Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!amdahl!nsc!voder!wlbr!mh
From: mh@wlbr.EATON.COM (Mike Hoegeman)
Newsgroups: comp.windows.news
Subject: Re: Freezing canvases
Message-ID: <17256@wlbr.EATON.COM>
Date: 10 Jun 88 00:29:14 GMT
References: <553@ecrcvax.UUCP>
Reply-To: mh@wlbr.UUCP (0000-Mike Hoegeman)
Organization: Eaton IMS, Westlake Village, CA
Lines: 17

In article <553@ecrcvax.UUCP> andy@ecrcvax.UUCP (Andrew Dwelly) writes:
>Is there any way of "freezing" a canvas so that output does not appear on the
>screen until the canvas is "unfrozen" ?. This is rather like the /Mapped field
>except that a frozen canvas does not vanish from the screen. 
>
>Why should I want such a facility ?. Well, it is often better to freeze a
>window before outputing a complex picture/diagram and then unfreeze it, so that
>the picture appears all at once. Watching a diagram form piece by piece on the
>screen seems to draw attention to the performance (or lack of it) of the NeWS
>server.

I don't think there's anything in NeWS akin to what you are asking for.
However you can accomplish  your goal by doing some sort of double buffering
scheme. One way to do this would be to do all your drawing on an unmapped canvas
and then use readcanvas  (or is it imagecanvas ? i always get the two confused)
to "blit" the unmapped canvas a the mapped canvas.

-mike