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Rev | Author | Line No. | Line |
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96 | giacomo | 1 | |
2 | #if 0 /* in case someone actually tries to compile this */ |
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3 | |||
4 | /* example.c - an example of using libpng */ |
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5 | |||
6 | /* This is an example of how to use libpng to read and write PNG files. |
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7 | * The file libpng.txt is much more verbose then this. If you have not |
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8 | * read it, do so first. This was designed to be a starting point of an |
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9 | * implementation. This is not officially part of libpng, is hereby placed |
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10 | * in the public domain, and therefore does not require a copyright notice. |
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11 | * |
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12 | * This file does not currently compile, because it is missing certain |
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13 | * parts, like allocating memory to hold an image. You will have to |
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14 | * supply these parts to get it to compile. For an example of a minimal |
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15 | * working PNG reader/writer, see pngtest.c, included in this distribution; |
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16 | * see also the programs in the contrib directory. |
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17 | */ |
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18 | |||
19 | #include "png.h" |
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20 | |||
21 | /* The png_jmpbuf() macro, used in error handling, became available in |
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22 | * libpng version 1.0.6. If you want to be able to run your code with older |
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23 | * versions of libpng, you must define the macro yourself (but only if it |
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24 | * is not already defined by libpng!). |
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25 | */ |
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26 | |||
27 | #ifndef png_jmpbuf |
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28 | # define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf) |
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29 | #endif |
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30 | |||
31 | /* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp() |
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32 | * returns zero if the image is a PNG and nonzero if it isn't a PNG. |
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33 | * |
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34 | * The function check_if_png() shown here, but not used, returns nonzero (true) |
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35 | * if the file can be opened and is a PNG, 0 (false) otherwise. |
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36 | * |
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37 | * If this call is successful, and you are going to keep the file open, |
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38 | * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once |
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39 | * you have created the png_ptr, so that libpng knows your application |
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40 | * has read that many bytes from the start of the file. Make sure you |
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41 | * don't call png_set_sig_bytes() with more than 8 bytes read or give it |
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42 | * an incorrect number of bytes read, or you will either have read too |
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43 | * many bytes (your fault), or you are telling libpng to read the wrong |
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44 | * number of magic bytes (also your fault). |
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45 | * |
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46 | * Many applications already read the first 2 or 4 bytes from the start |
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47 | * of the image to determine the file type, so it would be easiest just |
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48 | * to pass the bytes to png_sig_cmp() or even skip that if you know |
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49 | * you have a PNG file, and call png_set_sig_bytes(). |
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50 | */ |
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51 | #define PNG_BYTES_TO_CHECK 4 |
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52 | int check_if_png(char *file_name, FILE **fp) |
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53 | { |
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54 | char buf[PNG_BYTES_TO_CHECK]; |
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55 | |||
56 | /* Open the prospective PNG file. */ |
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57 | if ((*fp = fopen(file_name, "rb")) == NULL) |
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58 | return 0; |
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59 | |||
60 | /* Read in some of the signature bytes */ |
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61 | if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK) |
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62 | return 0; |
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63 | |||
64 | /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature. |
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65 | Return nonzero (true) if they match */ |
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66 | |||
67 | return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK)); |
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68 | } |
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69 | |||
70 | /* Read a PNG file. You may want to return an error code if the read |
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71 | * fails (depending upon the failure). There are two "prototypes" given |
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72 | * here - one where we are given the filename, and we need to open the |
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73 | * file, and the other where we are given an open file (possibly with |
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74 | * some or all of the magic bytes read - see comments above). |
