Custom Control Help: Draw a line and output start and end points

Question

I'm looking to find or make a custom control (or simple subVI) that will appear as a 100x100 unit grid and allow me to draw a line from one point to another on that grid. It will then output the (x,y) of the starting and end point of that line on the grid.  Any help or ideas?
Thanks,
Steve
LabVIEW 2009 SP1
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Answer 1

What you basically want is a loop with an event structure where you process Mouse Down, Move and Up events for your controls. There are any number of ways of implementing something like this, but this one will probably be the simplest:
Use a multicolumn listbox or a table for your grid. Hide the scrollbars and headers.
You can use the ActiveCell property with -2,-2 to select all cells. You can then use the cell size property to set the exact size of the cell.
Next, you put a picture control on top of the table and color its background transparent so that the table shows through. You use property node to make sure the two are aligned to exactly the same spot and size.
You use the mouse events on the picture control to detect the clicks and moves.
You use the table's Point to Row Column method to translate the event's position data to a cell.
You use the picture control VIs to draw the line on the picture based on that data.
You can even color the selected cells in the table using the table properties.
If you want to simplify things somewhat, you can also use the timeout event instead of the Mouse Move event to draw the line, but then you'll need to keep the timeout value in a shift register and reset it to -1 (no timeout) when the Mouse Up event happens.
I would also suggest processing Mouse Enter and Leave events to change the cursor and cancel if the user leaves in the middle of dragging.
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