external/io_grib2/g2lib/enc_png.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include <png.h>
   5 #include "proto.h"
   6
   7 #ifdef __64BIT__
   8   typedef int g2int;
   9 #else
  10   typedef long g2int;
  11 #endif
  12
  13 struct png_stream {
  14    unsigned char *stream_ptr;     /*  location to write PNG stream  */
  15    g2int stream_len;               /*  number of bytes written       */
  16 };
  17 typedef struct png_stream png_stream;
  18
  19 void user_write_data(png_structp ,png_bytep , png_uint_32 );
  20 void user_flush_data(png_structp );
  21
  22 void user_write_data(png_structp png_ptr,png_bytep data, png_uint_32 length)
  23 /*
  24         Custom write function used to that libpng will write
  25         to memory location instead of a file on disk
  26 */
  27 {
  28      unsigned char *ptr;
  29      g2int offset;
  30      png_stream *mem;
  31
  32      mem=(png_stream *)png_get_io_ptr(png_ptr);
  33      ptr=mem->stream_ptr;
  34      offset=mem->stream_len;
  35 /*     printf("SAGwr %ld %ld %x\n",offset,length,ptr);    */
  36      /*for (j=offset,k=0;k<length;j++,k++) ptr[j]=data[k];*/
  37      memcpy(ptr+offset,data,length);
  38      mem->stream_len += length;
  39 }
  40
  41
  42 void user_flush_data(png_structp png_ptr)
  43 /*
  44         Dummy Custom flush function
  45 */
  46 {
  47    int *do_nothing=NULL;
  48 }
  49
  50
  51 int ENC_PNG(char *data,g2int *width,g2int *height,g2int *nbits,char *pngbuf)
  52 {
  53
  54     int color_type;
  55     g2int j,bytes,pnglen,bit_depth;
  56     png_structp png_ptr;
  57     png_infop info_ptr;
  58 //    png_bytep *row_pointers[*height];
  59     png_bytep **row_pointers;
  60     png_stream write_io_ptr;
  61
  62 /* create and initialize png_structs  */
  63
  64     png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL,
  65                                       NULL, NULL);
  66     if (!png_ptr)
  67        return (-1);
  68
  69     info_ptr = png_create_info_struct(png_ptr);
  70     if (!info_ptr)
  71     {
  72        png_destroy_write_struct(&png_ptr,(png_infopp)NULL);
  73        return (-2);
  74     }
  75
  76 /*     Set Error callback   */
  77
  78     if (setjmp(png_jmpbuf(png_ptr)))
  79     {
  80        png_destroy_write_struct(&png_ptr, &info_ptr);
  81        return (-3);
  82     }
  83
  84 /*    Initialize info for writing PNG stream to memory   */
  85
  86     write_io_ptr.stream_ptr=(png_voidp)pngbuf;
  87     write_io_ptr.stream_len=0;
  88
  89 /*    Set new custom write functions    */
  90
  91     png_set_write_fn(png_ptr,(voidp)&write_io_ptr,(png_rw_ptr)user_write_data,
  92                     (png_flush_ptr)user_flush_data);
  93 /*    png_init_io(png_ptr, fptr);   */
  94 /*    png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);  */
  95
  96 /*     Set the image size, colortype, filter type, etc...      */
  97
  98 /*    printf("SAGTsettingIHDR %d %d %d\n",*width,*height,bit_depth); */
  99     bit_depth=*nbits;
 100     color_type=PNG_COLOR_TYPE_GRAY;
 101     if (*nbits == 24 ) {
 102         bit_depth=8;
 103         color_type=PNG_COLOR_TYPE_RGB;
 104     }
 105     else if (*nbits == 32 ) {
 106         bit_depth=8;
 107         color_type=PNG_COLOR_TYPE_RGB_ALPHA;
 108     }
 109     png_set_IHDR(png_ptr, info_ptr, *width, *height,
 110        bit_depth, color_type, PNG_INTERLACE_NONE,
 111        PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
 112
 113 /*     Put image data into the PNG info structure    */
 114
 115     /*bytes=bit_depth/8;*/
 116     bytes=*nbits/8;
 117     row_pointers=malloc((*height)*sizeof(png_bytep));
 118     for (j=0;j<*height;j++) row_pointers[j]=(png_bytep *)(data+(j*(*width)*bytes));
 119     png_set_rows(png_ptr, info_ptr, (png_bytepp)row_pointers);
 120
 121 /*     Do the PNG encoding, and write out PNG stream  */
 122
 123     png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
 124
 125 /*     Clean up   */
 126
 127     png_destroy_write_struct(&png_ptr, &info_ptr);
 128     free(row_pointers);
 129     pnglen=write_io_ptr.stream_len;
 130     return pnglen;
 131
 132 }
 133