Article View: comp.sys.amiga.tech
Article #8353Multiple viewports
From: Chuck Baldwin
Date: Fri, 25 Mar 1988 07:11
Date: Fri, 25 Mar 1988 07:11
36 lines
1768 bytes
1768 bytes
[Not being entirely sure where this should go, I post to both]
I am trying to perform a conceptually simple task, of showing two
different views of a large bitmap by using two ViewPorts. My code
is not in obvious error, and I get bizarre but repeatable results.
Allocate a View, two ViewPorts, two RasInfos, one RastPort, and one BitMap
Initialize these items appropriately:
Point both RasInfo to BitMap
Give each ViewPort it's own RasInfo
Link two ViewPorts through vp.Next field
Link ViewPorts into View
Do arcane things to generate copper lists
ON_DISPLAY;
The problem is this ... the first ViewPort has graphics correctly
rendered, but the second doesn't. In fact, the second ViewPort is black, which
is not the currently defined background color. It's as if the display
is not spewing electrons for the bottom half of the screen.
The program exits okay, so it's not as if I were corrupting system structures
or anything similarly catastrophic.
Anybody able to shed some light on this? If you really need to see the
code, I can post it, but it's almost exactly like the example code in
RKM vol1 about using Views and ViewPorts. Really!
Mitch
(Hiding out here under an assumed name ...)
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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!tut.cis.ohio-state.edu!bloom-beacon!gatech!hubcap!ncrcae!usceast!baldwin From: baldwin@usceast.UUCP (Chuck Baldwin) Newsgroups: comp.sys.amiga.tech,comp.sys.amiga Subject: Multiple viewports Message-ID: <2554@usceast.UUCP> Date: 25 Mar 88 07:11:40 GMT Lines: 36 Keywords: two viewports for every bitmap