/*
 * Thumb.java
 */

import java.awt.*;

/* Thumb Object */
public class Thumb extends Canvas3D {
    static int THUMB     =  0;  /* Thumb Area */
    static int PAGE_DOWN = -1;  /* Page Down Constant */
    static int PAGE_UP   = -2;  /* Page Up Constant */
    int type;                   /* HORIZONAL/VERTICAL */
    int value;                  /* Current Value */
    int visible;                /* Current Visible Size */
    int minimum;                /* Minimum Value */
    int maximum;                /* Maximum Value */
    boolean mousePressed = false;  /* Is Mouse Pressed */
    int area = THUMB;           /* Current Pressed Area */
    int offset;                 /* Thumb Offset */
    int length;                 /* Thumb Length */
    int mofs;                   /* Mouse pressed Offset */
    int range;                  /* Maximum-Minimum */

    /** Thumb Constructor */
    public Thumb(int _type) {
        type = _type;
        setValue(0, 1, 0, 1, false);
    }

    /** Internal Check Value */
    private void checkValue() {
        if ( maximum <= minimum ) maximum = minimum+1;
        if ( visible < 1 ) visible = 1;
        if ( visible > maximum-minimum ) visible = maximum-minimum;
        if ( value > maximum-visible ) value = maximum-visible;
        if ( value < minimum ) value = minimum;
    }

    /** Internal Thumb Setup */
    private synchronized boolean setThumb() {
        validate();
        boolean changed;
        int _length, _offset;
        int wRange = (type == Scrollbar.HORIZONTAL) ?
          size().width : size().height;
        _length = Math.max(depth*4, visible*wRange/range);
        _offset = (value-minimum)*Math.max(1, wRange-_length)/
          Math.max(1, range-visible);
        changed = ((offset != _offset) || (length != _length));
        offset = _offset;
        length = _length;
        return changed;
    }

    /** Set Current Value */
    public synchronized boolean setValue(int _value, int _visible,
        int _minimum, int _maximum, boolean frepaint) {
        visible = _visible;
        minimum = _minimum;
        maximum = _maximum;
        value = _value;
        checkValue();
        range = maximum-minimum;
        boolean _active = (range > visible);
        if ( setThumb() && frepaint ) repaint();
        return true;
    }

    /** Set Current Value */
    public synchronized boolean setValue(int _value, boolean frepaint) {
        int oldvalue = value;
        value = _value;
        checkValue();
        if ( setThumb() && frepaint ) repaint();
        return (value != oldvalue);
    }

    /** Drawing Action Here */
    public void update(Graphics g) {
        setThumb();
        g.setColor(getBackground());
        if ( type == Scrollbar.HORIZONTAL ) {
          if ( offset > 0 )
            g.fillRect(0, 0, offset, size().height);
          Draw3DRect(g, offset, 0,
            length, size().height, depth, gray);
          int delta = size().width-offset-length;
          if ( delta > 0 ) 
            g.fillRect(offset+length, 0, delta, size().height);
        } else {
          if ( offset > 0 )
            g.fillRect(0, 0, size().width, offset);
          Draw3DRect(g, 0, offset,
            size().width, length, depth, gray);
          int delta = size().height-offset-length;
          if ( delta > 0 ) 
            g.fillRect(0, offset+length, size().width, delta);
        }
    }

    /** Move Thumb */
    public void moveThumb(int delta) {
        if ( delta == 0 ) return;
        if ( setValue(value+delta, true) )
          Notify(null, this);
    }

    /** Respond to Delay Event Action */
    public boolean keyDown(Event ev, int key) {
        if ( key < 0 ) {
          if ( mousePressed ) {
            action(ev, this);
            new Delay(100, key, this);
          }
        }
        return true;
    }

    /** Mouse Down Event */
    public boolean mouseDown(Event ev, int x, int y) {
        if ( !isEnabled() ) return true;
        area = THUMB;
        if ( type == Scrollbar.HORIZONTAL ) {
          if ( x < offset ) area = PAGE_UP;
          else if ( x >= offset+length ) area = PAGE_DOWN;
          else mofs = x-offset;
        } else {
          if ( y < offset ) area = PAGE_UP;
          else if ( y >= offset+length ) area = PAGE_DOWN;
          else mofs = y-offset;
        }
        mousePressed = true;
        action(ev, this);
        new Delay(500, -1, this);
        return true;
    }

    /** Mouse Up Event */
    public boolean mouseUp(Event ev, int x, int y) {
        mousePressed = false;
        return true;
    }

    /** Delay Mouse Drag Event */
    public boolean delayDrag(Event ev, int x, int y) {
        if ( !mousePressed || (area != THUMB) ) return false;
        int wRange = (type == Scrollbar.HORIZONTAL) ?
          size().width : size().height;
        int kRange = Math.max(1, range-visible);
        wRange = Math.max(1, wRange-length);
        moveThumb((((type == Scrollbar.HORIZONTAL) ? x : y)-
          mofs-offset)*kRange/wRange);
        return true;
    }

    /** Component Action Event */
    public boolean action(Event ev, Object arg) {
        if (arg == this) {
          if ( area == PAGE_DOWN ) moveThumb(visible);
          else if ( area == PAGE_UP ) moveThumb(-visible);
          return true;
        }
	return false;
    }
}