Visualization Library 2.0.0-b5

A lightweight C++ OpenGL middleware for 2D/3D graphics

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pngrio.c
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1 
2 /* pngrio.c - functions for data input
3  *
4  * Copyright (c) 1998-2002,2004,2006-2010 Glenn Randers-Pehrson
5  * Copyright (c) 1998-2010 Glenn Randers-Pehrson
6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8  *
9  * This code is released under the libpng license.
10  * For conditions of distribution and use, see the disclaimer
11  * and license in png.h
12  *
13  * This file provides a location for all input. Users who need
14  * special handling are expected to write a function that has the same
15  * arguments as this and performs a similar function, but that possibly
16  * has a different input method. Note that you shouldn't change this
17  * function, but rather write a replacement function and then make
18  * libpng use it at run time with png_set_read_fn(...).
19  */
20 
21 #define PNG_INTERNAL
22 #define PNG_NO_PEDANTIC_WARNINGS
23 #include "png.h"
24 #ifdef PNG_READ_SUPPORTED
25 
26 /* Read the data from whatever input you are using. The default routine
27  * reads from a file pointer. Note that this routine sometimes gets called
28  * with very small lengths, so you should implement some kind of simple
29  * buffering if you are using unbuffered reads. This should never be asked
30  * to read more then 64K on a 16 bit machine.
31  */
32 void /* PRIVATE */
34 {
35  png_debug1(4, "reading %d bytes", (int)length);
36 
37  if (png_ptr->read_data_fn != NULL)
38  (*(png_ptr->read_data_fn))(png_ptr, data, length);
39  else
40  png_error(png_ptr, "Call to NULL read function");
41 }
42 
43 #ifdef PNG_STDIO_SUPPORTED
44 /* This is the function that does the actual reading of data. If you are
45  * not reading from a standard C stream, you should create a replacement
46  * read_data function and use it at run time with png_set_read_fn(), rather
47  * than changing the library.
48  */
49 #ifndef USE_FAR_KEYWORD
50 void PNGAPI
52 {
53  png_size_t check;
54 
55  if (png_ptr == NULL)
56  return;
57  /* fread() returns 0 on error, so it is OK to store this in a png_size_t
58  * instead of an int, which is what fread() actually returns.
59  */
60 #ifdef _WIN32_WCE
61  if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
62  check = 0;
63 #else
64  check = (png_size_t)fread(data, (png_size_t)1, length,
65  (png_FILE_p)png_ptr->io_ptr);
66 #endif
67 
68  if (check != length)
69  png_error(png_ptr, "Read Error");
70 }
71 #else
72 /* This is the model-independent version. Since the standard I/O library
73  can't handle far buffers in the medium and small models, we have to copy
74  the data.
75 */
76 
77 #define NEAR_BUF_SIZE 1024
78 #define MIN(a,b) (a <= b ? a : b)
79 
80 static void PNGAPI
82 {
83  int check;
84  png_byte *n_data;
86 
87  if (png_ptr == NULL)
88  return;
89  /* Check if data really is near. If so, use usual code. */
90  n_data = (png_byte *)CVT_PTR_NOCHECK(data);
91  io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
92  if ((png_bytep)n_data == data)
93  {
94 #ifdef _WIN32_WCE
95  if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check,
96  NULL) )
97  check = 0;
98 #else
99  check = fread(n_data, 1, length, io_ptr);
100 #endif
101  }
102  else
103  {
104  png_byte buf[NEAR_BUF_SIZE];
105  png_size_t read, remaining, err;
106  check = 0;
107  remaining = length;
108  do
109  {
110  read = MIN(NEAR_BUF_SIZE, remaining);
111 #ifdef _WIN32_WCE
112  if ( !ReadFile((HANDLE)(io_ptr), buf, read, &err, NULL) )
113  err = 0;
114 #else
115  err = fread(buf, (png_size_t)1, read, io_ptr);
116 #endif
117  png_memcpy(data, buf, read); /* copy far buffer to near buffer */
118  if (err != read)
119  break;
120  else
121  check += err;
122  data += read;
123  remaining -= read;
124  }
125  while (remaining != 0);
126  }
127  if ((png_uint_32)check != (png_uint_32)length)
128  png_error(png_ptr, "read Error");
129 }
130 #endif
131 #endif
132 
133 /* This function allows the application to supply a new input function
134  * for libpng if standard C streams aren't being used.
