SketchPanel.java Source code

Introduction

Here is the source code for SketchPanel.java

Source

import java.awt.Container;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class SketchPanel extends JPanel implements KeyListener {

    private Point startPoint = new Point(0, 0);

    private Point endPoint = new Point(0, 0);

    public SketchPanel() {
        addKeyListener(this);
    }

    public void keyPressed(KeyEvent evt) {
        int keyCode = evt.getKeyCode();
        int d;
        if (evt.isShiftDown())
            d = 5;
        else
            d = 1;
        if (keyCode == KeyEvent.VK_LEFT)
            add(-d, 0);
        else if (keyCode == KeyEvent.VK_RIGHT)
            add(d, 0);
        else if (keyCode == KeyEvent.VK_UP)
            add(0, -d);
        else if (keyCode == KeyEvent.VK_DOWN)
            add(0, d);
    }

    public void keyReleased(KeyEvent evt) {
    }

    public void keyTyped(KeyEvent evt) {
    }

    public boolean isFocusTraversable() {
        return true;
    }

    public void add(int dx, int dy) {
        endPoint.x += dx;
        endPoint.y += dy;
        Graphics g = getGraphics();
        g.drawLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y);
        g.dispose();
        startPoint.x = endPoint.x;
        startPoint.y = endPoint.y;
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setTitle("Sketch");
        frame.setSize(300, 200);
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        Container contentPane = frame.getContentPane();
        contentPane.add(new SketchPanel());

        frame.show();
    }
}