Well firstly you'll need to build a class that can wrap the native C++ function pointer in a TagCallback compatible base class:
public class NativeTagCallback : TagCallback
{
protected long cppCallbackPtr;
public NativeTagCallback( long callbackPtr )
{
cppCallbackPtr = callbackPtr;
}
public native void NativeCallback( long callbackPtr, int arg0, String arg1, Set<String> arg2 );
public void callback(int arg0, String arg1, Set<String> arg2)
{
NativeCallback( cppCallbackPtr, arg0, arg2, arg2 );
}
}
The native code would be defined as follows:
extern "C" jvoid Java_com_wrapper_NativeTagCallback_NativeCallback( JNIEnv* pEnv, jobject jCaller, jlong cppCallbackPtr, jint arg0, jstring arg1, jobject arg2 )
{
MyCallback cppCallback = (MyCallback)cppCallbackPtr;
const char* pCString = pEnv->GetStringUTFChars( arg1, 0);
string arg1Str( pCString );
pEnv->ReleaseStringUTFChars( arg1, pCString );
set< string > arg2Set = ConvertJavaSetToCPPSet( arg2 ); // Perform your java to CPP set conversion here.
cppCallbackPtr( (int)arg0, arg1Str, arg2Set );
}
Then you would create the relevant class and pass it to your function from C++ as follows:
void MyCpp::setTags(set<string> tags, MyCallback callback)
{
extern __thread JNIEnv* gpEnv;
// Get the setTags function.
jclass jWrapperClass = gpEnv->FindClass( "com/wrapper/cocoswrapper" ); // Insert the correct class name here.
jmethodID jWrapperSetTag = gpEnv->GetStaticMethodID( jWrapperClass, "setTags", "(Landroid/content/Context;Ljava/util/Set;Lcom/wrapper/TagCallback)V;" );
// Get the TagCallback related function
jclass jNativeTagCallbackClass = gpEnv->FindClass( "com/wrapper/NativeTagCallback" );
jclass jNativeTagCallbackConstructor = gpEnv->GetMethodID( jNativeTagCallbackClass, "<init>", "(J)V" );
jobject jNativeTagCallbackObject = gpEnv->NewObject( jNativeTagCallbackClass, jNativeTagCallbackConstructor, (jlong)callback)
// Make function call.
gpEnv->CallStaticVoidMethod( jWrapperClass, jWrapperSetTag, jAndroidContext, tags.GetJNIObject(), jNativeTagCallbackObject );
}