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Rev | Author | Line No. | Line |
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96 | giacomo | 1 | |
2 | /* pngwio.c - functions for data output |
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3 | * |
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4 | * libpng 1.2.5 - October 3, 2002 |
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5 | * For conditions of distribution and use, see copyright notice in png.h |
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6 | * Copyright (c) 1998-2002 Glenn Randers-Pehrson |
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7 | * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) |
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8 | * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) |
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9 | * |
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10 | * This file provides a location for all output. Users who need |
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11 | * special handling are expected to write functions that have the same |
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12 | * arguments as these and perform similar functions, but that possibly |
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13 | * use different output methods. Note that you shouldn't change these |
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14 | * functions, but rather write replacement functions and then change |
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15 | * them at run time with png_set_write_fn(...). |
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16 | */ |
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17 | |||
18 | #define PNG_INTERNAL |
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19 | #include "png.h" |
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20 | #ifdef PNG_WRITE_SUPPORTED |
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21 | |||
22 | /* Write the data to whatever output you are using. The default routine |
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23 | writes to a file pointer. Note that this routine sometimes gets called |
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24 | with very small lengths, so you should implement some kind of simple |
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25 | buffering if you are using unbuffered writes. This should never be asked |
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26 | to write more than 64K on a 16 bit machine. */ |
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27 | |||
28 | void /* PRIVATE */ |
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29 | png_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
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30 | { |
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31 | if (png_ptr->write_data_fn != NULL ) |
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32 | (*(png_ptr->write_data_fn))(png_ptr, data, length); |
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33 | else |
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34 | png_error(png_ptr, "Call to NULL write function"); |
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35 | } |
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36 | |||
37 | #if !defined(PNG_NO_STDIO) |
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38 | /* This is the function that does the actual writing of data. If you are |
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39 | not writing to a standard C stream, you should create a replacement |
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40 | write_data function and use it at run time with png_set_write_fn(), rather |
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41 | than changing the library. */ |
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42 | #ifndef USE_FAR_KEYWORD |
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43 | void PNGAPI |
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44 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
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45 | { |
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46 | png_uint_32 check; |
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47 | |||
48 | #if defined(_WIN32_WCE) |
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49 | if ( !WriteFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) ) |
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50 | check = 0; |
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51 | #else |
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52 | check = fwrite(data, 1, length, (png_FILE_p)(png_ptr->io_ptr)); |
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53 | #endif |
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54 | if (check != length) |
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55 | png_error(png_ptr, "Write Error"); |
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56 | } |
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57 | #else |
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58 | /* this is the model-independent version. Since the standard I/O library |
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59 | can't handle far buffers in the medium and small models, we have to copy |
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60 | the data. |
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61 | */ |
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62 | |||
63 | #define NEAR_BUF_SIZE 1024 |
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64 | #define MIN(a,b) (a <= b ? a : b) |
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65 | |||
66 | void PNGAPI |
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67 | png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length) |
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68 | { |
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69 | png_uint_32 check; |
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70 | png_byte *near_data; /* Needs to be "png_byte *" instead of "png_bytep" */ |
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71 | png_FILE_p io_ptr; |
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72 | |||
73 | /* Check if data really is near. If so, use usual code. */ |
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74 | near_data = (png_byte *)CVT_PTR_NOCHECK(data); |
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75 | io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr); |
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76 | if ((png_bytep)near_data == data) |
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77 | { |
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78 | #if defined(_WIN32_WCE) |
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79 | if ( !WriteFile(io_ptr, near_data, length, &check, NULL) ) |
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80 | check = 0; |
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81 | #else |
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82 | check = fwrite(near_data, 1, length, io_ptr); |
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83 | #endif |
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84 | } |
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85 | else |
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86 | { |
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87 | png_byte buf[NEAR_BUF_SIZE]; |
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88 | png_size_t written, remaining, err; |
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89 | check = 0; |
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90 | remaining = length; |
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91 | do |
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92 | { |
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93 | written = MIN(NEAR_BUF_SIZE, remaining); |
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94 | png_memcpy(buf, data, written); /* copy far buffer to near buffer */ |
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95 | #if defined(_WIN32_WCE) |
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96 | if ( !WriteFile(io_ptr, buf, written, &err, NULL) ) |
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97 | err = 0; |
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98 | #else |
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99 | err = fwrite(buf, 1, written, io_ptr); |
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100 | #endif |
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101 | if (err != written) |
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102 | break; |
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103 | else |
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104 | check += err; |
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105 | data += written; |
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106 | remaining -= written; |
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107 | } |
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108 | while (remaining != 0); |
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109 | } |
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110 | if (check != length) |
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111 | png_error(png_ptr, "Write Error"); |
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112 | } |
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113 | |||
114 | #endif |
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115 | #endif |
