API Overview API Index Package Overview Direct link to this page
JDK 1.6
  javax.swing. ViewportLayout View Javadoc
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185

/*
 * @(#)ViewportLayout.java	1.39 05/11/17
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

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}.
 *
 * @version 1.39 11/17/05
 * @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);
    }
}

Generated By: JavaOnTracks Doclet 0.1.4     ©Thibaut Colar