Method Image.GIF.__decode()

Method __decode

array __decode()

Description

Decodes a GIF image structure down to chunks and

({int xsize,int ysize,      // 0: size of image drawing area
  int numcol,               // 2: suggested number of colors
  void|string colortable,   // 3: opt. global colortable
  ({ int aspx, int aspy,    // 4,0: aspect ratio or 0, 0 if not set
     int background }),     //   1: index of background color

followed by any number these blocks in any order:

  ({ GIF.EXTENSION,         //   0: block identifier
     int extension,         //   1: extension number
     string data })         //   2: extension data
 
  ({ GIF.RENDER,            //   0: block identifier
     int x, int y,          //   1: position of render
     int xsize, int ysize,  //   3: size of render
     int interlace,         //   5: interlace flag
     void|string colortbl,  //   6: opt. local colortable
     int lzwsize,           //   7: lzw code size
     string lzwdata })      //   8: packed lzw data

and possibly ended with one of these:

  ({ GIF.ERROR_PREMATURE_EOD })   // premature end-of-data
 
  ({ GIF.ERROR_TOO_MUCH_DATA,     // data following end marker
     string data })               // (rest of file)
 
  ({ GIF.ERROR_UNKNOWN_DATA,      // unknown data
     string data })               // (rest of file)

Returns

the above array

Note

May throw errors if the GIF header is incomplete or illegal.

This is in the very advanced sector of the GIF support; please read about how GIF files works.