/*
 * @(#)CellRendererPane.java	1.34 00/08/05
 *
 * Copyright 1997-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */
package javax.swing;

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.beans.PropertyChangeListener;
import java.util.Locale;
import java.util.Vector;

import javax.accessibility.*;

/** 
 * This class is inserted in between cell renderers and the components that 
 * use them.  It just exists to thwart the repaint() and invalidate() methods 
 * which would otherwise propogate up the tree when the renderer was configured.
 * It's used by the implementations of JTable, JTree, and JList.  For example,
 * here's how CellRendererPane is used in the code the paints each row
 * in a JList:
 * <pre>
 *   cellRendererPane = new CellRendererPane();
 *   ...
 *   Component rendererComponent = renderer.getListCellRendererComponent();
 *   renderer.configureListCellRenderer(dataModel.getElementAt(row), row);
 *   cellRendererPane.paintComponent(g, rendererComponent, this, x, y, w, h);
 * </pre>
 * <p>
 * A renderer component must override isShowing() and unconditionally return
 * true to work correctly because the Swing paint does nothing for components
 * with isShowing false.  
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with 
 * future Swing releases.  The current serialization support is appropriate
 * for short term storage or RMI between applications running the same
 * version of Swing.  A future release of Swing will provide support for
 * long term persistence.
 *
 * @version 1.34 08/05/00
 * @author Hans Muller
 */
public class CellRendererPane extends Container implements Accessible
{
    /**
     * Construct a CellRendererPane object.
     */
    public CellRendererPane() {
	super();
	setLayout(null);
	setVisible(false);
    }

    /** 
     * Overridden to avoid propogating a invalidate up the tree when the
     * cell renderer child is configured.
     */
    public void invalidate() { }


    /** 
     * Shouldn't be called.
     */
    public void paint(Graphics g) { }

  
    /**
     * Shouldn't be called.
     */
    public void update(Graphics g) { }


    /** 
     * If the specified component is already a child of this then we don't
     * bother doing anything - stacking order doesn't matter for cell
     * renderer components (CellRendererPane doesn't paint anyway).<
     */
    protected void addImpl(Component x, Object constraints, int index) {
	if (x.getParent() == this) {
	    return;
	}
	else {
	    super.addImpl(x, constraints, index);
	}
    }


    /** 
     * Paint a cell renderer component c on graphics object g.  Before the component
     * is drawn it's reparented to this (if that's neccessary), it's bounds 
     * are set to w,h and the graphics object is (effectively) translated to x,y.  
     * If it's a JComponent, double buffering is temporarily turned off. After 
     * the component is painted it's bounds are reset to -w, -h, 0, 0 so that, if 
     * it's the last renderer component painted, it will not start consuming input.  
     * The Container p is the component we're actually drawing on, typically it's 
     * equal to this.getParent(). If shouldValidate is true the component c will be 
     * validated before painted.
     */
    public void paintComponent(Graphics g, Component c, Container p, int x, int y, int w, int h, boolean shouldValidate) {
	if (c == null) {
	    if (p != null) {
		Color oldColor = g.getColor();
		g.setColor(p.getBackground());
		g.fillRect(x, y, w, h);
		g.setColor(oldColor);
	    }
	    return;
	}

	if (c.getParent() != this) {
	    this.add(c);
	}

	c.setBounds(x, y, w, h);

	if(shouldValidate) {
	    c.validate();
	}

	boolean wasDoubleBuffered = false;
	if ((c instanceof JComponent) && ((JComponent)c).isDoubleBuffered()) {
	    wasDoubleBuffered = true;
	    ((JComponent)c).setDoubleBuffered(false);
	}

	Graphics cg = SwingGraphics.createSwingGraphics(g, x, y, w, h);
	try {
	    c.paint(cg);
	}
	finally {
	    cg.dispose();
	}

	if ((c instanceof JComponent) && wasDoubleBuffered) {
	    ((JComponent)c).setDoubleBuffered(true);
	}

	if (c instanceof JComponent) {
	    JComponent jc = (JComponent)c;
	    jc.setDoubleBuffered(wasDoubleBuffered);
	}

	c.setBounds(-w, -h, 0, 0);
    }


    /**
     * Calls this.paintComponent(g, c, p, x, y, w, h, false).
     */
    public void paintComponent(Graphics g, Component c, Container p, int x, int y, int w, int h) {
	paintComponent(g, c, p, x, y, w, h, false);
    }


    /**
     * Calls this.paintComponent() with the rectangles x,y,width,height fields.
     */
    public void paintComponent(Graphics g, Component c, Container p, Rectangle r) {
	paintComponent(g, c, p, r.x, r.y, r.width, r.height);
    }


    private void writeObject(ObjectOutputStream s) throws IOException {
	removeAll();
	s.defaultWriteObject();
    }


/////////////////
// Accessibility support
////////////////

    protected AccessibleContext accessibleContext = null;

    /**
     * Gets the AccessibleContext associated with this CellRendererPane. 
     * For CellRendererPanes, the AccessibleContext takes the form of an 
     * AccessibleCellRendererPane. 
     * A new AccessibleCellRendererPane instance is created if necessary.
     *
     * @return an AccessibleCellRendererPane that serves as the 
     *         AccessibleContext of this CellRendererPane
     */
    public AccessibleContext getAccessibleContext() {
	if (accessibleContext == null) {
	    accessibleContext = new AccessibleCellRendererPane();
	}
	return accessibleContext;
    }

    /**
     * This class implements accessibility support for the 
     * <code>CellRendererPane</code> class.
     */
    protected class AccessibleCellRendererPane extends AccessibleAWTContainer {

        // AccessibleContext methods
        //
        /**
         * Get the role of this object.
         *
         * @return an instance of AccessibleRole describing the role of the 
	 * object
         * @see AccessibleRole
         */
        public AccessibleRole getAccessibleRole() {
	    return AccessibleRole.PANEL;
        }

    } // inner class AccessibleCellRendererPane
}