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Article #165 (419 is last):
Newsgroups: freenet.sci.comp.atari.questions
From: visitor
Subject: DRAW AND FILL (XIO) COMMANDS
Date: Tue Aug 15 08:57:37 1989


 I have heard and seen it in the books about an XIO command 18.
It's supposed to fill in a graphic with color. How can I do this?
Please explain.
      Thank you for any information.

** Answered by DOUG WOKOUN (aa384) on Mon Jul 31 04:01:23 1989 **

The DRAW or FILL command is simply a
command to fill in all points from the
one selected to the right to the next
plotted point.

To make this clearer.

    +                 +     +
    A                 B     C

if you did an XIO 18 at point A, you
would get this:

    +++++++++++++++++++     +
    A                 B     C

In my experience, I have not had much
use for this command.  It will not fill
a closed object like the fill commands
in a paint program.

The disadvantage to this command is 
that you must load the values for the
coordinates into memory before calling
it.  loc.90 is the row coordinate and
91,92 is the LSB/MSB for the column.
You must also set loc.695 to a non-zero
number to enable the fill.

The other drawing commands can be
executed from XIO also.  This acts
like a call to a library of OS routines
including commands to various devices
when needed.

        Thanks for asking.

|Doug Wokoun|aa384|Atari SigOp|


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