checkboxmenu.java

JAVA网络三维技术3D的设计与实现

//
//  CLASS
//    CheckboxMenu  -  build a menu of grouped checkboxes
//
//  DESCRIPTION
//    The class creates a menu with one or more CheckboxMenuItem's
//    and monitors that menu.  When a menu checkbox is picked, the
//    previous one is turned off (in radio-button style).  Then,
//    a given listener's checkboxChanged method is called, passing it
//    the menu and the item checked.
//

package Java3DApplet;
import java.awt.*;
import java.awt.event.*;

class CheckboxMenu
	extends Menu
	implements ItemListener
{
	// State
	protected CheckboxMenuItem[] checks = null;
	protected int current = 0;
	protected CheckboxMenuListener listener = null;


	//  Construct
	public CheckboxMenu( String name, NameValue[] items,
		CheckboxMenuListener listen )
	{
		this( name, items, 0, listen );
	}

	public CheckboxMenu( String name, NameValue[] items, int cur,
		CheckboxMenuListener listen )
	{
		super( name );
		current = cur;
		listener = listen;

		if ( items == null )
			return;

		checks = new CheckboxMenuItem[items.length];
		for ( int i = 0; i < items.length; i++ )
		{
			checks[i] = new CheckboxMenuItem( items[i].name, false );
			checks[i].addItemListener( this );
			add( checks[i] );
		}
		checks[cur].setState( true );
	}


	//  Handle checkbox changed events
	public void itemStateChanged( ItemEvent event )
	{
		Object src = event.getSource( );

		for ( int i = 0; i < checks.length; i++ )
		{
			if ( src == checks[i] )
			{
				// Update the checkboxes
				checks[current].setState( false );
				current = i;
				checks[current].setState( true );

				if ( listener != null )
					listener.checkboxChanged( this, i );
				return;
			}
		}
	}


	// Methods to get and set state
	public int getCurrent( )
	{
		return current;
	}

	public void setCurrent( int cur )
	{
		if ( cur < 0 || cur >= checks.length )
			return;  // ignore out of range choices
		if ( checks == null )
			return;
		checks[current].setState( false );
		current = cur;
		checks[current].setState( true );
	}

	public CheckboxMenuItem getSelectedCheckbox( )
	{
		if ( checks == null )
			return null;
		return checks[current];
	}

	public void setSelectedCheckbox( CheckboxMenuItem item )
	{
		if ( checks == null )
			return;
		for ( int i = 0; i < checks.length; i++ )
		{
			if ( item == checks[i] )
			{
				checks[i].setState( false );
				current = i;
				checks[i].setState( true );
			}
		}
	}
}