/src/FreeImage/Source/LibPNG/pngwio.c
C | 254 lines | 144 code | 41 blank | 69 comment | 36 complexity | 42ab7f5ea0cd388d24c038b1c2e911bd MD5 | raw file
1 2/* pngwio.c - functions for data output 3 * 4 * Last changed in libpng 1.5.0 [January 6, 2011] 5 * Copyright (c) 1998-2011 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 32void /* PRIVATE */ 33png_write_data(png_structp 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_bytep)data, length); 38 39 else 40 png_error(png_ptr, "Call to NULL write function"); 41} 42 43#ifdef PNG_STDIO_SUPPORTED 44/* This is the function that does the actual writing of data. If you are 45 * not writing to a standard C stream, you should create a replacement 46 * write_data function and use it at run time with png_set_write_fn(), rather 47 * than changing the library. 48 */ 49#ifndef USE_FAR_KEYWORD 50void PNGCBAPI 51png_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#else 64/* This is the model-independent version. Since the standard I/O library 65 * can't handle far buffers in the medium and small models, we have to copy 66 * the data. 67 */ 68 69#define NEAR_BUF_SIZE 1024 70#define MIN(a,b) (a <= b ? a : b) 71 72void PNGCBAPI 73png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) 74{ 75 png_uint_32 check; 76 png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */ 77 png_FILE_p io_ptr; 78 79 if (png_ptr == NULL) 80 return; 81 82 /* Check if data really is near. If so, use usual code. */ 83 near_data = (png_byte *)CVT_PTR_NOCHECK(data); 84 io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr); 85 86 if ((png_bytep)near_data == data) 87 { 88 check = fwrite(near_data, 1, length, io_ptr); 89 } 90 91 else 92 { 93 png_byte buf[NEAR_BUF_SIZE]; 94 png_size_t written, remaining, err; 95 check = 0; 96 remaining = length; 97 98 do 99 { 100 written = MIN(NEAR_BUF_SIZE, remaining); 101 png_memcpy(buf, data, written); /* Copy far buffer to near buffer */ 102 err = fwrite(buf, 1, written, io_ptr); 103 104 if (err != written) 105 break; 106 107 else 108 check += err; 109 110 data += written; 111 remaining -= written; 112 } 113 while (remaining != 0); 114 } 115 116 if (check != length) 117 png_error(png_ptr, "Write Error"); 118} 119 120#endif 121#endif 122 123/* This function is called to output any data pending writing (normally 124 * to disk). After png_flush is called, there should be no data pending 125 * writing in any buffers. 126 */ 127#ifdef PNG_WRITE_FLUSH_SUPPORTED 128void /* PRIVATE */ 129png_flush(png_structp png_ptr) 130{ 131 if (png_ptr->output_flush_fn != NULL) 132 (*(png_ptr->output_flush_fn))(png_ptr); 133} 134 135# ifdef PNG_STDIO_SUPPORTED 136void PNGCBAPI 137png_default_flush(png_structp png_ptr) 138{ 139 png_FILE_p io_ptr; 140 141 if (png_ptr == NULL) 142 return; 143 144 io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr)); 145 fflush(io_ptr); 146} 147# endif 148#endif 149 150/* This function allows the application to supply new output functions for 151 * libpng if standard C streams aren't being used. 152 * 153 * This function takes as its arguments: 154 * png_ptr - pointer to a png output data structure 155 * io_ptr - pointer to user supplied structure containing info about 156 * the output functions. May be NULL. 157 * write_data_fn - pointer to a new output function that takes as its 158 * arguments a pointer to a png_struct, a pointer to 159 * data to be written, and a 32-bit unsigned int that is 160 * the number of bytes to be written. The new write 161 * function should call png_error(png_ptr, "Error msg") 162 * to exit and output any fatal error messages. May be 163 * NULL, in which case libpng's default function will 164 * be used. 165 * flush_data_fn - pointer to a new flush function that takes as its 166 * arguments a pointer to a png_struct. After a call to 167 * the flush function, there should be no data in any buffers 168 * or pending transmission. If the output method doesn't do 169 * any buffering of output, a function prototype must still be 170 * supplied although it doesn't have to do anything. If 171 * PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile 172 * time, output_flush_fn will be ignored, although it must be 173 * supplied for compatibility. May be NULL, in which case 174 * libpng's default function will be used, if 175 * PNG_WRITE_FLUSH_SUPPORTED is defined. This is not 176 * a good idea if io_ptr does not point to a standard 177 * *FILE structure. 178 */ 179void PNGAPI 180png_set_write_fn(png_structp png_ptr, png_voidp io_ptr, 181 png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn) 182{ 183 if (png_ptr == NULL) 184 return; 185 186 png_ptr->io_ptr = io_ptr; 187 188#ifdef PNG_STDIO_SUPPORTED 189 if (write_data_fn != NULL) 190 png_ptr->write_data_fn = write_data_fn; 191 192 else 193 png_ptr->write_data_fn = png_default_write_data; 194#else 195 png_ptr->write_data_fn = write_data_fn; 196#endif 197 198#ifdef PNG_WRITE_FLUSH_SUPPORTED 199# ifdef PNG_STDIO_SUPPORTED 200 201 if (output_flush_fn != NULL) 202 png_ptr->output_flush_fn = output_flush_fn; 203 204 else 205 png_ptr->output_flush_fn = png_default_flush; 206 207# else 208 png_ptr->output_flush_fn = output_flush_fn; 209# endif 210#endif /* PNG_WRITE_FLUSH_SUPPORTED */ 211 212 /* It is an error to read while writing a png file */ 213 if (png_ptr->read_data_fn != NULL) 214 { 215 png_ptr->read_data_fn = NULL; 216 217 png_warning(png_ptr, 218 "Can't set both read_data_fn and write_data_fn in the" 219 " same structure"); 220 } 221} 222 223#ifdef USE_FAR_KEYWORD 224# ifdef _MSC_VER 225void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check) 226{ 227 void *near_ptr; 228 void FAR *far_ptr; 229 FP_OFF(near_ptr) = FP_OFF(ptr); 230 far_ptr = (void FAR *)near_ptr; 231 232 if (check != 0) 233 if (FP_SEG(ptr) != FP_SEG(far_ptr)) 234 png_error(png_ptr, "segment lost in conversion"); 235 236 return(near_ptr); 237} 238# else 239void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check) 240{ 241 void *near_ptr; 242 void FAR *far_ptr; 243 near_ptr = (void FAR *)ptr; 244 far_ptr = (void FAR *)near_ptr; 245 246 if (check != 0) 247 if (far_ptr != ptr) 248 png_error(png_ptr, "segment lost in conversion"); 249 250 return(near_ptr); 251} 252# endif 253#endif 254#endif /* PNG_WRITE_SUPPORTED */