/* ComponentOrientation.java -- describes a component's orientation
Copyright (C) 2000, 2001, 2002 Free Software Foundation
This file is part of GNU Classpath.
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package java.awt;
import java.io.Serializable;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
/**
* This class is used to differentiate different orientations for text layout.
* It controls whether text flows left-to-right or right-to-left, and whether
* lines are horizontal or vertical, as in this 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>
* <b>LT</b> languages are most common (left-to-right lines, top-to-bottom).
* This includes Western European languages, and optionally includes Japanese,
* Chinese, and Korean. <b>RT</b> languages (right-to-left lines,
* top-to-bottom) are mainly middle eastern, such as Hebrew and Arabic.
* <b>TR</b> languages flow top-to-bottom in a line, right-to-left, and are
* the basis of Japanese, Chinese, and Korean. Finally, <b>TL</b> languages
* flow top-to-bottom in a line, left-to-right, as in Mongolian.
*
* <p>This is a pretty poor excuse for a type-safe enum, since it is not
* guaranteed that orientation objects are unique (thanks to serialization),
* yet there is no equals() method. You would be wise to compare the output
* of isHorizontal() and isLeftToRight() rather than comparing objects with
* ==, especially since more constants may be added in the future.
*
* @author Bryce McKinlay <bryce@albatross.co.nz>
* @since 1.0
* @status updated to 1.4
*/
public final class ComponentOrientation implements Serializable
{
/**
* Compatible with JDK 1.0+.
*/
private static final long serialVersionUID = -4113291392143563828L;
/** Constant for unknown orientation. */
private static final int UNKNOWN_ID = 1;
/** Constant for horizontal line orientation. */
private static final int HORIZONTAL_ID = 2;
/** Constant for left-to-right orientation. */
private static final int LEFT_TO_RIGHT_ID = 4;
/**
* Items run left to right, and lines flow top to bottom. Examples: English,
* French.
*/
public static final ComponentOrientation LEFT_TO_RIGHT
= new ComponentOrientation(HORIZONTAL_ID | LEFT_TO_RIGHT_ID);
/**
* Items run right to left, and lines flow top to bottom. Examples: Arabic,
* Hebrew.
*/
public static final ComponentOrientation RIGHT_TO_LEFT
= new ComponentOrientation(HORIZONTAL_ID);
/**
* The orientation is unknown for the locale. For backwards compatibility,
* this behaves like LEFT_TO_RIGHT in the instance methods.
*/
public static final ComponentOrientation UNKNOWN
= new ComponentOrientation(UNKNOWN_ID | HORIZONTAL_ID | LEFT_TO_RIGHT_ID);
/**
* The orientation of this object; bitwise-or of unknown (1), horizontal (2),
* and left-to-right (4).
*
* @serial the orientation
*/
private final int orientation;
/**
* Construct a given orientation.
*
* @param orientation the orientation
*/
private ComponentOrientation(int orientation)
{
this.orientation = orientation;
}
/**
* Returns true if the lines are horizontal, in which case lines flow
* top-to-bottom. For example, English, Hebrew. Counterexamples: Japanese,
* Chinese, Korean, Mongolian.
*
* @return true if this orientation has horizontal lines
*/
public boolean isHorizontal()
{
return (orientation & HORIZONTAL_ID) != 0;
}
/**
* If isHorizontal() returns true, then this determines whether items in
* the line flow left-to-right. If isHorizontal() returns false, items in
* a line flow top-to-bottom, and this determines if lines flow
* left-to-right.
*
* @return true if this orientation flows left-to-right
*/
public boolean isLeftToRight()
{
return (orientation & LEFT_TO_RIGHT_ID) != 0;
}
/**
* Gets an orientation appropriate for the locale.
*
* @param locale the locale
* @return the orientation for that locale
* @throws NullPointerException if locale is null
*/
public static ComponentOrientation getOrientation(Locale locale)
{
// Based on iterating over all languages defined in JDK 1.4, this behavior
// matches Sun's. However, it makes me wonder if any non-horizontal
// orientations even exist, as it sure contradicts their documentation.
String language = locale.getLanguage();
if ("ar".equals(language) || "fa".equals(language) || "iw".equals(language)
|| "ur".equals(language))
return RIGHT_TO_LEFT;
return LEFT_TO_RIGHT;
}
/**
* Gets an orientation from a resource bundle. This tries the following:
*
* <ul>
* <li>Use the key "Orientation" to find an instance of ComponentOrientation
* in the bundle.</li>
* <li>Get the locale of the resource bundle, and get the orientation of
* that locale.</li>
* <li>Give up and get the orientation of the default locale.</li>
* </ul>
*
* @param bdl the bundle to use
* @return the orientation
* @throws NullPointerException if bdl is null
* @deprecated use {@link #getOrientation(Locale)} instead
*/
public static ComponentOrientation getOrientation(ResourceBundle bdl)
{
ComponentOrientation r;
try
{
r = (ComponentOrientation) bdl.getObject("Orientation");
if (r != null)
return r;
}
catch (MissingResourceException ignored)
{
}
catch (ClassCastException ignored)
{
}
try
{
r = getOrientation(bdl.getLocale());
if (r != null)
return r;
}
catch (Exception ignored)
{
}
return getOrientation(Locale.getDefault());
}
} // class ComponentOrientation