Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!abvax!iccgcc!klimas
From: klimas@iccgcc.decnet.ab.com
Newsgroups: comp.lang.smalltalk
Subject: Re: optimising redraws of graphic panes in  ST/V 286
Message-ID: <3201.27b6a2ea@iccgcc.decnet.ab.com>
Date: 11 Feb 91 18:58:02 GMT
References: <1991Feb8.102528.10392@runx.oz.au>
Lines: 29

In article <1991Feb8.102528.10392@runx.oz.au>, timm@runx.oz.au (Tim Menzies) writes:
> Dear netland,
> 
> I've got a graphics application written in Smalltalk V/286. One 
> problem with it is that the screen redraws are a slow. I've
> got a display of a X-Y plot with lots of  lines/ text labels on it. 
> I've tried various ways to speed up the redraws. The manuals isn't exactly 
> helpful and so I include below a sample listing and ask the following
> questions...
> 
> - would you expect that writing to a virtual form, then copying
>   this to the display, would speed up the redraw? If yes, then
>   how is this done? I've tried every variant I can think of on
>   setting drawLine's pen's dest/sourceForm to Display/form etc.,
>   etc.
> - any other ideas on how to speed up the redraws on the following
>   sample system?
>  
> There must be a way. The standard Smalltalk window redraws are 
> FASTTTT. What am I doing wrong?
	One simple trick to significantly speeding up windows is
	to simply byte align your windows (i.e. make the X coordinate
	of a pane's origin an even multiple of 8, such as 0,8,16,24, etc.).
	I have observed a significant speedup by this simple guideline
	and I believe it may hold for other windowing systems also (note
	that OS/2 PM byte aligns your windows when you try to reposition
	them less than 8 pixels).

	Ed Klimas