/*
* Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
package java.awt;
import java.io.
ObjectInputStream;
import java.io.
IOException;
/**
* A flow layout arranges components in a directional flow, much
* like lines of text in a paragraph. The flow direction is
* determined by the container's <code>componentOrientation</code>
* property and may be one of two values:
* <ul>
* <li><code>ComponentOrientation.LEFT_TO_RIGHT</code>
* <li><code>ComponentOrientation.RIGHT_TO_LEFT</code>
* </ul>
* Flow layouts are typically used
* to arrange buttons in a panel. It arranges buttons
* horizontally until no more buttons fit on the same line.
* The line alignment is determined by the <code>align</code>
* property. The possible values are:
* <ul>
* <li>{@link #LEFT LEFT}
* <li>{@link #RIGHT RIGHT}
* <li>{@link #CENTER CENTER}
* <li>{@link #LEADING LEADING}
* <li>{@link #TRAILING TRAILING}
* </ul>
* <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="doc-files/FlowLayout-1.gif"
* ALT="Graphic of Layout for Three Buttons"
* style="float:center; margin: 7px 10px;">
* <p>
* Here is the code for this applet:
*
* <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.
*
* @author Arthur van Hoff
* @author Sami Shaio
* @since JDK1.0
* @see ComponentOrientation
*/
public class
FlowLayout implements
LayoutManager, java.io.
Serializable {
/**
* This value indicates that each row of components
* should be left-justified.
*/
public static final int
LEFT = 0;
/**
* This value indicates that each row of components
* should be centered.
*/
public static final int
CENTER = 1;
/**
* This value indicates that each row of components
* should be right-justified.
*/
public static final int
RIGHT = 2;
/**
* This value indicates that each row of components
* should be justified to the leading edge of the container's
* orientation, for example, to the left in left-to-right orientations.
*
* @see java.awt.Component#getComponentOrientation
* @see java.awt.ComponentOrientation
* @since 1.2
*/
public static final int
LEADING = 3;
/**
* This value indicates that each row of components
* should be justified to the trailing edge of the container's
* orientation, for example, to the right in left-to-right orientations.
*
* @see java.awt.Component#getComponentOrientation
* @see java.awt.ComponentOrientation
* @since 1.2
*/
public static final int
TRAILING = 4;
/**
* <code>align</code> is the property that determines
* how each row distributes empty space.
* It can be one of the following values:
* <ul>
* <li><code>LEFT</code>
* <li><code>RIGHT</code>
* <li><code>CENTER</code>
* </ul>
*
* @serial
* @see #getAlignment
* @see #setAlignment
*/
int
align; // This is for 1.1 serialization compatibility
/**
* <code>newAlign</code> is the property that determines
* how each row distributes empty space for the Java 2 platform,
* v1.2 and greater.
* It can be one of the following three values:
* <ul>
* <li><code>LEFT</code>
* <li><code>RIGHT</code>
* <li><code>CENTER</code>
* <li><code>LEADING</code>
* <li><code>TRAILING</code>
* </ul>
*
* @serial
* @since 1.2
* @see #getAlignment
* @see #setAlignment
*/
int
newAlign; // This is the one we actually use
/**
* The flow layout manager allows a seperation of
* components with gaps. The horizontal gap will
* specify the space between components and between
* the components and the borders of the
* <code>Container</code>.
*
* @serial
* @see #getHgap()
* @see #setHgap(int)
*/
int
hgap;
/**
* The flow layout manager allows a seperation of
* components with gaps. The vertical gap will
* specify the space between rows and between the
* the rows and the borders of the <code>Container</code>.
*
* @serial
* @see #getHgap()
* @see #setHgap(int)
*/
int
vgap;
/**
* If true, components will be aligned on their baseline.
*/
private boolean
alignOnBaseline;
/*
* JDK 1.1 serialVersionUID
*/
private static final long
serialVersionUID = -7262534875583282631L;
/**
* Constructs a new <code>FlowLayout</code> with a centered alignment and a
* default 5-unit horizontal and vertical gap.
