Implemented proper debug levels

src/java/org/lwjgl/Display.java

@@ -80,9 +80,7 @@ public final class Display {
 	static {
 		System.loadLibrary(Sys.getLibraryName());
 		init();
-		if (Sys.atDebugLevel()) {
-			System.out.println("Adapter: "+getAdapter()+" Version: "+getVersion());
-		}
+		Sys.log(Sys.DEBUG, "Adapter: "+getAdapter()+" Version: "+getVersion());
 	}
 
 	/**
@@ -120,9 +118,7 @@ public final class Display {
 		DisplayMode[] filteredModes = new DisplayMode[modes.size()];
 		modes.toArray(filteredModes);
 
-		if (Sys.atDebugLevel()) {
-			System.out.println("Removed " + (unfilteredModes.length - filteredModes.length) + " duplicate displaymodes");
-		}
+		Sys.log(Sys.DEBUG, "Removed " + (unfilteredModes.length - filteredModes.length) + " duplicate displaymodes");
 
 		return filteredModes;
 	}
@@ -239,9 +235,7 @@ public final class Display {
 			gammaRamp.put(i, rampEntry);
 		}
 		setGammaRamp(gammaRamp);
-		if (Sys.atDebugLevel()) {
-			System.out.println("Gamma set, gamma = " + gamma + ", brightness = " + brightness + ", contrast = " + contrast);
-		}
+		Sys.log(Sys.DEBUG, "Gamma set, gamma = " + gamma + ", brightness = " + brightness + ", contrast = " + contrast);
 	}
 
 	/**

src/java/org/lwjgl/Sys.java

@@ -48,8 +48,12 @@ import org.lwjgl.input.Mouse;
  */
 public final class Sys {
 	/** Debug level constants */
-	public static final int DEBUG_DISABLED = 1;
-	public static final int DEBUG_ENABLED = 2;
+	public static final int DEBUG = 6;
+	public static final int INFO = 5;
+	public static final int WARN = 4;
+	public static final int ERROR = 3;
+	public static final int FATAL = 2;
+	public static final int NONE = 1;
 
 	/** Low process priority. @see #setProcessPriority() */
 	public static final int LOW_PRIORITY = -1;
@@ -84,22 +88,28 @@ public final class Sys {
 	private static String LIBRARY_NAME = "lwjgl";
 	
 	/**
-	 * Debug level. This will tell you if you are using the debug version of
-	 * the library, and whether assertions are enabled or not.
+	 * Debug level. 
 	 */
-	public static final int DEBUG;
+	public static final int debug_level;
 
 	static {
-		int _debug = DEBUG_DISABLED;
-		try {
-			assert false;
-		} catch (AssertionError e) {
-			// Assertions are enabled, so we'll enabled debugging
-			_debug = DEBUG_ENABLED;
-		} finally {
-			DEBUG = _debug;
-			initialize();
+		String debug_level_prop = System.getProperty("lwjgl.debuglevel", "NONE");
+		int _debug = NONE;
+		if (debug_level_prop.equals("DEBUG")) {
+			_debug = DEBUG;
+		} else if (debug_level_prop.equals("INFO")) {
+			_debug = INFO;
+		} else if (debug_level_prop.equals("WARN")) {
+			_debug = WARN;
+		} else if (debug_level_prop.equals("ERROR")) {
+			_debug = ERROR;
+		} else if (debug_level_prop.equals("FATAL")) {
+			_debug = FATAL;
+		} else if (debug_level_prop.equals("NONE")) {
+			_debug = NONE;
 		}
+		debug_level = _debug;
+		initialize();
 	}
 
 	/**
@@ -114,9 +124,21 @@ public final class Sys {
 	 */
 	private Sys() {
 	}
-	
-	public static boolean atDebugLevel() {
-		return DEBUG >= DEBUG_ENABLED;
+
+	/**
+	 * Prints the given message to System.err if atDebugLevel(debug_level)
+	 * is true.
+	 */
+	public static void log(int debug_level, String msg) {
+		if (atDebugLevel(debug_level))
+			System.err.println(msg);
+	}
+
+	/**
+	 * @return true if the debug level is greater than or equal to level
+	 */
+	public static boolean atDebugLevel(int level) {
+		return debug_level >= level;
 	}
 
 	/**
@@ -124,7 +146,7 @@ public final class Sys {
 	 */
 	private static void initialize() {
 		System.loadLibrary(LIBRARY_NAME);
-		setDebugLevel(DEBUG);
+		setDebugLevel(debug_level);
 		setTime(0);
 
 		Runtime.getRuntime().addShutdownHook(new Thread() {

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

@@ -142,9 +142,7 @@ public abstract class BaseAL {
 	private static String getPathFromJWS(String libname) {
 		try {			
 
-			if(Sys.atDebugLevel()) {			
-				System.out.println("JWS Classloader looking for: " + libname);
-			}
+			Sys.log(Sys.DEBUG, "JWS Classloader looking for: " + libname);
 			
 			Object o = BaseAL.class.getClassLoader();
 			Class c = o.getClass();
@@ -154,10 +152,7 @@ public abstract class BaseAL {
 			return (String) findLibrary.invoke(o, arguments);
 
 		} catch (Exception e) {
-			if(Sys.atDebugLevel()) {
-				System.out.println("Failure locating OpenAL using classloader:");
-				e.printStackTrace();
-			}
+			Sys.log(Sys.INFO, "Failure locating OpenAL using classloader:" + e);
 		}
 		return null;
 	}	

src/java/org/lwjgl/opengl/GLCaps.java

@@ -162,15 +162,11 @@ public abstract class GLCaps {
 	}
 
 	private static void setExtensionFields(HashSet exts, HashMap field_map) {
-		if(org.lwjgl.Sys.atDebugLevel()) {
-			System.out.println("Available extensions:");
-		}
+		Sys.log(Sys.DEBUG, "Available extensions:");
 		Iterator it = exts.iterator();
 		while (it.hasNext()) {
 			String ext = (String)it.next();
-			if(org.lwjgl.Sys.atDebugLevel()) {
-				System.out.println(ext);
-			}
+			Sys.log(Sys.DEBUG, ext);
 
 			Field f = (Field)field_map.get(ext);
 			if (f != null) {