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75 | */ |
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76 | #ifdef open_file /* prototype 1 */ |
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77 | void read_png(char *file_name) /* We need to open the file */ |
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78 | { |
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79 | png_structp png_ptr; |
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80 | png_infop info_ptr; |
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81 | unsigned int sig_read = 0; |
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82 | png_uint_32 width, height; |
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83 | int bit_depth, color_type, interlace_type; |
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84 | FILE *fp; |
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85 | |||
86 | if ((fp = fopen(file_name, "rb")) == NULL) |
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87 | return (ERROR); |
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88 | #else no_open_file /* prototype 2 */ |
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89 | void read_png(FILE *fp, unsigned int sig_read) /* file is already open */ |
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90 | { |
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91 | png_structp png_ptr; |
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92 | png_infop info_ptr; |
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93 | png_uint_32 width, height; |
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94 | int bit_depth, color_type, interlace_type; |
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95 | #endif no_open_file /* only use one prototype! */ |
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96 | |||
97 | /* Create and initialize the png_struct with the desired error handler |
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98 | * functions. If you want to use the default stderr and longjump method, |
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99 | * you can supply NULL for the last three parameters. We also supply the |
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100 | * the compiler header file version, so that we know if the application |
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101 | * was compiled with a compatible version of the library. REQUIRED |
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102 | */ |
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103 | png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, |
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104 | png_voidp user_error_ptr, user_error_fn, user_warning_fn); |
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105 | |||
106 | if (png_ptr == NULL) |
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107 | { |
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108 | fclose(fp); |
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109 | return (ERROR); |
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110 | } |
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111 | |||
112 | /* Allocate/initialize the memory for image information. REQUIRED. */ |
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113 | info_ptr = png_create_info_struct(png_ptr); |
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114 | if (info_ptr == NULL) |
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115 | { |
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116 | fclose(fp); |
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117 | png_destroy_read_struct(&png_ptr, png_infopp_NULL, png_infopp_NULL); |
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118 | return (ERROR); |
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119 | } |
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120 | |||
121 | /* Set error handling if you are using the setjmp/longjmp method (this is |
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122 | * the normal method of doing things with libpng). REQUIRED unless you |
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123 | * set up your own error handlers in the png_create_read_struct() earlier. |
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124 | */ |
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125 | |||
126 | if (setjmp(png_jmpbuf(png_ptr))) |
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127 | { |
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128 | /* Free all of the memory associated with the png_ptr and info_ptr */ |
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129 | png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL); |
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130 | fclose(fp); |
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131 | /* If we get here, we had a problem reading the file */ |
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132 | return (ERROR); |
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133 | } |
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134 | |||
135 | /* One of the following I/O initialization methods is REQUIRED */ |
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136 | #ifdef streams /* PNG file I/O method 1 */ |
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137 | /* Set up the input control if you are using standard C streams */ |
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138 | png_init_io(png_ptr, fp); |
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139 | |||
140 | #else no_streams /* PNG file I/O method 2 */ |
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141 | /* If you are using replacement read functions, instead of calling |
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142 | * png_init_io() here you would call: |
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143 | */ |
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144 | png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn); |
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145 | /* where user_io_ptr is a structure you want available to the callbacks */ |
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146 | #endif no_streams /* Use only one I/O method! */ |
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147 | |||
148 | /* If we have already read some of the signature */ |
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149 | png_set_sig_bytes(png_ptr, sig_read); |
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150 | |||
151 | #ifdef hilevel |
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152 | /* |
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153 | * If you have enough memory to read in the entire image at once, |
