Re: [ft] Modifying/Enhancing the Truetype Interpreter

[Werner LEMBERG]

> I'm interested in using the details described in this whitepaper to
> make a patch (official or unofficial, don't care) to enhance the
> existing TT interpreter in Freetype.  The enhanced TT interpreter
> would probably be most useful with AA or subpixel, but not with B/W,
> where the existing TT is preferable.  Essentially it would modify
> the TT interpreter to ignore DELTAP instructions in the X direction
> under various conditions.

Please go ahead!  This is definitely a good idea to try.

> * Is anybody with more knowledge / experience with TT instrucing /
>   Freetype willing to attempt to implement this enhanced TT
>   interpreter?

Sorry, I have no time to do that.

> * How difficult of a problem is this?  Is this feasible?

It's not very difficult, I believe.  You probably have to add some
flags to one of the internal TrueType interpreter structures to store
the results of the bytecode signature scanning.

Do you have any ideas how many fonts are affected?  Which of them are
important/well known?  And finally, do you have a working ClearType
emulation, this is, at least tripling the horizontal resolution for
calling the bytecode interpreter, then compressing the results again
for proper subpixel positioning?


    Werner