Re: [cc65] TGI bitmap fnts revisited

From: "Ullrich von Bassewitz"; on Sun, July 10, 2011; at 06:56 AM -0400
>
> For stroke fonts,
> the horizontal co-ordinate is the baseline of the characters.

It's the vertical (Y, height) coördinate when printing horizontally,
and the horizontal (X, width) coördinate when printing vertically.

>
> > 2. Our last TGI discussions lead to the result that the TGI kernel
> > takes care of clipping for about all drawing primitives. However,
> > there's currently no clipping for bitmap-font text output
> > implemented in the TGI kernel. But, for consistency reasons,
> > I believe it should be done there.
> > ...
> > - Characters not fitting on the screen are omitted completely.
> >   a) The TGI kernel creates a copy of the substring that fits
> >      on the screen (and potentially, adjusts a co-ordinate).
> >   b) The TGI kernel creates a single-character string for every
> >      character that can fit on the screen; and, calls into the
> >      driver, in a loop (leveraging the cursor movement feature).
>
> Because a) needs some unknown amount of extra memory,
> b) is probably the way to go.

There is a third (Pascal) way:
  c) Separately pass in the (sub)string's length.  The kernel clips off
     the end of the string simply by reducing the claimed length.
     It clips off the beginning by changing the string-pointer,
     moving a coördinate, and reducing the claimed length.

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