Java tutorial
/* * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing; import java.awt.*; import sun.awt.ModalExclude; import sun.awt.SunToolkit; /** * Popups are used to display a <code>Component</code> to the user, typically * on top of all the other <code>Component</code>s in a particular containment * hierarchy. <code>Popup</code>s have a very small life cycle. Once you * have obtained a <code>Popup</code>, and hidden it (invoked the * <code>hide</code> method), you should no longer * invoke any methods on it. This allows the <code>PopupFactory</code> to cache * <code>Popup</code>s for later use. * <p> * The general contract is that if you need to change the size of the * <code>Component</code>, or location of the <code>Popup</code>, you should * obtain a new <code>Popup</code>. * <p> * <code>Popup</code> does not descend from <code>Component</code>, rather * implementations of <code>Popup</code> are responsible for creating * and maintaining their own <code>Component</code>s to render the * requested <code>Component</code> to the user. * <p> * You typically do not explicitly create an instance of <code>Popup</code>, * instead obtain one from a <code>PopupFactory</code>. * * @see PopupFactory * * @since 1.4 */ public class Popup { /** * The Component representing the Popup. */ private Component component; /** * Creates a <code>Popup</code> for the Component <code>owner</code> * containing the Component <code>contents</code>. <code>owner</code> * is used to determine which <code>Window</code> the new * <code>Popup</code> will parent the <code>Component</code> the * <code>Popup</code> creates to. * A null <code>owner</code> implies there is no valid parent. * <code>x</code> and * <code>y</code> specify the preferred initial location to place * the <code>Popup</code> at. Based on screen size, or other paramaters, * the <code>Popup</code> may not display at <code>x</code> and * <code>y</code>. * * @param owner Component mouse coordinates are relative to, may be null * @param contents Contents of the Popup * @param x Initial x screen coordinate * @param y Initial y screen coordinate * @exception IllegalArgumentException if contents is null */ protected Popup(Component owner, Component contents, int x, int y) { this(); if (contents == null) { throw new IllegalArgumentException("Contents must be non-null"); } reset(owner, contents, x, y); } /** * Creates a <code>Popup</code>. This is provided for subclasses. */ protected Popup() { } /** * Makes the <code>Popup</code> visible. If the <code>Popup</code> is * currently visible, this has no effect. */ @SuppressWarnings("deprecation") public void show() { Component component = getComponent(); if (component != null) { component.show(); } } /** * Hides and disposes of the <code>Popup</code>. Once a <code>Popup</code> * has been disposed you should no longer invoke methods on it. A * <code>dispose</code>d <code>Popup</code> may be reclaimed and later used * based on the <code>PopupFactory</code>. As such, if you invoke methods * on a <code>disposed</code> <code>Popup</code>, indeterminate * behavior will result. */ @SuppressWarnings("deprecation") public void hide() { Component component = getComponent(); if (component instanceof JWindow) { component.hide(); ((JWindow) component).getContentPane().removeAll(); } dispose(); } /** * Frees any resources the <code>Popup</code> may be holding onto. */ void dispose() { Component component = getComponent(); Window window = SwingUtilities.getWindowAncestor(component); if (component instanceof JWindow) { ((Window) component).dispose(); component = null; } // If our parent is a DefaultFrame, we need to dispose it, too. if (window instanceof DefaultFrame) { window.dispose(); } } /** * Resets the <code>Popup</code> to an initial state. */ void reset(Component owner, Component contents, int ownerX, int ownerY) { if (getComponent() == null) { component = createComponent(owner); } Component c = getComponent(); if (c instanceof JWindow) { JWindow component = (JWindow) getComponent(); component.setLocation(ownerX, ownerY); component.getContentPane().add(contents, BorderLayout.CENTER); component.invalidate(); component.validate(); if (component.isVisible()) { // Do not call pack() if window is not visible to // avoid early native peer creation pack(); } } } /** * Causes the <code>Popup</code> to be sized to fit the preferred size * of the <code>Component</code> it contains. */ void pack() { Component component = getComponent(); if (component instanceof Window) { ((Window) component).pack(); } } /** * Returns the <code>Window</code> to use as the parent of the * <code>Window</code> created for the <code>Popup</code>. This creates * a new <code>DefaultFrame</code>, if necessary. */ private Window getParentWindow(Component owner) { Window window = null; if (owner instanceof Window) { window = (Window) owner; } else if (owner != null) { window = SwingUtilities.getWindowAncestor(owner); } if (window == null) { window = new DefaultFrame(); } return window; } /** * Creates the Component to use as the parent of the <code>Popup</code>. * The default implementation creates a <code>Window</code>, subclasses * should override. */ Component createComponent(Component owner) { if (GraphicsEnvironment.isHeadless()) { // Generally not useful, bail. return null; } return new HeavyWeightWindow(getParentWindow(owner)); } /** * Returns the <code>Component</code> returned from * <code>createComponent</code> that will hold the <code>Popup</code>. */ Component getComponent() { return component; } /** * Component used to house window. */ @SuppressWarnings("serial") // Superclass is not serializable across versions static class HeavyWeightWindow extends JWindow implements ModalExclude { HeavyWeightWindow(Window parent) { super(parent); setFocusableWindowState(false); setType(Window.Type.POPUP); // Popups are typically transient and most likely won't benefit // from true double buffering. Turn it off here. getRootPane().setUseTrueDoubleBuffering(false); // Try to set "always-on-top" for the popup window. // Applets usually don't have sufficient permissions to do it. // In this case simply ignore the exception. try { setAlwaysOnTop(true); } catch (SecurityException se) { // setAlwaysOnTop is restricted, // the exception is ignored } } public void update(Graphics g) { paint(g); } @SuppressWarnings("deprecation") public void show() { this.pack(); if (getWidth() > 0 && getHeight() > 0) { super.show(); } } } /** * Used if no valid Window ancestor of the supplied owner is found. * <p> * PopupFactory uses this as a way to know when the Popup shouldn't * be cached based on the Window. */ @SuppressWarnings("serial") // JDK-implementation class static class DefaultFrame extends Frame { } }