/*******************************************************************************
* Mission Control Technologies, Copyright (c) 2009-2012, United States Government
* as represented by the Administrator of the National Aeronautics and Space
* Administration. All rights reserved.
*
* The MCT platform is licensed under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0.
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*
* MCT includes source code licensed under additional open source licenses. See
* the MCT Open Source Licenses file included with this distribution or the About
* MCT Licenses dialog available at runtime from the MCT Help menu for additional
* information.
*******************************************************************************/
package gov.nasa.arc.mct.table.view;
import java.awt.Color;
import java.awt.Component;
import java.awt.Rectangle;
import javax.swing.JLabel;
import javax.swing.JTable;
/**
* Implements a panel which is optimized for rendering inside a table cell. An
* instance of this class assumes that it is used inside a <code>JTable</code>.
* That class reuses the same renderer instance while drawing
* portions of the table, updating the origin and properties before rendering
* each new cell. This class optimizes such rendering by disabling certain events, to
* avoid unnecessary propagation to the current parent of the label.
*
* More details, copied from the Javadoc of <code>DefaultTableCellRenderer</code>:
*
* <strong><a name="override">Implementation Note:</a></strong>
* This class inherits from <code>JLabel</code>, a standard component class.
* However <code>JTable</code> employs a unique mechanism for rendering
* its cells and therefore requires some slightly modified behavior
* from its cell renderer.
* The table class defines a single cell renderer and uses it as a
* as a rubber-stamp for rendering all cells in the table;
* it renders the first cell,
* changes the contents of that cell renderer,
* shifts the origin to the new location, re-draws it, and so on.
* The standard <code>JLabel</code> component was not
* designed to be used this way and we want to avoid
* triggering a <code>revalidate</code> each time the
* cell is drawn. This would greatly decrease performance because the
* <code>revalidate</code> message would be
* passed up the hierarchy of the container to determine whether any other
* components would be affected.
* As the renderer is only parented for the lifetime of a painting operation
* we similarly want to avoid the overhead associated with walking the
* hierarchy for painting operations.
* So this class
* overrides the <code>validate</code>, <code>invalidate</code>,
* <code>revalidate</code>, <code>repaint</code>, and
* <code>firePropertyChange</code> methods to be
* no-ops and override the <code>isOpaque</code> method solely to improve
* performance. If you write your own renderer,
* please keep this performance consideration in mind.
*/
@SuppressWarnings("serial")
public class LightweightLabel extends JLabel {
/**
* Creates a lightweight label that is initially opaque.
*/
public LightweightLabel() {
super();
setOpaque(true);
}
/**
* Overridden for performance reasons.
* See the <a href="#override">Implementation Note</a>
* for more information.
*
* For the purposes of rendering as a table cell, a component are "opaque,"
* and thus need to draw its background, only if it is marked as opaque, and its
* parent is opaque, and if its background color doesn't match its parent.
*/
@Override
public boolean isOpaque() {
Color back = getBackground();
Component p = getParent();
while (p!=null && !(p instanceof JTable)) {
p = p.getParent();
}
// p should now be the JTable.
boolean colorMatch =
(back != null) && (p != null)
&& back.equals(p.getBackground())
&& p.isOpaque();
return !colorMatch && super.isOpaque();
}
/**
* Overridden for performance reasons.
* See the <a href="#override">Implementation Note</a>
* for more information.
*
* @since 1.5
*/
@Override
public void invalidate() {}
/**
* Overridden for performance reasons.
* See the <a href="#override">Implementation Note</a>
* for more information.
*/
@Override
public void validate() {}
/**
* Overridden for performance reasons.
* See the <a href="#override">Implementation Note</a>
* for more information.
*/
@Override
public void revalidate() {}
/**
* Overridden for performance reasons.
* See the <a href="#override">Implementation Note</a>
* for more information.
*/
@Override
public void repaint(long tm, int x, int y, int width, int height) {}
/**
* Overridden for performance reasons.
* See the <a href="#override">Implementation Note</a>
* for more information.
*/
@Override
public void repaint(Rectangle r) {}
/**
* Overridden for performance reasons.
* See the <a href="#override">Implementation Note</a>
* for more information.
*
* @since 1.5
*/
@Override
public void repaint() {}
/**
* Overridden for performance reasons.
* See the <a href="#override">Implementation Note</a>
* for more information.
*/
@Override
protected void firePropertyChange(String propertyName, Object oldValue, Object newValue) {
// Strings get interned...
if (propertyName == "text"
|| propertyName == "labelFor"
|| propertyName == "displayedMnemonic"
|| ((propertyName == "font" || propertyName == "foreground")
&& oldValue != newValue
&& getClientProperty(javax.swing.plaf.basic.BasicHTML.propertyKey) != null)) {
super.firePropertyChange(propertyName, oldValue, newValue);
}
}
/**
* Overridden for performance reasons.
* See the <a href="#override">Implementation Note</a>
* for more information.
*/
@Override
public void firePropertyChange(String propertyName, boolean oldValue, boolean newValue) {}
}