[Tier2] trying to build a NFC class

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Jack

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Joined: 4th Oct 2004

Location: [Germany]

Posted: 26th Jan 2017 14:18 Edited at: 26th Jan 2017 20:04

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Guys, I need your help.

I am trying to bring NFC functionality to my NDK project.
So far I have managed to recieve integers using jni based on a function in AGKHelper.java
(I used the GetOrientation function as a template)

Now it seems like I have to create a listener for the nfc device and a nfc class in AGKHelper.java
but I don't know how to start.

My Target is to get the "NFC Tag ID" as integer into my NDK project.
I am quite desperate at this point. It is hard to good tutorials for this problem.

This is what I got so far:

It`s a working code to get Integers from Java functions to NDK

I have added this in the Core.cpp to get an Integer from a Helper Class function:
This after the includes:

+ Code Snippet

int deviceNFCexist = 0;
int deviceNFCtag;

int GetNFCDeviceexist()
{
 return deviceNFCexist;	
}

int GetNFCDeviceTag()
{
 return deviceNFCtag;	
}

And this after the getorientation call (there are two places in the code):

+ Code Snippet

				// nfc from java helper class
				jmethodID methodGetNFCDevice = lJNIEnv->GetStaticMethodID( classHelper, "GetNFCDeviceexist","(Landroid/app/Activity;)I");
				if ( !methodGetNFCDevice ) agk::Warning("Failed to get method GetNFCDeviceexist");
				// get nfc device exist number from JDK to NDK
				deviceNFCexist = lJNIEnv->CallStaticIntMethod( classHelper, methodGetNFCDevice, lNativeActivity );				

				jmethodID methodGetNFCTag = lJNIEnv->GetStaticMethodID( classHelper, "GetNFCDevicetag","(Landroid/app/Activity;)I");
				if ( !methodGetNFCTag ) agk::Warning("Failed to get method GetNFCDevicetag");
				// get nfc device exist number from JDK to NDK
				deviceNFCtag = lJNIEnv->CallStaticIntMethod( classHelper, methodGetNFCTag, lNativeActivity );

In the template.h file I added:

+ Code Snippet

extern int GetNFCDeviceexist();
extern int GetNFCDeviceTag();

So I can use it in the template.cpp like that:

+ Code Snippet

agk::Print(GetNFCDeviceexist());
agk::Print(GetNFCDeviceTag());

And this to the AGKHelper.java, after the getorientation command:

+ Code Snippet

	public static int GetNFCDeviceexist( Activity act )
	{
		int outnum = 1234321;
		return outnum;
	}


	public static int GetNFCDevicetag( Activity act )
	{
		int outnum = 222;
		return outnum;
	}

So It works, I can get the right integers in the template.cpp from AppGameKit ( still havn't figured out how to pass strings.

)
Now I have no Idea how to fill the java functions returns with correct nfc information.

Any help?

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Jack

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Joined: 4th Oct 2004

Location: [Germany]

Posted: 27th Jan 2017 14:53 Edited at: 27th Jan 2017 15:44

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This is my Class Template inside the AGKHelper.java
and this should be combined with the Android NFC api "Foreground Dispatch System"
https://developer.android.com/guide/topics/connectivity/nfc/index.html

But I also think, that it should be possible to approach the NFC data by using the Android NfcAdapter class

https://developer.android.com/reference/android/nfc/NfcAdapter.html
Anyone knows how?

+ Code Snippet

class RunnableNFCController implements Runnable
{
	public Activity act;	// the activity of the APP
	public int action = 0;	// action to run

	public void run()
	{
		switch ( action )
		{
			case 1: // initialize controller
			{

			}

			case 2: // Get Tag ID
			{

			}

			case 3: // deinit controller
			{

			}

		}
	}
}

Right now I do not even have a clue how to initialize the nfc Foreground Dispatch System

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CJB

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Joined: 10th Feb 2004

Location: Essex, UK

Posted: 27th Jan 2017 16:33

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I have a project on the back burner that requires NFC communication so will be following this thread!

