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/*
 * (C) Copyright IBM Corp. 1998 - All Rights Reserved
 *
 * The original version of this source code and documentation is copyrighted
 * and owned by IBM, Inc. These materials are provided under terms of a
 * License Agreement between IBM and Sun. This technology is protected by
 * multiple US and International patents. This notice and attribution to IBM
 * may not be removed.
 *
 */

package java.awt;

import java.util.Locale;
import java.util.ResourceBundle;

The ComponentOrientation class encapsulates the language-sensitive
orientation that is to be used to order the elements of a component
or of text. It is used to reflect the differences in this ordering
between Western alphabets, Middle Eastern (such as Hebrew), and Far
Eastern (such as Japanese).

Fundamentally, this governs items (such as characters) which are laid out
in lines, with the lines then laid out in a block. This also applies
to items in a widget: for example, in a check box where the box is
positioned relative to the text.

There are four different orientations used in modern languages
as in the following table.

LT          RT          TL          TR
A B C       C B A       A D G       G D A
D E F       F E D       B E H       H E B
G H I       I H G       C F I       I F C


(In the header, the two-letter abbreviation represents the item direction
in the first letter, and the line direction in the second. For example,
LT means "items left-to-right, lines top-to-bottom",
TL means "items top-to-bottom, lines left-to-right", and so on.)

The orientations are:

LT - Western Europe (optional for Japanese, Chinese, Korean)
RT - Middle East (Arabic, Hebrew)
TR - Japanese, Chinese, Korean
TL - Mongolian

Components whose view and controller code depends on orientation
should use the isLeftToRight() and
isHorizontal() methods to
determine their behavior. They should not include switch-like
code that keys off of the constants, such as:
if (orientation == LEFT_TO_RIGHT) {
  ...
} else if (orientation == RIGHT_TO_LEFT) {
  ...
} else {
  // Oops
}

This is unsafe, since more constants may be added in the future and
since it is not guaranteed that orientation objects will be unique.
/**
  * The ComponentOrientation class encapsulates the language-sensitive
  * orientation that is to be used to order the elements of a component
  * or of text. It is used to reflect the differences in this ordering
  * between Western alphabets, Middle Eastern (such as Hebrew), and Far
  * Eastern (such as Japanese).
  * <p>
  * Fundamentally, this governs items (such as characters) which are laid out
  * in lines, with the lines then laid out in a block. This also applies
  * to items in a widget: for example, in a check box where the box is
  * positioned relative to the text.
  * <p>
  * There are four different orientations used in modern languages
  * as in the following table.<br>
  * <pre>
  * LT          RT          TL          TR
  * A B C       C B A       A D G       G D A
  * D E F       F E D       B E H       H E B
  * G H I       I H G       C F I       I F C
  * </pre><br>
  * (In the header, the two-letter abbreviation represents the item direction
  * in the first letter, and the line direction in the second. For example,
  * LT means "items left-to-right, lines top-to-bottom",
  * TL means "items top-to-bottom, lines left-to-right", and so on.)
  * <p>
  * The orientations are:
  * <ul>
  * <li>LT - Western Europe (optional for Japanese, Chinese, Korean)
  * <li>RT - Middle East (Arabic, Hebrew)
  * <li>TR - Japanese, Chinese, Korean
  * <li>TL - Mongolian
  * </ul>
  * Components whose view and controller code depends on orientation
  * should use the <code>isLeftToRight()</code> and
  * <code>isHorizontal()</code> methods to
  * determine their behavior. They should not include switch-like
  * code that keys off of the constants, such as:
  * <pre>
  * if (orientation == LEFT_TO_RIGHT) {
  *   ...
  * } else if (orientation == RIGHT_TO_LEFT) {
  *   ...
  * } else {
  *   // Oops
  * }
  * </pre>
  * This is unsafe, since more constants may be added in the future and
  * since it is not guaranteed that orientation objects will be unique.
  */
public final class ComponentOrientation implements java.io.Serializable
{
    /*
     * serialVersionUID
     */
    private static final long serialVersionUID = -4113291392143563828L;

    // Internal constants used in the implementation
    private static final int UNK_BIT      = 1;
    private static final int HORIZ_BIT    = 2;
    private static final int LTR_BIT      = 4;

