* This library is free software; you can redistribute it and/or
6	* modify it either under the terms of the GNU Lesser General Public	6	* modify it either under the terms of the GNU Lesser General Public
7	* License version 2.1 as published by the Free Software Foundation	7	* License version 2.1 as published by the Free Software Foundation
8	* (the "LGPL") or, at your option, under the terms of the Mozilla	8	* (the "LGPL") or, at your option, under the terms of the Mozilla
9	* Public License Version 1.1 (the "MPL"). If you do not alter this	9	* Public License Version 1.1 (the "MPL"). If you do not alter this
10	* notice, a recipient may use your version of this file under either	10	* notice, a recipient may use your version of this file under either
11	* the MPL or the LGPL.	11	* the MPL or the LGPL.
12	*	12	*
13	* You should have received a copy of the LGPL along with this library	13	* You should have received a copy of the LGPL along with this library
14	* in the file COPYING-LGPL-2.1; if not, write to the Free Software	14	* in the file COPYING-LGPL-2.1; if not, write to the Free Software
15	* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA	15	* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
16	* You should have received a copy of the MPL along with this library	16	* You should have received a copy of the MPL along with this library
17	* in the file COPYING-MPL-1.1	17	* in the file COPYING-MPL-1.1
18	*	18	*
19	* The contents of this file are subject to the Mozilla Public License	19	* The contents of this file are subject to the Mozilla Public License
20	* Version 1.1 (the "License"); you may not use this file except in	20	* Version 1.1 (the "License"); you may not use this file except in
21	* compliance with the License. You may obtain a copy of the License at	21	* compliance with the License. You may obtain a copy of the License at
22	* http://www.mozilla.org/MPL/	22	* http://www.mozilla.org/MPL/
23	*	23	*
24	* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY	24	* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
25	* OF ANY KIND, either express or implied. See the LGPL or the MPL for	25	* OF ANY KIND, either express or implied. See the LGPL or the MPL for
26	* the specific language governing rights and limitations.	26	* the specific language governing rights and limitations.
27	*	27	*
28	* The Original Code is the cairo graphics library.	28	* The Original Code is the cairo graphics library.
29	*	29	*
30	* The Initial Developer of the Original Code is Adrian Johnson.	30	* The Initial Developer of the Original Code is Adrian Johnson.
31	*	31	*
32	* Contributor(s):	32	* Contributor(s):
33	* Adrian Johnson	33	* Adrian Johnson
34	*/	34	*/
35		35
36	#include "cairoint.h"	36	#include "cairoint.h"
-		37
-		38	#include "cairo-error-private.h"
37	#include "cairo-image-info-private.h"	39	#include "cairo-image-info-private.h"
38		40
39	static uint32_t	41	static uint32_t
40	_get_be32 (const unsigned char *p)	42	_get_be32 (const unsigned char *p)
41	{	43	{
42	return p[0] << 24 \| p[1] << 16 \| p[2] << 8 \| p[3];	44	return p[0] << 24 \| p[1] << 16 \| p[2] << 8 \| p[3];
43	}	45	}
44		46
45	/* JPEG (image/jpeg)	47	/* JPEG (image/jpeg)
46	*	48	*
47	* http://www.w3.org/Graphics/JPEG/itu-t81.pdf	49	* http://www.w3.org/Graphics/JPEG/itu-t81.pdf
48	*/	50	*/
49		51
50	/* Markers with no parameters. All other markers are followed by a two	52	/* Markers with no parameters. All other markers are followed by a two
51	* byte length of the parameters. */	53	* byte length of the parameters. */
52	#define TEM 0x01	54	#define TEM 0x01
53	#define RST_begin 0xd0	55	#define RST_begin 0xd0
54	#define RST_end 0xd7	56	#define RST_end 0xd7
