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1 | ||
2 | /* pngwio.c - functions for data output | |
3 | * | |
4 | * libpng 1.2.6 - August 15, 2004 | |
5 | * For conditions of distribution and use, see copyright notice in png.h | |
6 | * Copyright (c) 1998-2004 Glenn Randers-Pehrson | |
7 | * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) | |
8 | * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) | |
9 | * | |
10 | * This file provides a location for all output. Users who need | |
11 | * special handling are expected to write functions that have the same | |
12 | * arguments as these and perform similar functions, but that possibly | |
13 | * use different output methods. Note that you shouldn't change these | |
14 | * functions, but rather write replacement functions and then change | |
15 | * them at run time with png_set_write_fn(...). | |
16 | */ | |
17 | ||
18 | #define PNG_INTERNAL | |
19 | #include "png.h" | |
20 | #ifdef PNG_WRITE_SUPPORTED | |
21 | ||
22 | /* Write the data to whatever output you are using. The default routine | |
23 | writes to a file pointer. Note that this routine sometimes gets called | |
24 | with very small lengths, so you should implement some kind of simple | |
25 | buffering if you are using unbuffered writes. This should never be asked | |
26 | to write more than 64K on a 16 bit machine. */ | |
27 | ||
28 | void /* PRIVATE */ | |
29 | png_write_data(png_structp png_ptr, png_bytep data, png_size_t length) | |
30 | { | |
31 | if (png_ptr->write_data_fn != NULL ) | |
32 | (*(png_ptr->write_data_fn))(png_ptr, data, length); | |
33 | else | |
34 | png_error(png_ptr, "Call to NULL write function"); | |
35 | } | |
36 | ||
37 | #if !defined(PNG_NO_STDIO) | |
38 | /* This is the function that does the actual writing of data. If you are | |
39 | not writing to a standard C stream, you should create a replacement | |
40 | write_data function and use it at run time with png_set_write_fn(), rather | |
41 | than changing the library. */ | |
42 | #ifndef USE_FAR_KEYWORD | |
43 | void PNGAPI | |
44 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) | |
45 | { | |
46 | png_uint_32 check; | |
47 | ||
48 | #if defined(_WIN32_WCE) | |
49 | if ( !WriteFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) ) | |
50 | check = 0; | |
51 | #else | |
52 | check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr)); | |
53 | #endif | |
54 | if (check != length) | |
55 | png_error(png_ptr, "Write Error"); | |
56 | } | |
57 | #else | |
58 | /* this is the model-independent version. Since the standard I/O library | |
59 | can't handle far buffers in the medium and small models, we have to copy | |
60 | the data. | |
61 | */ | |
62 | ||
63 | #define NEAR_BUF_SIZE 1024 | |
64 | #define MIN(a,b) (a <= b ? a : b) | |
65 | ||
66 | void PNGAPI | |
67 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) | |
68 | { | |
69 | png_uint_32 check; | |
70 | png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */ | |
71 | png_FILE_p io_ptr; | |
72 | ||
73 | /* Check if data really is near. If so, use usual code. */ | |
74 | near_data = (png_byte *)CVT_PTR_NOCHECK(data); | |
75 | io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr); | |
76 | if ((png_bytep)near_data == data) | |
77 | { | |
78 | #if defined(_WIN32_WCE) | |
79 | if ( !WriteFile(io_ptr, near_data, length, &check, NULL) ) | |
80 | check = 0; | |
81 | #else | |
82 | check = fwrite(near_data, 1, length, io_ptr); | |
83 | #endif | |
84 | } | |
85 | else | |
86 | { | |
87 | png_byte buf[NEAR_BUF_SIZE]; | |
88 | png_size_t written, remaining, err; | |
89 | check = 0; | |
90 | remaining = length; | |
91 | do | |
92 | { | |
93 | written = MIN(NEAR_BUF_SIZE, remaining); | |
94 | png_memcpy(buf, data, written); /* copy far buffer to near buffer */ | |
95 | #if defined(_WIN32_WCE) | |
96 | if ( !WriteFile(io_ptr, buf, written, &err, NULL) ) | |
97 | err = 0; | |
98 | #else | |
99 | err = fwrite(buf, 1, written, io_ptr); | |
100 | #endif | |
101 | if (err != written) | |
102 | break; | |
103 | else | |
104 | check += err; | |
105 | data += written; | |
106 | remaining -= written; | |
107 | } | |
108 | while (remaining != 0); | |
109 | } | |
110 | if (check != length) | |
111 | png_error(png_ptr, "Write Error"); | |
112 | } | |
113 | ||
114 | #endif | |
115 | #endif | |
116 | ||
