I tried this on a different machine (800 MHz) and got the behavior like you.
But on my own machine a long polygon gets jerky also without other morphs.

Steffen

-----Original Message-----
From: Lex Spoon [mailto:lex at cc.gatech.edu]
Sent: Donnerstag, 7. Dezember 2000 18:49
To: squeak at cs.uiuc.edu
Subject: RE: Question: How do I delete a simple line



I guess it's the morphic redraws that are causing you trouble.  Have you
tried your experiment in a region of the screen which doesn't have any
morphs in it?  I've got a little connector-morph kind of thingie on my
screen here, and feedback is immediate so long as I don't extend the
line over any neighboring windows.  When I do, it suddenly gets really
jerky.


-Lex



Steffen.Mueller at phaidros.com wrote:
> Hallo Bert,
> 
> Thanks for your tip. You are right, Morphic does all that for me but to
slow
> for big morphs! I am working on a 350 MHz Pentium with Win2000 and the
> performance for dragging  big morphs (or long polygons) is terrible.
> This code now works for me:
> 
> 	(Line
> 		from: 100 at 100
> 		to: 200 at 200
> 		withForm: (Form extent: 1 @ 1))
> 		displayOn: Display
> 		at: 0 @ 0
> 		clippingBox: Display boundingBox
> 		rule: Form reverse
> 		fillColor: nil
> 
> 
> The first call draws a line, the next removes this line from display.
> 
> Steffen
> 
> 
> 
> -----Original Message-----
> From: Bert Freudenberg [mailto:bert at isg.cs.uni-magdeburg.de]
> Sent: Freitag, 1. Dezember 2000 13:01
> To: squeak at cs.uiuc.edu
> Subject: RE: Question: How do I delete a simple line
> 
> 
> On Fri, 1 Dec 2000 Steffen.Mueller at phaidros.com wrote:
> 
> > Hallo Hans-Martin,
> > 
> > I want to drag a line very fast from one point to another and I hoped I
> > could use the same method like in SystemWindow (see doFastFrameDrag).
> > I'm afraid 'restore display' is not the right method to do this.
> 
> Checkout DisplayObject>>follow:while:bitsBehind:startingLoc: . This gives
> an example how to save the bits before drawing, then drawing something,
> then restoring the contents when the object moves. Try
> 	Form fromUser followCursor
> to see it in action. You would have to adapt this to draw something
> different each time (it currently only displays a fixed size form).
> 
> Btw: Morphic does all that for you ;^)
> 
> -- Bert