🚀 go-pugleaf

In article <478@mks.UUCP>, wheels@mks.UUCP (Gerry Wheeler) writes:
> In article <8806151250.AA29397@ucbvax.Berkeley.EDU>, U211510@HNYKUN11.BITNET (Wil Groenen) writes:
> > I have a problem [...] reading a character from screen at current
> > cursor position.
> 
>             ... but I would theorise that this is not possible.
> Remember, once the character is drawn on the screen it is just a
> bunch of bits. This is quite unlike the usual video screens for
> IBM-type computers. It would take quite a program to read the pattern
> of bits and tell which character it was.

If you use the BIOS/GEMDOS to write to the screen, the characters are
in fixed positions.  If you also had access to the font used, the problem
is one of (bit) pattern matching.  In high resolution, a screen character
is contained in 16 bytes, all you have to do is match this set of 16 bytes
against 256 sets in the font table.  This is actually what happens in
IBM-type computers when in graphics mode.

Things are a little bit more complicated if you use the DVI since the
area of the screen that contains the character might be "corrupted"
by other things and the character might not be normal sized.

- Robert Ling   <rling@june.cs.washington.edu>