[comp.windows.x] Transparent Windows --- Any info Wanted

mouse@lightning.mcrcim.mcgill.EDU (03/03/91)

> I know this topic has been discussed before,

Indeed it has.  It comes up periodically in various (slightly
different) forms.

> Could someone give me some info on how to make a transparent window.

It depends on precisely what you mean.  For example, do you want to be
able to display graphics in this window?  If the stuff underneath
changes, do the changes have to show through as well?

If you don't want to display anything in the transparent window, there
is a perfect solution: use an InputOnly window.

If you want to display stuff, but don't care if hidden changes don't
get updated until the "transparent" window goes away, you may be able
to use an InputOutput window with a background of None.

If you want to display stuff and want changes to show through, and are
willing to require the server to support the SHAPE extension (not
unreasonable, IMO) you may be able to reshape the overlying window to
match the graphics.  (This causes the window to be nonexistent rather
than existing but transparent in the "show-through" areas.  If this
bothers you, use an InputOnly overlay to deal with input.)
Unfortunately in most implementations of SHAPE, changing shapes is
comparatively slow, so this doesn't work very well if you change shape
often.

I think that covers most possibilities.  If you want to display stuff,
want changes to show through, and want to change the shape of the
opaque area often, I have no suggestions, except to use the SHAPE
solution and beat on your server vendor to speed up shape changes.

					der Mouse

			old: mcgill-vision!mouse
			new: mouse@larry.mcrcim.mcgill.edu