[Freetype] FT_Outline_Decompose

[Wallace Chigona]

I don't know what's wrong with the following code.  I am getting a bus
error on FT_Outline_Decompose(gOutline->outline, &_interface, this )). 
What am I possibly doing wrong.

Regards,

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 _interface.line_to = (FT_Outline_LineTo_Func)lineToCallback;
  _interface.conic_to = (FT_Outline_ConicTo_Func)conicToCallback;
  _interface.cubic_to = (FT_Outline_CubicTo_Func)cubicToCallback;
  _interface.shift = 0;
  _interface.delta = 0;
  if (FT_Init_FreeType( &library ))
    cerr << "error on library";
  error  = FT_New_Face( library,
"/usr/lib/X11/fonts/Type1/Helvetica.pfa",
                       0, &face );
  if ( error == FT_Err_Unknown_File_Format )
    cerr << "can be open but not read\n";
  else if ( error )
    cerr << "could not be opened\n";
  FT_Set_Pixel_Sizes(face, 20, 0);
  FT_UInt glyph_index = FT_Get_Char_Index( face, 'A' );
  FT_Load_Glyph(face, glyph_index, FT_LOAD_DEFAULT);
  FT_OutlineGlyph gOutline;
  if ( FT_Get_Glyph( face->glyph, (FT_Glyph*)&gOutline ))
    cerr << "error outline\n";
  if (FT_Outline_Decompose(&gOutline->outline, &_interface, this ))
    cerr << " error decomposing\n";