rwhitby@lennon.austek.oz (Rod Whitby) (05/02/90)
be drawn with. I have an exposure handler that accumulates the Expose rectangles and marks the objects which are in the Exposed region. When the Exposure count reaches zero, the handler then redraws the marked objects, setting the clip mask of each using XSetClipRectangles to be the Exposed region. I only allow objects to set their GC values using XCreateGC and an XGCValues structure, and I keep a copy of the XGCValues used, so I have knowledge of what values are in the object's GC (including the Clip Mask). My first question is: > Is there any way to set the GCDashList without using the > XSetDashes 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). A problem with my exposure handler's strategy arises when one of the objects already has a clip mask in it's GC. If I just use XSetClipRectangles to set the Clip Mask, then the object's existing Clip Mask will be overwritten. If the object sets its clip mask using the XGCValues structure, then I have knowledge of the Pixmap it used. My second question is: > 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. My thanks in advance for any answers to these questions. Any comments on my exposure handler's strategy are also welcome. Rod Whitby Austek Microsystems Pty. Ltd. Technology Park Adelaide, SA 5095 Australia ACSnet: rwhitby@austek.oz ARPA: rwhitby@austek.oz.au UUCP: uunet.uu.net!munnari!austek.oz.au!rwhitby
rws@EXPO.LCS.MIT.EDU (Bob Scheifler) (05/02/90)
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.