ShapeMover.java Source code

Introduction

Here is the source code for ShapeMover.java

Source

import java.applet.Applet;
import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Label;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JApplet;

//Use double buffering to remove rectangle flickers and make it repaint faster.
public class ShapeMover extends JApplet {
    static protected Label label = new Label("Drag rectangle around within the area");

    public void init() {

        getContentPane().setLayout(new BorderLayout());
        getContentPane().add(new MyCanvas());

        getContentPane().add("South", label);
    }

    public static void main(String s[]) {
        Frame f = new Frame("ShapeMover");
        f.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        Applet applet = new ShapeMover();
        f.add("Center", applet);
        applet.init();
        f.pack();
        f.setSize(new Dimension(550, 250));
        f.show();
    }
}

class MyCanvas extends Canvas implements MouseListener, MouseMotionListener {
    Rectangle rect = new Rectangle(0, 0, 100, 50);

    Graphics2D g2;

    int preX, preY;

    boolean isFirstTime = true;

    Rectangle area;

    boolean pressOut = false;

    public MyCanvas() {
        setBackground(Color.white);
        addMouseMotionListener(this);
        addMouseListener(this);
    }

    public void mousePressed(MouseEvent e) {
        preX = rect.x - e.getX();
        preY = rect.y - e.getY();

        if (rect.contains(e.getX(), e.getY()))
            updateLocation(e);
        else {
            ShapeMover.label.setText("Drag it.");
            pressOut = true;
        }
    }

    public void mouseDragged(MouseEvent e) {
        if (!pressOut)
            updateLocation(e);
        else
            ShapeMover.label.setText("Drag it.");
    }

    public void mouseReleased(MouseEvent e) {
        if (rect.contains(e.getX(), e.getY()))
            updateLocation(e);
        else {
            ShapeMover.label.setText("Drag it.");
            pressOut = false;
        }
    }

    public void mouseMoved(MouseEvent e) {
    }

    public void mouseClicked(MouseEvent e) {
    }

    public void mouseExited(MouseEvent e) {
    }

    public void mouseEntered(MouseEvent e) {
    }

    public void updateLocation(MouseEvent e) {
        rect.setLocation(preX + e.getX(), preY + e.getY());

        if (checkRect()) {
            ShapeMover.label.setText(rect.getX() + ", " + rect.getY());
        } else {
            ShapeMover.label.setText("drag inside the area.");
        }

        repaint();
    }

    public void paint(Graphics g) {
        update(g);
    }

    public void update(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
        Dimension dim = getSize();
        int w = (int) dim.getWidth();
        int h = (int) dim.getHeight();
        g2.setStroke(new BasicStroke(8.0f));

        if (isFirstTime) {
            area = new Rectangle(dim);
            rect.setLocation(w / 2 - 50, h / 2 - 25);
            isFirstTime = false;
        }

        // Clears the rectangle that was previously drawn.
        g2.setPaint(Color.white);
        g2.fillRect(0, 0, w, h);

        g2.setColor(Color.red);
        g2.draw(rect);
        g2.setColor(Color.black);
        g2.fill(rect);
    }

    boolean checkRect() {
        if (area == null) {
            return false;
        }

        if (area.contains(rect.x, rect.y, 100, 50)) {
            return true;
        }
        int new_x = rect.x;
        int new_y = rect.y;

        if ((rect.x + 100) > area.getWidth()) {
            new_x = (int) area.getWidth() - 99;
        }
        if (rect.x < 0) {
            new_x = -1;
        }
        if ((rect.y + 50) > area.getHeight()) {
            new_y = (int) area.getHeight() - 49;
        }
        if (rect.y < 0) {
            new_y = -1;
        }
        rect.setLocation(new_x, new_y);
        return false;
    }
}