/*
 * Copyright (c) 2005, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation. Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package sun.swing;

import java.awt.Container;
import java.awt.Insets;
import javax.swing.*;
import javax.swing.LayoutStyle.ComponentPlacement;
import javax.swing.border.Border;
import javax.swing.plaf.UIResource;

/**
 * An implementation of <code>LayoutStyle</code> that returns 6 for related
 * components, otherwise 12. This class also provides helper methods for
 * subclasses.
 *
 */
public class DefaultLayoutStyle extends LayoutStyle {
 private static final DefaultLayoutStyle INSTANCE =
 new DefaultLayoutStyle();

 public static LayoutStyle getInstance() {
 return INSTANCE;
 }

 @Override
 public int getPreferredGap(JComponent component1, JComponent component2,
 ComponentPlacement type, int position, Container parent) {
 if (component1 == null || component2 == null || type == null) {
 throw new NullPointerException();
 }

 checkPosition(position);

 if (type == ComponentPlacement.INDENT &&
 (position == SwingConstants.EAST ||
 position == SwingConstants.WEST)) {
 int indent = getIndent(component1, position);
 if (indent > 0) {
 return indent;
 }
 }
 return (type == ComponentPlacement.UNRELATED) ? 12 : 6;
 }

 @Override
 public int getContainerGap(JComponent component, int position,
 Container parent) {
 if (component == null) {
 throw new NullPointerException();
 }
 checkPosition(position);
 return 6;
 }

 /**
 * Returns true if the classes identify a JLabel and a non-JLabel
 * along the horizontal axis.
 */
 protected boolean isLabelAndNonlabel(JComponent c1, JComponent c2,
 int position) {
 if (position == SwingConstants.EAST ||
 position == SwingConstants.WEST) {
 boolean c1Label = (c1 instanceof JLabel);
 boolean c2Label = (c2 instanceof JLabel);
 return ((c1Label || c2Label) && (c1Label != c2Label));
 }
 return false;
 }

 /**
 * For some look and feels check boxs and radio buttons typically
 * don't paint the border, yet they have padding for a border. Look
 * and feel guidelines generally don't include this space. Use
 * this method to subtract this space from the specified
 * components.
 *
 * @param source First component
 * @param target Second component
 * @param position Position doing layout along.
 * @param offset Ideal offset, not including border/margin
 * @return offset - border/margin around the component.
 */
 protected int getButtonGap(JComponent source, JComponent target,
 int position, int offset) {
 offset -= getButtonGap(source, position);
 if (offset > 0) {
 offset -= getButtonGap(target, flipDirection(position));
 }
 if (offset < 0) {
 return 0;
 }
 return offset;
 }

 /**
 * For some look and feels check boxs and radio buttons typically
 * don't paint the border, yet they have padding for a border. Look
 * and feel guidelines generally don't include this space. Use
 * this method to subtract this space from the specified
 * components.
 *
 * @param source Component
 * @param position Position doing layout along.
 * @param offset Ideal offset, not including border/margin
 * @return offset - border/margin around the component.
 */
 protected int getButtonGap(JComponent source, int position, int offset) {
 offset -= getButtonGap(source, position);
 return Math.max(offset, 0);
 }

 /**
 * If <code>c</code> is a check box or radio button, and the border is
 * not painted this returns the inset along the specified axis.
 */
 public int getButtonGap(JComponent c, int position) {
 String classID = c.getUIClassID();
 if ((classID == "CheckBoxUI" || classID == "RadioButtonUI") &&
 !((AbstractButton)c).isBorderPainted()) {
 Border border = c.getBorder();
 if (border instanceof UIResource) {
 return getInset(c, position);
 }
 }
 return 0;
 }

 private void checkPosition(int position) {
 if (position != SwingConstants.NORTH &&
 position != SwingConstants.SOUTH &&
 position != SwingConstants.WEST &&
 position != SwingConstants.EAST) {
 throw new IllegalArgumentException();
 }
 }

 protected int flipDirection(int position) {
 switch(position) {
 case SwingConstants.NORTH:
 return SwingConstants.SOUTH;
 case SwingConstants.SOUTH:
 return SwingConstants.NORTH;
 case SwingConstants.EAST:
 return SwingConstants.WEST;
 case SwingConstants.WEST:
 return SwingConstants.EAST;
 }
 assert false;
 return 0;
 }

 /**
 * Returns the amount to indent the specified component if it's
 * a JCheckBox or JRadioButton. If the component is not a JCheckBox or
 * JRadioButton, 0 will be returned.
 */
 protected int getIndent(JComponent c, int position) {
 String classID = c.getUIClassID();
 if (classID == "CheckBoxUI" || classID == "RadioButtonUI") {
 AbstractButton button = (AbstractButton)c;
 Insets insets = c.getInsets();
 Icon icon = getIcon(button);
 int gap = button.getIconTextGap();
 if (isLeftAligned(button, position)) {
 return insets.left + icon.getIconWidth() + gap;
 } else if (isRightAligned(button, position)) {
 return insets.right + icon.getIconWidth() + gap;
 }
 }
 return 0;
 }

 private Icon getIcon(AbstractButton button) {
 Icon icon = button.getIcon();
 if (icon != null) {
 return icon;
 }
 String key = null;
 if (button instanceof JCheckBox) {
 key = "CheckBox.icon";
 } else if (button instanceof JRadioButton) {
 key = "RadioButton.icon";
 }
 if (key != null) {
 Object oIcon = UIManager.get(key);
 if (oIcon instanceof Icon) {
 return (Icon)oIcon;
 }
 }
 return null;
 }

 private boolean isLeftAligned(AbstractButton button, int position) {
 if (position == SwingConstants.WEST) {
 boolean ltr = button.getComponentOrientation().isLeftToRight();
 int hAlign = button.getHorizontalAlignment();
 return ((ltr && (hAlign == SwingConstants.LEFT ||
 hAlign == SwingConstants.LEADING)) ||
 (!ltr && (hAlign == SwingConstants.TRAILING)));
 }
 return false;
 }

 private boolean isRightAligned(AbstractButton button, int position) {
 if (position == SwingConstants.EAST) {
 boolean ltr = button.getComponentOrientation().isLeftToRight();
 int hAlign = button.getHorizontalAlignment();
 return ((ltr && (hAlign == SwingConstants.RIGHT ||
 hAlign == SwingConstants.TRAILING)) ||
 (!ltr && (hAlign == SwingConstants.LEADING)));
 }
 return false;
 }

 private int getInset(JComponent c, int position) {
 return getInset(c.getInsets(), position);
 }

 private int getInset(Insets insets, int position) {
 if (insets == null) {
 return 0;
 }
 switch(position) {
 case SwingConstants.NORTH:
 return insets.top;
 case SwingConstants.SOUTH:
 return insets.bottom;
 case SwingConstants.EAST:
 return insets.right;
 case SwingConstants.WEST:
 return insets.left;
 }
 assert false;
 return 0;
 }
}