[vtkusers] check for pending tk events

[Kevin Wright]

At 12:00 PM 7/23/2002 -0400, you wrote:
>Hi All,
>
>I'm looking for a way to abort a render if a user interacts with the
>window, and the easiest way seems to be for the window's AbortCheck
>method to check if there are any tk events pending.
>
>Is there a way, either in raw tk or within the vtkTkRenderWidget, to
>check if there are events pending?  I've searched the tk documentation
>with no luck.

I've never tried this, so I'm not entirely sure it would work, but I think 
if you call Tcl_DoOneEvent with flags set to make it only process window 
events, and not to wait, if there are no window events present, it will 
return 0, otherwise it will process one event and return 1.  So something 
like this, I think:

if ( Tcl_DoOneEvent ( TCL_DONT_WAIT | TCL_WINDOW_EVENTS ) ) {
   // BAIL OUT
}

As long as you don't mind processing the next event on the queue.  If you 
don't want to do that, then you can actually get a handle to the event 
queue itself and work along the linked list looking for certain events, but 
I'm afraid I wouldn't be much help with that.  Look in tclNotify.c for some 
of the code that controls the event queue itself.

Hope that helps,
Kevin.