The source file has grown by some 53 lines so what have we gained:
- A more colourful palette, the values of which are pre-computed for each possible iteration value:
palette = new int[MAX_ITER];
for (int i = 0; i<palette.length; i++)
palette[i] = java.awt.Color.HSBtoRGB(i/256f, 1, i/(i+8f));
- The ability to zoom in and out of the set based on mouse location:
imageView.addEventHandler(MouseEvent.MOUSE_CLICKED, (mouseEvent) -> {
if(mouseEvent.getButton() == javafx.scene.input.MouseButton.PRIMARY) {
ZOOM = ZOOM * 0.5;
}
if(mouseEvent.getButton() == javafx.scene.input.MouseButton.SECONDARY) {
ZOOM = ZOOM / 0.5;
}
offsetX = offsetX+ ZOOM *(mouseEvent.getX()-(width/2));
offsetY = offsetY+ ZOOM *(mouseEvent.getY()-(height/2));
System.out.printf("offset (x/y): (%f / %f)", offsetX, offsetY);
calculate();
});
- The method which computes the Mandelbrot set is run in a separate thread to the application. The result of which is then displayed in the imageView:
private void calculate() {
if (!calculationInProgress.getAndSet(true)) {
System.out.println("calculate spawned");
Task calculate = createWorker();
new Thread(calculate).start();
} else {
System.out.println("someone beat us to it!");
}
}
private Task createWorker() {
return new Task() {
@Override protected Object call() throws Exception {
Platform.runLater(() -> {
currentImageView.setImage(createMandelbrotImage());
calculationInProgress.set(false);
});
return true;
}
};
}
What’s left to do?
- Refine the colour palette used, produce one with more subtle variation.
- Implement a panning function with the mouse
- Improve the speed of rendering by using additional threads to produce an inter-laced image.
- Sort out the ugly pixelation encountered after several zooms
Full source code available here
CS7 Networks 
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