Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!apple!agate!mindseye!izumi
From: izumi@mindseye.berkeley.edu (Izumi Ohzawa)
Newsgroups: comp.sys.next
Subject: Re: Caching Images for Views ....
Message-ID: <1991May15.183632.22391@agate.berkeley.edu>
Date: 15 May 91 18:36:32 GMT
References: <1991May15.161837.27550@noose.ecn.purdue.edu>
Sender: root@agate.berkeley.edu (Charlie Root)
Distribution: usa
Organization: /etc/organization
Lines: 45

In article <1991May15.161837.27550@noose.ecn.purdue.edu> songer@orchestra.ecn.purdue.edu (Christopher M Songer) writes:
>Hi,
>
>     I'm looking to put a Postscript image in a view smaller than the
>total image -- ie, I would like to be able to scroll around in it. I
>looked through the concepts manual and it seemed to indicate that the
>best way to do fast updates is to draw to a bitmap and then copy the
>bit map into the view (no suprise there.) The on-line manual describes
>a "Bitmap" object. It does not seem to be present in 2.0.
>

Bitmap object is obsolete.  Its functionality has been
expanded by NXImage object.

This is what I do with NXImage and compositing,
it may not be exactly what you need, but should contain
most of the steps needed.

 ....
NXRect myRect;
id myImage;

.... where you prepare cached bitmaps...
//	initialize myRect to size and location of bitmap.

	myImage = [[NXImage alloc] initSize:&myRect.size];
//	You can do Zone allocation above if necessary.

	[myImage useCacheWithDepth: NX_TwoBitGrayDepth];
	[myImage lockFocus];	/* focus on NXImage to work on */

.... standard drawing code into myImage

	[myImage unlockFocus];


.... In your compositing section, in another method...

	[myImage composite: NX_COPY toPoint: &myRect.origin ];


Izumi Ohzawa             [ $@Bg_78^=;(J ]
USMail: University of California, 360 Minor Hall, Berkeley, CA 94720
Telephone: (415) 642-6440             Fax:  (415) 642-3323
Internet: izumi@violet.berkeley.edu   NeXTmail: izumi@pinoko.berkeley.edu