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116 | |||
117 | /* This function is called to output any data pending writing (normally |
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118 | to disk). After png_flush is called, there should be no data pending |
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119 | writing in any buffers. */ |
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120 | #if defined(PNG_WRITE_FLUSH_SUPPORTED) |
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121 | void /* PRIVATE */ |
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122 | png_flush(png_structp png_ptr) |
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123 | { |
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124 | if (png_ptr->output_flush_fn != NULL) |
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125 | (*(png_ptr->output_flush_fn))(png_ptr); |
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126 | } |
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127 | |||
128 | #if !defined(PNG_NO_STDIO) |
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129 | void PNGAPI |
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130 | png_default_flush(png_structp png_ptr) |
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131 | { |
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132 | #if !defined(_WIN32_WCE) |
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133 | png_FILE_p io_ptr; |
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134 | io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr)); |
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135 | if (io_ptr != NULL) |
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136 | fflush(io_ptr); |
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137 | #endif |
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138 | } |
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139 | #endif |
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140 | #endif |
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141 | |||
142 | /* This function allows the application to supply new output functions for |
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143 | libpng if standard C streams aren't being used. |
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144 | |||
145 | This function takes as its arguments: |
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146 | png_ptr - pointer to a png output data structure |
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147 | io_ptr - pointer to user supplied structure containing info about |
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148 | the output functions. May be NULL. |
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149 | write_data_fn - pointer to a new output function that takes as its |
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150 | arguments a pointer to a png_struct, a pointer to |
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151 | data to be written, and a 32-bit unsigned int that is |
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152 | the number of bytes to be written. The new write |
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153 | function should call png_error(png_ptr, "Error msg") |
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154 | to exit and output any fatal error messages. |
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155 | flush_data_fn - pointer to a new flush function that takes as its |
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156 | arguments a pointer to a png_struct. After a call to |
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157 | the flush function, there should be no data in any buffers |
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158 | or pending transmission. If the output method doesn't do |
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159 | any buffering of ouput, a function prototype must still be |
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160 | supplied although it doesn't have to do anything. If |
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161 | PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile |
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162 | time, output_flush_fn will be ignored, although it must be |
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163 | supplied for compatibility. */ |
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164 | void PNGAPI |
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165 | png_set_write_fn(png_structp png_ptr, png_voidp io_ptr, |
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166 | png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn) |
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167 | { |
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168 | png_ptr->io_ptr = io_ptr; |
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169 | |||
170 | #if !defined(PNG_NO_STDIO) |
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171 | if (write_data_fn != NULL) |
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172 | png_ptr->write_data_fn = write_data_fn; |
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173 | else |
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174 | png_ptr->write_data_fn = png_default_write_data; |
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175 | #else |
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176 | png_ptr->write_data_fn = write_data_fn; |
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177 | #endif |
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178 | |||
179 | #if defined(PNG_WRITE_FLUSH_SUPPORTED) |
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180 | #if !defined(PNG_NO_STDIO) |
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181 | if (output_flush_fn != NULL) |
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182 | png_ptr->output_flush_fn = output_flush_fn; |
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183 | else |
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184 | png_ptr->output_flush_fn = png_default_flush; |
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185 | #else |
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186 | png_ptr->output_flush_fn = output_flush_fn; |
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187 | #endif |
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188 | #endif /* PNG_WRITE_FLUSH_SUPPORTED */ |
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189 | |||
190 | /* It is an error to read while writing a png file */ |
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191 | if (png_ptr->read_data_fn != NULL) |
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192 | { |
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193 | png_ptr->read_data_fn = NULL; |
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194 | png_warning(png_ptr, |
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195 | "Attempted to set both read_data_fn and write_data_fn in"); |
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196 | png_warning(png_ptr, |
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197 | "the same structure. Resetting read_data_fn to NULL."); |
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198 | } |
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199 | } |
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200 | |||
201 | #if defined(USE_FAR_KEYWORD) |
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202 | #if defined(_MSC_VER) |
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203 | void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) |
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204 | { |
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205 | void *near_ptr; |
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206 | void FAR *far_ptr; |
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207 | FP_OFF(near_ptr) = FP_OFF(ptr); |
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208 | far_ptr = (void FAR *)near_ptr; |
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209 | if(check != 0) |
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210 | if(FP_SEG(ptr) != FP_SEG(far_ptr)) |
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211 | png_error(png_ptr,"segment lost in conversion"); |
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212 | return(near_ptr); |
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213 | } |
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214 | # else |
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215 | void *png_far_to_near(png_structp png_ptr,png_voidp ptr, int check) |
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216 | { |
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217 | void *near_ptr; |
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218 | void FAR *far_ptr; |
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219 | near_ptr = (void FAR *)ptr; |
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220 | far_ptr = (void FAR *)near_ptr; |
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221 | if(check != 0) |
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222 | if(far_ptr != ptr) |
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223 | png_error(png_ptr,"segment lost in conversion"); |
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224 | return(near_ptr); |
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225 | } |
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226 | # endif |
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227 | # endif |
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228 | #endif /* PNG_WRITE_SUPPORTED */ |