[Devel] FT_Face_GetAdvancesFunc

[Masatake YAMATO]

Hi,

I'd like to know about FT_Face_GetAdvancesFunc and 
FT_Driver_ClassRec::get_advances.

It seems that none driver uses this field. Right?
Will you use this field in the future?
Will you move this field to a service?


  typedef FT_Error
  (*FT_Face_GetAdvancesFunc)( FT_Face     face,
                              FT_UInt     first,
                              FT_UInt     count,
                              FT_Bool     vertical,
                              FT_UShort*  advances );

  /*    get_advances     :: A function handle used to return the advances  */
  /*                        of 'count' glyphs, starting at `index'.  the   */
  /*                        `vertical' flags must be set when vertical     */
  /*                        advances are queried.  The advances buffer is  */
  /*                        caller-allocated.                              */

I cannot find `index' in the typedef. Maybe the correct typedef is

  typedef FT_Error
  (*FT_Face_GetAdvancesFunc)( FT_Face     face,
                              FT_UInt*    index,
                              FT_UInt     count,
                              FT_Bool     vertical,
                              FT_UShort*  advances );

Here, I assume index points a glyph array.

BTW, what is `advance'? 
I guess the the advance is something like kerning:
kerning value between index[n-1] and index[n] is advance[n]
Right? Misunderstanding?

If my guessing is correct, I propose to change the typedef to


  typedef FT_Error
  (*FT_Face_GetAdvancesFunc)( FT_Face     face,
                              FT_UInt*    index,
                              FT_UInt     count,
                              FT_Bool     vertical,
                              FT_Vector*  advances );

So we can support corss-stream kerning like TeX.

Masatake YAMATO