swingx-master/swingx-core/src/main/java/org/jdesktop/swingx/plaf/BuddyLayoutAndBorder.java
package org.jdesktop.swingx.plaf;

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.awt.Rectangle;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.border.Border;
import javax.swing.plaf.UIResource;
import javax.swing.plaf.basic.BasicBorders.MarginBorder;

import org.jdesktop.swingx.prompt.BuddySupport;
import org.jdesktop.swingx.prompt.BuddySupport.Position;

public class BuddyLayoutAndBorder implements LayoutManager, Border, PropertyChangeListener, UIResource {
	private JTextField textField;

	private Border borderDelegate;

	/**
	 * Installs a {@link BuddyLayoutAndBorder} as a layout and border of the
	 * given text field. Registers a {@link PropertyChangeListener} to wrap any
	 * subsequently set border on the text field.
	 */
	protected void install(JTextField textField) {
		uninstall();
		this.textField = textField;

		textField.setLayout(this);

		replaceBorderIfNecessary();
		textField.addPropertyChangeListener("border", this);
	}

	public Border getBorderDelegate() {
		return borderDelegate;
	}

	/**
	 * Wraps and replaces the text fields default border with this object, to
	 * honor the button margins and sizes of the search, clear and popup buttons
	 * and the layout style.
	 */
	protected void replaceBorderIfNecessary() {
		Border original = textField.getBorder();

		if (!(original instanceof BuddyLayoutAndBorder)) {
			borderDelegate = original;
			textField.setBorder(this);
		}
	}

	/**
	 * Does nothing.
	 * 
	 * @see BuddySupport#add(javax.swing.JComponent, Position, JTextField)
	 */
	@Override
    public void addLayoutComponent(String name, Component comp) {
	}

	@Override
    public Dimension minimumLayoutSize(Container parent) {
		return preferredLayoutSize(parent);
	}

	@Override
    public Dimension preferredLayoutSize(Container parent) {
		Dimension d = new Dimension();

		// height of highest buddy.
		for (Component c : BuddySupport.getLeft(textField)) {
			d.height = Math.max(d.height, c.getPreferredSize().height);
		}
		for (Component c : BuddySupport.getRight(textField)) {
			d.height = Math.max(d.height, c.getPreferredSize().height);
		}

		Insets insets = getRealBorderInsets();
		d.height += insets.top + insets.bottom;
		d.width += insets.left + insets.right;

		Insets outerMargin = BuddySupport.getOuterMargin(textField);
		if (outerMargin != null) {
			d.width += outerMargin.left + outerMargin.right;
			d.height += outerMargin.bottom + outerMargin.top;
		}

		return d;
	}

	/**
	 * Does nothing.
	 * 
	 * @see BuddySupport#remove(javax.swing.JComponent, JTextField)
	 */
	@Override
    public void removeLayoutComponent(Component comp) {
	}

	@Override
    public void layoutContainer(Container parent) {
		Rectangle visibleRect = getVisibleRect();
		Dimension size;

		for (Component comp : BuddySupport.getLeft(textField)) {
			if (!comp.isVisible()) {
				continue;
			}
			size = comp.getPreferredSize();
			comp.setBounds(visibleRect.x, centerY(visibleRect, size), size.width, size.height);

			visibleRect.x += size.width;
			visibleRect.width -= size.width;
		}

		for (Component comp : BuddySupport.getRight(textField)) {
			if (!comp.isVisible()) {
				continue;
			}

			size = comp.getPreferredSize();
			comp.setBounds(visibleRect.x + visibleRect.width - size.width, centerY(visibleRect, size), size.width,
					size.height);
			visibleRect.width -= size.width;
		}
	}

	protected int centerY(Rectangle rect, Dimension size) {
		return (int) (rect.getCenterY() - (size.height / 2));
	}

	/**
	 * @return the rectangle allocated by the text field, including the space
	 *         allocated by the child components left and right, the text fields
	 *         original border insets and the outer margin.
	 * 
	 */
	protected Rectangle getVisibleRect() {
		Rectangle alloc = SwingUtilities.getLocalBounds(textField);

		substractInsets(alloc, getRealBorderInsets());
		substractInsets(alloc, BuddySupport.getOuterMargin(textField));

		return alloc;
	}

	private void substractInsets(Rectangle alloc, Insets insets) {
		if (insets != null) {
			alloc.x += insets.left;
			alloc.y += insets.top;
			alloc.width -= insets.left + insets.right;
			alloc.height -= insets.top + insets.bottom;
		}
	}

	/**
	 * Returns the {@link Insets} of the original {@link Border} plus the space
	 * required by the child components.
	 * 
	 * @see javax.swing.border.Border#getBorderInsets(java.awt.Component)
	 */
	@Override
    public Insets getBorderInsets(Component c) {
		Insets insets = null;
		if (borderDelegate != null) {
			// Original insets are cloned to make it work in Mac OS X Aqua LnF.
			// Seems that this LnF uses a shared insets instance which should
			// not be modified.
			// Include margin here
			insets = (Insets) borderDelegate.getBorderInsets(textField).clone();
		} else {
			insets = new Insets(0, 0, 0, 0);
		}
		//somehow this happens sometimes
		if (textField == null) {
			return insets;
		}
		
		for (Component comp : BuddySupport.getLeft(textField)) {
			insets.left += comp.isVisible() ? comp.getPreferredSize().width : 0;
		}
		for (Component comp : BuddySupport.getRight(textField)) {
			insets.right += comp.isVisible() ? comp.getPreferredSize().width : 0;
		}

		Insets outerMargin = BuddySupport.getOuterMargin(textField);
		if (outerMargin != null) {
			insets.left += outerMargin.left;
			insets.right += outerMargin.right;
			insets.top += outerMargin.top;
			insets.bottom += outerMargin.bottom;
		}

		return insets;
	}

	/**
	 * Returns the insets of the original border (without the margin! Beware of
	 * {@link MarginBorder}!).
	 * 
	 * @return the insets of the border delegate
	 */
	public Insets getRealBorderInsets() {
		if (borderDelegate == null) {
		    //SwingX 1287: null borders are possible and give no insets
			return new Insets(0, 0, 0, 0);
		}

		Insets insets = borderDelegate.getBorderInsets(textField);

		// for some reason, all LnFs add the margin to the insets.
		// we want the insets without the margin, so substract the margin here!!
		// TODO: consider checking, if the current border really includes the
		// margin. Consider:
		// 1. Not only MarginBorder adds margin
		// 2. Calling getBorderInsets(null) is not appropriate, since some
		// Borders can't handle null values.
		Insets margin = textField.getMargin();
		if (margin != null) {
			insets.left -= margin.left;
			insets.right -= margin.right;
			insets.top -= margin.top;
			insets.bottom -= margin.bottom;
		}

		return insets;
	}

	@Override
    public boolean isBorderOpaque() {
		if (borderDelegate == null) {
			return false;
		}
		return borderDelegate.isBorderOpaque();
	}

	@Override
    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
		if (borderDelegate != null) {
			borderDelegate.paintBorder(c, g, x, y, width, height);
		}
	}

	@Override
    public void propertyChange(PropertyChangeEvent evt) {
		replaceBorderIfNecessary();
	}

	public void uninstall() {
		if (textField != null) {
			textField.removePropertyChangeListener("border", this);
			if (textField.getBorder() == this) {
				textField.setBorder(borderDelegate);
			}
			textField.setLayout(null);
			textField = null;
		}
	}

	@Override
	public String toString() {
		return String.format("%s (%s): %s", getClass().getName(), getBorderInsets(null), borderDelegate);
	}
}