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 #include <zlib.h>
   7 #endif /* USE_PNG */
   8
   9 #ifdef __64BIT__
  10   typedef int g2int;
  11 #else
  12   typedef long g2int;
  13 #endif
  14
  15 #if defined _UNDERSCORE
  16    #define dec_png dec_png_
  17 #elif defined _DOUBLEUNDERSCORE
  18    #define dec_png dec_png__
  19 #endif
  20
  21 #ifdef USE_PNG
  22 struct png_stream {
  23    unsigned char *stream_ptr;     /*  location to write PNG stream  */
  24    g2int stream_len;               /*  number of bytes written       */
  25 };
  26 typedef struct png_stream png_stream;
  27
  28 void user_read_data(png_structp , png_bytep , png_uint_32 );
  29
  30 void user_read_data(png_structp png_ptr,png_bytep data, png_uint_32 length)
  31 /*
  32         Custom read function used so that libpng will read a PNG stream
  33         from memory instead of a file on disk.
  34 */
  35 {
  36      char *ptr;
  37      g2int offset;
  38      png_stream *mem;
  39
  40      mem=(png_stream *)png_get_io_ptr(png_ptr);
  41      ptr=(void *)mem->stream_ptr;
  42      offset=mem->stream_len;
  43 /*     printf("SAGrd %ld %ld %x\n",offset,length,ptr);  */
  44      memcpy(data,ptr+offset,length);
  45      mem->stream_len += length;
  46 }
  47 #endif /* USE_PNG */
  48
  49
  50
  51 int dec_png(unsigned char *pngbuf,g2int *width,g2int *height,char *cout)
  52 {
  53 #ifdef USE_PNG
  54     int interlace,color,compres,filter,bit_depth;
  55     g2int j,k,n,bytes,clen;
  56     png_structp png_ptr;
  57     png_infop info_ptr,end_info;
  58     png_bytepp row_pointers;
  59     png_stream read_io_ptr;
  60     png_uint_32 h32, w32;
  61
  62 /*  check if stream is a valid PNG format   */
  63
  64     if ( png_sig_cmp(pngbuf,0,8) != 0)
  65        return (-3);
  66
  67 /* create and initialize png_structs  */
  68
  69     png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL,
  70                                       NULL, NULL);
  71     if (!png_ptr)
  72        return (-1);
  73
  74     info_ptr = png_create_info_struct(png_ptr);
  75     if (!info_ptr)
  76     {
  77        png_destroy_read_struct(&png_ptr,(png_infopp)NULL,(png_infopp)NULL);
  78        return (-2);
  79     }
  80
  81     end_info = png_create_info_struct(png_ptr);
  82     if (!end_info)
  83     {
  84        png_destroy_read_struct(&png_ptr,(png_infopp)info_ptr,(png_infopp)NULL);
  85        return (-2);
  86     }
  87
  88 /*     Set Error callback   */
  89
  90     if (setjmp(png_jmpbuf(png_ptr)))
  91     {
  92        png_destroy_read_struct(&png_ptr, &info_ptr,&end_info);
  93        return (-3);
  94     }
  95
  96 /*    Initialize info for reading PNG stream from memory   */
  97
  98     read_io_ptr.stream_ptr=(png_voidp)pngbuf;
  99     read_io_ptr.stream_len=0;
 100
 101 /*    Set new custom read function    */
 102
 103     png_set_read_fn(png_ptr,(png_voidp)&read_io_ptr,(png_rw_ptr)user_read_data);
 104 /*     png_init_io(png_ptr, fptr);   */
 105
 106 /*     Read and decode PNG stream   */
 107
 108     png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
 109
 110 /*     Get pointer to each row of image data   */
 111
 112     row_pointers = png_get_rows(png_ptr, info_ptr);
 113
 114 /*     Get image info, such as size, depth, colortype, etc...   */
 115
 116     /*printf("SAGT:png %d %d %d\n",info_ptr->width,info_ptr->height,info_ptr->bit_depth);*/
 117 /*    (void)png_get_IHDR(png_ptr, info_ptr, (png_uint_32 *)width, (png_uint_32 *)height,
 118                &bit_depth, &color, &interlace, &compres, &filter);*/
 119     (void)png_get_IHDR(png_ptr, info_ptr, &w32, &h32,
 120                &bit_depth, &color, &interlace, &compres, &filter);
 121
 122     *height = h32;
 123     *width = w32;
 124
 125 /*     Check if image was grayscale      */
 126
 127 /*
 128     if (color != PNG_COLOR_TYPE_GRAY ) {
 129        fprintf(stderr,"dec_png: Grayscale image was expected. \n");
 130     }
 131 */
 132     if ( color == PNG_COLOR_TYPE_RGB ) {
 133        bit_depth=24;
 134     }
 135     else if ( color == PNG_COLOR_TYPE_RGB_ALPHA ) {
 136        bit_depth=32;
 137     }
 138 /*     Copy image data to output string   */
 139
 140     n=0;
 141     bytes=bit_depth/8;
 142     clen=(*width)*bytes;
 143     for (j=0;j<*height;j++) {
 144       for (k=0;k<clen;k++) {
 145         cout[n]=*(row_pointers[j]+k);
 146         n++;
 147       }
 148     }
 149
 150 /*      Clean up   */
 151
 152     png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
 153 #endif /* USE_PNG */
 154     return 0;
 155
 156 }
 157