55	#define SOI 0xd8	57	#define SOI 0xd8
56	#define EOI 0xd9	58	#define EOI 0xd9
57		59
58	/* Start of frame markers. */	60	/* Start of frame markers. */
59	#define SOF0 0xc0	61	#define SOF0 0xc0
60	#define SOF1 0xc1	62	#define SOF1 0xc1
61	#define SOF2 0xc2	63	#define SOF2 0xc2
62	#define SOF3 0xc3	64	#define SOF3 0xc3
63	#define SOF5 0xc5	65	#define SOF5 0xc5
64	#define SOF6 0xc6	66	#define SOF6 0xc6
65	#define SOF7 0xc7	67	#define SOF7 0xc7
66	#define SOF9 0xc9	68	#define SOF9 0xc9
67	#define SOF10 0xca	69	#define SOF10 0xca
68	#define SOF11 0xcb	70	#define SOF11 0xcb
69	#define SOF13 0xcd	71	#define SOF13 0xcd
70	#define SOF14 0xce	72	#define SOF14 0xce
71	#define SOF15 0xcf	73	#define SOF15 0xcf
72		74
73	static const unsigned char *	75	static const unsigned char *
74	_jpeg_skip_segment (const unsigned char *p)	76	_jpeg_skip_segment (const unsigned char *p)
75	{	77	{
76	int len;	78	int len;
77		79
78	p++;	80	p++;
79	len = (p[0] << 8) \| p[1];	81	len = (p[0] << 8) \| p[1];
80		82
81	return p + len;	83	return p + len;
82	}	84	}
83		85
84	static void	86	static void
85	_jpeg_extract_info (cairo_image_info_t info, const unsigned char p)	87	_jpeg_extract_info (cairo_image_info_t info, const unsigned char p)
86	{	88	{
87	info->width = (p[6] << 8) + p[7];	89	info->width = (p[6] << 8) + p[7];
88	info->height = (p[4] << 8) + p[5];	90	info->height = (p[4] << 8) + p[5];
89	info->num_components = p[8];	91	info->num_components = p[8];
90	info->bits_per_component = p[3];	92	info->bits_per_component = p[3];
91	}	93	}
92		94
93	cairo_int_status_t	95	cairo_int_status_t
94	_cairo_image_info_get_jpeg_info (cairo_image_info_t *info,	96	_cairo_image_info_get_jpeg_info (cairo_image_info_t *info,
95	const unsigned char *data,	97	const unsigned char *data,
96	long length)	98	long length)
97	{	99	{
98	const unsigned char *p = data;	100	const unsigned char *p = data;
99		101
100	while (p + 1 < data + length) {	102	while (p + 1 < data + length) {
101	if (*p != 0xff)	103	if (*p != 0xff)
102	return CAIRO_INT_STATUS_UNSUPPORTED;	104	return CAIRO_INT_STATUS_UNSUPPORTED;
103	p++;	105	p++;
104		106
105	switch (*p) {	107	switch (*p) {
106	/* skip fill bytes */	108	/* skip fill bytes */
107	case 0xff:	109	case 0xff:
108	p++;	110	p++;
109	break;	111	break;
110		112
111	case TEM:	113	case TEM:
112	case SOI:	114	case SOI:
113	case EOI:	115	case EOI:
114	p++;	116	p++;
115	break;	117	break;
116		118
117	case SOF0:	119	case SOF0:
118	case SOF1:	120	case SOF1:
119	case SOF2:	121	case SOF2:
120	case SOF3:	122	case SOF3:
121	case SOF5:	123	case SOF5:
122	case SOF6:	124	case SOF6:
123	case SOF7:	125	case SOF7:
124	case SOF9:	126	case SOF9:
125	case SOF10:	127	case SOF10:
126	case SOF11:	128	case SOF11:
127	case SOF13:	129	case SOF13:
128	case SOF14:	130	case SOF14:
129	case SOF15:	131	case SOF15:
130	/* Start of frame found. Extract the image parameters. */	132	/* Start of frame found. Extract the image parameters. */
131	if (p + 8 > data + length)	133	if (p + 8 > data + length)
132	return CAIRO_INT_STATUS_UNSUPPORTED;	134	return CAIRO_INT_STATUS_UNSUPPORTED;
133		135
134	_jpeg_extract_info (info, p);	136	_jpeg_extract_info (info, p);
135	return CAIRO_STATUS_SUCCESS;	137	return CAIRO_STATUS_SUCCESS;
136		138
137	default:	139	default:
138	if (p >= RST_begin && p <= RST_end) {	140	if (p >= RST_begin && p <= RST_end) {
139	p++;	141	p++;
140	break;	142	break;
141	}	143	}
142		144
143	if (p + 2 > data + length)	145	if (p + 2 > data + length)
144	return CAIRO_INT_STATUS_UNSUPPORTED;	146	return CAIRO_INT_STATUS_UNSUPPORTED;
145		147
146	p = _jpeg_skip_segment (p);	148	p = _jpeg_skip_segment (p);
147	break;	149	break;
148	}	150	}
149	}	151	}
150		152
