2011/1/21 WoodHacker <ramsa...@comcast.net>
> I'm converting the java code examples in Killer Game Programming in
> Java by Andrew Davison to Clojure and am having great fun doing it.
> But I've hit wall where I can't seem to get the code to work.
>
> The following code moves an animated gif strip to a java array:
>
> public BufferedImage[] loadStripImageArray(String fnm, int number)
> {
> if (number <= 0) {
> System.out.println("number <= 0; returning null");
> return null;
> }
>
> BufferedImage stripIm;
> if ((stripIm = loadImage(fnm)) == null) {
> System.out.println("Returning null");
> return null;
> }
>
> int imWidth = (int) stripIm.getWidth() / number;
> int height = stripIm.getHeight();
> int transparency = stripIm.getColorModel().getTransparency();
>
> BufferedImage[] strip = new BufferedImage[number];
> Graphics2D stripGC;
>
> // each BufferedImage from the strip file is stored in strip[]
> for (int i=0; i < number; i++) {
> strip[i] = gc.createCompatibleImage(imWidth, height,
> transparency); <=====
>
> // create a graphics context
> stripGC = strip[i].createGraphics();
> <=====
> // stripGC.setComposite(AlphaComposite.Src);
>
> // copy image
> stripGC.drawImage(stripIm,
> 0,0, imWidth,height,
> i*imWidth,0, (i*imWidth)+imWidth,height,
> null);
> stripGC.dispose();
> }
> return strip;
> } // end of loadStripImageArray()
>
> The problem I'm having is with the for loop. If I create an abject
> array of say 6 buffered images, how do I reference the indexed image
> array to match the lines pointed to? In other words what is the
> equivalent of strip[i] in Clojure?
>
Hello,
As far as possible, the equivalent of a java anArray[anIndex] expression
will be of not using an index in the first place in Clojure (*).
In your example, I'm not sure there is a compelling reason for having strip
be a true java array. A clojure vector would probably be sufficient.
So AFAICT, I would write your "loop" as:
(defn with-gc* [gc f]
(try (f gc)
(finally (when gc (.dispose gc)))))
(defmacro with-gc [[name gc-expr] & body] `(with-gc* ~gc-expr (fn [~name]
~@body)))
(let [get-strip (fn [offset] (let [strip (.createCompatibleImage gc imWidth
height transparency)] (with-gc [gc (.createGraphics strip ....)] (.drawImage
gc) strip)))]
(into [] (map get-strip (map #(* imWidth) (range number)))))
Not tested, would probably place the fn on more than one line
(*): of course, for when you /really/ want to do that / can't possibly do
without that, you can , by using nth or get functions. Or by directly using
java arrays. Sometimes. When you really don't see how to avoid this.
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