path: root/qtjava/javalib/org/kde/qt/qtjava.java

/***************************************************************************
                            qtjava.java -  description
                             -------------------
    begin                : Tue Oct 31 06:12:14 2000
    copyright            : (C) 2000 Lost Highway Ltd. All rights reserved.
    email                : Lost_Highway@tipitina.demon.co.uk
    written by           : Richard Dale.
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program 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 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

package org.kde.qt;

import java.util.*;
import java.lang.Error;

/** The 'Run the Qt Java library' class'. Various utility methods to manage
	the mapping between C++ and java instances. Used in conjunction the C++ methods
	in QtSupport.cpp and JavaSlot.cpp.
	
	@author Richard Dale <Richard_Dale@tipitina.demon.co.uk>
	*/
public class qtjava {
	/** Uses a C++ key to retrieve the corresponding Java instance */
	public static WeakValueMap	qtKeyToJavaMap = null;
	
	/** Allows a JavaSignal proxy instance to be retrieved for a given Java
		instance/Signal name combination */
	public static HashMap 		qtSignalDictionary = null;
	
	/** Allows a JavaSlot proxy instance to be retrieved for a given Java
		instance/Slot name combination */
	public static HashMap 		qtSlotDictionary = null;
	
	/** Register a JavaVM pointer to make it easy to retrieve the current
		JNIEnv later */
	private native static void registerJVM();
	
	/** Get/set the C++ instance for a given Java instance */
	private native static void setQt(Object obj, long qt);
	private native static long getQt(Object obj);
	
	/** If a C++ instance has been allocated in the Java World, it will
		be deleted within the corresponding Java instance's finalize method.  */
	private native static void setAllocatedInJavaWorld(Object obj, boolean yn);
	private native static boolean allocatedInJavaWorld(Object obj);
	
	/** This member allows a typecast of an instance which wraps a
		Qt instance, to a more specialized type. */
	private static QtSupport dynamicCast(String type, QtSupport source) {
		boolean sourceAllocatedInJavaWorld	= allocatedInJavaWorld(source);
		long	qtHandle					= getQt(source);

		removeObjectForQtKey(qtHandle);
		setAllocatedInJavaWorld(source, false);
		return (QtSupport) objectForQtKey(qtHandle, type, sourceAllocatedInJavaWorld);
	}
	
	/** Add a 'C++ qt instance key/Java instance value' pair to the map */
	public static void setObjectForQtKey(Object obj, long qt) {
		qtKeyToJavaMap.put(Long.toString(qt).intern(), obj);
		return;
	}

	/** Remove a 'C++ qt instance key/Java instance value' pair from the map.
		Normally an entry would be removed when its map value is the last reference
		left to the java instance, and it becomes a weak reference to be reaped.
		But C++ can reuse a heap address for a C++ ref without giving the java runtime
		a chance to do any garbage collection and tidy up the corresponding entry in the
		qtKeyToJavaMap (tricky!).
		
		So it is useful to be able to force the early removal of an entry, when the C++
		instance has a known lifetime (eg a QEvent after its event handler has
		returned).
	 */
	public static void removeObjectForQtKey(long qt) {
		qtKeyToJavaMap.remove(Long.toString(qt).intern());
		return;
	}

	/** Allocates an instance of a class without initializing it */
	private native static Object allocateInstance(Class cls) throws InstantiationException, IllegalAccessException;
	
	/** If the C++ qt instance is an instance of QObject, then
		use the Qt runtime meta-data to retrieve the class name.
		If there is a Java class with the same name, then return
		a Class object for that class. Otherwise, just return the
		original 'approximate' Class passed to the method.
		
		Note that a java equivalent of the C++ instance doesn't have
		to be instantiated to do this */
	private native static Class classFromQtMetaData(Class approximateClass, String approximateClassName, long qt);
	
	/** Retrieves a corresponding Java instance for a given C++ instance. Allocates
		the Java instance if it doesn't already exist. */
	public static Object objectForQtKey(long qt, String className, boolean allocatedInJavaWorld) {
		Object	result;
		Class	aClass;
		
		result = qtKeyToJavaMap.get(Long.toString(qt).intern());

		if (result == null) {
			try {
				aClass = Class.forName(toFullyQualifiedClassName(className));
			} catch (ClassNotFoundException e) {
				Qt.qWarning("Error class not found: " + toFullyQualifiedClassName(className));
				return null;
			}
			
			if (QtSupport.class.isAssignableFrom(aClass)) {
				if (QObject.class.isAssignableFrom(aClass)) {
					aClass = qtjava.classFromQtMetaData(aClass, aClass.getName(), qt);
				}
			
				try {
					result = qtjava.allocateInstance(aClass);
				} catch (InstantiationException e) {
					Qt.qWarning("Can't instantiate : " + toFullyQualifiedClassName(className));
					return null;
				} catch (IllegalAccessException e) {
					Qt.qWarning("Illegal access to class : " + toFullyQualifiedClassName(className));
					return null;
				}
			