151	return CAIRO_STATUS_SUCCESS;	153	return CAIRO_STATUS_SUCCESS;
152	}	154	}
153		155
154	/* JPEG 2000 (image/jp2)	156	/* JPEG 2000 (image/jp2)
155	*	157	*
156	* http://www.jpeg.org/public/15444-1annexi.pdf	158	* http://www.jpeg.org/public/15444-1annexi.pdf
157	*/	159	*/
158		160
159	#define JPX_FILETYPE 0x66747970	161	#define JPX_FILETYPE 0x66747970
160	#define JPX_JP2_HEADER 0x6A703268	162	#define JPX_JP2_HEADER 0x6A703268
161	#define JPX_IMAGE_HEADER 0x69686472	163	#define JPX_IMAGE_HEADER 0x69686472
162		164
163	static const unsigned char _jpx_signature[] = {	165	static const unsigned char _jpx_signature[] = {
164	0x00, 0x00, 0x00, 0x0c, 0x6a, 0x50, 0x20, 0x20, 0x0d, 0x0a, 0x87, 0x0a	166	0x00, 0x00, 0x00, 0x0c, 0x6a, 0x50, 0x20, 0x20, 0x0d, 0x0a, 0x87, 0x0a
165	};	167	};
166		168
167	static const unsigned char *	169	static const unsigned char *
168	_jpx_next_box (const unsigned char *p)	170	_jpx_next_box (const unsigned char *p)
169	{	171	{
170	return p + _get_be32 (p);	172	return p + _get_be32 (p);
171	}	173	}
172		174
173	static const unsigned char *	175	static const unsigned char *
174	_jpx_get_box_contents (const unsigned char *p)	176	_jpx_get_box_contents (const unsigned char *p)
175	{	177	{
176	return p + 8;	178	return p + 8;
177	}	179	}
178		180
179	static cairo_bool_t	181	static cairo_bool_t
180	_jpx_match_box (const unsigned char p, const unsigned char end, uint32_t type)	182	_jpx_match_box (const unsigned char p, const unsigned char end, uint32_t type)
181	{	183	{
182	uint32_t length;	184	uint32_t length;
183		185
184	if (p + 8 < end) {	186	if (p + 8 < end) {
185	length = _get_be32 (p);	187	length = _get_be32 (p);
186	if (_get_be32 (p + 4) == type && p + length < end)	188	if (_get_be32 (p + 4) == type && p + length < end)
187	return TRUE;	189	return TRUE;
188	}	190	}
189		191
190	return FALSE;	192	return FALSE;
191	}	193	}
192		194
193	static const unsigned char *	195	static const unsigned char *
194	_jpx_find_box (const unsigned char p, const unsigned char end, uint32_t type)	196	_jpx_find_box (const unsigned char p, const unsigned char end, uint32_t type)
195	{	197	{
196	while (p < end) {	198	while (p < end) {
197	if (_jpx_match_box (p, end, type))	199	if (_jpx_match_box (p, end, type))
198	return p;	200	return p;
199	p = _jpx_next_box (p);	201	p = _jpx_next_box (p);
200	}	202	}
201		203
202	return NULL;	204	return NULL;
203	}	205	}
204		206
205	static void	207	static void
206	_jpx_extract_info (const unsigned char p, cairo_image_info_t info)	208	_jpx_extract_info (const unsigned char p, cairo_image_info_t info)
207	{	209	{
208	info->height = _get_be32 (p);	210	info->height = _get_be32 (p);
209	info->width = _get_be32 (p + 4);	211	info->width = _get_be32 (p + 4);
210	info->num_components = (p[8] << 8) + p[9];	212	info->num_components = (p[8] << 8) + p[9];
211	info->bits_per_component = p[10];	213	info->bits_per_component = p[10];
212	}	214	}
213		215
214	cairo_int_status_t	216	cairo_int_status_t
215	_cairo_image_info_get_jpx_info (cairo_image_info_t *info,	217	_cairo_image_info_get_jpx_info (cairo_image_info_t *info,
216	const unsigned char *data,	218	const unsigned char *data,
217	unsigned long length)	219	unsigned long length)
218	{	220	{
219	const unsigned char *p = data;	221	const unsigned char *p = data;
220	const unsigned char *end = data + length;	222	const unsigned char *end = data + length;
221		223
222	/* First 12 bytes must be the JPEG 2000 signature box. */	224	/* First 12 bytes must be the JPEG 2000 signature box. */
223	if (length < ARRAY_LENGTH(_jpx_signature) \|\|	225	if (length < ARRAY_LENGTH(_jpx_signature) \|\|
224	memcmp(p, _jpx_signature, ARRAY_LENGTH(_jpx_signature)) != 0)	226	memcmp(p, _jpx_signature, ARRAY_LENGTH(_jpx_signature)) != 0)
