AutoCAD .NET - Transient Graphics.. is my approach correct?

Question

I'm trying to write a simple script to prompt for two points and draw the line between them. It works completely fine, until the part "promptForPoint(promptMsgEnd)" where if the users cancels during the command (hits ESC) the entire program crashes with a fatal exception. Is my approach to transient graphics reasonably correct? How do I properly handle the user cancelling?

        IntegerCollection ints = new IntegerCollection(new int[] { });
        TransientManager ctm = TransientManager.CurrentTransientManager;
        Line l = new Line(startPoint, new Point3d(startPoint.X + 0.00000001, startPoint.Y, startPoint.Z));
        ctm.AddTransient(l, TransientDrawingMode.DirectShortTerm, 128, ints);

        //handle event - pointer movement
        PointMonitorEventHandler handler =
            delegate (object sender, PointMonitorEventArgs e)
            {
                l.EndPoint = e.Context.RawPoint;
                ctm.UpdateTransient(l, ints);
            };

        //add handler for visual
        _editor.PointMonitor += handler;

        //prompt for point
        ppr = promptForPoint(promptMsgEnd);

        //remove handler and erase
        _editor.PointMonitor -= handler;
        ctm.EraseTransient(l, ints);

score 0 · Accepted Answer · answered May 24 '17 at 02:09

Looks like the approach is okay- the issue was TransientManager which requires a "using" block to dispose of in the event the user cancels out of the program.

using (TransientManager ctm = TransientManager.CurrentTransientManager)            
{
//code here
}

AutoCAD .NET - Transient Graphics.. is my approach correct?

1 Answers1