				setQt(result, qt);
				setAllocatedInJavaWorld(result, allocatedInJavaWorld);
			} else {
				// A Java instance without a wrapped Qt C++ instance (eg a list)
				try {
					result = aClass.newInstance();
				} catch (InstantiationException e) {
					return null;
				} catch (IllegalAccessException e) {
					return null;
				}
			}
			
			setObjectForQtKey(result, qt);
		}
		
		return result;
	}
	
	/** When a C++ instance has been deleted. Retrieves a corresponding Java instance for a given C++ instance. Sets
		the '_allocatedInJavaWorld' flag to false. */
	public static void qtKeyDeleted(long qt) {
		Object result = qtKeyToJavaMap.get(Long.toString(qt).intern());

		if (	result != null
				&& QtSupport.class.isAssignableFrom(result.getClass()) )
		{
			setAllocatedInJavaWorld(result, false);
		}
	}
	
	/** Converts any unqualified class names in a signal or slot string to the fully qualified versions */
	public static String toFullyQualifiedClassName(String className) {
		if (className.equals("String")) {
			return "java.lang.String";
		} else if (className.equals("Date")) {
			return "java.util.Date";
		} else if (className.equals("Calendar")) {
			return "java.util.GregorianCalendar";
		} else if (className.equals("ArrayList")) {
			return "java.util.ArrayList";
		} else if (className.equals("ByteArrayOutputStream")) {
			return "java.io.ByteArrayOutputStream";
		} else if (className.equals("Job")) {
			return "org.kde.koala.Job";
		} else if (className.equals("Part")) {
			return "org.kde.koala.Part";
		} else if (className.equals("Slave")) {
			return "org.kde.koala.Slave";
		} else if (className.equals("DOMNode")) {
			return "org.kde.koala.DOMNode";
		} else if (className.startsWith("Q")) {
			return "org.kde.qt." + className;
		} else if (className.startsWith("K")) {
			return "org.kde.koala." + className;
		}
		return className;
	}
		
	/** Converts from a list Java types in a signal or slot string, to the fully qualified equivalent */
	private static String toNormalizedTypeSignature(String typeSignature) {
		StringBuffer normalizedTypeSignature = new StringBuffer(	typeSignature.substring(	0,
																	typeSignature.indexOf('(') + 1 ) );
		StringTokenizer tokenizer = new StringTokenizer(	typeSignature.substring(	typeSignature.indexOf('(') + 1,
																						typeSignature.indexOf(')') ),
															"," );
		
		while (tokenizer.hasMoreTokens()) {
			String token = tokenizer.nextToken();
			
			if (	token.equals("boolean")
					|| token.equals("byte")
					|| token.equals("char")
					|| token.equals("long")
					|| token.equals("int")
					|| token.equals("short")
					|| token.equals("float")
					|| token.equals("double") )
			{
				normalizedTypeSignature.append(token);
			} else {
				normalizedTypeSignature.append(toFullyQualifiedClassName(token));
			}
			
			if (tokenizer.hasMoreTokens()) {
				normalizedTypeSignature.append(",");
			}
		}
		
		normalizedTypeSignature.append(")");
		return normalizedTypeSignature.toString();
	}

	/** Returns a new C++ JavaSignal proxy instance, to forward the signal
		onto the target Java slot */
	private native static long newJavaSignal();
	
	/** Looks up a 'qt instance/signal name' key and returns the corresponding
		JavaSignal instance */
	public static long signalForSender(long qt, String signal) {
		String normalizedSignal = toNormalizedTypeSignature(signal);
		String key = (Long.toString(qt) +  normalizedSignal).intern();
		Long result = (Long) qtSignalDictionary.get(key);
		
		if (result == null) {
			long javaSignal = newJavaSignal();
			qtSignalDictionary.put(key, new Long(javaSignal));
			return javaSignal;
		} else {
			return result.longValue();
		}
	}
	
	/** Initialises the JavaSlot factory */
	private native static void setJavaSlotFactory();
	
	/** Returns a new C++ JavaSlot proxy instance, to receive signals
		and invoke the target Java slot */
	private native static long newJavaSlot(QObject receiver, String member);
	
	/** Looks up a 'qt instance/slot name' key and returns the corresponding
		JavaSlot instance */
	public static long slotForReceiver(long qt, QObject receiver, String slot) {
		String normalizedSlot = toNormalizedTypeSignature(slot);
		String key = (Long.toString(qt) +  normalizedSlot).intern();
		Long result = (Long) qtSlotDictionary.get(key);
		
		if (result == null) {
			long javaSlot = newJavaSlot(receiver, normalizedSlot);
			qtSlotDictionary.put(key, new Long(javaSlot));
			return javaSlot;
		} else {
			return result.longValue();
		}
	}
	
	private static boolean _initialized = false;
	
	public static void initialize() {
		if (!_initialized) {
			System.loadLibrary("qtjava");
			qtjava.registerJVM();
			qtjava.setJavaSlotFactory();
			qtKeyToJavaMap = new WeakValueMap();
			qtSignalDictionary = new HashMap();
			qtSlotDictionary = new HashMap();
			_initialized = true;
		}
	}
	
	static {
		initialize();
	}
}