Hello, I have been working on a racket GUI recently. So far it's been wonderfully smooth sailing, especially compared to Java. I had a couple of questions about the canvas object. Any help would be wonderful.
Many Thanks, Hillary Questions: 1) Why does this work? (define canvas (new canvas% [parent window] [paint-callback (lambda (canvas dc) (draw canvas dc))])) But this doesn't (define canvas (new canvas% [parent window] [paint-callback (draw canvas dc)])) It seems that in both cases the paint-callback is being set to a 2-arity procedure. However, in the second case the window doesn't update unless draw is called from REPL. 2) I have a bunch (two dozen) of little objects that I would like to be able to draw on one canvas. At the moment I am passing each object the drawing context which comes from the canvas, letting the object draw itself and then moving onto the next object. By this method, if one object changes I have to redraw the entire canvas. I know in Java you can redraw only part of the canvas. Is there a standard method in Racket for drawing a bunch of objects on a canvas efficiently?
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