/**************************************************
*   Author: Morrison
*   Date:  27 Oct 202020
**************************************************/

import javafx.application.Application;
import javafx.application.Platform;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.paint.Color;
import javafx.scene.layout.HBox;
import javafx.scene.layout.BorderPane;
import javafx.scene.control.Label;
import javafx.scene.control.Slider;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;

public class SliderDemo extends Application
{
    private Stage primary;
    private Color color;
    public SliderDemo()
    {
        color = Color.BLACK;
    }
    
    @Override
    public void init()
    {
    }
    private Color greyScale(int value)
    {
        return Color.rgb(value, 0, 0);
    }

    @Override
    public void start(Stage primary)
    {
        this.primary = primary;
        
        BorderPane bp = new BorderPane();
        HBox hbox = new HBox();
        Slider s = new Slider(0, 255, 127);
        Label level = new Label("127");
        Canvas canvas = new Canvas(500,500);
        hbox.getChildren().addAll(s, level);
        bp.setTop(hbox);
        bp.setCenter(canvas);
        GraphicsContext pen = canvas.getGraphicsContext2D();
        pen.setFill(greyScale(127));
        pen.fillRect(0, 0, canvas.getWidth(), canvas.getHeight());
        s.valueProperty().addListener( (observable, oldValue, newValue) ->
        {
            level.setText("" + newValue.intValue());
            pen.setFill(greyScale(newValue.intValue()));
            pen.fillRect(0, 0, canvas.getWidth(), canvas.getHeight());
        });
        primary.setScene(new Scene(bp));
        primary.show();
    }

    @Override
    public void stop()
    {
    }
}