*/
public
FlowLayout() {
this(
CENTER, 5, 5);
}
/**
* Constructs a new <code>FlowLayout</code> 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>,
* <code>FlowLayout.CENTER</code>, <code>FlowLayout.LEADING</code>,
* or <code>FlowLayout.TRAILING</code>.
* @param align the alignment value
*/
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>,
* <code>FlowLayout.CENTER</code>, <code>FlowLayout.LEADING</code>,
* or <code>FlowLayout.TRAILING</code>.
* @param align the alignment value
* @param hgap the horizontal gap between components
* and between the components and the
* borders of the <code>Container</code>
* @param vgap the vertical gap between components
* and between the components and the
* borders of the <code>Container</code>
*/
public
FlowLayout(int
align, int
hgap, int
vgap) {
this.
hgap =
hgap;
this.
vgap =
vgap;
setAlignment(
align);
}
/**
* Gets the alignment for this layout.
* Possible values are <code>FlowLayout.LEFT</code>,
* <code>FlowLayout.RIGHT</code>, <code>FlowLayout.CENTER</code>,
* <code>FlowLayout.LEADING</code>,
* or <code>FlowLayout.TRAILING</code>.
* @return the alignment value for this layout
* @see java.awt.FlowLayout#setAlignment
* @since JDK1.1
*/
public int
getAlignment() {
return
newAlign;
}
/**
* Sets the alignment for this layout.
* Possible values are
* <ul>
* <li><code>FlowLayout.LEFT</code>
* <li><code>FlowLayout.RIGHT</code>
* <li><code>FlowLayout.CENTER</code>
* <li><code>FlowLayout.LEADING</code>
* <li><code>FlowLayout.TRAILING</code>
* </ul>
* @param align one of the alignment values shown above
* @see #getAlignment()
* @since JDK1.1
*/
public void
setAlignment(int
align) {
this.
newAlign =
align;
// this.align is used only for serialization compatibility,
// so set it to a value compatible with the 1.1 version
// of the class
switch (
align) {
case
LEADING:
this.
align =
LEFT;
break;
case
TRAILING:
this.
align =
RIGHT;
break;
default:
this.
align =
align;
break;
}
}
/**
* Gets the horizontal gap between components
* and between the components and the borders
* of the <code>Container</code>
*
* @return the horizontal gap between components
* and between the components and the borders
* of the <code>Container</code>
* @see java.awt.FlowLayout#setHgap
* @since JDK1.1
*/
public int
getHgap() {
return
hgap;
}
/**
* Sets the horizontal gap between components and
* between the components and the borders of the
* <code>Container</code>.
*
* @param hgap the horizontal gap between components
* and between the components and the borders
* of the <code>Container</code>
* @see java.awt.FlowLayout#getHgap
* @since JDK1.1
*/
public void
setHgap(int
hgap) {
this.
hgap =
hgap;
}
/**
* Gets the vertical gap between components and
* between the components and the borders of the
* <code>Container</code>.
*
* @return the vertical gap between components
* and between the components and the borders
* of the <code>Container</code>
* @see java.awt.FlowLayout#setVgap
* @since JDK1.1
*/
public int
getVgap() {
return
vgap;
}
/**
* Sets the vertical gap between components and between
* the components and the borders of the <code>Container</code>.
*
* @param vgap the vertical gap between components
* and between the components and the borders
* of the <code>Container</code>
* @see java.awt.FlowLayout#getVgap
* @since JDK1.1
*/
public void
setVgap(int
vgap) {
this.
vgap =
vgap;
}
/**
* Sets whether or not components should be vertically aligned along their
* baseline. Components that do not have a baseline will be centered.
* The default is false.
*
* @param alignOnBaseline whether or not components should be
* vertically aligned on their baseline
* @since 1.6
*/
public void
setAlignOnBaseline(boolean
alignOnBaseline) {
this.
alignOnBaseline =
alignOnBaseline;
}
/**
* Returns true if components are to be vertically aligned along
* their baseline. The default is false.
