/*
* @(#)FlowLayout.java 1.9 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program 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.
*
* This program 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 at /legal/license.txt).
*
* 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 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.awt;
/**
* A flow layout arranges components in a left-to-right flow, much
* like lines of text in a paragraph. Flow layouts are typically used
* to arrange buttons in a panel. It will arrange
* buttons left to right until no more buttons fit on the same line.
* Each line is centered.
* <p>
* For example, the following picture shows an applet using the flow
* layout manager (its default layout manager) to position three buttons:
* <p>
* <img src="images-awt/FlowLayout-1.gif"
* ALT="Graphic of Layout for Three Buttons"
* ALIGN=center HSPACE=10 VSPACE=7>
* <p>
* Here is the code for this applet:
* <p>
* <hr><blockquote><pre>
* import java.awt.*;
* import java.applet.Applet;
*
* public class myButtons extends Applet {
* Button button1, button2, button3;
* public void init() {
* button1 = new Button("Ok");
* button2 = new Button("Open");
* button3 = new Button("Close");
* add(button1);
* add(button2);
* add(button3);
* }
* }
* </pre></blockquote><hr>
* <p>
* A flow layout lets each component assume its natural (preferred) size.
*
* @version 1.27, 07/01/98
* @author Arthur van Hoff
* @author Sami Shaio
* @since JDK1.0
*/
public class FlowLayout implements LayoutManager, java.io.Serializable {
/**
* This value indicates that each row of components
* should be left-justified.
* @since JDK1.0
*/
public static final int LEFT = 0;
/**
* This value indicates that each row of components
* should be centered.
* @since JDK1.0
*/
public static final int CENTER = 1;
/**
* This value indicates that each row of components
* should be right-justified.
* @since JDK1.0
*/
public static final int RIGHT = 2;
int align;
int hgap;
int vgap;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -7262534875583282631L;
/**
* Constructs a new Flow Layout with a centered alignment and a
* default 5-unit horizontal and vertical gap.
* @since JDK1.0
*/
public FlowLayout() {
this(CENTER, 5, 5);
}
/**
* Constructs a new Flow Layout with the specified alignment and a
* default 5-unit horizontal and vertical gap.
* The value of the alignment argument must be one of
* <code>FlowLayout.LEFT</code>, <code>FlowLayout.RIGHT</code>,
* or <code>FlowLayout.CENTER</code>.
* @param align the alignment value
* @since JDK1.0
*/
public FlowLayout(int align) {
this(align, 5, 5);
}
/**
* Creates a new flow layout manager with the indicated alignment
* and the indicated horizontal and vertical gaps.
* <p>
* The value of the alignment argument must be one of
* <code>FlowLayout.LEFT</code>, <code>FlowLayout.RIGHT</code>,
* or <code>FlowLayout.CENTER</code>.
* @param align the alignment value.
* @param hgap the horizontal gap between components.
* @param vgap the vertical gap between components.
* @since JDK1.0
*/
public FlowLayout(int align, int hgap, int vgap) {
this.align = align;
this.hgap = hgap;
this.vgap = vgap;
}
/**
* Gets the alignment for this layout.
* Possible values are <code>FlowLayout.LEFT</code>,
* <code>FlowLayout.RIGHT</code>, or <code>FlowLayout.CENTER</code>.
* @return the alignment value for this layout.
* @see java.awt.FlowLayout#setAlignment
* @since JDK1.1
*/
public int getAlignment() {
return align;
}
/**
* Sets the alignment for this layout.
* Possible values are <code>FlowLayout.LEFT</code>,
* <code>FlowLayout.RIGHT</code>, and <code>FlowLayout.CENTER</code>.
* @param align the alignment value.
* @see java.awt.FlowLayout#getAlignment
* @since JDK1.1
*/
public void setAlignment(int align) {
this.align = align;
}
/**
* Gets the horizontal gap between components.
* @return the horizontal gap between components.
* @see java.awt.FlowLayout#setHgap
* @since JDK1.1
*/
public int getHgap() {
return hgap;
}
/**
* Sets the horizontal gap between components.
* @param hgap the horizontal gap between components
* @see java.awt.FlowLayout#getHgap
* @since JDK1.1
*/
public void setHgap(int hgap) {
this.hgap = hgap;
}
/**
* Gets the vertical gap between components.
* @return the vertical gap between components.
* @see java.awt.FlowLayout#setVgap
* @since JDK1.1
*/
public int getVgap() {
return vgap;
}
/**
* Sets the vertical gap between components.
* @param vgap the vertical gap between components
* @see java.awt.FlowLayout#getVgap
* @since JDK1.1
*/
public void setVgap(int vgap) {
this.vgap = vgap;
}
/**
* Adds the specified component to the layout. Not used by this class.
