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 * 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 + "]";
 }


}