com.projecttango.examples.java.pointtopoint.PointToPointActivity.java Source code

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Here is the source code for com.projecttango.examples.java.pointtopoint.PointToPointActivity.java

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/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.projecttango.examples.java.pointtopoint;

import com.google.atap.tangoservice.Tango;
import com.google.atap.tangoservice.Tango.OnTangoUpdateListener;
import com.google.atap.tangoservice.TangoCameraIntrinsics;
import com.google.atap.tangoservice.TangoConfig;
import com.google.atap.tangoservice.TangoCoordinateFramePair;
import com.google.atap.tangoservice.TangoErrorException;
import com.google.atap.tangoservice.TangoEvent;
import com.google.atap.tangoservice.TangoException;
import com.google.atap.tangoservice.TangoInvalidException;
import com.google.atap.tangoservice.TangoOutOfDateException;
import com.google.atap.tangoservice.TangoPointCloudData;
import com.google.atap.tangoservice.TangoPoseData;
import com.google.atap.tangoservice.TangoXyzIjData;
import com.google.atap.tangoservice.experimental.TangoImageBuffer;

import android.Manifest;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.display.DisplayManager;
import android.opengl.Matrix;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.util.Log;
import android.view.Display;
import android.view.MotionEvent;
import android.view.View;
import android.widget.CheckBox;
import android.widget.TextView;
import android.widget.Toast;

import org.rajawali3d.math.vector.Vector3;
import org.rajawali3d.scene.ASceneFrameCallback;
import org.rajawali3d.view.SurfaceView;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Stack;
import java.util.concurrent.atomic.AtomicBoolean;

import com.projecttango.tangosupport.TangoPointCloudManager;
import com.projecttango.tangosupport.TangoSupport;

/**
 * An example showing how to build a very simple point-to-point measurement app
 * in Java. It uses the Tango Support Library to do depth calculations using
 * the point cloud data. Whenever the user clicks on the camera display, a point
 * is recorded from the point cloud data closest to the point of the touch;
 * consecutive touches are used as the two points for a distance measurement.
 * <p/>
 * Note that it is important to include the KEY_BOOLEAN_LOWLATENCYIMUINTEGRATION
 * configuration parameter in order to achieve best results synchronizing the
 * Rajawali virtual world with the RGB camera.
 * <p/>
 * For more details on the augmented reality effects, including color camera texture rendering,
 * see java_augmented_reality_example or java_hello_video_example.
 */
public class PointToPointActivity extends Activity implements View.OnTouchListener {
    private static final String TAG = PointToPointActivity.class.getSimpleName();

    private static final String CAMERA_PERMISSION = Manifest.permission.CAMERA;
    private static final int CAMERA_PERMISSION_CODE = 0;

    // The interval at which we'll update our UI debug text in milliseconds.
    // This is the rate at which we query for distance data.
    private static final int UPDATE_UI_INTERVAL_MS = 100;

    private static final int INVALID_TEXTURE_ID = 0;

    private SurfaceView mSurfaceView;
    private PointToPointRenderer mRenderer;
    private TangoPointCloudManager mPointCloudManager;
    private Tango mTango;
    private TangoConfig mConfig;
    private boolean mIsConnected = false;
    private double mCameraPoseTimestamp = 0;
    private TextView mDistanceMeasure;
    private CheckBox mBilateralBox;
    private volatile TangoImageBuffer mCurrentImageBuffer;

    // Texture rendering related fields.
    // NOTE: Naming indicates which thread is in charge of updating this variable.
    private int mConnectedTextureIdGlThread = INVALID_TEXTURE_ID;
    private AtomicBoolean mIsFrameAvailableTangoThread = new AtomicBoolean(false);
    private double mRgbTimestampGlThread;

    private float[][] mLinePoints = new float[2][3];
    private boolean mPointSwitch = true;

    // Handles the debug text UI update loop.
    private Handler mHandler = new Handler();

    private int mDisplayRotation = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mSurfaceView = (SurfaceView) findViewById(R.id.ar_view);
        mRenderer = new PointToPointRenderer(this);
        mSurfaceView.setSurfaceRenderer(mRenderer);
        mSurfaceView.setOnTouchListener(this);
        mPointCloudManager = new TangoPointCloudManager();
        mDistanceMeasure = (TextView) findViewById(R.id.distance_textview);
        mBilateralBox = (CheckBox) findViewById(R.id.check_box);
        mLinePoints[0] = null;
        mLinePoints[1] = null;

