NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/comp/windows/x/16238

Text File | 1992-09-08 | 1.8 KB | 40 lines

Newsgroups: comp.windows.x
Path: sparky!uunet!snorkelwacker.mit.edu!thunder.mcrcim.mcgill.edu!mouse
From: [e-mail] (der Mouse)
Subject: Re: Getting foreground/background colors of a window.
Message-ID: <[e-mail]>
Organization: McGill Research Centre for Intelligent Machines
References: <[e-mail]>
Date: Sun, 6 Sep 92 06:59:37 GMT
Lines: 30

In article <[e-mail]>, [e-mail] (Mats L|fstr|m) writes:

> For reasons of my own, I want to know the foreground and background
> colors used in a window.  But the window isn't created by my
> application, but rather by any other application.  Is there any way
> of getting this information?

Only by inference, by reading back what's in the window and trying to
figure it out.  One problem is that foreground and background may not
be well-defined; consider a GIF file displayer, for example.  Another
problem is telling the difference; consider an xterm with large
quantities of text displayed reversed - how are you to know which part
of the window is "reverse" and which is "normal"?

It's true that every window has a background of some sort.  But this
can be a pixel value, a pixmap, ParentRelative, or None.  In only one
of these cases is it even conceptually well-defined to ask what the
window's background color is, and in any case, you can't even find out
which alternative is in effect for a given window, never mind telling
what the pixel value is or pixmap contents are.  (Not
non-destructively, that is.  By playing games with obscuring portions
of the window in various ways and other things, you may be able to
deduce some things about the window's background.  All such attempts
suffer from races with the window's application redrawing the window's
contents.)

                    der Mouse

                [e-mail]