[671] in The GTK GIMP ToolKit mailing list archive
[gtk-list] Re: Many novice GTK questions + a new Colormap rotation plug-in.
daemon@ATHENA.MIT.EDU (Owen Taylor)
Thu Aug 7 03:31:35 1997
To: gtk-list@redhat.com
From: Owen Taylor <owt1@cornell.edu>
Date: 07 Aug 1997 03:20:45 -0400
In-Reply-To: Pavel Greenfield's message of Tue, 5 Aug 1997 12:52:45 -0400 (EDT)
Resent-From: gtk-list@redhat.com
Reply-To: gtk-list@redhat.com
Pavel Greenfield <pavel@riskdevel.ml.com> writes:
> 1. How do I erase an arrow without having to redraw the preview (all of it
> or even part of it)? If that's impossible, how about a few suggestions how
> to make redrawing more efficient? (Something beyond "redraw the part
> covered by the arrow only.")
If redrawing the relevant portion of the preview isn't satisfactory,
you could investigate drawing your arrows in XOR mode. You need to
create a GC with the mode set to XOR - something like:
GdkGCValues values;
GdkGC xor_gc;
values.foreground = widget->style->white;
values.function = GDK_XOR;
xor_gc = gdk_gc_new_with_values (widget->window,
&values,
GDK_GC_FOREGROUND |
GDK_GC_FUNCTION);
Then to erase it, all you have to do is draw it again. (But you have
to make sure it _is_ there ...)
> 2. How do I draw an arc centered at a certain point, of certain radius,
> from angle A to angle B?
How about
void gdk_draw_arc (GdkDrawable *drawable,
GdkGC *gc,
gint filled,
gint x,
gint y,
gint width,
gint height,
gint angle1,
gint angle2);
(The angles are in units of degrees * 64 from the three-o'clock
position, ala XDrawArc)
> 3. Can someone write a definitive (-ish) tut on how to control colors of
> the gdk-objects. A few people tried to explain that to me (Thank you very
> much, BTW) but I still don't get it!
[ not right now, anyways ]
> 4. My preview captures all the mouse events. When I tried to make the
> frame the preview is in capture these events it didn't work (except for
> GTK_EXPOSE). Why?
The frame doesn't have it's own window (the preview does). Only things
with an X-window can receive events. So you need to put the frame
inside something with a window. The best choice might be the EventBox
widget that I posted to this list some while ago. I probably should
clean it up a little and post a new version with documentation, but
what I posted before should work. (Of course, it won't be useful for
a plug-in unless it becomes standard - but no current widget is really
suitable - the viewport widget might work in some circumstances.)
Hope this helps,
Owen
--
To unsubscribe: mail -s unsubscribe gtk-list-request@redhat.com < /dev/null
