/*
* Copyright 1997-2003 Sun Microsystems, Inc. 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. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package javax.swing;
import java.awt.LayoutManager;
import java.awt.Component;
import java.awt.Container;
import java.awt.Rectangle;
import java.awt.Point;
import java.awt.Dimension;
import java.awt.Insets;
import java.io.Serializable;
/**
* The default layout manager for <code>JViewport</code>.
* <code>ViewportLayout</code> defines
* a policy for layout that should be useful for most applications.
* The viewport makes its view the same size as the viewport,
* however it will not make the view smaller than its minimum size.
* As the viewport grows the view is kept bottom justified until
* the entire view is visible, subsequently the view is kept top
* justified.
* <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. As of 1.4, support for long term storage
* of all JavaBeans<sup><font size="-2">TM</font></sup>
* has been added to the <code>java.beans</code> package.
* Please see {@link java.beans.XMLEncoder}.
*
* @author Hans Muller
*/
public class ViewportLayout implements LayoutManager, Serializable
{
// Single instance used by JViewport.
static ViewportLayout SHARED_INSTANCE = new ViewportLayout();
/**
* Adds the specified component to the layout. Not used by this class.
* @param name the name of the component
* @param c the the component to be added
*/
public void addLayoutComponent(String name, Component c) { }
/**
* Removes the specified component from the layout. Not used by
* this class.
* @param c the component to remove
*/
public void removeLayoutComponent(Component c) { }
/**
* Returns the preferred dimensions for this layout given the components
* in the specified target container.
* @param parent the component which needs to be laid out
* @return a <code>Dimension</code> object containing the
* preferred dimensions
* @see #minimumLayoutSize
*/
public Dimension preferredLayoutSize(Container parent) {
Component view = ((JViewport)parent).getView();
if (view == null) {
return new Dimension(0, 0);
}
else if (view instanceof Scrollable) {
return ((Scrollable)view).getPreferredScrollableViewportSize();
}
else {
return view.getPreferredSize();
}
}
/**
* Returns the minimum dimensions needed to layout the components
* contained in the specified target container.
*
* @param parent the component which needs to be laid out
* @return a <code>Dimension</code> object containing the minimum
* dimensions
* @see #preferredLayoutSize
*/
public Dimension minimumLayoutSize(Container parent) {
return new Dimension(4, 4);
}
/**
* Called by the AWT when the specified container needs to be laid out.
*
* @param parent the container to lay out
*
* @exception AWTError if the target isn't the container specified to the
* <code>BoxLayout</code> constructor
*/
public void layoutContainer(Container parent)
{
JViewport vp = (JViewport)parent;
Component view = vp.getView();
Scrollable scrollableView = null;
if (view == null) {
return;
}
else if (view instanceof Scrollable) {
scrollableView = (Scrollable) view;
}
/* All of the dimensions below are in view coordinates, except
* vpSize which we're converting.
*/
Insets insets = vp.getInsets();
Dimension viewPrefSize = view.getPreferredSize();
Dimension vpSize = vp.getSize();
Dimension extentSize = vp.toViewCoordinates(vpSize);
Dimension viewSize = new Dimension(viewPrefSize);
if (scrollableView != null) {
if (scrollableView.getScrollableTracksViewportWidth()) {
viewSize.width = vpSize.width;
}
if (scrollableView.getScrollableTracksViewportHeight()) {
viewSize.height = vpSize.height;
}
}
Point viewPosition = vp.getViewPosition();
/* If the new viewport size would leave empty space to the
* right of the view, right justify the view or left justify
* the view when the width of the view is smaller than the
* container.
*/
if (scrollableView == null ||
vp.getParent() == null ||
vp.getParent().getComponentOrientation().isLeftToRight()) {
if ((viewPosition.x + extentSize.width) > viewSize.width) {
viewPosition.x = Math.max(0, viewSize.width - extentSize.width);
}
} else {
if (extentSize.width > viewSize.width) {
viewPosition.x = viewSize.width - extentSize.width;
} else {
viewPosition.x = Math.max(0, Math.min(viewSize.width - extentSize.width, viewPosition.x));
}
}
/* If the new viewport size would leave empty space below the
* view, bottom justify the view or top justify the view when
* the height of the view is smaller than the container.
*/
if ((viewPosition.y + extentSize.height) > viewSize.height) {
viewPosition.y = Math.max(0, viewSize.height - extentSize.height);
}
/* If we haven't been advised about how the viewports size
* should change wrt to the viewport, i.e. if the view isn't
* an instance of Scrollable, then adjust the views size as follows.
*
* If the origin of the view is showing and the viewport is
* bigger than the views preferred size, then make the view
* the same size as the viewport.
*/
if (scrollableView == null) {
if ((viewPosition.x == 0) && (vpSize.width > viewPrefSize.width)) {
viewSize.width = vpSize.width;
}
if ((viewPosition.y == 0) && (vpSize.height > viewPrefSize.height)) {
viewSize.height = vpSize.height;
}
}
vp.setViewPosition(viewPosition);
vp.setViewSize(viewSize);
}
}