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From: rws@EXPO.LCS.MIT.EDU (Bob Scheifler)
Newsgroups: comp.windows.x
Subject: Re: Questions about ORing Clip Rectangles into a GC and setting DashList
Message-ID: <9005021343.AA11503@expire.lcs.mit.edu>
Date: 2 May 90 13:43:39 GMT
References: <328@lennon.austek.oz>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
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    Is there any way to set the GCDashList without using the
    XSetDashes convenience function ?

Not for a list of length greater than one (i.e., it isn't really a
convenience function).

    XSetDashes takes a dash list (char
    dash_list[]) and the length of the list, but the XGCValues structure
    only defines a single dash character (char dashes).

If you want to keep a copy of the GC state, including full dash and clip
state, you'll have to keep more information than just the XGCValues structure.

    Is there a way to OR a set of XRectangles (i.e the
    arguments to XSetClipRectangles) into a Pixmap (the value already
    stored in the object's GC)?  I want the clipped region to be the
    intersection of the existing Clip Mask and the Exposed region.

OR is like union, AND is like intersection.  Either way, you can't do it
directly if the clip state is really a Pixmap.  I'm afraid you'd have
to create a new bitmap, and then or/and the two regions together using
graphics operations into the bitmap.