The Net: Ultimate Internet Guide/WWLCD1.ISO/pc/java/in4wjcxu/src/como/awt/imagebutton.java

Java Source | 1996-08-14 | 6.5 KB | 299 lines

/*
 * @(#)ImageButton.java  (c) 1996 Jan Kautz
 */

package como.awt;

import como.util.*;
import java.awt.*;
import java.awt.image.*;

/**
 * ImageButton is a button which uses images to represent
 * the states of the button - normal, pressed.
 * They don't have to be fully loaded! They will be loaded
 * asynchronously here!
 */

public class ImageButton extends Canvas {
    Image normal;
    Image pressed;
    Image current;
    boolean down = false;
    boolean focus = false;
    boolean isswitch = false;
    boolean nopush = false;
    int width, height;
    String text;

    /**
     * Construct an image button. We have two states:
     * Normal and pressed. They both must be non-null.
     * Then you must specify the width and height of the button.
     * (May be different from the ■icture's size and the picture
     * will be loaded asynchronously!)
     */
    public ImageButton( Image normal, Image pressed, int w, int h ) {
        width = w;
    height = h;

    down = false;

    // set my current size to width/height
    resize( width, height );

    setImages( normal, pressed );
    }

    public ImageButton( int w, int h, String text ) {
        width = w;
    height = h;
    down = false;

    this.normal = null;
    this.pressed = null;
    this.text = text;
    this.current = null;

    drawIt();
    }

    /**
     * Here you may change the pictures used in the button.
     */
    public void setImages( Image normal, Image pressed ) {
    this.normal = normal;
    this.pressed = pressed;

    this.current = normal;

    // let's load and scale the image
    if( normal != null )
        prepareImage( normal, width, height, this );

    if( pressed != null )
        prepareImage( pressed, width, height, this );

    drawIt();
    }

    /**
     * Make it a Switch instead of a Button. Now the user can press
     * the switch and it's on or off then! You will get an action-message
     * that the state changed. Get state with getState().
     */
    public void setSwitch( boolean sw ) {
        isswitch = sw;
    drawIt();
    }

    /**
     * Here you can set, if you want the button to be pushed
     * down, if someone clicks or not.
     * (Usefull if you just want to display a picture!)
     */
    public void setNoPush( boolean np ) {
        nopush = np;
    drawIt();
    }

    /**
     * Set the current state of the switch!
     * (If it is a button then do nothing!)
     * @param onoff indicating on or off
     */
    public void setState( boolean onoff ) {
        if( isswitch ) {
        down = onoff;

        if( onoff == true )
            current = pressed;
        else
            current = normal;

        drawIt();
    }
    }

    /**
     * Get the current state of the switch! (if it's a button
     * you will get true if it's currently pressed).
     * @return if the switch is on then return true; else false.
     */
    public boolean getState() {
        return down;
    }

    /**
     * Move the focus to the next component
     * Does NOT work! (cause nextFocus() doesn't do what I wanted)
     */
    public boolean keyDown( Event evt, int key ) {
        if( key == (int)'\t' || key == Event.DOWN || key == Event.RIGHT )
    {
        nextFocus();    // let's move to the next focus

        // it seems not to work like this!
        // It would work like this I think:
        // getParent().getComponents()[me+1].requestFocus()

        return true;
    }
        return false;
    }

    /**
     * This delivers the Event to the parent.
     */
    public void sendEvent() {
        if( getParent() != null )
        getParent().postEvent( new Event( this, Event.ACTION_EVENT, this ) );
    }

    /**
     * handle the MouseDownEvents.
     */
    public boolean mouseDown(Event event, int x, int y) {
        if( isswitch == false )
    {
        down = true;
        current = pressed;
        drawIt();
    }
    else {
        if( down == true ) {
            down = false;
            current = normal;
        }
        else {
            down = true;
            current = pressed;
        }
        drawIt();

        // now send an Event, that the state has changed!
        sendEvent();
    }

    return true;
    }

    /**
     * handle the MouseUpEvent.
     */
    public boolean mouseUp(Event event, int x, int y) {
    if( down && isswitch == false ) {
        down = false;
        current = normal;
        drawIt();

        // let's see if it's within my boundaries.
        if((x >= 0) && (y >= 0) &&
           (x < width) && (y < height))
        sendEvent();
    }
    if( isswitch == true ) {
        // think nothing has to be done here
        ;
    }
    return true;
    }

    /**
     * updates the image on screen
     */
    void drawIt() {
    Graphics g = getGraphics();
    if( g != null ) paint( g );
    }

    /**
     * Draws the picture on the screen (if parts are loaded,
     * then it draws those parts).
     * Overrides paint-Method.
     */
    public void paint(Graphics graphics) {
    boolean raise = true;

        if( current != null &&
        (checkImage( current, width, height, this ) & (WIDTH|HEIGHT|ALLBITS)) != 0 ) {
        // we know width and height of it -> draw it.
        // or the image is complete -> draw it
        graphics.clearRect(0,0,width,height);
        graphics.drawImage(current, 0, 0, width, height, this);
    }
    else {
        if( text != null )
            graphics.drawString( text, 2, height/2 );
    }

    if( nopush )
       raise = true;    // always remain raised.
    else
       raise = !down;

    // just show a border!
    graphics.setColor( Color.white );
    graphics.draw3DRect( 0, 0, width-1, height-1, raise );
    graphics.setColor( Color.white );
    graphics.draw3DRect( 1, 1, width-3, height-3, raise );

    /* some lostFocus() Events don't come!
    // and the nextFocus does not work!
    if( focus == true ) {
        do something
    }
    */
    }

    /**
     * tell my preferred-size
     */
    public Dimension preferredSize() {
    return new Dimension( width, height );
    }

    /**
     * tell my minimum-size
     */
    public Dimension minimumSize() {
    return new Dimension( width, height );
    }

    public boolean gotFocus( Event evt, Object what ) {
        focus = true;
    drawIt();

    // pass it back
        return false;
    }

    public boolean lostFocus( Event evt, Object what ) {
        focus = false;
    drawIt();

    // pass it back
        return false;
    }

    /**
     * Tell me all about the image ;-)
     * (inspired from Component.java)
     */
    public boolean imageUpdate(Image img, int flags,
                               int x, int y, int w, int h) {
        int rate = -1;

        if ((flags & (FRAMEBITS|ALLBITS)) != 0) {
            rate = 0;
        } else if ((flags & SOMEBITS) != 0) {
        rate = 100;
        }
        if (rate >= 0) {
            repaint(rate, 0, 0, width, height);
        }
        return (flags & (ALLBITS|ABORT)) == 0;
    }
}