scrollingbuttonpanel.java

PIY(Program It Yourself)是一个基于Java的应用程序开发环境

package piy;

import java.util.ArrayList;
import javax.swing.*;
import javax.swing.border.EtchedBorder;
import javax.swing.event.*;
import java.awt.event.*;
import java.awt.*;

/**
* A panel which displays buttons horizontally along it, and has arrows at the end to scroll
* if the number of buttons to display is too much for the panel.  Only one of the buttons
* may be selected at any particular time.
* @author David Vivash
* @version 1.0, 26/11/00
*/
public class ScrollingButtonPanel extends JPanel implements SingleSelectionModel, ActionListener
{
	private int buttonWidth, buttonHeight, spacing;
	private JPanel viewPort = new JPanel(new FlowLayout()), left, right;
	private JScrollPane scroller;

	private ArrayList buttons;

	/**
	* Construct a basic scrolling button panel with specified button sizing and spacing.
	* @param size the initial capacity for buttons
	* @param buttonWidth the standard width of the added buttons
	* @param buttonHeight the standard height of the added buttons
	* @param spacing the amount of space to allow between buttons
	*/
	public ScrollingButtonPanel(int size, int buttonWidth, int buttonHeight, int spacing) {

		setBorder(null);

		scroller = new JScrollPane(viewPort, ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);

		scroller.setBorder(null);

		left = new JPanel(null);
		left.setBorder(null);
		left.setMinimumSize(new Dimension(16,32));
		left.setPreferredSize(new Dimension(16,32));
		right = new JPanel(null);
		right.setBorder(null);
		right.setMinimumSize(new Dimension(16,32));
		right.setPreferredSize(new Dimension(16,32));

		String sep = java.io.File.separator;

		FloatingButton leftButton = new FloatingButton(new ImageIcon("piy" + sep + "images" + sep + "left.gif").getImage(), "left", false);
		FloatingButton rightButton = new FloatingButton(new ImageIcon("piy" + sep + "images" + sep + "right.gif").getImage(), "right", false);
		leftButton.addActionListener(this);
		rightButton.addActionListener(this);

		left.add(leftButton);
		leftButton.setBounds(0,0,16,32);
		right.add(rightButton);
		rightButton.setBounds(0,0,16,32);

		setLayout(new BorderLayout());
		add(left, BorderLayout.WEST);
		add(right, BorderLayout.EAST);
		add(scroller, BorderLayout.CENTER);
		

		buttons = new ArrayList(size > 1 ? size : 2);
		this.buttonWidth = buttonWidth > 3 ? buttonWidth : 4;
		this.buttonHeight = buttonHeight > 3 ? buttonHeight : 4;
		this.spacing = spacing >=0 ? spacing : 0;

		scroller.getViewport().setViewPosition(new Point(0,0));
	}	

	/**
	* Add a component (a button) to the panel.  The component is added to the end of the
	* buttons on the panel.
	* @param button the button to add
	* @return the number assigned to the button
	*/
	public int addButton(AbstractButton button) {
		buttons.add(button);

		viewPort.add(button);

		button.setMinimumSize(new Dimension(buttonWidth, buttonHeight));
		button.setPreferredSize(new Dimension(buttonWidth, buttonHeight));

		button.addActionListener(this);
		button.setActionCommand("" + (buttons.size() - 1)); //ie. actionCommand = "0", "2" etc.

		return buttons.size()-1;

	}

	/**
	* Returns the reference to the currently selected button.
	* @return the currently selected button, or null if no button is currently selected
	*/
	public AbstractButton getSelectedButton() {
		return current == -1 ? null : (AbstractButton)buttons.get(current);	
	}

	//---- SingleSelectionModel Methods ----
	private java.util.Vector changeListeners = new java.util.Vector(1);
	int current = -1; //currently selected button

	/**
	* Adds listener as a listener to changes in the model. 
	* @param listener a ChangeListener object that wishes to be notified of changes in
	* this object's selection state
	*/
	public void addChangeListener(ChangeListener listener) {
		changeListeners.add(listener);
	}

	/**
	* Clears the selection (to -1), and notifies all registered listeners to the change.
	*/
	public void clearSelection() {
		current = -1;

		for (int i=0; i<buttons.size(); i++)
			((AbstractButton)buttons.get(i)).setSelected(false);

		notifyListeners();
	}

	/**
	* Retrieve the index of the currently selected button.
	* @return the selected button's index, or -1 if there is no currently selected button
	*/
	public int getSelectedIndex() {
		return current;
	}

	/**
	* Determines whether there is a currently selected button.
	* @return true if the selection model currently has a selected value. 
	*/
	public boolean isSelected() {
		return current != -1;
	}

	//Removes listener as a listener to changes in the model. Not currently implemented.
	public void removeChangeListener(ChangeListener listener) {
	}

	/**
	* Sets the model's selected index to index. Fires an event - ie. the change listeners
	* are notified.
	* @param index a value between 0 and numberOfButtons-1
	*/
	public void setSelectedIndex(int index) {
		if ( (index > -1) && (index < buttons.size()) ) {
			//update buttons to reflect change
			for (int i=0; i<buttons.size(); i++) {
				if (i==index) ((AbstractButton)buttons.get(i)).setSelected(true);
				else ((AbstractButton)buttons.get(i)).setSelected(false);				
			}

			//tell all change listeners of the change
			notifyListeners();
		}
	}

	//------- ActionListener Methods ----------
	public void actionPerformed(ActionEvent e) {
		JViewport port = scroller.getViewport(); 
		int x = port.getViewPosition().x;
		String action = e.getActionCommand();

		if (action.equals("left")) {
			x -= 10;

			if (x < 0) x=0;

		} else if (action.equals("right")) {
			x += 10;

			if (port.getWidth() - x > scroller.getWidth())
				x = port.getWidth() - scroller.getWidth();

		} else {
			current = Integer.valueOf(action).intValue();

			for (int i=0; i<buttons.size(); i++) {
				if (i==current) continue;
				((AbstractButton)buttons.get(i)).setSelected(false);
			}

			if ( !((AbstractButton)buttons.get(current)).isSelected() ) current = -1;

			notifyListeners();
		}

		port.setViewPosition(new Point(x, 0));

	}

	/**
	* Notifies all registered changeListeners of a change in selection value
	*/
	private void notifyListeners() {
		for (int i=0; i<changeListeners.size(); i++)
			((ChangeListener)changeListeners.get(i)).stateChanged(new ChangeEvent(this));
	}
}