435 lines
15 KiB
Java
435 lines
15 KiB
Java
/* InputContext.java -- provides the context for text input
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Copyright (C) 2002 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.awt.im;
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import java.awt.AWTEvent;
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import java.awt.AWTException;
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import java.awt.Component;
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import java.awt.im.spi.InputMethod;
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import java.awt.im.spi.InputMethodDescriptor;
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import java.io.BufferedReader;
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import java.io.InputStreamReader;
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import java.io.IOException;
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import java.net.URL;
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import java.net.URLConnection;
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import java.util.ArrayList;
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import java.util.Enumeration;
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import java.util.HashMap;
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import java.util.Locale;
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import gnu.java.util.EmptyEnumeration;
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/**
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* Provides a context for controlling input methods and keyboard layouts.
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* This class provides the communication layer between the client component,
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* and the various locale-dependent text entry input methods that can be used
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* for the client. By default, there is one instance per Window, shared among
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* all components, but this limits text entry to one component at a time.
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* Thus, text components can create their own instance to allow text entry
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* in multiple components at a time.
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*
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* <p>By using the interfaces of {@link java.awt.im.spi}, you can install
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* extensions which allow additional input methods. Some of these may use
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* platform native input methods, or keyboard layouts provided by the platform.
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* Input methods are unavailable if none have been installed and the platform
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* has no underlying native input methods. Extensions are installed as jar
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* files, usually accessed in the default extension location or specified by
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* the -extdir VM flag. The jar must contain a file named
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* "META_INF/services/java.awt.im.spi.InputMethodDescriptor" which lists,
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* one entry per line in UTF-8 encoding, each class in the jar that implements
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* java.awt.im.spi.InputMethodDescriptor.
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*
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* @author Eric Blake <ebb9@email.byu.edu>
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* @see Component#getInputContext()
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* @see Component#enableInputMethods(boolean)
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* @since 1.2
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* @status updated to 1.4, but unverified
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*/
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public class InputContext
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{
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/**
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* The list of installed input method descriptors.
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*/
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private static final ArrayList descriptors = new ArrayList();
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static
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{
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Enumeration enum;
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try
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{
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enum = ClassLoader.getSystemResources
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("META_INF/services/java.awt.im.spi.InputMethodDescriptor");
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}
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catch (IOException ex)
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{
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// XXX Should we do something else?
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enum = EmptyEnumeration.getInstance();
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}
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while (enum.hasMoreElements())
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{
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URL url = (URL) enum.nextElement();
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BufferedReader in;
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String line;
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try
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{
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in = new BufferedReader
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(new InputStreamReader(url.openConnection().getInputStream(),
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"UTF-8"));
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line = in.readLine().trim();
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}
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catch (IOException ignored)
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{
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continue;
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}
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outer:
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while (line != null)
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{
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try
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{
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if (line.charAt(0) != '#')
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{
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Class c = Class.forName(line);
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descriptors.add((InputMethodDescriptor) c.newInstance());
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}
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line = in.readLine().trim();
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}
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catch (IOException e)
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{
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continue outer;
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}
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catch (Exception ignored)
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{
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}
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}
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}
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}
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/** The current input method; null if no input methods are installed. */
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private InputMethod im;
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/** Map of locales to the most recently selected input method. */
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private final HashMap recent = new HashMap();
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/** The list of acceptable character subsets. */
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private Character.Subset[] subsets;
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/**
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* Construct an InputContext. This is protected, so clients must use
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* {@link #getInstance()} instead.
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*/
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protected InputContext()
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{
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}
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/**
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* Returns a new InputContext.
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*
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* @return a new instance, initialized to the default locale if available
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*/
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public static InputContext getInstance()
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{
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InputContext ic = new InputContext();
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ic.selectInputMethod(Locale.getDefault());
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return ic;
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}
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/**
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* Attempts to select an input method or keyboard layout which supports the
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* given locale. This returns true if a locale is available and was selected.
