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25 
26 package javax.swing;
27 
28 import java.awt.*;
29 
30 import sun.awt.ModalExclude;
31 import sun.awt.SunToolkit;
32 
33 /**
34  * Popups are used to display a <code>Component</code> to the user, typically
35  * on top of all the other <code>Component</code>s in a particular containment
36  * hierarchy. <code>Popup</code>s have a very small life cycle. Once you
37  * have obtained a <code>Popup</code>, and hidden it (invoked the
38  * <code>hide</code> method), you should no longer
39  * invoke any methods on it. This allows the <code>PopupFactory</code> to cache
40  * <code>Popup</code>s for later use.
41  * <p>
42  * The general contract is that if you need to change the size of the
43  * <code>Component</code>, or location of the <code>Popup</code>, you should
44  * obtain a new <code>Popup</code>.
45  * <p>
46  * <code>Popup</code> does not descend from <code>Component</code>, rather
47  * implementations of <code>Popup</code> are responsible for creating
48  * and maintaining their own <code>Component</code>s to render the
49  * requested <code>Component</code> to the user.
50  * <p>
51  * You typically do not explicitly create an instance of <code>Popup</code>,
52  * instead obtain one from a <code>PopupFactory</code>.
53  *
54  * @see PopupFactory
55  *
56  * @since 1.4
57  */
58 public class Popup {
59     /**
60      * The Component representing the Popup.
61      */
62     private Component component;
63 
64     /**
65      * Creates a <code>Popup</code> for the Component <code>owner</code>
66      * containing the Component <code>contents</code>. <code>owner</code>
67      * is used to determine which <code>Window</code> the new
68      * <code>Popup</code> will parent the <code>Component</code> the
69      * <code>Popup</code> creates to.
70      * A null <code>owner</code> implies there is no valid parent.
71      * <code>x</code> and
72      * <code>y</code> specify the preferred initial location to place
73      * the <code>Popup</code> at. Based on screen size, or other paramaters,
74      * the <code>Popup</code> may not display at <code>x</code> and
75      * <code>y</code>.
76      *
77      * @param owner    Component mouse coordinates are relative to, may be null
78      * @param contents Contents of the Popup
79      * @param x        Initial x screen coordinate
80      * @param y        Initial y screen coordinate
81      * @exception IllegalArgumentException if contents is null
82      */
Popup(Component owner, Component contents, int x, int y)83     protected Popup(Component owner, Component contents, int x, int y) {
84         this();
85         if (contents == null) {
86             throw new IllegalArgumentException("Contents must be non-null");
87         }
88         reset(owner, contents, x, y);
89     }
90 
91     /**
92      * Creates a <code>Popup</code>. This is provided for subclasses.
93      */
Popup()94     protected Popup() {
95     }
96 
97     /**
98      * Makes the <code>Popup</code> visible. If the <code>Popup</code> is
99      * currently visible, this has no effect.
100      */
101 
102     @SuppressWarnings("deprecation")
show()103     public void show() {
104         Component component = getComponent();
105 
106         if (component != null) {
107             component.show();
108         }
109     }
110 
111     /**
112      * Hides and disposes of the <code>Popup</code>. Once a <code>Popup</code>
113      * has been disposed you should no longer invoke methods on it. A
114      * <code>dispose</code>d <code>Popup</code> may be reclaimed and later used
115      * based on the <code>PopupFactory</code>. As such, if you invoke methods
116      * on a <code>disposed</code> <code>Popup</code>, indeterminate
117      * behavior will result.
118      */
119 
120     @SuppressWarnings("deprecation")
hide()121     public void hide() {
122         Component component = getComponent();
123 
124         if (component instanceof JWindow) {
125             component.hide();
126             ((JWindow)component).getContentPane().removeAll();
127         }
128         dispose();
129     }
130 
131     /**
132      * Frees any resources the <code>Popup</code> may be holding onto.