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154 | * and you need to specify only transforms that can be controlled |
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155 | * with one of the PNG_TRANSFORM_* bits (this presently excludes |
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156 | * dithering, filling, setting background, and doing gamma |
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157 | * adjustment), then you can read the entire image (including |
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158 | * pixels) into the info structure with this call: |
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159 | */ |
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160 | png_read_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL); |
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161 | #else |
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162 | /* OK, you're doing it the hard way, with the lower-level functions */ |
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163 | |||
164 | /* The call to png_read_info() gives us all of the information from the |
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165 | * PNG file before the first IDAT (image data chunk). REQUIRED |
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166 | */ |
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167 | png_read_info(png_ptr, info_ptr); |
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168 | |||
169 | png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, |
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170 | &interlace_type, int_p_NULL, int_p_NULL); |
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171 | |||
172 | /* Set up the data transformations you want. Note that these are all |
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173 | * optional. Only call them if you want/need them. Many of the |
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174 | * transformations only work on specific types of images, and many |
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175 | * are mutually exclusive. |
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176 | */ |
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177 | |||
178 | /* tell libpng to strip 16 bit/color files down to 8 bits/color */ |
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179 | png_set_strip_16(png_ptr); |
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180 | |||
181 | /* Strip alpha bytes from the input data without combining with the |
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182 | * background (not recommended). |
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183 | */ |
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184 | png_set_strip_alpha(png_ptr); |
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185 | |||
186 | /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single |
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187 | * byte into separate bytes (useful for paletted and grayscale images). |
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188 | */ |
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189 | png_set_packing(png_ptr); |
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190 | |||
191 | /* Change the order of packed pixels to least significant bit first |
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192 | * (not useful if you are using png_set_packing). */ |
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193 | png_set_packswap(png_ptr); |
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194 | |||
195 | /* Expand paletted colors into true RGB triplets */ |
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196 | if (color_type == PNG_COLOR_TYPE_PALETTE) |
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197 | png_set_palette_rgb(png_ptr); |
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198 | |||
199 | /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */ |
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200 | if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) |
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201 | png_set_gray_1_2_4_to_8(png_ptr); |
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202 | |||
203 | /* Expand paletted or RGB images with transparency to full alpha channels |
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204 | * so the data will be available as RGBA quartets. |
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205 | */ |
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206 | if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) |
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207 | png_set_tRNS_to_alpha(png_ptr); |
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208 | |||
209 | /* Set the background color to draw transparent and alpha images over. |
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210 | * It is possible to set the red, green, and blue components directly |
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211 | * for paletted images instead of supplying a palette index. Note that |
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212 | * even if the PNG file supplies a background, you are not required to |
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213 | * use it - you should use the (solid) application background if it has one. |
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214 | */ |
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215 | |||
216 | png_color_16 my_background, *image_background; |
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217 | |||
218 | if (png_get_bKGD(png_ptr, info_ptr, &image_background)) |
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219 | png_set_background(png_ptr, image_background, |
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220 | PNG_BACKGROUND_GAMMA_FILE, 1, 1.0); |
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221 | else |
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222 | png_set_background(png_ptr, &my_background, |
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223 | PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0); |
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224 | |||
225 | /* Some suggestions as to how to get a screen gamma value */ |
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226 | |||
227 | /* Note that screen gamma is the display_exponent, which includes |
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228 | * the CRT_exponent and any correction for viewing conditions */ |
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229 | if (/* We have a user-defined screen gamma value */) |
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230 | { |
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231 | screen_gamma = user-defined screen_gamma; |
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232 | } |