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* The following steps are taken in choosing an input method:<ul>
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* <li>If the currently selected input method or keyboard layout supports
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* the requested locale, it remains selected.</li>
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* <li>If there is no input method or keyboard layout available that
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* supports the requested locale, the current input method or keyboard
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* layout remains selected.</li>
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* <li>If the user has previously selected an input method or keyboard
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* layout for the requested locale from the user interface, then the most
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* recently selected such input method or keyboard layout is reselected.</li>
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* <li>Otherwise, an input method or keyboard layout that supports the
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* requested locale is selected in an implementation dependent way. This
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* implementation chooses the first input method which supports the requested
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* locale based on the InputMethodDescriptors loaded from the extensions
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* installed on the CLASSPATH.</li>
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* </ul>
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*
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* <p>Before switching away from an input method, any currently uncommitted
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* text is committed. Not all host operating systems provide API to
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* determine the locale of the currently selected native input method or
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* keyboard layout, and to select a native input method or keyboard layout
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* by locale. For host operating systems that don't provide such API,
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* selectInputMethod assumes that native input methods or keyboard layouts
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* provided by the host operating system support only the system's default
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* locale.
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*
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* <p>An example of where this may be called is in a multi-language document,
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* when moving the insertion point between sections of different locale, so
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* that the user may use the input method appropriate to that section of the
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* document.
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*
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* @param locale the desired new locale
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* @return true if the new locale is active
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* @throws NullPointerException if locale is null
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*/
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public boolean selectInputMethod(Locale locale)
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{
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if (im != null && im.setLocale(locale))
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{
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recent.put(locale, im);
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return true;
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}
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InputMethod next = (InputMethod) recent.get(locale);
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outer:
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if (next != null)
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for (int i = 0, limit = descriptors.size(); i < limit; i++)
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{
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InputMethodDescriptor d = (InputMethodDescriptor) descriptors.get(i);
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Locale[] list;
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try
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{
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list = d.getAvailableLocales();
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}
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catch (AWTException ignored)
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{
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continue;
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}
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for (int j = list.length; --j >= 0; )
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if (locale.equals(list[j]))
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{
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try
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{
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next = d.createInputMethod();
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recent.put(locale, next);
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}
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catch (Exception ignored)
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{
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continue;
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}
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}
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}
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if (next == null)
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return false;
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// XXX I'm not sure if this does all the necessary steps in the switch.
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if (im != null)
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{
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try
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{
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next.setCompositionEnabled(im.isCompositionEnabled());
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}
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catch (UnsupportedOperationException ignored)
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{
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}
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im.endComposition();
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im.deactivate(false);
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im.hideWindows();
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}
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im = next;
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im.setLocale(locale);
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im.setCharacterSubsets(subsets);
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return true;
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}
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/**
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* Returns the current locale of the current input method or keyboard
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* layout. Returns null if the input context does not have a current input
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* method or keyboard layout or if the current input method's
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* {@link InputMethod#getLocale()} method returns null. Not all host
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* operating systems provide API to determine the locale of the currently
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* selected native input method or keyboard layout. For host operating
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* systems that don't provide such API, getLocale assumes that the current
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* locale of all native input methods or keyboard layouts provided by the
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* host operating system is the system's default locale.
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*
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* @return the locale of the current input method, or null
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* @since 1.3
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*/
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public Locale getLocale()
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{
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return im == null ? null : im.getLocale();
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}
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/**
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* Sets the subsets of Unicode characters allowed to be input by the current
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* input method, as well as subsequent input methods. The value of null
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* implies all characters are legal. Applications should not rely on this
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* behavior, since native host input methods may not allow restrictions.
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* If no current input method is available, this has no immediate effect.