117 | /* This function is called to output any data pending writing (normally | |
118 | to disk). After png_flush is called, there should be no data pending | |
119 | writing in any buffers. */ | |
120 | #if defined(PNG_WRITE_FLUSH_SUPPORTED) | |
121 | void /* PRIVATE */ | |
122 | png_flush(png_structp png_ptr) | |
123 | { | |
124 | if (png_ptr->output_flush_fn != NULL) | |
125 | (*(png_ptr->output_flush_fn))(png_ptr); | |
126 | } | |
127 | ||
128 | #if !defined(PNG_NO_STDIO) | |
129 | void PNGAPI | |
130 | png_default_flush(png_structp png_ptr) | |
131 | { | |
132 | #if !defined(_WIN32_WCE) | |
133 | png_FILE_p io_ptr; | |
134 | io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr)); | |
135 | if (io_ptr != NULL) | |
136 | fflush(io_ptr); | |
137 | #endif | |
138 | } | |
139 | #endif | |
140 | #endif | |
141 | ||
142 | /* This function allows the application to supply new output functions for | |
143 | libpng if standard C streams aren't being used. | |
144 | ||
145 | This function takes as its arguments: | |
146 | png_ptr - pointer to a png output data structure | |
147 | io_ptr - pointer to user supplied structure containing info about | |
148 | the output functions. May be NULL. | |
149 | write_data_fn - pointer to a new output function that takes as its | |
150 | arguments a pointer to a png_struct, a pointer to | |
151 | data to be written, and a 32-bit unsigned int that is | |
152 | the number of bytes to be written. The new write | |
153 | function should call png_error(png_ptr, "Error msg") | |
154 | to exit and output any fatal error messages. | |
155 | flush_data_fn - pointer to a new flush function that takes as its | |
156 | arguments a pointer to a png_struct. After a call to | |
157 | the flush function, there should be no data in any buffers | |
158 | or pending transmission. If the output method doesn't do | |
159 | any buffering of ouput, a function prototype must still be | |
160 | supplied although it doesn't have to do anything. If | |
161 | PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile | |
162 | time, output_flush_fn will be ignored, although it must be | |
163 | supplied for compatibility. */ | |
164 | void PNGAPI | |
165 | png_set_write_fn(png_structp png_ptr, png_voidp io_ptr, | |
166 | png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn) | |
167 | { | |
168 | png_ptr->io_ptr = io_ptr; | |
169 | ||
170 | #if !defined(PNG_NO_STDIO) | |
171 | if (write_data_fn != NULL) | |
172 | png_ptr->write_data_fn = write_data_fn; | |
173 | else | |
174 | png_ptr->write_data_fn = png_default_write_data; | |
175 | #else | |
176 | png_ptr->write_data_fn = write_data_fn; | |
177 | #endif | |
178 | ||
179 | #if defined(PNG_WRITE_FLUSH_SUPPORTED) | |
180 | #if !defined(PNG_NO_STDIO) | |
181 | if (output_flush_fn != NULL) | |
182 | png_ptr->output_flush_fn = output_flush_fn; | |
183 | else | |
184 | png_ptr->output_flush_fn = png_default_flush; | |
185 | #else | |
186 | png_ptr->output_flush_fn = output_flush_fn; | |
187 | #endif | |
188 | #endif /* PNG_WRITE_FLUSH_SUPPORTED */ | |
189 | ||
190 | /* It is an error to read while writing a png file */ | |
191 | if (png_ptr->read_data_fn != NULL) | |
192 | { | |
193 | png_ptr->read_data_fn = NULL; | |
194 | png_warning(png_ptr, | |
195 | "Attempted to set both read_data_fn and write_data_fn in"); | |
196 | png_warning(png_ptr, | |
197 | "the same structure. Resetting read_data_fn to NULL."); | |
198 | } | |
199 | } | |
200 | ||
201 | #if defined(USE_FAR_KEYWORD) | |
202 | #if defined(_MSC_VER) | |
203 | void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) | |
204 | { | |
205 | void *near_ptr; | |
206 | void FAR *far_ptr; | |
207 | FP_OFF(near_ptr) = FP_OFF(ptr); | |
208 | far_ptr = (void FAR *)near_ptr; | |
209 | if(check != 0) | |
210 | if(FP_SEG(ptr) != FP_SEG(far_ptr)) | |
211 | png_error(png_ptr,"segment lost in conversion"); | |
212 | return(near_ptr); | |
213 | } | |
214 | # else | |
215 | void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) | |
216 | { | |
217 | void *near_ptr; | |
218 | void FAR *far_ptr; | |
219 | near_ptr = (void FAR *)ptr; | |
220 | far_ptr = (void FAR *)near_ptr; | |
221 | if(check != 0) | |
222 | if(far_ptr != ptr) | |
223 | png_error(png_ptr,"segment lost in conversion"); | |
224 | return(near_ptr); | |
225 | } | |
226 | # endif | |
227 | # endif | |
228 | #endif /* PNG_WRITE_SUPPORTED */ |