    
Items run left to right and lines flow top to bottom
Examples: English, French.
/**
     * Items run left to right and lines flow top to bottom
     * Examples: English, French.
     */
    public static final ComponentOrientation LEFT_TO_RIGHT =
                    new ComponentOrientation(HORIZ_BIT|LTR_BIT);

    
Items run right to left and lines flow top to bottom
Examples: Arabic, Hebrew.
/**
     * Items run right to left and lines flow top to bottom
     * Examples: Arabic, Hebrew.
     */
    public static final ComponentOrientation RIGHT_TO_LEFT =
                    new ComponentOrientation(HORIZ_BIT);

    
Indicates that a component's orientation has not been set.
To preserve the behavior of existing applications,
isLeftToRight will return true for this value.
/**
     * Indicates that a component's orientation has not been set.
     * To preserve the behavior of existing applications,
     * isLeftToRight will return true for this value.
     */
    public static final ComponentOrientation UNKNOWN =
                    new ComponentOrientation(HORIZ_BIT|LTR_BIT|UNK_BIT);

    
Are lines horizontal?
This will return true for horizontal, left-to-right writing
systems such as Roman.
/**
     * Are lines horizontal?
     * This will return true for horizontal, left-to-right writing
     * systems such as Roman.
     */
    public boolean isHorizontal() {
        return (orientation & HORIZ_BIT) != 0;
    }

    
HorizontalLines: Do items run left-to-right?

Vertical Lines:  Do lines run left-to-right?

This will return true for horizontal, left-to-right writing
systems such as Roman.
/**
     * HorizontalLines: Do items run left-to-right?<br>
     * Vertical Lines:  Do lines run left-to-right?<br>
     * This will return true for horizontal, left-to-right writing
     * systems such as Roman.
     */
    public boolean isLeftToRight() {
        return (orientation & LTR_BIT) != 0;
    }

    
Returns the orientation that is appropriate for the given locale.
Params:
locale – the specified locale/**
     * Returns the orientation that is appropriate for the given locale.
     * @param locale the specified locale
     */
    public static ComponentOrientation getOrientation(Locale locale) {
        // A more flexible implementation would consult a ResourceBundle
        // to find the appropriate orientation.  Until pluggable locales
        // are introduced however, the flexiblity isn't really needed.
        // So we choose efficiency instead.
        String lang = locale.getLanguage();
        if( "iw".equals(lang) || "ar".equals(lang)
            || "fa".equals(lang) || "ur".equals(lang) )
        {
            return RIGHT_TO_LEFT;
        } else {
            return LEFT_TO_RIGHT;
        }
    }

    
Returns the orientation appropriate for the given ResourceBundle's
localization.  Three approaches are tried, in the following order:

Retrieve a ComponentOrientation object from the ResourceBundle
     using the string "Orientation" as the key.
Use the ResourceBundle.getLocale to determine the bundle's
     locale, then return the orientation for that locale.
Return the default locale's orientation.

Deprecated:
As of J2SE 1.4, use getOrientation(Locale)./**
     * Returns the orientation appropriate for the given ResourceBundle's
     * localization.  Three approaches are tried, in the following order:
     * <ol>
     * <li>Retrieve a ComponentOrientation object from the ResourceBundle
     *      using the string "Orientation" as the key.
     * <li>Use the ResourceBundle.getLocale to determine the bundle's
     *      locale, then return the orientation for that locale.
     * <li>Return the default locale's orientation.
     * </ol>
     *
     * @deprecated As of J2SE 1.4, use {@link #getOrientation(java.util.Locale)}.
     */
    @Deprecated
    public static ComponentOrientation getOrientation(ResourceBundle bdl)
    {
        ComponentOrientation result = null;

        try {
            result = (ComponentOrientation)bdl.getObject("Orientation");
        }
        catch (Exception e) {
        }

        if (result == null) {
            result = getOrientation(bdl.getLocale());
        }
        if (result == null) {
            result = getOrientation(Locale.getDefault());
        }
        return result;
    }

    private int orientation;

    private ComponentOrientation(int value)
    {
        orientation = value;
    }
 }