Gfrktyl

I am making my own JavaFX color picker just for learning more about JavaFX. I am rendering color wheel in JavaFX using WritableImage and I have renderImage method to render color wheel in my program. And I am using Slider to change brightness of the color wheel.

The code is working fine but it's rendering slower. And the other reason I asked this question is also to learn about fast rendering algorithms in Java because if I make something else like Mandelbrot set or If I want to zoom that canvas containing WritableImage then just using image as resource(As suggested in comment below) won't work.

How can I improve my code to render the color wheel faster?

import javafx.application.Application;

import javafx.beans.Observable;

import javafx.beans.property.IntegerProperty;

import javafx.beans.property.SimpleIntegerProperty;

import javafx.geometry.Insets;

import javafx.scene.Scene;

import javafx.scene.canvas.Canvas;

import javafx.scene.control.Slider;

import javafx.scene.image.PixelWriter;

import javafx.scene.image.WritableImage;

import javafx.scene.layout.VBox;

import javafx.scene.paint.Color;

import javafx.stage.Stage;



import static java.lang.Math.atan2;

import static java.lang.Math.toDegrees;



public class Example extends Application{



    private static final int ANTIALIASING_BASE = 3;



    private WritableImage writableImage;

    private PixelWriter pixelWriter;

    private Canvas canvas;



    private IntegerProperty w;

    private IntegerProperty h;

    private Slider slider;



    public static void main(String... arguments){

        launch(arguments);

    }



    @Override

    public void start(Stage primaryStage){



        w = new SimpleIntegerProperty(255 + 42);

        h = new SimpleIntegerProperty(360);

        slider = new Slider(0, 100, 100);



        primaryStage.setWidth(w.get());

        primaryStage.setHeight(h.get());



        canvas = new Canvas(255, 255);

        writableImage = new WritableImage(255, 255);

        pixelWriter = writableImage.getPixelWriter();



        canvas.getGraphicsContext2D()

              .drawImage(writableImage, 0, 0, w.get(), h.get(), 0, 0, w.get(), h.get());



        renderImage();



        slider.valueProperty().addListener(this::change);



        VBox root = new VBox(12.5, canvas, slider);

        root.setPadding(new Insets(12.5));



        primaryStage.setScene(new Scene(root));

        primaryStage.setResizable(false);

        primaryStage.show();

    }



    //method to change brightness using slider

    private void change(Observable observable){

        writableImage = new WritableImage(255, 255);

        pixelWriter = writableImage.getPixelWriter();

        canvas.getGraphicsContext2D()

              .drawImage(writableImage, 0, 0, w.get(), h.get(), 0, 0, w.get(), h.get());



        renderImage();

    }



    //method that renders color wheel image

    private void renderImage(){

        for(int x = 0; x < 255; x++){

            for(int y = 0; y < 255; y++){

                Color c = getAntialiasedPixel(x, y);

                if(c.getRed() == 0.0 && c.getGreen() == 0.0 && c.getBlue() == 0.0

                        && slider.valueProperty().get() != 0.0){

                    c = Color.web("#f4f4f4");

                }

                pixelWriter.setColor(x, y, c);

            }

        }



    }



    //method that calculates color

    private Color getColor(double x, double y){



        double distance = getDistance(x, y);



        if(distance > 127.5){

            return Color.web("#f4f4f4");

        }



        double h = getAngle(x, y);

        double s = (distance / 127.5);

        double b = slider.valueProperty().get() / 100;



        return Color.hsb(h, s, b);

    }



    //method to make color wheel look smoother

    private Color getAntialiasedPixel(int x, int y){

        double step = 1d / ANTIALIASING_BASE;

        double N = ANTIALIASING_BASE * ANTIALIASING_BASE;

        double r = 0, g = 0, b = 0;



        for(int i = 0; i < ANTIALIASING_BASE; i++){

            for(int j = 0; j < ANTIALIASING_BASE; j++){

                Color c = getColor(x + step * (i + 0.5) - 0.5,

                                   y + step * (j + 0.5) - 0.5);

                r += c.getRed() / N;

                g += c.getGreen() / N;

                b += c.getBlue() / N;

            }

        }



        return new Color(clamp(r), clamp(g), clamp(b), 1);

    }



    private double clamp(double val){

        return val > 1 ? 1 : val < 0 ? 0 : val;

    }



    private double getDistance(double x1, double y1){

        var y = 127.5 - y1;

        var x = 127.5 - x1;

        return Math.sqrt(y * y + x * x);

    }



    private double getAngle(double x1, double y1){

        var angle = toDegrees(atan2(y1 - 127.5, x1 - 127.5));

        if(angle < 0) angle += 360;

        return angle;

    }



}