224 lines
6.5 KiB
Java
224 lines
6.5 KiB
Java
/* ButtonGroup.java --
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Copyright (C) 2002, 2006, Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package javax.swing;
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import java.io.Serializable;
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import java.util.Enumeration;
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import java.util.Vector;
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/**
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* Logically groups a set of buttons, so that only one of the buttons in
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* a <code>ButtonGroup</code> can be selected at the same time. If one
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* button in a <code>ButtonGroup</code> is selected, all other buttons
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* are automatically deselected.
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*
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* While <code>ButtonGroup</code> can be used for all buttons that are derived
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* from {@link AbstractButton}, it is normally only used for
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* {@link JRadioButton}s, {@link JRadioButtonMenuItem}s and
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* {@link JToggleButton}s.
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*
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* You could use it for {@link JCheckBox}es, but for the sake of usability
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* this is strongly discouraged because the common expectation of checkboxes
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* is that the user is allowed to make multiple selections.
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*
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* It makes no sense to put {@link JButton}s or {@link JMenuItem}s in
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* a <code>ButtonGroup</code> because they don't implement the
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* <code>selected</code> semantics.
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*
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* @author original author unknown
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*/
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public class ButtonGroup implements Serializable
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{
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private static final long serialVersionUID = 4259076101881721375L;
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/** Stores references to the buttons added to this button group. */
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protected Vector<AbstractButton> buttons = new Vector<AbstractButton>();
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/** The currently selected button model. */
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ButtonModel sel;
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/**
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* Creates a new button group.
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*/
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public ButtonGroup()
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{
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// Nothing to do here.
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}
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/**
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* Adds a button to this group. If the button is in the selected state, then:
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* <ul>
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* <li>if the group has no current selection, the new button becomes the
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* selected button for the group;</li>
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* <li>if the group already has a selected button, the new button is set to
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* "not selected".</li>
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* </ul>
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*
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* @param b the button to add (<code>null</code> is ignored).
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*/
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public void add(AbstractButton b)
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{
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if (b == null)
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return;
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b.getModel().setGroup(this);
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if (b.isSelected())
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{
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if (sel == null)
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sel = b.getModel();
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else
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b.setSelected(false);
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}
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buttons.addElement(b);
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}
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/**
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* Removes the specified button from this group. If the button is the
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* selected button, the current selection is set to <code>null</code>.
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* The group for the removed button's model is set to <code>null</code>.
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*
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* @param b the button to remove (<code>null</code> is ignored).
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*/
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public void remove(AbstractButton b)
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{
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if (b == null)
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return;
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b.getModel().setGroup(null);
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if (b.getModel() == sel)
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sel = null;
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buttons.removeElement(b);
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}
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/**
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* Returns the currently added buttons.
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*
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* @return <code>Enumeration</code> over all added buttons
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*/
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public Enumeration<AbstractButton> getElements()
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{
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return buttons.elements();
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}
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/**
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* Returns the currently selected button model.
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*
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* @return the currently selected button model, null if none was selected
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* yet
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*/
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public ButtonModel getSelection()
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{
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return sel;
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}
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/**
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* Returns the button that has the specified model, or <code>null</code> if
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* there is no such button in the group.
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*
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* @param m the button model.
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*
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* @return The button that has the specified model, or <code>null</code>.
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*/
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AbstractButton findButton(ButtonModel m)
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{
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for (int i = 0; i < buttons.size(); i++)
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{
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AbstractButton a = (AbstractButton) buttons.get(i);
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if (a.getModel() == m)
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return a;
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}
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return null;
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}
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/**
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* Sets the currently selected button model. Only one button of a group can
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* be selected at a time.
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*
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* @param m the model to select
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* @param b true if this button is to be selected, false otherwise
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*/
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public void setSelected(ButtonModel m, boolean b)
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{
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if ((sel != m || b) && (! b || sel == m))
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return;
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if (b && sel != m)
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{
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ButtonModel old = sel;
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sel = m;
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if (old != null)
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old.setSelected(false);
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if (m != null)
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sel.setSelected(true);
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AbstractButton button = findButton(old);
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if (button != null)
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button.repaint();
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}
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else if (!b && sel == m)
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m.setSelected(true);
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}
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/**
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* Checks if the given <code>ButtonModel</code> is selected in this button
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* group.
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*
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* @param m the button model (<code>null</code> permitted).
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*
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* @return <code>true</code> if <code>m</code> is the selected button model
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* in this group, and <code>false</code> otherwise.
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*/
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public boolean isSelected(ButtonModel m)
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{
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return m == sel;
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}
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/**
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* Return the number of buttons in this button group.
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*
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* @return the number of buttons
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*
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* @since 1.3
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*/
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public int getButtonCount()
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{
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return buttons.size();
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}
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}
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