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233 | /* This is one way that applications share the same screen gamma value */ |
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234 | else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL) |
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235 | { |
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236 | screen_gamma = atof(gamma_str); |
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237 | } |
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238 | /* If we don't have another value */ |
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239 | else |
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240 | { |
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241 | screen_gamma = 2.2; /* A good guess for a PC monitors in a dimly |
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242 | lit room */ |
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243 | screen_gamma = 1.7 or 1.0; /* A good guess for Mac systems */ |
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244 | } |
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245 | |||
246 | /* Tell libpng to handle the gamma conversion for you. The final call |
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247 | * is a good guess for PC generated images, but it should be configurable |
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248 | * by the user at run time by the user. It is strongly suggested that |
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249 | * your application support gamma correction. |
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250 | */ |
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251 | |||
252 | int intent; |
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253 | |||
254 | if (png_get_sRGB(png_ptr, info_ptr, &intent)) |
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255 | png_set_gamma(png_ptr, screen_gamma, 0.45455); |
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256 | else |
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257 | { |
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258 | double image_gamma; |
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259 | if (png_get_gAMA(png_ptr, info_ptr, &image_gamma)) |
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260 | png_set_gamma(png_ptr, screen_gamma, image_gamma); |
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261 | else |
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262 | png_set_gamma(png_ptr, screen_gamma, 0.45455); |
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263 | } |
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264 | |||
265 | /* Dither RGB files down to 8 bit palette or reduce palettes |
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266 | * to the number of colors available on your screen. |
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267 | */ |
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268 | if (color_type & PNG_COLOR_MASK_COLOR) |
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269 | { |
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270 | int num_palette; |
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271 | png_colorp palette; |
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272 | |||
273 | /* This reduces the image to the application supplied palette */ |
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274 | if (/* we have our own palette */) |
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275 | { |
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276 | /* An array of colors to which the image should be dithered */ |
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277 | png_color std_color_cube[MAX_SCREEN_COLORS]; |
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278 | |||
279 | png_set_dither(png_ptr, std_color_cube, MAX_SCREEN_COLORS, |
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280 | MAX_SCREEN_COLORS, png_uint_16p_NULL, 0); |
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281 | } |
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282 | /* This reduces the image to the palette supplied in the file */ |
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283 | else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette)) |
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284 | { |
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285 | png_uint_16p histogram = NULL; |
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286 | |||
287 | png_get_hIST(png_ptr, info_ptr, &histogram); |
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288 | |||
289 | png_set_dither(png_ptr, palette, num_palette, |
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290 | max_screen_colors, histogram, 0); |
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291 | } |
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292 | } |
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293 | |||
294 | /* invert monochrome files to have 0 as white and 1 as black */ |
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295 | png_set_invert_mono(png_ptr); |
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296 | |||
297 | /* If you want to shift the pixel values from the range [0,255] or |
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298 | * [0,65535] to the original [0,7] or [0,31], or whatever range the |
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299 | * colors were originally in: |
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300 | */ |
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301 | if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT)) |
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302 | { |
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303 | png_color_8p sig_bit; |
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304 | |||
305 | png_get_sBIT(png_ptr, info_ptr, &sig_bit); |
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306 | png_set_shift(png_ptr, sig_bit); |
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307 | } |
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308 | |||
309 | /* flip the RGB pixels to BGR (or RGBA to BGRA) */ |
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310 | if (color_type & PNG_COLOR_MASK_COLOR) |
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311 | png_set_bgr(png_ptr); |
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312 | |||
313 | /* swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ |
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314 | png_set_swap_alpha(png_ptr); |
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315 | |||
316 | /* swap bytes of 16 bit files to least significant byte first */ |
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317 | png_set_swap(png_ptr); |
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318 | |||
