| Re: user graphics drawing without prior current image knowledge [message #20405] |
Mon, 19 June 2000 00:00 |
Ben Tupper
Messages: 186
Registered: August 1999
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Senior Member |
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pdesmedt wrote:
> Hi,
>
> what is the best way in IDL to allow a user to draw graphics (ROI,
> lines)
> without having to inform IDL on which image or drawing area the drawing
> should take
> place. E.g., one gives the draw roi command, the user then draws on any
> of the visible drawing areas
> the ROI and after the program is returned the ROI coordinates AND the
> viewport ID (or image)
> is returned to the user...
>
>
Hello,
I assume that you are using a widget based application. The event
structure returned by the draw widget contains its ID.
{WIDGET_DRAW, ID:0L, TOP:0L, HANDLER:0L, TYPE: 0, X:0, Y:0, PRESS:0B,
RELEASE:0B, CLICKS:0}
If the user has a selection of draw widgets upon which to draw an ROI, you
can use the EVENT.ID value to keep track of which ID is active.
You should build an event handler (or set of handlers if you prefer) which
will be responsive to the EVENT.TYPE field (watch for press, release and
motion) events. David Fanning has a routine called ZIMAGE (and an
object based ZOOMBOX routine) on his website that provides a well
annotated example.
Good luck,
Ben
--
Ben Tupper
Bigelow Laboratory for Ocean Science
tupper@seadas.bigelow.org
pemaquidriver@tidewater.net
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