Internet News 1999 October/INEWS_10_CD.ISO/pc/jdk/jdk1.2.2/docs/guide/2d/samples/BufferedShapeMover.java

Java Source | 1999-09-19 | 6.1 KB | 205 lines

import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
import java.awt.image.*;

public class BufferedShapeMover extends Applet{

    static protected Label label;

    public void init(){
        //Initialize the layout.
        setLayout(new BorderLayout());
        add(new BSMCanvas());
        label = new Label("Drag rectangle around within the area");
        add("South", label);
    }

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

}

class BSMCanvas extends Canvas implements MouseListener, MouseMotionListener{

    Rectangle rect = new Rectangle(0, 0, 100, 50);
    BufferedImage bi;
    Graphics2D big;

        // Holds the coordinates of the user's last mousePressed event.
    int last_x, last_y;
    boolean firstTime = true;
    TexturePaint fillPolka, strokePolka;
        Rectangle area;

        // True if the user pressed, dragged or released the mouse outside of the rectangle; false otherwise.
    boolean pressOut = false;

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

        // Creates the fill texture paint pattern.
                bi = new BufferedImage(5, 5, BufferedImage.TYPE_INT_RGB);
                big = bi.createGraphics();
                big.setColor(Color.pink);
                big.fillRect(0, 0, 7, 7);
                big.setColor(Color.cyan);
                big.fillOval(0, 0, 3, 3);
                Rectangle r = new Rectangle(0,0,5,5);
                fillPolka = new TexturePaint(bi, r);
        big.dispose();

        //Creates the stroke texture paint pattern.
                bi = new BufferedImage(5, 5, BufferedImage.TYPE_INT_RGB);
        big = bi.createGraphics();
        big.setColor(Color.cyan);
                big.fillRect(0, 0, 7, 7);
                big.setColor(Color.pink);
                big.fillOval(0, 0, 3, 3);
                r = new Rectangle(0,0,5,5);
                strokePolka = new TexturePaint(bi, r);
        big.dispose();
    }

        // Handles the event of the user pressing down the mouse button.
    public void mousePressed(MouseEvent e){

        last_x = rect.x - e.getX();
        last_y = rect.y - e.getY();

                // Checks whether or not the cursor is inside of the rectangle while the user is pressing themouse.
        if(rect.contains(e.getX(), e.getY())){
            updateLocation(e);
        } else {
        BufferedShapeMover.label.setText("First position the cursor on the rectangle and then drag.");
            pressOut = true;
        }
    }

        // Handles the event of a user dragging the mouse while holding down the mouse button.
    public void mouseDragged(MouseEvent e){

        if(!pressOut){
             updateLocation(e);
        } else {
        BufferedShapeMover.label.setText("First position the cursor on the rectangle and then drag.");
        }
    }

        // Handles the event of a user releasing the mouse button.
    public void mouseReleased(MouseEvent e){

                // Checks whether or not the cursor is inside of the rectangle when the user releases the
        // mouse button.
        if(rect.contains(e.getX(), e.getY())){
            updateLocation(e);
        } else {
        BufferedShapeMover.label.setText("First position the cursor on the rectangle and then drag.");
            pressOut = false;
        }
    }

    // This method required by MouseListener.
    public void mouseMoved(MouseEvent e){}

        // These methods are required by MouseMotionListener.
    public void mouseClicked(MouseEvent e){}
    public void mouseExited(MouseEvent e){}
    public void mouseEntered(MouseEvent e){}
    public void updateLocation(MouseEvent e){

        rect.setLocation(last_x + e.getX(), last_y + e.getY());
                /*
                 * Updates the label to reflect the location of the
                 * current rectangle
                 * if checkRect returns true; otherwise, returns error message.
                 */
                if (checkRect()) {
                    BufferedShapeMover.label.setText("Rectangle located at " +
                                                     rect.getX() + ", " +
                                                     rect.getY());
                } else {
                    BufferedShapeMover.label.setText("Please don't try to "+
                                                     " drag outside the area.");
                }
        repaint();
    }

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

    public void update(Graphics g){
        Graphics2D g2 = (Graphics2D)g;

              if(firstTime){
                    Dimension dim = getSize();
                    int w = dim.width;
                    int h = dim.height;
                    area = new Rectangle(dim);
            bi = (BufferedImage)createImage(w, h);
            big = bi.createGraphics();
            rect.setLocation(w/2-50, h/2-25);
            big.setStroke(new BasicStroke(8.0f));
            firstTime = false;
        }

        // Clears the rectangle that was previously drawn.
        big.setColor(Color.white);
        big.clearRect(0, 0, area.width, area.height);

        // Draws and fills the newly positioned rectangle to the buffer.
        big.setPaint(strokePolka);
        big.draw(rect);
        big.setPaint(fillPolka);
        big.fill(rect);

        // Draws the buffered image to the screen.
        g2.drawImage(bi, 0, 0, this);
    }
    /*
         * Checks if the rectangle is contained within the applet window.  If the rectangle
         * is not contained withing the applet window, it is redrawn so that it is adjacent
         * to the edge of the window and just inside the window.
     */
    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.width){
            new_x = area.width-99;
        }
        if(rect.x < 0){
            new_x = -1;
        }
        if((rect.y+50)>area.height){
            new_y = area.height-49;
        }
        if(rect.y < 0){
            new_y = -1;
        }
        rect.setLocation(new_x, new_y);
        return false;
    }

}