/*
* 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);
}