225	return CAIRO_INT_STATUS_UNSUPPORTED;	227	return CAIRO_INT_STATUS_UNSUPPORTED;
226		228
227	p += ARRAY_LENGTH(_jpx_signature);	229	p += ARRAY_LENGTH(_jpx_signature);
228		230
229	/* Next box must be a File Type Box */	231	/* Next box must be a File Type Box */
230	if (! _jpx_match_box (p, end, JPX_FILETYPE))	232	if (! _jpx_match_box (p, end, JPX_FILETYPE))
231	return CAIRO_INT_STATUS_UNSUPPORTED;	233	return CAIRO_INT_STATUS_UNSUPPORTED;
232		234
233	p = _jpx_next_box (p);	235	p = _jpx_next_box (p);
234		236
235	/* Locate the JP2 header box. */	237	/* Locate the JP2 header box. */
236	p = _jpx_find_box (p, end, JPX_JP2_HEADER);	238	p = _jpx_find_box (p, end, JPX_JP2_HEADER);
237	if (!p)	239	if (!p)
238	return CAIRO_INT_STATUS_UNSUPPORTED;	240	return CAIRO_INT_STATUS_UNSUPPORTED;
239		241
240	/* Step into the JP2 header box. First box must be the Image	242	/* Step into the JP2 header box. First box must be the Image
241	* Header */	243	* Header */
242	p = _jpx_get_box_contents (p);	244	p = _jpx_get_box_contents (p);
243	if (! _jpx_match_box (p, end, JPX_IMAGE_HEADER))	245	if (! _jpx_match_box (p, end, JPX_IMAGE_HEADER))
244	return CAIRO_INT_STATUS_UNSUPPORTED;	246	return CAIRO_INT_STATUS_UNSUPPORTED;
245		247
246	/* Get the image info */	248	/* Get the image info */
247	p = _jpx_get_box_contents (p);	249	p = _jpx_get_box_contents (p);
248	_jpx_extract_info (p, info);	250	_jpx_extract_info (p, info);
249		251
250	return CAIRO_STATUS_SUCCESS;	252	return CAIRO_STATUS_SUCCESS;
251	}	253	}
252		254
253	/* PNG (image/png)	255	/* PNG (image/png)
254	*	256	*
255	* http://www.w3.org/TR/2003/REC-PNG-20031110/	257	* http://www.w3.org/TR/2003/REC-PNG-20031110/
256	*/	258	*/
257		259
258	#define PNG_IHDR 0x49484452	260	#define PNG_IHDR 0x49484452
259		261
260	static const unsigned char _png_magic[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };	262	static const unsigned char _png_magic[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
261		263
262	cairo_int_status_t	264	cairo_int_status_t
263	_cairo_image_info_get_png_info (cairo_image_info_t *info,	265	_cairo_image_info_get_png_info (cairo_image_info_t *info,
264	const unsigned char *data,	266	const unsigned char *data,
265	unsigned long length)	267	unsigned long length)
266	{	268	{
267	const unsigned char *p = data;	269	const unsigned char *p = data;
268	const unsigned char *end = data + length;	270	const unsigned char *end = data + length;
269		271
270	if (length < 8 \|\| memcmp (data, _png_magic, 8) != 0)	272	if (length < 8 \|\| memcmp (data, _png_magic, 8) != 0)
271	return CAIRO_INT_STATUS_UNSUPPORTED;	273	return CAIRO_INT_STATUS_UNSUPPORTED;
272		274
273	p += 8;	275	p += 8;
274		276
275	/* The first chunk must be IDHR. IDHR has 13 bytes of data plus	277	/* The first chunk must be IDHR. IDHR has 13 bytes of data plus
276	* the 12 bytes of overhead for the chunk. */	278	* the 12 bytes of overhead for the chunk. */
277	if (p + 13 + 12 > end)	279	if (p + 13 + 12 > end)
278	return CAIRO_INT_STATUS_UNSUPPORTED;	280	return CAIRO_INT_STATUS_UNSUPPORTED;
279		281
280	p += 4;	282	p += 4;
281	if (_get_be32 (p) != PNG_IHDR)	283	if (_get_be32 (p) != PNG_IHDR)
282	return CAIRO_INT_STATUS_UNSUPPORTED;	284	return CAIRO_INT_STATUS_UNSUPPORTED;
283		285
284	p += 4;	286	p += 4;
285	info->width = _get_be32 (p);	287	info->width = _get_be32 (p);
286	p += 4;	288	p += 4;
287	info->height = _get_be32 (p);	289	info->height = _get_be32 (p);
288		290
289	return CAIRO_STATUS_SUCCESS;	291	return CAIRO_STATUS_SUCCESS;
290	}	292	}

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(root)/programs/develop/libraries/cairo/src/cairo-image-info.c – Rev 1892 → 3959