Re: [Devel] Disabling the autohinter

[David Turner]

Detlef Würkner wrote:
> address@hidden (Keith Packard) wrote:
>
>
> > That's not quite what I want; I'd like to have no hinting when a 
> > format-specific hinter is not available.  When anti-aliasing most fonts, 
> > the autohinter generally produces worse looking output than the unhinted 
> > glyphs.
>
>
> So you want the autohinter to be never used? Then you dont need to link
> it. Comment out the line
>
> FT_USE_MODULE(autohint_module_class)
Yes, but this requires a custom build of the library, not a very good
idea, since Keith wants to use FreeType as available on a given system.

> in config/ftmodule.h and rebuild (here this works as expected).
> In source code the only possibility I'm aware of is (untested)
>
> if ( !FT_DRIVER_HAS_HINTER( face->driver ) )
>   flags |= FT_LOAD_NO_HINTING;

FT_DRIVER_HAS_HINTER is an internal macro and should never be
used by client applications, so this is not a very good thing
to do either. The only orking solutions I'm thinking of are:

  - unload the "autohinter" module when initializing the
    library, something like:

        FT_Library  library;
        FT_Module   autohint;

        error = FT_Init_FreeType( &library );
        if ( error ) { .... }

        autohint = FT_Get_Module( library, "autohinter" );
        if ( autohing != NULL )
        {
          FT_Remove_Module( library, module );
        }

     Note that this is a global decision


   - lobby for the addition of a new function like
     FT_Set_AutoHint_Mode( library, mode ), where "mode"
     could take values like:

          FT_AUTOHINT_MODE_DEFAULT ::
              use the auto-hinter only when no format-specific
              hinter is available

          FT_AUTOHINT_MODE_NEVER ::
              never use the auto-hinter

     Again, a global decision


   - lobby for the addition of a new FT_LOAD_NO_AUTOHINT bit flag
     to be used with FT_Load_Glyph/FT_Load_Char. However, I'm strongly
     against this kind of addition since we're running out of bit flags
     unless we want to drop portability to 16-bit systems; I thus
     prefer other solutions.

     In this specific case, the decision is local and can be changed
     each time a glyph is loaded. But my opinion is that if you know
     precisely when to disable/enable it, you can directly use the
     "FT_LOAD_NO_HINTING" bit-flag anyway..


Keith, what would be reasonable for you ??

- David Turner
- The FreeType Project  (www.freetype.org)