On Sep 15, 2010, at 1:57 PM, Alan wrote:
> This looks a lot like what I would do - I'm afraid I don't have any
> brilliant insights for you. I do have a couple ways you could make
> this smaller, though:
>
> - Instead of (atom ()) and convoluted swap! logic, what about (atom
> []) and (swap! shapes conj new-shape)?
> - Similarly don't use (list shape-name...), try [shape-name...]
> -- (defn render-shape [shape-name [x y w h] color])
> -- (render-shape 'rect (take 4 (repeatedly #(rand-int 400))) blue)
>
> The last two combine to let you avoid writing rand-int so many times.
Thanks Alan. Using vectors instead of lists does clean things up a little. I've
spent a lot of my life in other Lisps and so lists spring to mind first.
FYI below is a slightly nicer version that uses vectors and also adds line
drawing. I didn't follow your other suggestions because I was interested in
minimizing the tool, not the example.
I'd still be quite interested in any advise anyone has on minimizing the code
for initializing/buffering the window (using only core, contrib, and built-in
java libraries -- but maybe different built-in java libraries? I'm coming from
Lisp, not from Java, and I'm not sure what's in there.)
Also, this would have a smaller impact but I'm curious about it: is there a way
to treat method names as data and then make calls to them, as one can with
clojure functions? Then I could pass things like fillRect, or map rect to
fillRect, etc. This would make things slightly simpler here but be handy in
other cases... but I don't see how to do it.
Thanks, -Lee
--------------
(def max-x 500)
(def max-y 500)
(def shapes (atom []))
(defn render-shape
[graphics [shape-name x y w h r g b a]]
(.setColor graphics (java.awt.Color. r g b a))
(case shape-name
rect (.fillRect graphics x y w h)
oval (.fillOval graphics x y w h)
line (.drawLine graphics x y w h)))
(def panel
(let [jp (proxy [javax.swing.JPanel]
[]
(getPreferredSize [] (java.awt.Dimension. max-x max-y))
(paint [g]
(render-shape g ['rect 0 0 max-x max-y 255 255 255 255])
(doall (map #(render-shape g %) @shapes))))]
(doto (new javax.swing.JFrame "My graphics window")
(.setSize max-x max-y)
(.add jp)
(.setVisible true))
jp))
(defn draw-shape [& shape]
"Adds a shape to the current drawing. The first argument should be one of
the following symbols: rect, oval, or line. For rect or oval this should
be followed by: x, y, width, height, red, green, blue, alpha. The x and y
coordinates specify the upper right corner. Color values (including alpha,
which is opacity) should range from 0 to 255. For line the arguments are
the remaining arguments are x-start, y-start, x-end, y-end, red, green,
blue, alpha."
(swap! shapes conj shape)
(.paint panel (.getGraphics panel)))
;; test it out by drawing a bunch of shapes
(draw-shape 'rect 20 20 460 80 255 128 0 255)
(draw-shape 'oval 120 120 300 100 100 100 0 20)
(draw-shape 'oval 300 50 100 300 10 100 200 20)
(draw-shape 'line 0 0 500 500 255 0 0 255)
--
Lee Spector, Professor of Computer Science
School of Cognitive Science, Hampshire College
893 West Street, Amherst, MA 01002-3359
[email protected], http://hampshire.edu/lspector/
Phone: 413-559-5352, Fax: 413-559-5438
Check out Genetic Programming and Evolvable Machines:
http://www.springer.com/10710 - http://gpemjournal.blogspot.com/
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