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*
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* @param subsets the set of Unicode subsets to accept, or null
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*/
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public void setCharacterSubsets(Character.Subset[] subsets)
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{
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this.subsets = subsets;
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if (im != null)
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im.setCharacterSubsets(subsets);
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}
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/**
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* Changes the enabled status of the current input method. An input method
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* that is enabled for composition interprets incoming events for both
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* composition and control purposes, while a disabled input method only
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* interprets control commands (including commands to enable itself).
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*
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* @param enable whether to enable the input method
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* @throws UnsupportedOperationException if there is no current input method,
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* or the input method does not support enabling
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* @see #isCompositionEnabled()
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* @since 1.3
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*/
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public void setCompositionEnabled(boolean enable)
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{
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if (im == null)
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throw new UnsupportedOperationException();
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im.setCompositionEnabled(enable);
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}
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/**
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* Find out if the current input method is enabled.
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*
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* @return true if the current input method is enabled
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* @throws UnsupportedOperationException if there is no current input method,
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* or the input method does not support enabling
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* @see #setCompositionEnabled(boolean)
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* @since 1.3
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*/
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public boolean isCompositionEnabled()
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{
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if (im == null)
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throw new UnsupportedOperationException();
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return im.isCompositionEnabled();
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}
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/**
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* Starts a reconversion operation in the current input method. The input
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* method gets theh text to reconvert from the client component, using
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* {@link InputMethodRequests#getSelectedText(Attribute[])}. Then the
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* composed and committed text produced by the operation is sent back to
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* the client using a sequence of InputMethodRequests.
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*
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* @throws UnsupportedOperationException if there is no current input method,
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* or the input method does not support reconversion
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* @throws UnsupportedOperationException if ther
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* @since 1.3
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*/
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public void reconvert()
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{
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if (im == null)
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throw new UnsupportedOperationException();
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im.reconvert();
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}
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/**
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* Dispatches an event to the current input method. This is called
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* automatically by AWT. If no input method is available, then the event
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* will never be consumed.
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*
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* @param event the event to dispatch
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* @throws NullPointerException if event is null
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*/
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public void dispatchEvent(AWTEvent event)
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{
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if (im != null)
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im.dispatchEvent(event);
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}
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/**
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* Notifies the input context that a client component has been removed from
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* its containment hierarchy, or that input method support has been disabled
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* for the component. This method is usually called from the client
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* component's {@link Component#removeNotify()} method. Potentially pending
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* input from input methods for this component is discarded. If no input
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* methods are available, then this method has no effect.
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*
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* @param client the client component
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* @throws NullPointerException if client is null
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*/
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public void removeNotify(Component client)
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{
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// XXX What to do with client information?
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if (im != null)
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{
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im.deactivate(false);
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im.removeNotify();
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}
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}
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/**
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* Ends any input composition that may currently be going on in this
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* context. Depending on the platform and possibly user preferences, this
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* may commit or delete uncommitted text. Any changes to the text are
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* communicated to the active component using an input method event. If no
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* input methods are available, then this method has no effect. This may
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* be called for a variety of reasons, such as when the user moves the
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* insertion point in the client text outside the range of the composed text,
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* or when text is saved to file.
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*/
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public void endComposition()
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{
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if (im != null)
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im.endComposition();
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}
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/**
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* Disposes of the input context and release the resources used by it.
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* Called automatically by AWT for the default input context of each
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* Window. If no input methods are available, then this method has no
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* effect.
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*/
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public void dispose()
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{
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if (im != null)
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{
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im.deactivate(false);
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im.dispose();
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}
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}
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/**
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* Returns a control object from the current input method, or null. A
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* control object provides implementation-dependent methods that control
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* the behavior of the input method or obtain information from the input
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* method. Clients have to compare the result against known input method
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* control object types. If no input methods are available or the current
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* input method does not provide an input method control object, then null
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* is returned.
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*
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* @return the control object, or null
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*/
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public Object getInputMethodControlObject()
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{
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return im == null ? null : im.getControlObject();
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}
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} // class InputContext
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