paint.clj

(import '(java.awt.image BufferedImage)
        '(java.awt Color Canvas Frame))

(def width 640)
(def height 480)
(def cs [16711680 167123])
(defonce image (BufferedImage. width height BufferedImage/TYPE_INT_RGB))
(defonce pixels (-> image .getRaster .getDataBuffer .getData))
(defonce canvas (doto (proxy [Frame] []
                        (update [g] (. this paint g))
                        (paint [g]
                          (. g drawImage image 0 0 nil)))
                  (.setSize width height)
                  (.setBackground Color/black)
                  (.setFocusableWindowState false)
                  (.setVisible true)))

(defmacro for-loop [[sym init check change :as params] & steps]
  `(loop [~sym ~init value# nil]
     (if ~check
       (let [new-value# (do ~@steps)]
         (recur ~change new-value#))
       value#)))
(time
 (for-loop
  [k 0 (< k 2) (inc k)]
  (for-loop
   [c 0 (< c 2) (inc c)]
   (for-loop
    [i 0 (< i width) (inc i)]
    (for-loop
     [j 0 (< j height) (inc j)]
     (aset pixels (+ i (* j width)) (get cs c))))
   (.repaint canvas))))

Paint.java

import java.awt.Frame;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferInt;

public class Paint extends Frame {
  public int width = 640;
  public int height = 480;
  public BufferedImage image;
  public int[] pixels;
  public int[] cs = {16711680, 167123};
  public static void main(String[] args) {
    new Paint();
  }
  public Paint() {
    image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    pixels = ((DataBufferInt) image.getRaster().getDataBuffer()).getData();
    setSize(width, height);
    setBackground(Color.black);
    setFocusableWindowState(false);
    setVisible(true);

    long t = System.currentTimeMillis();
    for (int k = 0 ; k < 2; k++) {
      for (int c = 0; c < 2; c++) {
        for (int i = 0 ; i < width; i++) {
          for (int j = 0; j < height; j++) {
            pixels[i + j * width] = cs[c];
          }
        }
        repaint();
      }
    }
    System.out.println(System.currentTimeMillis() - t);
  }
  public void update(Graphics g) {
    paint(g);
  }
  public void paint(Graphics g) {
    g.drawImage(image, 0, 0, null);
  }
}