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	/*
	* Copyright (c) 2005, 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 javax.swing;

	import java.awt.Container;
	import javax.swing.plaf.ComponentUI;
	import sun.awt.AppContext;

	/**
	* <code>LayoutStyle</code> provides information about how to position
	* components. This class is primarily useful for visual tools and
	* layout managers. Most developers will not need to use this class.
	* <p>
	* You typically don't set or create a
	* <code>LayoutStyle</code>. Instead use the static method
	* <code>getInstance</code> to obtain the current instance.
	*
	* @since 1.6
	*/
	public abstract class LayoutStyle {
	/**
	* Sets the shared instance of <code>LayoutStyle</code>. Specifying
	* <code>null</code> results in using the <code>LayoutStyle</code> from
	* the current <code>LookAndFeel</code>.
	*
	* @param style the <code>LayoutStyle</code>, or <code>null</code>
	* @see #getInstance
	*/
	public static void setInstance(LayoutStyle style) {
	synchronized(LayoutStyle.class) {
	if (style == null) {
	AppContext.getAppContext().remove(LayoutStyle.class);
	}
	else {
	AppContext.getAppContext().put(LayoutStyle.class, style);
	}
	}
	}

	/**
	* Returns the shared instance of <code>LayoutStyle</code>. If an instance
	* has not been specified in <code>setInstance</code>, this will return
	* the <code>LayoutStyle</code> from the current <code>LookAndFeel</code>.
	*
	* @see LookAndFeel#getLayoutStyle
	* @return the shared instance of <code>LayoutStyle</code>
	*/
	public static LayoutStyle getInstance() {
	LayoutStyle style;
	synchronized(LayoutStyle.class) {
	style = (LayoutStyle)AppContext.getAppContext().
	get(LayoutStyle.class);
	}
	if (style == null) {
	return UIManager.getLookAndFeel().getLayoutStyle();
	}
	return style;
	}


	/**
	* <code>ComponentPlacement</code> is an enumeration of the
	* possible ways two components can be placed relative to each
	* other. <code>ComponentPlacement</code> is used by the
	* <code>LayoutStyle</code> method <code>getPreferredGap</code>. Refer to
	* <code>LayoutStyle</code> for more information.
	*
	* @see LayoutStyle#getPreferredGap(JComponent,JComponent,
	* ComponentPlacement,int,Container)
	* @since 1.6
	*/
	public enum ComponentPlacement {
	/**
	* Enumeration value indicating the two components are
	* visually related and will be placed in the same parent.
	* For example, a <code>JLabel</code> providing a label for a
	* <code>JTextField</code> is typically visually associated
	* with the <code>JTextField</code>; the constant <code>RELATED</code>
	* is used for this.
	*/
	RELATED,

	/**
	* Enumeration value indicating the two components are
	* visually unrelated and will be placed in the same parent.
	* For example, groupings of components are usually visually
	* separated; the constant <code>UNRELATED</code> is used for this.
	*/
	UNRELATED,

	/**
	* Enumeration value indicating the distance to indent a component
	* is being requested. For example, often times the children of
	* a label will be horizontally indented from the label. To determine
	* the preferred distance for such a gap use the
	* <code>INDENT</code> type.
	* <p>
	* This value is typically only useful with a direction of
	* <code>EAST</code> or <code>WEST</code>.
	*/
	INDENT;
	}


	/**
	* Creates a new <code>LayoutStyle</code>. You generally don't
	* create a <code>LayoutStyle</code>. Instead use the method
	* <code>getInstance</code> to obtain the current
	* <code>LayoutStyle</code>.
	*/
	public LayoutStyle() {
	}

	/**
	* Returns the amount of space to use between two components.
	* The return value indicates the distance to place
	* <code>component2</code> relative to <code>component1</code>.
	* For example, the following returns the amount of space to place
	* between <code>component2</code> and <code>component1</code>
	* when <code>component2</code> is placed vertically above
	* <code>component1</code>:
	* <pre>
	* int gap = getPreferredGap(component1, component2,
	* ComponentPlacement.RELATED,
	* SwingConstants.NORTH, parent);
	* </pre>
	* The <code>type</code> parameter indicates the relation between
	* the two components. If the two components will be contained in
	* the same parent and are showing similar logically related
	* items, use <code>RELATED</code>. If the two components will be
	* contained in the same parent but show logically unrelated items
	* use <code>UNRELATED</code>. Some look and feels may not
	* distinguish between the <code>RELATED</code> and
	* <code>UNRELATED</code> types.
	* <p>
	* The return value is not intended to take into account the
	* current size and position of <code>component2</code> or
	* <code>component1</code>. The return value may take into
	* consideration various properties of the components. For
	* example, the space may vary based on font size, or the preferred
	* size of the component.
	*
	* @param component1 the <code>JComponent</code>
	* <code>component2</code> is being placed relative to
	* @param component2 the <code>JComponent</code> being placed
	* @param position the position <code>component2</code> is being placed
	* relative to <code>component1</code>; one of
	* <code>SwingConstants.NORTH</code>,
	* <code>SwingConstants.SOUTH</code>,
	* <code>SwingConstants.EAST</code> or
	* <code>SwingConstants.WEST</code>
	* @param type how the two components are being placed
	* @param parent the parent of <code>component2</code>; this may differ
	* from the actual parent and it may be <code>null</code>
	* @return the amount of space to place between the two components
	* @throws NullPointerException if <code>component1</code>,
	* <code>component2</code> or <code>type</code> is
	* <code>null</code>
	* @throws IllegalArgumentException if <code>position</code> is not
	* one of <code>SwingConstants.NORTH</code>,
	* <code>SwingConstants.SOUTH</code>,
	* <code>SwingConstants.EAST</code> or
	* <code>SwingConstants.WEST</code>
	* @see LookAndFeel#getLayoutStyle
	* @since 1.6
	*/
	public abstract int getPreferredGap(JComponent component1,
	JComponent component2,
	ComponentPlacement type, int position,
	Container parent);

	/**
	* Returns the amount of space to place between the component and specified
	* edge of its parent.
	*
	* @param component the <code>JComponent</code> being positioned
	* @param position the position <code>component</code> is being placed
	* relative to its parent; one of
	* <code>SwingConstants.NORTH</code>,
	* <code>SwingConstants.SOUTH</code>,
	* <code>SwingConstants.EAST</code> or
	* <code>SwingConstants.WEST</code>
	* @param parent the parent of <code>component</code>; this may differ
	* from the actual parent and may be <code>null</code>
	* @return the amount of space to place between the component and specified
	* edge
	* @throws IllegalArgumentException if <code>position</code> is not
	* one of <code>SwingConstants.NORTH</code>,
	* <code>SwingConstants.SOUTH</code>,
	* <code>SwingConstants.EAST</code> or
	* <code>SwingConstants.WEST</code>
	*/
	public abstract int getContainerGap(JComponent component, int position,
	Container parent);
	}

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