[pdftex] auto letter spacing

[Thanh Han The]

On Mon, Dec 11, 2006 at 10:52:57PM +0100, Thanh Han The wrote:
> Hi all,
>
> I am working on a primitive \letterspacefont that generates
> a letter-spaced font from another font like this:
>
> ,--------
> | \font\f=cmr10
> | \letterspacefont\fx=\f 100 % letterspace \f by a factor 100/1000
> | \fx This is a text in letter-spaced cmr10
> `--------
>
> the above example creates \fx as a virtual font, in which
> each charater is taken from \f, and have a kern of
> 50*quad(f)/1000 at each side. All this happens in pdftex
> memory.
>
> However I am not sure the "more right" way to do this is that
> each character c should have a kern of 5*width_of_c/1000 at
                                         ^^^^^^^^^^^^^^^^^
sorry, typo. It should be 50*width_of_c/1000

Thanh