319 | /* Add filler (or alpha) byte (before/after each RGB triplet) */ |
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320 | png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER); |
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321 | |||
322 | /* Turn on interlace handling. REQUIRED if you are not using |
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323 | * png_read_image(). To see how to handle interlacing passes, |
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324 | * see the png_read_row() method below: |
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325 | */ |
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326 | number_passes = png_set_interlace_handling(png_ptr); |
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327 | |||
328 | /* Optional call to gamma correct and add the background to the palette |
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329 | * and update info structure. REQUIRED if you are expecting libpng to |
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330 | * update the palette for you (ie you selected such a transform above). |
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331 | */ |
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332 | png_read_update_info(png_ptr, info_ptr); |
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333 | |||
334 | /* Allocate the memory to hold the image using the fields of info_ptr. */ |
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335 | |||
336 | /* The easiest way to read the image: */ |
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337 | png_bytep row_pointers[height]; |
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338 | |||
339 | for (row = 0; row < height; row++) |
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340 | { |
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341 | row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr, |
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342 | info_ptr)); |
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343 | } |
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344 | |||
345 | /* Now it's time to read the image. One of these methods is REQUIRED */ |
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346 | #ifdef entire /* Read the entire image in one go */ |
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347 | png_read_image(png_ptr, row_pointers); |
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348 | |||
349 | #else no_entire /* Read the image one or more scanlines at a time */ |
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350 | /* The other way to read images - deal with interlacing: */ |
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351 | |||
352 | for (pass = 0; pass < number_passes; pass++) |
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353 | { |
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354 | #ifdef single /* Read the image a single row at a time */ |
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355 | for (y = 0; y < height; y++) |
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356 | { |
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357 | png_read_rows(png_ptr, &row_pointers[y], png_bytepp_NULL, 1); |
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358 | } |
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359 | |||
360 | #else no_single /* Read the image several rows at a time */ |
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361 | for (y = 0; y < height; y += number_of_rows) |
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362 | { |
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363 | #ifdef sparkle /* Read the image using the "sparkle" effect. */ |
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364 | png_read_rows(png_ptr, &row_pointers[y], png_bytepp_NULL, |
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365 | number_of_rows); |
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366 | #else no_sparkle /* Read the image using the "rectangle" effect */ |
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367 | png_read_rows(png_ptr, png_bytepp_NULL, &row_pointers[y], |
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368 | number_of_rows); |
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369 | #endif no_sparkle /* use only one of these two methods */ |
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370 | } |
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371 | |||
372 | /* if you want to display the image after every pass, do |
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373 | so here */ |
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374 | #endif no_single /* use only one of these two methods */ |
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375 | } |
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376 | #endif no_entire /* use only one of these two methods */ |
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377 | |||
378 | /* read rest of file, and get additional chunks in info_ptr - REQUIRED */ |
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379 | png_read_end(png_ptr, info_ptr); |
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380 | #endif hilevel |
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381 | |||
382 | /* At this point you have read the entire image */ |
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383 | |||
384 | /* clean up after the read, and free any memory allocated - REQUIRED */ |
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385 | png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL); |
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386 | |||
387 | /* close the file */ |
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388 | fclose(fp); |
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389 | |||
390 | /* that's it */ |
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391 | return (OK); |
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392 | } |
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393 | |||
394 | /* progressively read a file */ |
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395 | |||
396 | int |
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397 | initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr) |
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398 | { |
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399 | /* Create and initialize the png_struct with the desired error handler |
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400 | * functions. If you want to use the default stderr and longjump method, |
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401 | * you can supply NULL for the last three parameters. We also check that |
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402 | * the library version is compatible in case we are using dynamically |
