#include <ft2build.h>
#include FT_ADVANCES_H
#include FT_INTERNAL_OBJECTS_H

  static FT_Error
  _ft_face_scale_advances( FT_Face    face,
                           FT_Fixed*  advances,
                           FT_UInt    count,
                           FT_UInt    flags )
  {
    FT_Fixed  scale;
    FT_UInt   nn;

    if ( (flags & FT_LOAD_NO_SCALE) )
      return FT_Err_Ok;

    if ( face->size == NULL )
      return FT_Err_Invalid_Size_Handle;

    if ( !(flags & FT_LOAD_VERTICAL_LAYOUT) )
      scale = face->size->metrics.x_scale;
    else
      scale = face->size->metrics.y_scale;

    /* this must be the same computation than to get linearHori/VertAdvance
     * (see FT_Load_Glyph() implementation in src/base/ftobjs.c */
    for (nn = 0; nn < count; nn++)
      advances[nn] = FT_MulDiv( advances[nn], scale, 64 );

    return 0;
  }


/* at the moment, we can perform fast advance retrieval only in
   the following cases:

       - unscaled load
       - unhinted load
       - light-hinted load
 */
#define  LOAD_ADVANCE_FAST_CHECK(flags)    \
    (((flags & (FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING)) != 0) || \
     FT_LOAD_TARGET_MODE(flags) == FT_RENDER_MODE_LIGHT)

  FT_EXPORT_DEF(FT_Error)
  FT_Get_Advance( FT_Face    face,
                  FT_UInt    gindex,
                  FT_UInt    flags,
                  FT_Fixed  *padvance )
  {
    FT_Face_GetAdvancesFunc  func;

    if ( !face )
      return FT_Err_Invalid_Face_Handle;

    if (gindex >= (FT_UInt) face->num_glyphs )
      return FT_Err_Invalid_Glyph_Index;

    func = face->driver->clazz->get_advances;
    if (func != NULL && LOAD_ADVANCE_FAST_CHECK(flags))
    {
      FT_Error  error;

      error = func( face, gindex, 1, flags, padvance );
      if (!error)
        return _ft_face_scale_advances( face, padvance, 1, flags );

      if (error != FT_Err_Unimplemented_Feature)
        return error;
    }

    return FT_Get_Advances( face, gindex, 1, flags, padvance );
  }


  FT_EXPORT_DEF(FT_Error)
  FT_Get_Advances( FT_Face    face,
                   FT_UInt    start,
                   FT_UInt    count,
                   FT_UInt    flags,
                   FT_Fixed  *padvances )
  {
    FT_Face_GetAdvancesFunc  func;
    FT_UInt                  num, end, nn;
    FT_Error                 error = 0;

    if ( !face )
      return FT_Err_Invalid_Face_Handle;

    num = (FT_UInt) face->num_glyphs;
    end = start + count;
    if (start >= num || end < start || end > num)
      return FT_Err_Invalid_Glyph_Index;

    if (count == 0)
        return FT_Err_Ok;

    func = face->driver->clazz->get_advances;
    if (func != NULL && LOAD_ADVANCE_FAST_CHECK(flags))
    {
      error = func( face, start, count, flags, padvances );
      if (!error) goto Exit;

      if (error != FT_Err_Unimplemented_Feature)
        return error;
    }

    error = 0;

    if ((flags & FT_ADVANCE_FLAG_FAST_ONLY) != 0)
      return FT_Err_Unimplemented_Feature;

    flags |= FT_LOAD_ADVANCE_ONLY;
    for (nn = 0; nn < count; nn++)
    {
      error = FT_Load_Glyph( face, start+nn, flags );
      if (error) break;

      padvances[nn] = (flags & FT_LOAD_VERTICAL_LAYOUT)
                    ? face->glyph->advance.x
                    : face->glyph->advance.y;
    }
    if (error) return error;

  Exit:
    return _ft_face_scale_advances( face, padvances, count, flags );
  }