Oh I think I can explain. You don't call the command; you add the command to the Map; and each time the map draws it will call your command (allowing the command to draw something on the screen).
When you are done with your visual feedback; you call command.setValid(false); and next time the map draws it will notice your command is no longer valid and stop using it. -- Jody Garnett On Saturday, 11 June 2011 at 12:52 AM, carlos henrique de souza junior wrote: > > Good afternoon guys I was looking at the code of this page: > http://udig.refractions.net/confluence/display/DEV/Providing+Visual+Feedback+from+a+View > my doubts is when I call the command I have to draw MapGraphicContext pass > an object as I take this object on the map I'm working? > > I'll paste the code down here > > public void draw( MapGraphicContext context ) { > > //initialize the graphics handle > ViewportGraphics g = context.getGraphics(); > g.setColor(Color.BLACK); > g.setStroke(ViewportGraphics.LINE_SOLID, 1); > > //get the map blackboard > IMap map = context.getLayer().getMap(); > IBlackboard blackboard = map.getBlackboard(); > > List<Coordinate> coordinates = (List<Coordinate>) blackboard.get("route"); > > if (coordinates == null) { > return; //no coordinates to draw > } > > MathTransform data2world = CRS.findMathTransform( > DefaultGeographicCRS.WGS84, context.getCRS() ); > > for (Coordinate coordinate : coordinates) { > Ellipse2D e = new Ellipse2D.Double( > coordinate.x-4, > coordinate.y-4, > 10,10); > g.draw(e); > try { > Coordinate worldCoord = JTS.transform(coordinate, null, data2world ); > Point point = context.worldToPixel(worldCoord); > g.drawOval( point.x-1, point.y-2, 3, 3); > } catch (TransformException e1) { > } > } > } > _______________________________________________ > User-friendly Desktop Internet GIS (uDig) > http://udig.refractions.net > http://lists.refractions.net/mailman/listinfo/udig-devel
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