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403 | * linked libraries. |
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404 | */ |
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405 | *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, |
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406 | png_voidp user_error_ptr, user_error_fn, user_warning_fn); |
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407 | |||
408 | if (*png_ptr == NULL) |
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409 | { |
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410 | *info_ptr = NULL; |
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411 | return (ERROR); |
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412 | } |
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413 | |||
414 | *info_ptr = png_create_info_struct(png_ptr); |
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415 | |||
416 | if (*info_ptr == NULL) |
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417 | { |
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418 | png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL); |
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419 | return (ERROR); |
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420 | } |
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421 | |||
422 | if (setjmp(png_jmpbuf((*png_ptr)))) |
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423 | { |
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424 | png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL); |
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425 | return (ERROR); |
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426 | } |
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427 | |||
428 | /* This one's new. You will need to provide all three |
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429 | * function callbacks, even if you aren't using them all. |
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430 | * If you aren't using all functions, you can specify NULL |
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431 | * parameters. Even when all three functions are NULL, |
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432 | * you need to call png_set_progressive_read_fn(). |
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433 | * These functions shouldn't be dependent on global or |
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434 | * static variables if you are decoding several images |
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435 | * simultaneously. You should store stream specific data |
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436 | * in a separate struct, given as the second parameter, |
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437 | * and retrieve the pointer from inside the callbacks using |
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438 | * the function png_get_progressive_ptr(png_ptr). |
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439 | */ |
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440 | png_set_progressive_read_fn(*png_ptr, (void *)stream_data, |
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441 | info_callback, row_callback, end_callback); |
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442 | |||
443 | return (OK); |
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444 | } |
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445 | |||
446 | int |
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447 | process_data(png_structp *png_ptr, png_infop *info_ptr, |
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448 | png_bytep buffer, png_uint_32 length) |
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449 | { |
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450 | if (setjmp(png_jmpbuf((*png_ptr)))) |
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451 | { |
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452 | /* Free the png_ptr and info_ptr memory on error */ |
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453 | png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL); |
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454 | return (ERROR); |
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455 | } |
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456 | |||
457 | /* This one's new also. Simply give it chunks of data as |
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458 | * they arrive from the data stream (in order, of course). |
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459 | * On Segmented machines, don't give it any more than 64K. |
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460 | * The library seems to run fine with sizes of 4K, although |
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461 | * you can give it much less if necessary (I assume you can |
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462 | * give it chunks of 1 byte, but I haven't tried with less |
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463 | * than 256 bytes yet). When this function returns, you may |
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464 | * want to display any rows that were generated in the row |
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465 | * callback, if you aren't already displaying them there. |
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466 | */ |
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467 | png_process_data(*png_ptr, *info_ptr, buffer, length); |
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468 | return (OK); |
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469 | } |
||
470 | |||
471 | info_callback(png_structp png_ptr, png_infop info) |
||
472 | { |
||
473 | /* do any setup here, including setting any of the transformations |
||
474 | * mentioned in the Reading PNG files section. For now, you _must_ |
||
475 | * call either png_start_read_image() or png_read_update_info() |
||
476 | * after all the transformations are set (even if you don't set |
||
477 | * any). You may start getting rows before png_process_data() |
||
478 | * returns, so this is your last chance to prepare for that. |
||
479 | */ |
||
480 | } |
||
481 | |||
482 | row_callback(png_structp png_ptr, png_bytep new_row, |
||
483 | png_uint_32 row_num, int pass) |
||
484 | { |
||
485 | /* |
||
486 | * This function is called for every row in the image. If the |
||
487 | * image is interlaced, and you turned on the interlace handler, |
||
488 | * this function will be called for every row in every pass. |
||
489 | * |
||
490 | * In this function you will receive a pointer to new row data from |
||
491 | * libpng called new_row that is to replace a corresponding row (of |
||
492 | * the same data format) in a buffer allocated by your application. |
