Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!sun-barr!newstop!sun!argv
From: argv@turnpike.Eng.Sun.COM (Dan Heller)
Newsgroups: comp.windows.x.motif
Subject: Re: Loading pixmap in drawn button on color display?
Message-ID: <141351@sun.Eng.Sun.COM>
Date: 27 Aug 90 16:04:08 GMT
References: <1990Aug27.005946.5857@elroy.jpl.nasa.gov> <1990Aug27.132311.11381@sunrise.com>
Sender: news@sun.Eng.Sun.COM
Organization: O'Reilly && Associates
Lines: 38

In article larry@sunrise.com (Larry Rogers) writes:
> In article pjs@aristotle.jpl.nasa.gov writes:
> >displays?  More to the point, why can't the drawnbutton figure
> >it out for itself???
> You have to generate an image and then generate a pixmap from the
> image.  An easier solution under Motif is to use XmGetPixmap.  It
> automatically generates a pixmap of the correct depth for the
> display.  It's also pretty quick becauuse it caches the pixmaps
> it creates.

In this particular person's application, he is allowing the user
to select (at run time) a bitmap file.  He's got to load the file
somehow, and the only way to do it is into a pixmap.  Then, he
would have to extract an image (big operation here; performance
hazard warning if this is going to be done frequently), then call
XmGetPixmap from the image just to get a pixmap that's the correct
depth.  Furthermore, this pixmap is _cached_ which means that if
he no longer needs it (it doesn't sound likely if the user is
browsing), the pixmap is saved anyway.

I would recommend using XmGetPixmap() under the following conditions:
    1) Bitmaps used are compiled into the code (they are not read dynamically)
       This means that bitmaps are specified using #include or the short[]'s
       are precoded (probably based on the same files).
    2) These pixmaps are to be used repeatedly throughout the life of the
       application, not just at UI initialization time.

For "this" particular problem, I backup my recommendation that a second
pixmap (of correct depth) is used and to use XCopyPlane() to render the
bitmap into the pixmap.  That is, until osf fixes this and the label
widget/gadget to test for the depth themselves and use XCopyPlane()
rather than XCopyArea() in the redisplay method (-very- simple fix).

--
dan
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O'Reilly && Associates   argv@sun.com / argv@ora.com
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