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source: vbox/trunk/src/libs/libpng-1.2.54/pngwio.c@ 65642

最後變更 在這個檔案從65642是 58796,由 vboxsync 提交於 9 年 前

libpng 1.2.54 unmodified

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1
2/* pngwio.c - functions for data output
3 *
4 * Last changed in libpng 1.2.41 [December 3, 2009]
5 * Copyright (c) 1998-2009 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 output. Users who need
14 * special handling are expected to write functions that have the same
15 * arguments as these and perform similar functions, but that possibly
16 * use different output methods. Note that you shouldn't change these
17 * functions, but rather write replacement functions and then change
18 * them at run time with png_set_write_fn(...).
19 */
20
21#define PNG_INTERNAL
22#define PNG_NO_PEDANTIC_WARNINGS
23#include "png.h"
24#ifdef PNG_WRITE_SUPPORTED
25
26/* Write the data to whatever output you are using. The default routine
27 * writes to 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 writes. This should never be asked
30 * to write more than 64K on a 16 bit machine.
31 */
32
33void /* PRIVATE */
34png_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
35{
36 if (png_ptr->write_data_fn != NULL )
37 (*(png_ptr->write_data_fn))(png_ptr, data, length);
38 else
39 png_error(png_ptr, "Call to NULL write function");
40}
41
42#ifdef PNG_STDIO_SUPPORTED
43/* This is the function that does the actual writing of data. If you are
44 * not writing to a standard C stream, you should create a replacement
45 * write_data function and use it at run time with png_set_write_fn(), rather
46 * than changing the library.
47 */
48#ifndef USE_FAR_KEYWORD
49void PNGAPI
50png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
51{
52 png_uint_32 check;
53
54 if (png_ptr == NULL)
55 return;
56#ifdef _WIN32_WCE
57 if ( !WriteFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
58 check = 0;
59#else
60 check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr));
61#endif
62 if (check != length)
63 png_error(png_ptr, "Write Error");
64}
65#else
66/* This is the model-independent version. Since the standard I/O library
67 * can't handle far buffers in the medium and small models, we have to copy
68 * the data.
69 */
70
71#define NEAR_BUF_SIZE 1024
72#define MIN(a,b) (a <= b ? a : b)
73
74void PNGAPI
75png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
76{
77 png_uint_32 check;
78 png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */
79 png_FILE_p io_ptr;
80
81 if (png_ptr == NULL)
82 return;
83 /* Check if data really is near. If so, use usual code. */
84 near_data = (png_byte *)CVT_PTR_NOCHECK(data);
85 io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
86 if ((png_bytep)near_data == data)
87 {
88#ifdef _WIN32_WCE
89 if ( !WriteFile(io_ptr, near_data, length, &check, NULL) )
90 check = 0;
91#else
92 check = fwrite(near_data, 1, length, io_ptr);
93#endif
94 }
95 else
96 {
97 png_byte buf[NEAR_BUF_SIZE];
98 png_size_t written, remaining, err;
99 check = 0;
100 remaining = length;
101 do
102 {
103 written = MIN(NEAR_BUF_SIZE, remaining);
104 png_memcpy(buf, data, written); /* Copy far buffer to near buffer */
105#ifdef _WIN32_WCE
106 if ( !WriteFile(io_ptr, buf, written, &err, NULL) )
107 err = 0;
108#else
109 err = fwrite(buf, 1, written, io_ptr);
110#endif
111 if (err != written)
112 break;
113
114 else
115 check += err;
116
117 data += written;
118 remaining -= written;
119 }
120 while (remaining != 0);
121 }
122 if (check != length)
123 png_error(png_ptr, "Write Error");
124}
125
126#endif
127#endif
128
129/* This function is called to output any data pending writing (normally
130 * to disk). After png_flush is called, there should be no data pending
131 * writing in any buffers.
132 */
133#ifdef PNG_WRITE_FLUSH_SUPPORTED
134void /* PRIVATE */
135png_flush(png_structp png_ptr)
