[comp.sys.next] Instance dwg & the Draw app

cc3z+@andrew.cmu.edu (Christopher N. Carlson) (08/21/90)

Can anyone explain why the Draw app doesn't use the instance drawing
mechanism?  Is this purely for pedagogical reasons?  Or is instance
drawing somehow inappropriate in this context?

chavez@quorum.com (R. Martin Chavez) (08/22/90)

cc3z+@andrew.cmu.edu (Christopher N. Carlson) writes:

>Can anyone explain why the Draw app doesn't use the instance drawing
>mechanism?  Is this purely for pedagogical reasons?  Or is instance
>drawing somehow inappropriate in this context?

Instance drawing, though extremely fast, leaves a noticeable flicker
on the screen (even with buffered windows).  The compositing algorihm
used by the Draw app provides for a much smoother rubberbanding effect.
TopDraw employs a similar mechanism.

In general, I'd recommend that you break out the Draw app's compositing
and offscreen-window code for most rubberbanding applications.

R. Martin Chavez
Quorum Software Systems, Inc.