focushandler.java

来自「纯java操作系统jnode,安装简单和操作简单的个人使用的Java操作系统」· Java 代码 · 共 64 行

/*
 * $Id: FocusHandler.java,v 1.1 2003/11/25 11:51:36 epr Exp $
 */
package org.jnode.awt.peer;

import java.awt.Component;
import java.awt.EventQueue;
import java.awt.event.FocusEvent;

/**
 * Class that holds the focused component.
 * 
 * @author Ewout Prangsma ([e-mail])
 */
public class FocusHandler {

	private Component focusedComponent;
	private final JNodeToolkit toolkit;

	/***********************************************************************************************
	 * Creates a new FocusHandler instance
	 * 
	 * @param toolkit
	 */
	public FocusHandler(JNodeToolkit toolkit) {
		this.toolkit = toolkit;
	}

	/***********************************************************************************************
	 * Gets the focused component.
	 * 
	 * @return The focused component
	 */
	public Component getFocusedComponent() {
		return focusedComponent;
	}

	/**
	 * Sets the new focused component and sends some focus events, if necessary.
	 * 
	 * @param c
	 */
	public void setFocusedComponent(Component c) {
		if (focusedComponent != null) {
			sendFocusEvent(focusedComponent, FocusEvent.FOCUS_LOST);
		}
		this.focusedComponent = c;
		if (focusedComponent != null) {
			sendFocusEvent(focusedComponent, FocusEvent.FOCUS_GAINED);
		}
	}

	/**
	 * Sends a focus event.
	 * 
	 * @param c
	 * @param what
	 */
	private final void sendFocusEvent(Component c, int what) {
		final EventQueue queue = toolkit.getSystemEventQueue();
		queue.postEvent(new FocusEvent(c, what, false));
	}
}