*
* @return true if components are to be vertically aligned along
* their baseline
* @since 1.6
*/
public boolean
getAlignOnBaseline() {
return
alignOnBaseline;
}
/**
* 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
*/
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
*/
public void
removeLayoutComponent(
Component comp) {
}
/**
* Returns the preferred dimensions for this layout given the
* <i>visible</i> components in the specified target container.
*
* @param target the container that 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
*/
public
Dimension preferredLayoutSize(
Container target) {
synchronized (
target.
getTreeLock()) {
Dimension dim = new
Dimension(0, 0);
int
nmembers =
target.
getComponentCount();
boolean
firstVisibleComponent = true;
boolean
useBaseline =
getAlignOnBaseline();
int
maxAscent = 0;
int
maxDescent = 0;
for (int
i = 0 ;
i <
nmembers ;
i++) {
Component m =
target.
getComponent(
i);
if (
m.
isVisible()) {
Dimension d =
m.
getPreferredSize();
dim.
height =
Math.
max(
dim.
height,
d.
height);
if (
firstVisibleComponent) {
firstVisibleComponent = false;
} else {
dim.
width +=
hgap;
}
dim.
width +=
d.
width;
if (
useBaseline) {
int
baseline =
m.
getBaseline(
d.
width,
d.
height);
if (
baseline >= 0) {
maxAscent =
Math.
max(
maxAscent,
baseline);
maxDescent =
Math.
max(
maxDescent,
d.
height -
baseline);
}
}
}
}
if (
useBaseline) {
dim.
height =
Math.
max(
maxAscent +
maxDescent,
dim.
height);
}
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 <i>visible</i>
* components contained in the specified target container.
* @param target the container that 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
*/
public
Dimension minimumLayoutSize(
Container target) {
synchronized (
target.
getTreeLock()) {
boolean
useBaseline =
getAlignOnBaseline();
Dimension dim = new
Dimension(0, 0);
int
nmembers =
target.
getComponentCount();
int
maxAscent = 0;
int
maxDescent = 0;
boolean
firstVisibleComponent = true;
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 (
firstVisibleComponent) {
firstVisibleComponent = false;
} else {
dim.
width +=
hgap;
}
dim.
width +=
d.
width;
if (
useBaseline) {
int
baseline =
m.
getBaseline(
d.
width,
d.
height);
if (
baseline >= 0) {
maxAscent =
Math.
max(
maxAscent,
baseline);
maxDescent =
Math.
max(
maxDescent,
dim.
height -
baseline);
}
}
}
}
if (
useBaseline) {
dim.
height =
Math.
max(
maxAscent +
maxDescent,
dim.
height);
}
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
* @param useBaseline Whether or not to align on baseline.
* @param ascent Ascent for the components. This is only valid if
* useBaseline is true.
* @param descent Ascent for the components. This is only valid if
* useBaseline is true.
* @return actual row height
*/
private int
moveComponents(
Container target, int
x, int
y, int
width, int
height,
int
rowStart, int
rowEnd, boolean
ltr,
boolean
useBaseline, int[]
ascent,
int[]
descent) {
switch (
newAlign) {
case
LEFT:
x +=
ltr ? 0 :
width;
break;
case
CENTER:
x +=
width / 2;
break;
case
RIGHT:
x +=
ltr ?
width : 0;
break;
case
LEADING:
break;
case
TRAILING:
x +=
width;
break;
}
int
maxAscent = 0;
int
nonbaselineHeight = 0;
int
baselineOffset = 0;
if (
useBaseline) {
int
maxDescent = 0;
for (int
i =
rowStart ;
i <
rowEnd ;
i++) {
Component m =
target.
getComponent(
i);
if (
m.
visible) {
if (
ascent[
i] >= 0) {
maxAscent =
Math.
max(
maxAscent,
ascent[
i]);
maxDescent =
Math.
max(
maxDescent,
descent[
i]);
}
else {
nonbaselineHeight =
Math.
max(
m.