Aaargh! Ducks!
Phone Tap!
Uzmadesign

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Jack

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Location: [Germany]

Posted: 27th Jan 2017 16:53

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Thanks CJB,
please add everything you know about JNI/ Java into this Thread

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Jack

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Location: [Germany]

Posted: 29th Jan 2017 11:48 Edited at: 29th Jan 2017 11:49

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I have still trouble to get strings from a java method inside AGKHelper,
I try to use this template to aquire the Model name, but it does not work with a method from AGKHelper. :S

The code is added in Core.cpp after the int getModel( ANativeActivity* pActivity, char *szOut ) function

void getAString( ANativeActivity* pActivity )
	{
		const char *TestString;
		
		JNIEnv* lJNIEnv = pActivity->env;

jint lFlags = 0;
		JavaVM* vm = pActivity->vm;
		bool attached = false;
		switch (vm->GetEnv((void**)&lJNIEnv, JNI_VERSION_1_6))
		{
			case JNI_OK: break;
			case JNI_EDETACHED:
			{
				vm->AttachCurrentThread(&lJNIEnv, NULL);
				break;
			}
			
		}

jobject lNativeActivity = pActivity->clazz;
		jclass ClassNativeActivity = lJNIEnv->GetObjectClass(lNativeActivity);
		jboolean isCopy;

// Retrieves Build class.
		jclass ClassContext = lJNIEnv->FindClass( "android/app/NativeActivity" );
if ( !ClassContext ) agk::Warning("Failed to get class ClassContext - GetAString");
		// Model
		jfieldID FieldMODEL = lJNIEnv->GetStaticFieldID( ClassContext, "MODEL", "Ljava/lang/String;" );
		jstring MODEL = (jstring) lJNIEnv->GetStaticObjectField( ClassContext, FieldMODEL );
		TestString = lJNIEnv->GetStringUTFChars( MODEL, &isCopy );
		
		lJNIEnv->ReleaseStringUTFChars( MODEL, TestString );

vm->DetachCurrentThread();

aString = TestString; // aString is like a global char variable to test this function

}

+ Code Snippet

	void getAString( ANativeActivity* pActivity )
	{
		const char *TestString;
		
		JNIEnv* lJNIEnv = pActivity->env;

		jint lFlags = 0;
		JavaVM* vm = pActivity->vm;
		bool attached = false;
		switch (vm->GetEnv((void**)&lJNIEnv, JNI_VERSION_1_6))
		{
			case JNI_OK: break;
			case JNI_EDETACHED:
			{
				vm->AttachCurrentThread(&lJNIEnv, NULL);
				break;
			}
			
		}

		jobject lNativeActivity = pActivity->clazz;
		jclass ClassNativeActivity = lJNIEnv->GetObjectClass(lNativeActivity);
		jboolean isCopy;

		// Retrieves Build class.
		jclass ClassContext = lJNIEnv->FindClass( "android/app/NativeActivity" );
if ( !ClassContext ) agk::Warning("Failed to get class ClassContext - GetAString");
		// Model
		jfieldID FieldMODEL = lJNIEnv->GetStaticFieldID( ClassContext, "MODEL", "Ljava/lang/String;" );
		jstring MODEL = (jstring) lJNIEnv->GetStaticObjectField( ClassContext, FieldMODEL );
		TestString = lJNIEnv->GetStringUTFChars( MODEL, &isCopy );
		
		lJNIEnv->ReleaseStringUTFChars( MODEL, TestString );

		vm->DetachCurrentThread();

		
		aString = TestString; // aString is like a global char variable to test this function

	}

Are there any ideas about this one ?

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Jack

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Joined: 4th Oct 2004

Location: [Germany]

Posted: 29th Jan 2017 15:29 Edited at: 29th Jan 2017 15:42

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I got the intent working, but it was not my target.
I need the "Foreground Dispatch" to recieve nfc data while the app is running - but it's still a nice litte feature. With a little work, you can also specify the intent on special Tag information, so the app will only start, when a special card is scanned.

Currently it's like that:
Scan NFC Tag => App will start => TagID send to NDK

in the "override on start" part of AGKActivity.java:

+ Code Snippet

        if (getIntent().getAction().equals(NfcAdapter.ACTION_TAG_DISCOVERED)) {
            Log.e("NFC","NFC Tag\n" + this.ByteArrayToHexString(getIntent().getByteArrayExtra(NfcAdapter.EXTRA_ID)));
            AGKHelper.m_NFCCode = Integer.parseInt(this.ByteArrayToHexString(getIntent().getByteArrayExtra(NfcAdapter.EXTRA_ID)), 16 );
        }

in the manifest.xml

You need to give your app permission for NFC first:

+ Code Snippet

    <uses-permission android:name="android.permission.NFC" />
    <uses-feature android:name="android.hardware.nfc" android:required="true"/>

(in the activity android:name..... AppGameKit Activity - section:

+ Code Snippet

            <intent-filter>
                <action android:name="android.nfc.action.TAG_DISCOVERED"/>
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>

this does also require a static integer defined in the Helper Class inside AGKHelper

+ Code Snippet

static int m_NFCCode = 0;

Combined with the NDK integer call function posted above, this can start your app by moving your device over a nfc tag, and the TagID can be recieved as integer in AGK.

Ahg this would be a very nice idea for a Tier1 plugin, but right now we have no infrastructure to archieve this.

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