I think you may have misunderstood the first suggestion I made, about
keeping (shape, color) pairs in your atomic vector. I really meant
java.awt.Shape and java.awt.Color objects, rather than a symbol
(keyword is better as Christophe suggests) and a bunch of numbers.
Like so:
(defn render-shape [g shape color]
(doto g
(.setColor color)
(.fill shape)))
(draw-shape (Rectangle. 50 50 200 100) (Color. 0 0 255 75))
Java already has the "multi-method" Christophe suggests, in the form
of Graphics.fill(Shape); you don't have to implement it yourself.
On Sep 15, 8:15 pm, Lee Spector <lspec...@hampshire.edu> wrote:
> 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
> lspec...@hampshire.edu,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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