[9209] in The GTK GIMP ToolKit mailing list archive
[gtk-list] Re: Clipping-Masks in Gdk
daemon@ATHENA.MIT.EDU (Stephan Krings)
Mon Oct 12 13:45:49 1998
From: Stephan Krings <slothkri@zedat.fu-berlin.de>
Date: Mon, 12 Oct 1998 17:01:22 +0200 (CEST)
To: blong@fiction.net
Cc: gtk-list@redhat.com
In-Reply-To: <19981011222401.A5475@shell9.ba.best.com>
Resent-From: gtk-list@redhat.com
Reply-To: gtk-list@redhat.com
Hello Brandon,
> A bitmask has 1 bit per pixel, and you probably aren't running X in
> black & white, so the default (-1) isn't what you want. Just take
> away the -.
Yes, I guessed that and tried it with 1 as an indicator for a simple
black and white mask, too. But that didn't change anything for me
cause the magic I was missing is...
> Additionally, the GC is dependent on the pixel depth, so you should
> create your GC for the mask using the mask instead of the drawing area
> window, so add this:
>
> gc = gdk_gc_new(mask);
...in this point here. I didn't know that it's necessary to create a
new GC dependent on that mask. And if I had known I'd have probably
been fooled by the prototype for gdk_gc_new, which takes a
GdkWindow-pointer as parameter. I've read somewhere that pixmaps and
bitmaps are just special kind of windows but I thought this similarity
would be restricted to the drawing-functions (gdk_draw_* etc).
Anyway this fixed all problems for me and the rest seems pretty clear
to me after that.
So, many thanks for your detailed code-examination and short tutorial!
Stephan
--
Stephan Krings Freie Universitaet Berlin
AG Kommunikationsserver Zentraleinrichtung fuer Datenverarbeitung (ZEDAT)
slothkri@zedat.fu-berlin.de Fabeckstr. 32
Tel: +49 30 838 3527 14195 Berlin
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