||
493 | * |
||
494 | * The new row data pointer new_row may be NULL, indicating there is |
||
495 | * no new data to be replaced (in cases of interlace loading). |
||
496 | * |
||
497 | * If new_row is not NULL then you need to call |
||
498 | * png_progressive_combine_row() to replace the corresponding row as |
||
499 | * shown below: |
||
500 | */ |
||
501 | /* Check if row_num is in bounds. */ |
||
502 | if((row_num >= 0) && (row_num < height)) |
||
503 | { |
||
504 | /* Get pointer to corresponding row in our |
||
505 | * PNG read buffer. |
||
506 | */ |
||
507 | png_bytep old_row = ((png_bytep *)our_data)[row_num]; |
||
508 | |||
509 | /* If both rows are allocated then copy the new row |
||
510 | * data to the corresponding row data. |
||
511 | */ |
||
512 | if((old_row != NULL) && (new_row != NULL)) |
||
513 | png_progressive_combine_row(png_ptr, old_row, new_row); |
||
514 | } |
||
515 | /* |
||
516 | * The rows and passes are called in order, so you don't really |
||
517 | * need the row_num and pass, but I'm supplying them because it |
||
518 | * may make your life easier. |
||
519 | * |
||
520 | * For the non-NULL rows of interlaced images, you must call |
||
521 | * png_progressive_combine_row() passing in the new row and the |
||
522 | * old row, as demonstrated above. You can call this function for |
||
523 | * NULL rows (it will just return) and for non-interlaced images |
||
524 | * (it just does the png_memcpy for you) if it will make the code |
||
525 | * easier. Thus, you can just do this for all cases: |
||
526 | */ |
||
527 | |||
528 | png_progressive_combine_row(png_ptr, old_row, new_row); |
||
529 | |||
530 | /* where old_row is what was displayed for previous rows. Note |
||
531 | * that the first pass (pass == 0 really) will completely cover |
||
532 | * the old row, so the rows do not have to be initialized. After |
||
533 | * the first pass (and only for interlaced images), you will have |
||
534 | * to pass the current row as new_row, and the function will combine |
||
535 | * the old row and the new row. |
||
536 | */ |
||
537 | } |
||
538 | |||
539 | end_callback(png_structp png_ptr, png_infop info) |
||
540 | { |
||
541 | /* this function is called when the whole image has been read, |
||
542 | * including any chunks after the image (up to and including |
||
543 | * the IEND). You will usually have the same info chunk as you |
||
544 | * had in the header, although some data may have been added |
||
545 | * to the comments and time fields. |
||
546 | * |
||
547 | * Most people won't do much here, perhaps setting a flag that |
||
548 | * marks the image as finished. |
||
549 | */ |
||
550 | } |
||
551 | |||
552 | /* write a png file */ |
||
553 | void write_png(char *file_name /* , ... other image information ... */) |
||
554 | { |
||
555 | FILE *fp; |
||
556 | png_structp png_ptr; |
||
557 | png_infop info_ptr; |
||
558 | png_colorp palette; |
||
559 | |||
560 | /* open the file */ |
||
561 | fp = fopen(file_name, "wb"); |
||
562 | if (fp == NULL) |
||
563 | return (ERROR); |
||
564 | |||
565 | /* Create and initialize the png_struct with the desired error handler |
||
566 | * functions. If you want to use the default stderr and longjump method, |
||
567 | * you can supply NULL for the last three parameters. We also check that |
||
568 | * the library version is compatible with the one used at compile time, |
||
569 | * in case we are using dynamically linked libraries. REQUIRED. |
||
570 | */ |
||
571 | png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, |
||
572 | png_voidp user_error_ptr, user_error_fn, user_warning_fn); |
||
573 | |||
574 | if (png_ptr == NULL) |
||
575 | { |
||
576 | fclose(fp); |
||
577 | return (ERROR); |
||
578 | } |
||
579 | |||
580 | /* Allocate/initialize the image information data. REQUIRED */ |
||
581 | info_ptr = png_create_info_struct(png_ptr); |
||
582 | if (info_ptr == NULL) |
||
583 | { |
||
584 | fclose(fp); |
||
585 | png_destroy_write_struct(&png_ptr, png_infopp_NULL); |
||
586 | return (ERROR); |
||
587 | } |
||
588 | |||
589 | /* Set error handling. REQUIRED if you aren't supplying your own |
||
590 | * error handling functions in the png_create_write_struct() call. |
||
591 | */ |
||
592 | if (setjmp(png_jmpbuf(png_ptr))) |
||
593 | { |
||
594 | /* If we get here, we had a problem reading the file */ |
||
595 | fclose(fp); |
||
596 | png_destroy_write_struct(&png_ptr, &info_ptr); |
||
597 | return (ERROR); |
||
598 | } |
||
599 | |||
600 | /* One of the following I/O initialization functions is REQUIRED */ |
||
601 | #ifdef streams /* I/O initialization method 1 */ |
||
602 | /* set up the output control if you are using standard C streams */ |
||
603 | png_init_io(png_ptr, fp); |
||
604 | #else no_streams /* I/O initialization method 2 */ |
||
605 | /* If you are using replacement read functions, instead of calling |
||
606 | * png_init_io() here you would call */ |
||
607 | png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn, |
||
608 | user_IO_flush_function); |
||
609 | /* where user_io_ptr is a structure you want available to the callbacks */ |
||
610 | #endif no_streams /* only use one initialization method */ |
||
611 | |||
612 | #ifdef hilevel |
||
613 | /* This is the easy way. Use it if you already have all the |
||
614 | * image info living info in the structure. You could "|" many |
||
615 | * PNG_TRANSFORM flags into the png_transforms integer here. |
||
616 | */ |
||
617 | png_write_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL); |
||
618 | #else |
||
619 | /* This is the hard way */ |
||
620 | |||
621 | /* Set the image information here. Width and height are up to 2^31, |
||
622 | * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on |
||
623 | * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY, |
||
624 | * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB, |
||
625 | * or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or |
||
626 | * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST |
||
627 | * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED |
||
628 | */ |
||
629 | png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???, |
||
630 | PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); |
||
631 | |||
632 | /* set the palette if there is one. REQUIRED for indexed-color images */ |
||
633 | palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH |
||
634 | * sizeof (png_color)); |
||
635 | /* ... set palette colors ... */ |
||
636 | png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH); |
||
637 | /* You must not free palette here, because png_set_PLTE only makes a link to |
||
638 | the palette that you malloced. Wait until you are about to destroy |
||
639 | the png structure. */ |
||
640 | |||
641 | /* optional significant bit chunk */ |
||
642 | /* if we are dealing with a grayscale image then */ |
||
643 | sig_bit.gray = true_bit_depth; |