136{
137 if (png_ptr->output_flush_fn != NULL)
138 (*(png_ptr->output_flush_fn))(png_ptr);
139}
140
141#ifdef PNG_STDIO_SUPPORTED
142void PNGAPI
143png_default_flush(png_structp png_ptr)
144{
145#ifndef _WIN32_WCE
146 png_FILE_p io_ptr;
147#endif
148 if (png_ptr == NULL)
149 return;
150#ifndef _WIN32_WCE
151 io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr));
152 fflush(io_ptr);
153#endif
154}
155#endif
156#endif
157
158/* This function allows the application to supply new output functions for
159 * libpng if standard C streams aren't being used.
160 *
161 * This function takes as its arguments:
162 * png_ptr - pointer to a png output data structure
163 * io_ptr - pointer to user supplied structure containing info about
164 * the output functions. May be NULL.
165 * write_data_fn - pointer to a new output function that takes as its
166 * arguments a pointer to a png_struct, a pointer to
167 * data to be written, and a 32-bit unsigned int that is
168 * the number of bytes to be written. The new write
169 * function should call png_error(png_ptr, "Error msg")
170 * to exit and output any fatal error messages. May be
171 * NULL, in which case libpng's default function will
172 * be used.
173 * flush_data_fn - pointer to a new flush function that takes as its
174 * arguments a pointer to a png_struct. After a call to
175 * the flush function, there should be no data in any buffers
176 * or pending transmission. If the output method doesn't do
177 * any buffering of output, a function prototype must still be
178 * supplied although it doesn't have to do anything. If
179 * PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile
180 * time, output_flush_fn will be ignored, although it must be
181 * supplied for compatibility. May be NULL, in which case
182 * libpng's default function will be used, if
183 * PNG_WRITE_FLUSH_SUPPORTED is defined. This is not
184 * a good idea if io_ptr does not point to a standard
185 * *FILE structure.
186 */
187void PNGAPI
188png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
189 png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
190{
191 if (png_ptr == NULL)
192 return;
193
194 png_ptr->io_ptr = io_ptr;
195
196#ifdef PNG_STDIO_SUPPORTED
197 if (write_data_fn != NULL)
198 png_ptr->write_data_fn = write_data_fn;
199
200 else
201 png_ptr->write_data_fn = png_default_write_data;
202#else
203 png_ptr->write_data_fn = write_data_fn;
204#endif
205
206#ifdef PNG_WRITE_FLUSH_SUPPORTED
207#ifdef PNG_STDIO_SUPPORTED
208 if (output_flush_fn != NULL)
209 png_ptr->output_flush_fn = output_flush_fn;
210
211 else
212 png_ptr->output_flush_fn = png_default_flush;
213#else
214 png_ptr->output_flush_fn = output_flush_fn;
215#endif
216#endif /* PNG_WRITE_FLUSH_SUPPORTED */
217
218 /* It is an error to read while writing a png file */
219 if (png_ptr->read_data_fn != NULL)
220 {
221 png_ptr->read_data_fn = NULL;
222 png_warning(png_ptr,
223 "Attempted to set both read_data_fn and write_data_fn in");
224 png_warning(png_ptr,
225 "the same structure. Resetting read_data_fn to NULL.");
226 }
227}
228
229#ifdef USE_FAR_KEYWORD
230#ifdef _MSC_VER
231void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
232{
233 void *near_ptr;
234 void FAR *far_ptr;
235 FP_OFF(near_ptr) = FP_OFF(ptr);
236 far_ptr = (void FAR *)near_ptr;
237
238 if (check != 0)
239 if (FP_SEG(ptr) != FP_SEG(far_ptr))
240 png_error(png_ptr, "segment lost in conversion");
241
242 return(near_ptr);
243}
244# else
245void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
246{
247 void *near_ptr;
248 void FAR *far_ptr;
249 near_ptr = (void FAR *)ptr;
250 far_ptr = (void FAR *)near_ptr;
251
252 if (check != 0)
253 if (far_ptr != ptr)
254 png_error(png_ptr, "segment lost in conversion");
255
256 return(near_ptr);
257}
258# endif
259# endif
260#endif /* PNG_WRITE_SUPPORTED */
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