I'm trying to develop Unreal Engine 4 plugin for Android camera API 2.
As I could read on unreal engine forums, there two possibilities to make a plugin for Android.
The first, consist on modifying the UE Android base project (GameActivity).
The second is a standalone plugin, which brings portability to add the plugins in any project.
According to this post, it is possible to make a camera Api1 standalone plugin, which uses APL.xml file to add java code.
But I think it is very limited to a Game activity, like the code below.
<?xml version="1.0" encoding="utf-8"?>
<!--ARToolKit plugin additions-->
<root xmlns:android="http://schemas.android.com/apk/res/android">
<!-- init section is always evaluated once per architecture -->
<init>
<log text="AndroidCamera init"/>
</init>
<androidManifestUpdates>
<addPermission android:name="android.permission.CAMERA"/>
<addFeature android:name="android.hardware.camera"/>
<addFeature android:name="android.hardware.camera.autofocus"/>
</androidManifestUpdates>
<!-- optional additions to the GameActivity imports in GameActivity.java -->
<gameActivityImportAdditions>
<insert>
import android.widget.Toast;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.PreviewCallback;
import android.graphics.SurfaceTexture;
import android.graphics.ImageFormat;
import android.graphics.PixelFormat;
import java.util.List;
import java.io.IOException;
import android.util.Log;
</insert>
</gameActivityImportAdditions>
<gameActivityClassAdditions>
<insert>
static String msg = "yes i am a rock!";
SurfaceTexture surfaceTexture;
Camera camera;
public native boolean nativeGetFrameData(int frameWidth, int frameHeight, byte[] data);
public void AndroidThunkJava_Toast()
{
try
{
_activity.runOnUiThread(new Runnable()
{
public void run()
{
Toast.makeText(_activity.getApplicationContext(), "cam o yeah!", Toast.LENGTH_SHORT).show();
}
});
}
catch (Exception e)
{
Log.debug("Toast failed with exception " + e.getMessage());
}
}
public void AndroidThunkJava_startCamera()
{
surfaceTexture = new SurfaceTexture(10);
surfaceTexture.setDefaultBufferSize(320,240);
camera = Camera.open();
try {
camera.setPreviewTexture(surfaceTexture);
} catch (IOException t) {
android.util.Log.e("ARToolKitLog", "Cannot set preview texture target!", t);
}
Parameters cameraParam = camera.getParameters();
cameraParam.setPreviewFormat(ImageFormat.NV21);
cameraParam.setPreviewSize(320, 240);
camera.setParameters(cameraParam);
camera.setPreviewCallback(new PreviewCallback() {
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
int Height = camera.getParameters().getPreviewSize().height;
int Width = camera.getParameters().getPreviewSize().width;
nativeGetFrameData(Width, Height, data);
}
});
camera.startPreview();
}
public void AndroidThunkJava_stopCamera()
{
if (camera != null)
{
camera.stopPreview();
camera.release();
camera = null;
}
}
</insert>
</gameActivityClassAdditions>
<!-- optional additions to GameActivity onCreate in GameActivity.java -->
<gameActivityOnCreateAdditions>
<insert>
//Toast.makeText(this,msg,Toast.LENGTH_LONG).show();
//AndroidThunkJava_Toast();
</insert>
</gameActivityOnCreateAdditions>
</root>So my questions are:
Is this the only way to make a standalone plugin for Unreal Engine 4?
Is there a XML tag to add custom classes in this APL files?
I found another way to use custom Java classes:
If I am not wrong, the unreal engine _APL.xml file is connected with ANT build system.
So, as in _APL.xml files in addition to define Java code in gameActivityClassAdditions, there is a tag to copy our .java files to Unreal Engine build directory.
I have taken the idea from this Unreal Engine plugin: https://github.com/jeevcat/GoogleMapsUE4Plugin
So, I made a plugin in 4 steps:
- Copy the custom java classes to the plugin source directory with package folder order, so the resultant folder structure should be something like this.
2.- Add the prebuilt copies tag to apply the Java class into the build directory:
<prebuildCopies> <copyDir src="$S(PluginDir)/Java" dst="$S(BuildDir)" /> </prebuildCopies>
3.- Add the imports in gameActivityImportAdditions:
import org.samples.camera2.CameraHandler;4.- use custom class
public void AndroidThunkJava_startCamera()
{
m_camHandler = new CameraHandler();
m_camHandler.setCallback(new CameraCallback() {
@Override
public void onGetFrame(byte[] data, int width, int height) {
Log.d(LOG_TAG,"MY CUSTOM CALLBACK"+width);
nativeGetFrameData(width, height, data);
}
});
m_camHandler.init(_activity, 0, 320, 240);
m_camHandler.start();
}Finally I show the resultant _APL.xml file:
<?xml version="1.0" encoding="utf-8"?>
<!--ARToolKit plugin additions-->
<root xmlns:android="http://schemas.android.com/apk/res/android">
<!-- init section is always evaluated once per architecture -->
<init>
<log text="AndroidCamera init"/>
</init>
<androidManifestUpdates>
<addPermission android:name="android.permission.CAMERA" />
<addFeature android:name="android.hardware.camera" />
<addFeature android:name="android.hardware.camera.autofocus" />
<addFeature android:name="android.hardware.camera2" />
</androidManifestUpdates>
<prebuildCopies>
<copyDir src="$S(PluginDir)/Java" dst="$S(BuildDir)" />
</prebuildCopies>
<!-- optional additions to the GameActivity imports in GameActivity.java -->
<gameActivityImportAdditions>
<insert>
import android.widget.Toast;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.PreviewCallback;
import android.graphics.SurfaceTexture;
import android.graphics.ImageFormat;
import android.graphics.PixelFormat;
import java.util.List;
import java.io.IOException;
import android.util.Log;
import org.samples.camera2.CameraHandler;