getHeight(),
nonbaselineHeight);
}
}
}
height =
Math.
max(
maxAscent +
maxDescent,
nonbaselineHeight);
baselineOffset = (
height -
maxAscent -
maxDescent) / 2;
}
for (int
i =
rowStart ;
i <
rowEnd ;
i++) {
Component m =
target.
getComponent(
i);
if (
m.
isVisible()) {
int
cy;
if (
useBaseline &&
ascent[
i] >= 0) {
cy =
y +
baselineOffset +
maxAscent -
ascent[
i];
}
else {
cy =
y + (
height -
m.
height) / 2;
}
if (
ltr) {
m.
setLocation(
x,
cy);
} else {
m.
setLocation(
target.
width -
x -
m.
width,
cy);
}
x +=
m.
width +
hgap;
}
}
return
height;
}
/**
* Lays out the container. This method lets each
* <i>visible</i> component take
* its preferred size by reshaping the components in the
* target container in order to satisfy the alignment of
* this <code>FlowLayout</code> object.
*
* @param target the specified component being laid out
* @see Container
* @see java.awt.Container#doLayout
*/
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;
boolean
ltr =
target.
getComponentOrientation().
isLeftToRight();
boolean
useBaseline =
getAlignOnBaseline();
int[]
ascent = null;
int[]
descent = null;
if (
useBaseline) {
ascent = new int[
nmembers];
descent = new int[
nmembers];
}
for (int
i = 0 ;
i <
nmembers ;
i++) {
Component m =
target.
getComponent(
i);
if (
m.
isVisible()) {
Dimension d =
m.
getPreferredSize();
m.
setSize(
d.
width,
d.
height);
if (
useBaseline) {
int
baseline =
m.
getBaseline(
d.
width,
d.
height);
if (
baseline >= 0) {
ascent[
i] =
baseline;
descent[
i] =
d.
height -
baseline;
}
else {
ascent[
i] = -1;
}
}
if ((
x == 0) || ((
x +
d.
width) <=
maxwidth)) {
if (
x > 0) {
x +=
hgap;
}
x +=
d.
width;
rowh =
Math.
max(
rowh,
d.
height);
} else {
rowh =
moveComponents(
target,
insets.
left +
hgap,
y,
maxwidth -
x,
rowh,
start,
i,
ltr,
useBaseline,
ascent,
descent);
x =
d.
width;
y +=
vgap +
rowh;
rowh =
d.
height;
start =
i;
}
}
}
moveComponents(
target,
insets.
left +
hgap,
y,
maxwidth -
x,
rowh,
start,
nmembers,
ltr,
useBaseline,
ascent,
descent);
}
}
//
// the internal serial version which says which version was written
// - 0 (default) for versions before the Java 2 platform, v1.2
// - 1 for version >= Java 2 platform v1.2, which includes "newAlign" field
//
private static final int
currentSerialVersion = 1;
/**
* This represent the <code>currentSerialVersion</code>
* which is bein used. It will be one of two values :
* <code>0</code> versions before Java 2 platform v1.2..
* <code>1</code> versions after Java 2 platform v1.2..
*
* @serial
* @since 1.2
*/
private int
serialVersionOnStream =
currentSerialVersion;
/**
* Reads this object out of a serialization stream, handling
* objects written by older versions of the class that didn't contain all
* of the fields we use now..
*/
private void
readObject(
ObjectInputStream stream)
throws
IOException,
ClassNotFoundException
{
stream.
defaultReadObject();
if (
serialVersionOnStream < 1) {
// "newAlign" field wasn't present, so use the old "align" field.
setAlignment(this.
align);
}
serialVersionOnStream =
currentSerialVersion;
}
/**
* Returns a string representation of this <code>FlowLayout</code>
* object and its values.
* @return a string representation of this layout
*/
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;
case
LEADING:
str = ",align=leading"; break;
case
TRAILING:
str = ",align=trailing"; break;
}
return
getClass().
getName() + "[hgap=" +
hgap + ",vgap=" +
vgap +
str + "]";
}
}