135  *
136  * This function takes as its arguments:
137  * png_ptr - pointer to a png input data structure
138  * io_ptr - pointer to user supplied structure containing info about
139  * the input functions. May be NULL.
140  * read_data_fn - pointer to a new input function that takes as its
141  * arguments a pointer to a png_struct, a pointer to
142  * a location where input data can be stored, and a 32-bit
143  * unsigned int that is the number of bytes to be read.
144  * To exit and output any fatal error messages the new write
145  * function should call png_error(png_ptr, "Error msg").
146  * May be NULL, in which case libpng's default function will
147  * be used.
148  */
149 void PNGAPI
151  png_rw_ptr read_data_fn)
152 {
153  if (png_ptr == NULL)
154  return;
155  png_ptr->io_ptr = io_ptr;
156 
157 #ifdef PNG_STDIO_SUPPORTED
158  if (read_data_fn != NULL)
159  png_ptr->read_data_fn = read_data_fn;
160  else
161  png_ptr->read_data_fn = png_default_read_data;
162 #else
163  png_ptr->read_data_fn = read_data_fn;
164 #endif
165 
166  /* It is an error to write to a read device */
167  if (png_ptr->write_data_fn != NULL)
168  {
169  png_ptr->write_data_fn = NULL;
170  png_warning(png_ptr,
171  "It's an error to set both read_data_fn and write_data_fn in the ");
172  png_warning(png_ptr,
173  "same structure. Resetting write_data_fn to NULL.");
174  }
175 
176 #ifdef PNG_WRITE_FLUSH_SUPPORTED
177  png_ptr->output_flush_fn = NULL;
178 #endif
179 }
180 #endif /* PNG_READ_SUPPORTED */
GLenum GLuint GLenum GLsizei length
int read(int fd, char *buf, int nbytes)
Definition: tif_acorn.c:331
#define NULL
Definition: ftobjs.h:61
png_byte FAR * png_bytep
Definition: pngconf.h:1328
#define MIN(a, b)
Definition: jpegint.h:269
#define CVT_PTR_NOCHECK(ptr)
Definition: pngconf.h:1636
GLenum GLuint GLenum GLsizei const GLchar * buf
#define PNGAPI
Definition: pngconf.h:1517
png_struct FAR * png_structp
Definition: png.h:973
#define png_error(s1, s2)
Definition: pngusr.h:25
unsigned char png_byte
Definition: pngconf.h:1251
#define png_memcpy
Definition: pngconf.h:1661
GLsizei GLsizei GLenum GLenum const GLvoid * data
void PNGAPI png_warning(png_structp png_ptr, png_const_charp warning_message)
Definition: pngerror.c:111
#define png_debug1(l, m, p1)
Definition: png.h:2464
void PNGAPI png_set_read_fn(png_structp png_ptr, png_voidp io_ptr, png_rw_ptr read_data_fn)
Definition: pngrio.c:150
png_voidp io_ptr
Definition: png.h:1819
void png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
Definition: pngrio.c:33
png_voidp png_rw_ptr read_data_fn
Definition: png.h:1823
void FAR * png_voidp
Definition: pngconf.h:1327
size_t png_size_t
Definition: pngconf.h:1259
void PNGAPI png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
Definition: pngrio.c:51
unsigned long png_uint_32
Definition: pngconf.h:1247
FILE * png_FILE_p
Definition: pngconf.h:1341
#define CVT_PTR(ptr)
Definition: pngconf.h:1635