Instructions for compiling JNI libraries.

1. Make java file w/ interface methods
2. Cygwin:

cd $WORKSPACE/jniTest/bin
"$JAVA"/javah -o jni_vrpn_button.h jni.VrpnButton

3. Move the created .h file into the $CRYSTAX/sources/xxx/jni folder
4. Implement in a .cpp file
5. Update the Android.mk file
6. Cygwin:

cd $CRYSTAX/sources/xxx
$CRYSTAX/ndk-build

7. Fix errors, rinse, repeat.



NOTE: To convert jstring to char* :

char* xxx = strdup(env->GetStringUTFChars(yyy, 0));

and back:

jstring yyy = env->NewStringUTF((xxx).c_str());


NOTE: To call java methods from c++:

	Log example:
	
	jclass c = env->GetObjectClass(obj);
	const char * name = "log";
	const char * type = "(Ljava/lang/String;)V";
	jmethodID method = env->GetMethodID(c, name, type);
	env->CallVoidMethod(obj, method, env->NewStringUTF((s).c_str()));
	
	Note that this calls the method: "void log(String s)" which must exist in the corresponding java class.
	
NOTE: To redirect stdio to Android log:
	Create a local.prop file.
	With the line: log.redirect-stdio=true
	Run the emulator and add the file to the /data/ folder.
	Restart the emulator.


NOTE: Some includes req'd: placed in "android_includes.h" and referenced in "vrpn_Types.h"
		Need to find the compiled versions (or source) for these.
		
		Also had to define __ANDROID__ in ndk/build/toolchains/arm-eabi4.4.0/setup.mk as well as forcing compilation as c++
		
CHANGES TO EXISTING VRPN:
	vrpn_Types.h		:	Added #include for __ANDROID__, lines 4-9
	vrpn_Connection.C	:	Added __ANDROID___ to ifdef on line 2424
						:	Added import "jni_layer" for logging
						:	Changed lines 3523, 2299, 198
	vrpn_Shared.h		:	Added extern pointer for logging on line 5
	vrpn_Shared.C		:	Line 196: added && !defined(__ANDROID__) to the ifdef
	
--- Testing the app with echo-apps on your local machine ---
	To access the virtual network on the android emulator, you must do port forwarding.
	Basic idea is that we'll take a port on our localhost (127.0.0.1) and map it to
	a port on the emulators virtual network interface (10.0.2.15)
	
	To set up port-forwarding, do the following:
	
	1) Have your emulator/virtual android instance running
	2) Open a terminal/command prompt (you must have Telnet to do this)
	3) Enter 'telnet localhost 5554'. This will connect you to the emulators console
	4) Enter 'redir add (udp|tcp):xxxx:yyyy', 
	   where:
			(udp|tcp) is your choice of either udp or tcp protocol,
	   		xxxx is the port on 127.0.0.1 you want to use (i.e. 127.0.0.1:5000, where xxxx = 5000*)
	   		yyyy is the port on the emulators network interface that you want to listen to (i.e. 10.0.2.15:3883, where yyyy = 3883**)
	   		
	   		* 5000 is just an arbitrary port
	   		** 3883 is the default port for vrpn to use. This will most likely always be the port you are forwarding to, unless you have
	   		changed something. 
	   		
	 5) Now you should have port forwarding to the emulator set up. Run your echo/test app with the target as 'name@127.0.0.1:xxxx'
	 6) ????
	 7) Profit