Initial revision

From-SVN: r102074

libjava/classpath/java/awt/ComponentOrientation.java

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+/* ComponentOrientation.java -- describes a component's orientation
+   Copyright (C) 2000, 2001, 2002 Free Software Foundation
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+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