lwjgl/src/java/org/lwjgl/openal/BaseAL.java

/* 
 * Copyright (c) 2002 Lightweight Java Game Library Project
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are 
 * met:
 * 
 * * Redistributions of source code must retain the above copyright 
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'Light Weight Java Game Library' nor the names of 
 *   its contributors may be used to endorse or promote products derived 
 *   from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.lwjgl.openal;

import java.io.File;
import java.util.StringTokenizer;
import java.lang.reflect.Method;

import org.lwjgl.Sys;

/**
 * $Id$
 * <br>
 * The base AL functionality (no actual AL methods).
 *
 * This has been provided as a base class that we can use for either the
 * full AL 1.0 specification or as a cut-down OpenAL embedded spec. (aka
 * a mini-driver).
 *
 * @author Brian Matzon <brian@matzon.dk>
 * @version $Revision$
 */
public abstract class BaseAL {
	/** Have we been created? */
	protected static boolean created;

	static {
		initialize();
	}

	/**
	 * Override to provide any initialization code after creation.
	 */
	protected static void init() throws OpenALException {
	}

	/**
	 * Static initialization
	 */
	private static void initialize() {
		System.loadLibrary(org.lwjgl.Sys.getLibraryName());
	}

	/**
	 * Creates the AL instance
	 * 
	 * @throws Exception if a failiure occured in the AL creation process
	 */
  public static void create() throws OpenALException {
    if (created) {
      return;
    }

    // need to pass path of possible locations of OAL to native side
    String libpath = System.getProperty("java.library.path");
    String seperator = System.getProperty("path.separator");
    String libname;

    // libname is hardcoded atm - this will change in a near future...
    libname =
      (System.getProperty("os.name").toLowerCase().indexOf("windows") == -1)
        ? "libopenal.so"
        : "lwjglaudio.dll";

    // try to get path from JWS (if possible)
    String jwsLibname = 
      (System.getProperty("os.name").toLowerCase().indexOf("windows") == -1)
      ? "openal"
      : "OpenAL32";
    
    String jwsPath = getPathFromJWS(jwsLibname);
    if (jwsPath != null) {
      libpath += seperator
        + jwsPath.substring(0, jwsPath.lastIndexOf(File.separator));
    }

    StringTokenizer st = new StringTokenizer(libpath, seperator);

    //create needed string array
    String[] oalPaths = new String[st.countTokens() + 1];

    //build paths
    for (int i = 0; i < oalPaths.length - 1; i++) {
      oalPaths[i] = st.nextToken() + File.separator + libname;
    }

    //add cwd path
    oalPaths[oalPaths.length - 1] = libname;
    if (!nCreate(oalPaths)) {
      throw new OpenALException("AL instance could not be created.");
    }

    init();
    created = true;
  }
  
  /**
   * Tries to locate OpenAL from the JWS Library path
   * This method exists because OpenAL is loaded from native code, and as such
   * is exempt from JWS library loading rutines. OpenAL therefore always fails.
   * We therefore invoke the protected method of the JWS classloader to see if it can
   * locate it. 
   * 
   * @param libname Name of library to search for
   * @return Absolute path to library if found, otherwise null
   */
  private static String getPathFromJWS(String libname) {
    try {      

      if(Sys.DEBUG) {      
        System.out.println("JWS Classloader looking for: " + libname);
      }
      
      Object o = BaseAL.class.getClassLoader();
      Class c = o.getClass();
      Method findLibrary =
        c.getMethod("findLibrary", new Class[] { String.class });
      Object[] arguments = new Object[] { libname };
      return (String) findLibrary.invoke(o, arguments);

    } catch (Exception e) {
      if(Sys.DEBUG) {
        System.out.println("Failure locating OpenAL using classloader:");
        e.printStackTrace();
      }
    }
    return null;
  }  

	/**
	 * Native method to create AL instance
	 * 
	 * @param oalPaths Array of strings containing paths to search for OpenAL library
	 * @return true if the AL creation process succeeded
	 */
	protected static native boolean nCreate(String[] oalPaths);

	/**
	 * Calls whatever destruction rutines that are needed
	 */
	public static void destroy() {
		if (!created) {
			return;
		}
		created = false;
		nDestroy();
	}

	/**
	 * Native method the destroy the AL
	 */
	protected static native void nDestroy();
	
	
	/**
	 * @return true if AL has been created
	 */
	public static boolean isCreated() {
		return created;
	}
}