File: pngwio.c

package info (click to toggle)
libpng 1.0.2b-0.1
  • links: PTS
  • area: main
  • in suites: slink
  • size: 1,152 kB
  • ctags: 1,040
  • sloc: ansic: 15,341; pascal: 141; makefile: 81; sh: 5
file content (213 lines) | stat: -rw-r--r-- 6,910 bytes parent folder | download
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

/* pngwio.c - functions for data output
 *
 * libpng 1.0.2b - January 6, 1999
 * For conditions of distribution and use, see copyright notice in png.h
 * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
 * Copyright (c) 1996, 1997 Andreas Dilger
 * Copyright (c) 1998, 1999 Glenn Randers-Pehrson
 *
 * This file provides a location for all output.  Users who need
 * special handling are expected to write functions that have the same
 * arguments as these and perform similar functions, but that possibly
 * use different output methods.  Note that you shouldn't change these
 * functions, but rather write replacement functions and then change
 * them at run time with png_set_write_fn(...).
 */

#define PNG_INTERNAL
#include "png.h"

/* Write the data to whatever output you are using.  The default routine
   writes to a file pointer.  Note that this routine sometimes gets called
   with very small lengths, so you should implement some kind of simple
   buffering if you are using unbuffered writes.  This should never be asked
   to write more than 64K on a 16 bit machine.  */

void
png_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   if (png_ptr->write_data_fn != NULL )
      (*(png_ptr->write_data_fn))(png_ptr, data, length);
   else
      png_error(png_ptr, "Call to NULL write function");
}

#if !defined(PNG_NO_STDIO)
/* This is the function that does the actual writing of data.  If you are
   not writing to a standard C stream, you should create a replacement
   write_data function and use it at run time with png_set_write_fn(), rather
   than changing the library. */
#ifndef USE_FAR_KEYWORD
static void
png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   png_uint_32 check;

   check = fwrite(data, 1, length, (FILE *)(png_ptr->io_ptr));
   if (check != length)
   {
      png_error(png_ptr, "Write Error");
   }
}
#else
/* this is the model-independent version. Since the standard I/O library
   can't handle far buffers in the medium and small models, we have to copy
   the data.
*/

#define NEAR_BUF_SIZE 1024
#define MIN(a,b) (a <= b ? a : b)

static void
png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   png_uint_32 check;
   png_byte *near_data;  /* Needs to be "png_byte *" instead of "png_bytep" */
   FILE *io_ptr;

   /* Check if data really is near. If so, use usual code. */
   near_data = (png_byte *)CVT_PTR_NOCHECK(data);
   io_ptr = (FILE *)CVT_PTR(png_ptr->io_ptr);
   if ((png_bytep)near_data == data)
   {
      check = fwrite(near_data, 1, length, io_ptr);
   }
   else
   {
      png_byte buf[NEAR_BUF_SIZE];
      png_size_t written, remaining, err;
      check = 0;
      remaining = length;
      do
      {
         written = MIN(NEAR_BUF_SIZE, remaining);
         png_memcpy(buf, data, written); /* copy far buffer to near buffer */
         err = fwrite(buf, 1, written, io_ptr);
         if (err != written)
            break;
         else
            check += err;
         data += written;
         remaining -= written;
      }
      while (remaining != 0);
   }
   if (check != length)
   {
      png_error(png_ptr, "Write Error");
   }
}

#endif
#endif

/* This function is called to output any data pending writing (normally
   to disk).  After png_flush is called, there should be no data pending
   writing in any buffers. */
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
void
png_flush(png_structp png_ptr)
{
   if (png_ptr->output_flush_fn != NULL)
      (*(png_ptr->output_flush_fn))(png_ptr);
}

#if !defined(PNG_NO_STDIO)
static void
png_default_flush(png_structp png_ptr)
{
   FILE *io_ptr;
   io_ptr = (FILE *)CVT_PTR((png_ptr->io_ptr));
   if (io_ptr != NULL)
      fflush(io_ptr);
}
#endif
#endif

/* This function allows the application to supply new output functions for
   libpng if standard C streams aren't being used.

   This function takes as its arguments:
   png_ptr       - pointer to a png output data structure
   io_ptr        - pointer to user supplied structure containing info about
                   the output functions.  May be NULL.
   write_data_fn - pointer to a new output function that takes as its
                   arguments a pointer to a png_struct, a pointer to
                   data to be written, and a 32-bit unsigned int that is
                   the number of bytes to be written.  The new write
                   function should call png_error(png_ptr, "Error msg")
                   to exit and output any fatal error messages.
   flush_data_fn - pointer to a new flush function that takes as its
                   arguments a pointer to a png_struct.  After a call to
                   the flush function, there should be no data in any buffers
                   or pending transmission.  If the output method doesn't do
                   any buffering of ouput, a function prototype must still be
                   supplied although it doesn't have to do anything.  If
                   PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
                   time, output_flush_fn will be ignored, although it must be
                   supplied for compatibility. */
void
png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
   png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
{
   png_ptr->io_ptr = io_ptr;

#if !defined(PNG_NO_STDIO)
   if (write_data_fn != NULL)
      png_ptr->write_data_fn = write_data_fn;
   else
      png_ptr->write_data_fn = png_default_write_data;
#else
   png_ptr->write_data_fn = write_data_fn;
#endif

#if defined(PNG_WRITE_FLUSH_SUPPORTED)
#if !defined(PNG_NO_STDIO)
   if (output_flush_fn != NULL)
      png_ptr->output_flush_fn = output_flush_fn;
   else
      png_ptr->output_flush_fn = png_default_flush;
#else
   png_ptr->output_flush_fn = output_flush_fn;
#endif
#endif /* PNG_WRITE_FLUSH_SUPPORTED */

   /* It is an error to read while writing a png file */
   if (png_ptr->read_data_fn != NULL)
   {
      png_ptr->read_data_fn = NULL;
      png_warning(png_ptr,
         "Attempted to set both read_data_fn and write_data_fn in");
      png_warning(png_ptr,
         "the same structure.  Resetting read_data_fn to NULL.");
   }
}

#if defined(USE_FAR_KEYWORD)
#if defined(_MSC_VER)
void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check)
{
   void *near_ptr;
   void FAR *far_ptr;
   FP_OFF(near_ptr) = FP_OFF(ptr);
   far_ptr = (void FAR *)near_ptr;
   if(check != 0)
      if(FP_SEG(ptr) != FP_SEG(far_ptr))
         png_error(png_ptr,"segment lost in conversion");
   return(near_ptr);
}
#  else
void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check)
{
   void *near_ptr;
   void FAR *far_ptr;
   near_ptr = (void FAR *)ptr;
   far_ptr = (void FAR *)near_ptr;
   if(check != 0)
      if(far_ptr != ptr)
         png_error(png_ptr,"segment lost in conversion");
   return(near_ptr);
}
#   endif
#   endif