org.nuclos.client.ui.CenteringPanel.java Source code

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Here is the source code for org.nuclos.client.ui.CenteringPanel.java

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//Copyright (C) 2010  Novabit Informationssysteme GmbH
//
//This file is part of Nuclos.
//
//Nuclos is free software: you can redistribute it and/or modify
//it under the terms of the GNU Affero General Public License as published by
//the Free Software Foundation, either version 3 of the License, or
//(at your option) any later version.
//
//Nuclos 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 Affero General Public License for more details.
//
//You should have received a copy of the GNU Affero General Public License
//along with Nuclos.  If not, see <http://www.gnu.org/licenses/>.
package org.nuclos.client.ui;

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.GridBagLayout;

import javax.swing.JPanel;

import org.apache.commons.lang.NullArgumentException;

/**
 * A panel that centers a given component in its bounds.
 * This is far more useful than a plain JPanel with its default <code>FlowLayout</code>.
 * <br>
 * <br>Created by Novabit Informationssysteme GmbH
 * <br>Please visit <a href="http://www.novabit.de">www.novabit.de</a>
 *
 * @author   <a href="mailto:christoph.radig@novabit.de">christoph.radig</a>
 * @version 01.00.00
 * @invariant this.getComponentCount() <= 1
 */
public class CenteringPanel extends JPanel {

    private final boolean bFilled;

    /**
     * creates a new CenteringPanel. The child to be centered can be added later.
     * @param bFilled If true, the size of the child is adjusted to <code>this</code>.
     * If <code>false</code>, the size of the child is not adjusted, but its location is adjusted
     * so it is always centered in <code>this</code>.
     * @postcondition this.getComponentCount() == 1
     * @postcondition this.isFilled() == bFilled
     */
    public CenteringPanel(boolean bFilled) {
        super(bFilled ? new BorderLayout(0, 0) : new GridBagLayout());

        this.bFilled = bFilled;

        assert this.getComponentCount() == 0;
        assert this.isFilled() == bFilled;
    }

    /**
     * creates a new CenteringPanel around the given component.
     * @param compChild
     * @precondition compChild != null
     * @postcondition this.getComponentCount() == 1
     * @postcondition compChild.getParent() == this
     * @postcondition !this.isFilled()
     */
    public CenteringPanel(Component compChild) {
        this(compChild, false);

        assert this.getComponentCount() == 1;
        assert compChild.getParent() == this;
        assert !this.isFilled();
    }

    /**
     * creates a new CenteringPanel around the given component.
     * @param compChild
     * @param bFilled If true, the size of the child is adjusted to <code>this</code>.
     * If <code>false</code>, the size of the child is not adjusted, but its location is adjusted
     * so it is always centered in <code>this</code>.
     * @precondition compChild != null
     * @postcondition this.getComponentCount() == 1
     * @postcondition compChild.getParent() == this
     * @postcondition this.isFilled() == bFilled
     */
    public CenteringPanel(Component compChild, boolean bFilled) {
        this(bFilled);

        if (compChild == null) {
            throw new NullArgumentException("compChild");
        }
        this.add(compChild);

        assert this.getComponentCount() == 1;
        assert compChild.getParent() == this;
        assert this.isFilled() == bFilled;
    }

    /**
     * @return Is the size of the child adjusted to <code>this</code>?
     * If <code>false</code>, the size of the child is not adjusted, but its location is adjusted
     * so it is always centered in <code>this</code>.
     */
    public boolean isFilled() {
        return this.bFilled;
    }

    /**
     * sets the given component as the (only) child of <code>this</code>.
     * @param compChild
     * @return compChild
     * @precondition compChild != null
     * @postcondition result == compChild
     */
    @Override
    public Component add(Component compChild) {
        this.setCenteredComponent(compChild);
        return compChild;
    }

    /**
     * @return the centered component, if any.
     */
    public Component getCenteredComponent() {
        return (this.getComponentCount() == 0) ? null : this.getComponent(0);
    }

    /**
     * sets compChild as the centered component. Does nothing, if <code>compChild</code> is already the centered component.
     * @param compChild
     * @postcondition compChild != null --> compChild.getParent() == this
     */
    public void setCenteredComponent(Component compChild) {
        if (this.getCenteredComponent() != compChild) {
            this.removeAll();
            if (compChild != null) {
                super.add(compChild, bFilled ? BorderLayout.CENTER : null);
            }
            this.validate();
        }
        assert compChild == null || compChild.getParent() == this;
    }

    @Override
    public Component add(String name, Component comp) throws UnsupportedOperationException {
        throw new UnsupportedOperationException("add");
    }

    @Override
    public Component add(Component comp, int index) throws UnsupportedOperationException {
        throw new UnsupportedOperationException("add");
    }

    @Override
    public void add(Component comp, Object constraints) throws UnsupportedOperationException {
        throw new UnsupportedOperationException("add");
    }

    @Override
    public void add(Component comp, Object constraints, int index) throws UnsupportedOperationException {
        throw new UnsupportedOperationException("add");
    }

} // class CenteringPanel