||
644 | /* otherwise, if we are dealing with a color image then */ |
||
645 | sig_bit.red = true_red_bit_depth; |
||
646 | sig_bit.green = true_green_bit_depth; |
||
647 | sig_bit.blue = true_blue_bit_depth; |
||
648 | /* if the image has an alpha channel then */ |
||
649 | sig_bit.alpha = true_alpha_bit_depth; |
||
650 | png_set_sBIT(png_ptr, info_ptr, sig_bit); |
||
651 | |||
652 | |||
653 | /* Optional gamma chunk is strongly suggested if you have any guess |
||
654 | * as to the correct gamma of the image. |
||
655 | */ |
||
656 | png_set_gAMA(png_ptr, info_ptr, gamma); |
||
657 | |||
658 | /* Optionally write comments into the image */ |
||
659 | text_ptr[0].key = "Title"; |
||
660 | text_ptr[0].text = "Mona Lisa"; |
||
661 | text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE; |
||
662 | text_ptr[1].key = "Author"; |
||
663 | text_ptr[1].text = "Leonardo DaVinci"; |
||
664 | text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE; |
||
665 | text_ptr[2].key = "Description"; |
||
666 | text_ptr[2].text = "<long text>"; |
||
667 | text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt; |
||
668 | #ifdef PNG_iTXt_SUPPORTED |
||
669 | text_ptr[0].lang = NULL; |
||
670 | text_ptr[1].lang = NULL; |
||
671 | text_ptr[2].lang = NULL; |
||
672 | #endif |
||
673 | png_set_text(png_ptr, info_ptr, text_ptr, 3); |
||
674 | |||
675 | /* other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs, */ |
||
676 | /* note that if sRGB is present the gAMA and cHRM chunks must be ignored |
||
677 | * on read and must be written in accordance with the sRGB profile */ |
||
678 | |||
679 | /* Write the file header information. REQUIRED */ |
||
680 | png_write_info(png_ptr, info_ptr); |
||
681 | |||
682 | /* If you want, you can write the info in two steps, in case you need to |
||
683 | * write your private chunk ahead of PLTE: |
||
684 | * |
||
685 | * png_write_info_before_PLTE(write_ptr, write_info_ptr); |
||
686 | * write_my_chunk(); |
||
687 | * png_write_info(png_ptr, info_ptr); |
||
688 | * |
||
689 | * However, given the level of known- and unknown-chunk support in 1.1.0 |
||
690 | * and up, this should no longer be necessary. |
||
691 | */ |
||
692 | |||
693 | /* Once we write out the header, the compression type on the text |
||
694 | * chunks gets changed to PNG_TEXT_COMPRESSION_NONE_WR or |
||
695 | * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again |
||
696 | * at the end. |
||
697 | */ |
||
698 | |||
699 | /* set up the transformations you want. Note that these are |
||
700 | * all optional. Only call them if you want them. |
||
701 | */ |
||
702 | |||
703 | /* invert monochrome pixels */ |
||
704 | png_set_invert_mono(png_ptr); |
||
705 | |||
706 | /* Shift the pixels up to a legal bit depth and fill in |
||
707 | * as appropriate to correctly scale the image. |
||
708 | */ |
||
709 | png_set_shift(png_ptr, &sig_bit); |
||
710 | |||
711 | /* pack pixels into bytes */ |
||
712 | png_set_packing(png_ptr); |
||
713 | |||
714 | /* swap location of alpha bytes from ARGB to RGBA */ |
||
715 | png_set_swap_alpha(png_ptr); |
||
716 | |||
717 | /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into |
||
718 | * RGB (4 channels -> 3 channels). The second parameter is not used. |
||
719 | */ |
||
720 | png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE); |
||
721 | |||
722 | /* flip BGR pixels to RGB */ |
||
723 | png_set_bgr(png_ptr); |
||
724 | |||
725 | /* swap bytes of 16-bit files to most significant byte first */ |
||
726 | png_set_swap(png_ptr); |
||
727 | |||
728 | /* swap bits of 1, 2, 4 bit packed pixel formats */ |
||
729 | png_set_packswap(png_ptr); |
||
730 | |||
731 | /* turn on interlace handling if you are not using png_write_image() */ |
||
732 | if (interlacing) |
||
733 | number_passes = png_set_interlace_handling(png_ptr); |
||
734 | else |
||
735 | number_passes = 1; |
||
736 | |||
737 | /* The easiest way to write the image (you may have a different memory |
||
738 | * layout, however, so choose what fits your needs best). You need to |
||
739 | * use the first method if you aren't handling interlacing yourself. |
||
740 | */ |
||
741 | png_uint_32 k, height, width; |
||
742 | png_byte image[height][width*bytes_per_pixel]; |
||
743 | png_bytep row_pointers[height]; |
||
744 | for (k = 0; k < height; k++) |
||
745 | row_pointers[k] = image + k*width*bytes_per_pixel; |
||
746 | |||
747 | /* One of the following output methods is REQUIRED */ |
||
748 | #ifdef entire /* write out the entire image data in one call */ |
||
749 | png_write_image(png_ptr, row_pointers); |
||
750 | |||
751 | /* the other way to write the image - deal with interlacing */ |
||
752 | |||
753 | #else no_entire /* write out the image data by one or more scanlines */ |
||
754 | /* The number of passes is either 1 for non-interlaced images, |
||
755 | * or 7 for interlaced images. |
||
756 | */ |
||
757 | for (pass = 0; pass < number_passes; pass++) |
||
758 | { |
||
759 | /* Write a few rows at a time. */ |
||
760 | png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows); |
||
761 | |||
762 | /* If you are only writing one row at a time, this works */ |
||
763 | for (y = 0; y < height; y++) |
||
764 | { |
||
765 | png_write_rows(png_ptr, &row_pointers[y], 1); |
||
766 | } |
||
767 | } |
||
768 | #endif no_entire /* use only one output method */ |
||
769 | |||
770 | /* You can write optional chunks like tEXt, zTXt, and tIME at the end |
||
771 | * as well. Shouldn't be necessary in 1.1.0 and up as all the public |
||
772 | * chunks are supported and you can use png_set_unknown_chunks() to |
||
773 | * register unknown chunks into the info structure to be written out. |
||
774 | */ |
||
775 | |||
776 | /* It is REQUIRED to call this to finish writing the rest of the file */ |
||
777 | png_write_end(png_ptr, info_ptr); |
||
778 | #endif hilevel |
||
779 | |||
780 | /* If you png_malloced a palette, free it here (don't free info_ptr->palette, |
||
781 | as recommended in versions 1.0.5m and earlier of this example; if |
||
782 | libpng mallocs info_ptr->palette, libpng will free it). If you |
||
783 | allocated it with malloc() instead of png_malloc(), use free() instead |
||
784 | of png_free(). */ |
||
785 | png_free(png_ptr, palette); |
||
786 | palette=NULL; |
||
787 | |||
788 | /* Similarly, if you png_malloced any data that you passed in with |
||
789 | png_set_something(), such as a hist or trans array, free it here, |
||
790 | when you can be sure that libpng is through with it. */ |
||
791 | png_free(png_ptr, trans); |
||
792 | trans=NULL; |
||
793 | |||
794 | /* clean up after the write, and free any memory allocated */ |
||
795 | png_destroy_write_struct(&png_ptr, &info_ptr); |
||
796 | |||
797 | /* close the file */ |
||
798 | fclose(fp); |
||
799 | |||
800 | /* that's it */ |
||
801 | return (OK); |
||
802 | } |
||
803 | |||
804 | #endif /* if 0 */ |