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| 1 | |
| 2 /* pngwio.c - functions for data output | |
| 3 * | |
| 4 * Last changed in libpng 1.6.15 [November 20, 2014] | |
| 5 * Copyright (c) 1998-2014 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 #include "pngpriv.h" | |
| 22 | |
| 23 #ifdef PNG_WRITE_SUPPORTED | |
| 24 | |
| 25 /* Write the data to whatever output you are using. The default routine | |
| 26 * writes to a file pointer. Note that this routine sometimes gets called | |
| 27 * with very small lengths, so you should implement some kind of simple | |
| 28 * buffering if you are using unbuffered writes. This should never be asked | |
| 29 * to write more than 64K on a 16-bit machine. | |
| 30 */ | |
| 31 | |
| 32 void /* PRIVATE */ | |
| 33 png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length) | |
| 34 { | |
| 35 /* NOTE: write_data_fn must not change the buffer! */ | |
| 36 if (png_ptr->write_data_fn != NULL ) | |
| 37 (*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data), | |
| 38 length); | |
| 39 | |
| 40 else | |
| 41 png_error(png_ptr, "Call to NULL write function"); | |
| 42 } | |
| 43 | |
| 44 #ifdef PNG_STDIO_SUPPORTED | |
| 45 /* This is the function that does the actual writing of data. If you are | |
| 46 * not writing to a standard C stream, you should create a replacement | |
| 47 * write_data function and use it at run time with png_set_write_fn(), rather | |
| 48 * than changing the library. | |
| 49 */ | |
| 50 void PNGCBAPI | |
| 51 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) | |
| 52 { | |
| 53 png_size_t check; | |
| 54 | |
| 55 if (png_ptr == NULL) | |
| 56 return; | |
| 57 | |
| 58 check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr)); | |
| 59 | |
| 60 if (check != length) | |
| 61 png_error(png_ptr, "Write Error"); | |
| 62 } | |
| 63 #endif | |
| 64 | |
| 65 /* This function is called to output any data pending writing (normally | |
| 66 * to disk). After png_flush is called, there should be no data pending | |
| 67 * writing in any buffers. | |
| 68 */ | |
| 69 #ifdef PNG_WRITE_FLUSH_SUPPORTED | |
| 70 void /* PRIVATE */ | |
| 71 png_flush(png_structrp png_ptr) | |
| 72 { | |
| 73 if (png_ptr->output_flush_fn != NULL) | |
| 74 (*(png_ptr->output_flush_fn))(png_ptr); | |
| 75 } | |
| 76 | |
| 77 # ifdef PNG_STDIO_SUPPORTED | |
| 78 void PNGCBAPI | |
| 79 png_default_flush(png_structp png_ptr) | |
| 80 { | |
| 81 png_FILE_p io_ptr; | |
| 82 | |
| 83 if (png_ptr == NULL) | |
| 84 return; | |
| 85 | |
| 86 io_ptr = png_voidcast(png_FILE_p, (png_ptr->io_ptr)); | |
| 87 fflush(io_ptr); | |
| 88 } | |
| 89 # endif | |
| 90 #endif | |
| 91 | |
| 92 /* This function allows the application to supply new output functions for | |
| 93 * libpng if standard C streams aren't being used. | |
| 94 * | |
| 95 * This function takes as its arguments: | |
| 96 * png_ptr - pointer to a png output data structure | |
| 97 * io_ptr - pointer to user supplied structure containing info about | |
| 98 * the output functions. May be NULL. | |
| 99 * write_data_fn - pointer to a new output function that takes as its | |
| 100 * arguments a pointer to a png_struct, a pointer to | |
| 101 * data to be written, and a 32-bit unsigned int that is | |
| 102 * the number of bytes to be written. The new write | |
| 103 * function should call png_error(png_ptr, "Error msg") | |
| 104 * to exit and output any fatal error messages. May be | |
| 105 * NULL, in which case libpng's default function will | |
| 106 * be used. | |
| 107 * flush_data_fn - pointer to a new flush function that takes as its | |
| 108 * arguments a pointer to a png_struct. After a call to | |
| 109 * the flush function, there should be no data in any buffers | |
| 110 * or pending transmission. If the output method doesn't do | |
| 111 * any buffering of output, a function prototype must still be | |
| 112 * supplied although it doesn't have to do anything. If | |
| 113 * PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile | |
| 114 * time, output_flush_fn will be ignored, although it must be | |
| 115 * supplied for compatibility. May be NULL, in which case | |
| 116 * libpng's default function will be used, if | |
| 117 * PNG_WRITE_FLUSH_SUPPORTED is defined. This is not | |
| 118 * a good idea if io_ptr does not point to a standard | |
| 119 * *FILE structure. | |
| 120 */ | |
| 121 void PNGAPI | |
| 122 png_set_write_fn(png_structrp png_ptr, png_voidp io_ptr, | |
| 123 png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn) | |
| 124 { | |
| 125 if (png_ptr == NULL) | |
| 126 return; | |
| 127 | |
| 128 png_ptr->io_ptr = io_ptr; | |
| 129 | |
| 130 #ifdef PNG_STDIO_SUPPORTED | |
| 131 if (write_data_fn != NULL) | |
| 132 png_ptr->write_data_fn = write_data_fn; | |
| 133 | |
| 134 else | |
| 135 png_ptr->write_data_fn = png_default_write_data; | |
| 136 #else | |
| 137 png_ptr->write_data_fn = write_data_fn; | |
| 138 #endif | |
| 139 | |
| 140 #ifdef PNG_WRITE_FLUSH_SUPPORTED | |
| 141 # ifdef PNG_STDIO_SUPPORTED | |
| 142 | |
| 143 if (output_flush_fn != NULL) | |
| 144 png_ptr->output_flush_fn = output_flush_fn; | |
| 145 | |
| 146 else | |
| 147 png_ptr->output_flush_fn = png_default_flush; | |
| 148 | |
| 149 # else | |
| 150 png_ptr->output_flush_fn = output_flush_fn; | |
| 151 # endif | |
| 152 #else | |
| 153 PNG_UNUSED(output_flush_fn) | |
| 154 #endif /* WRITE_FLUSH */ | |
| 155 | |
| 156 #ifdef PNG_READ_SUPPORTED | |
| 157 /* It is an error to read while writing a png file */ | |
| 158 if (png_ptr->read_data_fn != NULL) | |
| 159 { | |
| 160 png_ptr->read_data_fn = NULL; | |
| 161 | |
| 162 png_warning(png_ptr, | |
| 163 "Can't set both read_data_fn and write_data_fn in the" | |
| 164 " same structure"); | |
| 165 } | |
| 166 #endif | |
| 167 } | |
| 168 #endif /* WRITE */ | |
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