/**  *  simple patchwork graphics demo * @author: Jeremy Rayner, changes by Dierk Koenig */def width = 500; def height = 400; def blockSize = 10def g = createGraphics()// main loopwhile (true) {    drawBlock()}// --------------------------------------------------// random integerdef rnd(upperBound){    (int)(Math.random() * upperBound)}// draw a random coloured square within boundsdef drawBlock() {    def row    = rnd(height / blockSize)    def column = rnd(width  / blockSize)    def colour = new java.awt.Color(rnd(255),rnd(255),rnd(255))    g.setColor(colour)    g.fillRect(column * blockSize, row * blockSize, blockSize, blockSize)}// create a new frame and clear screendef createGraphics() {    def frame = new groovy.swing.SwingBuilder().              frame(title:'Painting by numbers',                     location:[20,20],                     size:[width,height],                    defaultCloseOperation:javax.swing.WindowConstants.EXIT_ON_CLOSE) {    }    frame.show()                  // obtain graphics context    def gfx = frame.getGraphics()                  // clear screen    gfx.setColor(java.awt.Color.BLACK)    gfx.fillRect(0,0,width,height)    return gfx}