Path: utzoo!censor!geac!jtsv16!uunet!bloom-beacon!ATHENA.MIT.EDU!swick
From: swick@ATHENA.MIT.EDU (Ralph R. Swick)
Newsgroups: comp.windows.x
Subject: Re: Colormaps and Visuals
Message-ID: <8909192040.AA08953@LYRE.MIT.EDU>
Date: 19 Sep 89 20:40:46 GMT
References: <8909191908.AA04405@popeye.nosc.mil.sun.com>
Organization: DEC/MIT Project Athena
Lines: 36

> But in the Toolkit, there is no way to set the visual
> for a given widget

None of the built-in widget classes (e.g. Core) have a Visual
resource, you are correct, but that does not prevent other
widgets from declaring such a resource and thereby giving
the application control.

In R3 the default visual type (in XtCreateWindow) is always
CopyFromParent. In the revisions just published for the R4
specification, the Shell class defines a Visual resource which
is intended to satisfy simple cases such as yours.

>     My question is this, how can I show true colors in a widget, when
> the default visual is of type StaticColor?

Until R4 is released, your only choice is to explicitly set
the visual type in the realize procedure of your widget.

>     Also, is the DefaultColormap apply to a window, or does it apply
> to a visual?

A colormap is associated with a specific visual when it is created,
and may only be used with that visual.  The DefaultColormap is
the colormap of the root window and can only be used with other
windows that have the same visual type as the root window.

>     One final note.  Is there a call that returns the number of
> un-allocated color cells in a Colormap?

Not in Xlib or in Xt.

> Is there a way to do
> this now?

Only by allocating until the server says 'no more'.