133      */
dispose()134     void dispose() {
135         Component component = getComponent();
136         Window window = SwingUtilities.getWindowAncestor(component);
137 
138         if (component instanceof JWindow) {
139             ((Window)component).dispose();
140             component = null;
141         }
142         // If our parent is a DefaultFrame, we need to dispose it, too.
143         if (window instanceof DefaultFrame) {
144             window.dispose();
145         }
146     }
147 
148     /**
149      * Resets the <code>Popup</code> to an initial state.
150      */
reset(Component owner, Component contents, int ownerX, int ownerY)151     void reset(Component owner, Component contents, int ownerX, int ownerY) {
152         if (getComponent() == null) {
153             component = createComponent(owner);
154         }
155 
156         Component c = getComponent();
157 
158         if (c instanceof JWindow) {
159             JWindow component = (JWindow)getComponent();
160 
161             component.setLocation(ownerX, ownerY);
162             component.getContentPane().add(contents, BorderLayout.CENTER);
163             component.invalidate();
164             component.validate();
165             if(component.isVisible()) {
166                 // Do not call pack() if window is not visible to
167                 // avoid early native peer creation
168                 pack();
169             }
170         }
171     }
172 
173 
174     /**
175      * Causes the <code>Popup</code> to be sized to fit the preferred size
176      * of the <code>Component</code> it contains.
177      */
pack()178     void pack() {
179         Component component = getComponent();
180 
181         if (component instanceof Window) {
182             ((Window)component).pack();
183         }
184     }
185 
186     /**
187      * Returns the <code>Window</code> to use as the parent of the
188      * <code>Window</code> created for the <code>Popup</code>. This creates
189      * a new <code>DefaultFrame</code>, if necessary.
190      */
getParentWindow(Component owner)191     private Window getParentWindow(Component owner) {
192         Window window = null;
193 
194         if (owner instanceof Window) {
195             window = (Window)owner;
196         }
197         else if (owner != null) {
198             window = SwingUtilities.getWindowAncestor(owner);
199         }
200         if (window == null) {
201             window = new DefaultFrame();
202         }
203         return window;
204     }
205 
206     /**
207      * Creates the Component to use as the parent of the <code>Popup</code>.
208      * The default implementation creates a <code>Window</code>, subclasses
209      * should override.
210      */
createComponent(Component owner)211     Component createComponent(Component owner) {
212         if (GraphicsEnvironment.isHeadless()) {
213             // Generally not useful, bail.
214             return null;
215         }
216         return new HeavyWeightWindow(getParentWindow(owner));
217     }
218 
219     /**
220      * Returns the <code>Component</code> returned from
221      * <code>createComponent</code> that will hold the <code>Popup</code>.
222      */
getComponent()223     Component getComponent() {
224         return component;
225     }
226 
227 
228     /**
229      * Component used to house window.
230      */
231     static class HeavyWeightWindow extends JWindow implements ModalExclude {
HeavyWeightWindow(Window parent)232         HeavyWeightWindow(Window parent) {
233             super(parent);
234             setFocusableWindowState(false);
235             setType(Window.Type.POPUP);
236 
237             // Popups are typically transient and most likely won't benefit
238             // from true double buffering.  Turn it off here.
239             getRootPane().setUseTrueDoubleBuffering(false);
240             // Try to set "always-on-top" for the popup window.
241             // Applets usually don't have sufficient permissions to do it.
242             // In this case simply ignore the exception.
243             try {
244                 setAlwaysOnTop(true);
245             } catch (SecurityException se) {
246                 // setAlwaysOnTop is restricted,
247                 // the exception is ignored
248             }
249         }
250 
update(Graphics g)251         public void update(Graphics g) {
252             paint(g);
253         }
254 
show()255         public void show() {
256             this.pack();
257             if (getWidth() > 0 && getHeight() > 0) {
258                 super.show();
259             }
260         }
261     }
262 
263 
264     /**
265      * Used if no valid Window ancestor of the supplied owner is found.
266      * <p>
267      * PopupFactory uses this as a way to know when the Popup shouldn't
268      * be cached based on the Window.
269      */
270     static class DefaultFrame extends Frame {
271     }
272 }
273