ungrib/src/ngl/g2/dec_png.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #ifdef USE_PNG
   5 #include <png.h>
   6 #endif /* USE_PNG */
   7
   8 #ifdef __64BIT__
   9   typedef int g2int;
  10 #else
  11   typedef long g2int;
  12 #endif
  13
  14 #if defined _UNDERSCORE
  15    #define dec_png dec_png_
  16 #elif defined _DOUBLEUNDERSCORE
  17    #define dec_png dec_png__
  18 #endif
  19
  20 #ifdef USE_PNG
  21 struct png_stream {
  22    unsigned char *stream_ptr;     /*  location to write PNG stream  */
  23    g2int stream_len;               /*  number of bytes written       */
  24 };
  25 typedef struct png_stream png_stream;
  26
  27 void user_read_data(png_structp , png_bytep , png_uint_32 );
  28
  29 void user_read_data(png_structp png_ptr,png_bytep data, png_uint_32 length)
  30 /*
  31         Custom read function used so that libpng will read a PNG stream
  32         from memory instead of a file on disk.
  33 */
  34 {
  35      char *ptr;
  36      g2int offset;
  37      png_stream *mem;
  38
  39      mem=(png_stream *)png_get_io_ptr(png_ptr);
  40      ptr=(void *)mem->stream_ptr;
  41      offset=mem->stream_len;
  42 /*     printf("SAGrd %ld %ld %x\n",offset,length,ptr);  */
  43      memcpy(data,ptr+offset,length);
  44      mem->stream_len += length;
  45 }
  46 #endif /* USE_PNG */
  47
  48
  49
  50 int dec_png(unsigned char *pngbuf,g2int *width,g2int *height,char *cout)
  51 {
  52 #ifdef USE_PNG
  53     int interlace,color,compres,filter,bit_depth;
  54     g2int j,k,n,bytes,clen;
  55     png_structp png_ptr;
  56     png_infop info_ptr,end_info;
  57     png_bytepp row_pointers;
  58     png_stream read_io_ptr;
  59     png_uint_32 h32, w32;
  60
  61 /*  check if stream is a valid PNG format   */
  62
  63     if ( png_sig_cmp(pngbuf,0,8) != 0)
  64        return (-3);
  65
  66 /* create and initialize png_structs  */
  67
  68     png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL,
  69                                       NULL, NULL);
  70     if (!png_ptr)
  71        return (-1);
  72
  73     info_ptr = png_create_info_struct(png_ptr);
  74     if (!info_ptr)
  75     {
  76        png_destroy_read_struct(&png_ptr,(png_infopp)NULL,(png_infopp)NULL);
  77        return (-2);
  78     }
  79
  80     end_info = png_create_info_struct(png_ptr);
  81     if (!end_info)
  82     {
  83        png_destroy_read_struct(&png_ptr,(png_infopp)info_ptr,(png_infopp)NULL);
  84        return (-2);
  85     }
  86
  87 /*     Set Error callback   */
  88
  89     if (setjmp(png_jmpbuf(png_ptr)))
  90     {
  91        png_destroy_read_struct(&png_ptr, &info_ptr,&end_info);
  92        return (-3);
  93     }
  94
  95 /*    Initialize info for reading PNG stream from memory   */
  96
  97     read_io_ptr.stream_ptr=(png_voidp)pngbuf;
  98     read_io_ptr.stream_len=0;
  99
 100 /*    Set new custom read function    */
 101
 102     png_set_read_fn(png_ptr,(png_voidp)&read_io_ptr,(png_rw_ptr)user_read_data);
 103 /*     png_init_io(png_ptr, fptr);   */
 104
 105 /*     Read and decode PNG stream   */
 106
 107     png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
 108
 109 /*     Get pointer to each row of image data   */
 110
 111     row_pointers = png_get_rows(png_ptr, info_ptr);
 112
 113 /*     Get image info, such as size, depth, colortype, etc...   */
 114
 115     /*printf("SAGT:png %d %d %d\n",info_ptr->width,info_ptr->height,info_ptr->bit_depth);*/
 116 /*    (void)png_get_IHDR(png_ptr, info_ptr, (png_uint_32 *)width, (png_uint_32 *)height,
 117                &bit_depth, &color, &interlace, &compres, &filter);*/
 118     (void)png_get_IHDR(png_ptr, info_ptr, &w32, &h32,
 119                &bit_depth, &color, &interlace, &compres, &filter);
 120
 121     *height = h32;
 122     *width = w32;
 123
 124 /*     Check if image was grayscale      */
 125
 126 /*
 127     if (color != PNG_COLOR_TYPE_GRAY ) {
 128        fprintf(stderr,"dec_png: Grayscale image was expected. \n");
 129     }
 130 */
 131     if ( color == PNG_COLOR_TYPE_RGB ) {
 132        bit_depth=24;
 133     }
 134     else if ( color == PNG_COLOR_TYPE_RGB_ALPHA ) {
 135        bit_depth=32;
 136     }
 137 /*     Copy image data to output string   */
 138
 139     n=0;
 140     bytes=bit_depth/8;
 141     clen=(*width)*bytes;
 142     for (j=0;j<*height;j++) {
 143       for (k=0;k<clen;k++) {
 144         cout[n]=*(row_pointers[j]+k);
 145         n++;
 146       }
 147     }
 148
 149 /*      Clean up   */
 150
 151     png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
 152 #endif /* USE_PNG */
 153     return 0;
 154
 155 }
 156