* @param name the name of the component
* @param comp the component to be added
* @since JDK1.0
*/
public void addLayoutComponent(String name, Component comp) {}
/**
* Removes the specified component from the layout. Not used by
* this class.
* @param comp the component to remove
* @see java.awt.Container#removeAll
* @since JDK1.0
*/
public void removeLayoutComponent(Component comp) {}
/**
* Returns the preferred dimensions for this layout given the components
* in the specified target container.
* @param target the component which needs to be laid out
* @return the preferred dimensions to lay out the
* subcomponents of the specified container.
* @see Container
* @see #minimumLayoutSize
* @see java.awt.Container#getPreferredSize
* @since JDK1.0
*/
public Dimension preferredLayoutSize(Container target) {
synchronized (target.getTreeLock()) {
Dimension dim = new Dimension(0, 0);
int nmembers = target.getComponentCount();
for (int i = 0; i < nmembers; i++) {
Component m = target.getComponent(i);
if (m.visible) {
Dimension d = m.getPreferredSize();
dim.height = Math.max(dim.height, d.height);
if (i > 0) {
dim.width += hgap;
}
dim.width += d.width;
}
}
Insets insets = target.getInsets();
dim.width += insets.left + insets.right + hgap * 2;
dim.height += insets.top + insets.bottom + vgap * 2;
return dim;
}
}
/**
* Returns the minimum dimensions needed to layout the components
* contained in the specified target container.
* @param target the component which needs to be laid out
* @return the minimum dimensions to lay out the
* subcomponents of the specified container.
* @see #preferredLayoutSize
* @see java.awt.Container
* @see java.awt.Container#doLayout
* @since JDK1.0
*/
public Dimension minimumLayoutSize(Container target) {
synchronized (target.getTreeLock()) {
Dimension dim = new Dimension(0, 0);
int nmembers = target.getComponentCount();
for (int i = 0; i < nmembers; i++) {
Component m = target.getComponent(i);
if (m.visible) {
Dimension d = m.getMinimumSize();
dim.height = Math.max(dim.height, d.height);
if (i > 0) {
dim.width += hgap;
}
dim.width += d.width;
}
}
Insets insets = target.getInsets();
dim.width += insets.left + insets.right + hgap * 2;
dim.height += insets.top + insets.bottom + vgap * 2;
return dim;
}
}
/**
* Centers the elements in the specified row, if there is any slack.
* @param target the component which needs to be moved
* @param x the x coordinate
* @param y the y coordinate
* @param width the width dimensions
* @param height the height dimensions
* @param rowStart the beginning of the row
* @param rowEnd the the ending of the row
*/
private void moveComponents(Container target, int x, int y, int width, int height, int rowStart, int rowEnd) {
synchronized (target.getTreeLock()) {
switch (align) {
case LEFT:
break;
case CENTER:
x += width / 2;
break;
case RIGHT:
x += width;
break;
}
for (int i = rowStart; i < rowEnd; i++) {
Component m = target.getComponent(i);
if (m.visible) {
m.setLocation(x, y + (height - m.height) / 2);
x += hgap + m.width;
}
}
}
}
/**
* Lays out the container. This method lets each component take
* its preferred size by reshaping the components in the
* target container in order to satisfy the constraints of
* this <code>FlowLayout</code> object.
* @param target the specified component being laid out.
* @see Container
* @see java.awt.Container#doLayout
* @since JDK1.0
*/
public void layoutContainer(Container target) {
synchronized (target.getTreeLock()) {
Insets insets = target.getInsets();
int maxwidth = target.width - (insets.left + insets.right + hgap * 2);
int nmembers = target.getComponentCount();
int x = 0, y = insets.top + vgap;
int rowh = 0, start = 0;
for (int i = 0; i < nmembers; i++) {
Component m = target.getComponent(i);
if (m.visible) {
Dimension d = m.getPreferredSize();
m.setSize(d.width, d.height);
if ((x == 0) || ((x + d.width) <= maxwidth)) {
if (x > 0) {
x += hgap;
}
x += d.width;
rowh = Math.max(rowh, d.height);
} else {
moveComponents(target, insets.left + hgap, y, maxwidth - x, rowh, start, i);
x = d.width;
y += vgap + rowh;
rowh = d.height;
start = i;
}
}
}
moveComponents(target, insets.left + hgap, y, maxwidth - x, rowh, start, nmembers);
}
}
/**
* Returns a string representation of this <code>FlowLayout</code>
* object and its values.
* @return a string representation of this layout.
* @since JDK1.0
*/
public String toString() {
String str = "";
switch (align) {
case LEFT:
str = ",align=left";
break;
case CENTER:
str = ",align=center";
break;
case RIGHT:
str = ",align=right";
break;
}
return getClass().getName() + "[hgap=" + hgap + ",vgap=" + vgap + str + "]";
}
}