        DisplayManager displayManager = (DisplayManager) getSystemService(DISPLAY_SERVICE);
        if (displayManager != null) {
            displayManager.registerDisplayListener(new DisplayManager.DisplayListener() {
                @Override
                public void onDisplayAdded(int displayId) {
                }

                @Override
                public void onDisplayChanged(int displayId) {
                    synchronized (this) {
                        setDisplayRotation();
                    }
                }

                @Override
                public void onDisplayRemoved(int displayId) {
                }
            }, null);
        }
    }

    @Override
    protected void onStart() {
        super.onStart();

        // Check and request camera permission at run time.
        if (checkAndRequestPermissions()) {
            bindTangoService();
        }
    }

    @Override
    protected void onStop() {
        super.onStop();
        clearLine();
        // Synchronize against disconnecting while the service is being used in the OpenGL thread or
        // in the UI thread.
        // NOTE: DO NOT lock against this same object in the Tango callback thread. Tango.disconnect
        // will block here until all Tango callback calls are finished. If you lock against this
        // object in a Tango callback thread it will cause a deadlock.
        synchronized (this) {
            try {
                mRenderer.getCurrentScene().clearFrameCallbacks();
                mTango.disconnectCamera(TangoCameraIntrinsics.TANGO_CAMERA_COLOR);
                // We need to invalidate the connected texture ID so that we cause a
                // re-connection in the OpenGL thread after resume.
                mConnectedTextureIdGlThread = INVALID_TEXTURE_ID;
                mTango.disconnect();
                mIsConnected = false;
            } catch (TangoErrorException e) {
                Log.e(TAG, getString(R.string.exception_tango_error), e);
            }
        }
    }

    /**
     * Initialize Tango Service as a normal Android Service.
     */
    private void bindTangoService() {
        // Initialize Tango Service as a normal Android Service. Since we call mTango.disconnect()
        // in onPause, this will unbind Tango Service, so every time onResume gets called we
        // should create a new Tango object.
        mTango = new Tango(PointToPointActivity.this, new Runnable() {
            // Pass in a Runnable to be called from UI thread when Tango is ready; this Runnable
            // will be running on a new thread.
            // When Tango is ready, we can call Tango functions safely here only when there are no
            // UI thread changes involved.
            @Override
            public void run() {
                // Synchronize against disconnecting while the service is being used in the OpenGL
                // thread or in the UI thread.
                synchronized (PointToPointActivity.this) {
                    try {
                        TangoSupport.initialize();
                        mConfig = setupTangoConfig(mTango);
                        mTango.connect(mConfig);
                        startupTango();
                        connectRenderer();
                        mIsConnected = true;
                        setDisplayRotation();
                    } catch (TangoOutOfDateException e) {
                        Log.e(TAG, getString(R.string.exception_out_of_date), e);
                        showsToastAndFinishOnUiThread(R.string.exception_out_of_date);
                    } catch (TangoErrorException e) {
                        Log.e(TAG, getString(R.string.exception_tango_error), e);
                        showsToastAndFinishOnUiThread(R.string.exception_tango_error);
                    } catch (TangoInvalidException e) {
                        Log.e(TAG, getString(R.string.exception_tango_invalid), e);
                        showsToastAndFinishOnUiThread(R.string.exception_tango_invalid);
                    }
                }
            }
        });
        mHandler.post(mUpdateUiLoopRunnable);
    }

    /**
     * Sets up the Tango configuration object. Make sure mTango object is initialized before
     * making this call.
     */
    private TangoConfig setupTangoConfig(Tango tango) {
        // Use default configuration for Tango Service (motion tracking), plus low latency
        // IMU integration, color camera, depth and drift correction.
        TangoConfig config = tango.getConfig(TangoConfig.CONFIG_TYPE_DEFAULT);
        // NOTE: Low latency integration is necessary to achieve a
        // precise alignment of virtual objects with the RBG image and
        // produce a good AR effect.
        config.putBoolean(TangoConfig.KEY_BOOLEAN_LOWLATENCYIMUINTEGRATION, true);
        config.putBoolean(TangoConfig.KEY_BOOLEAN_COLORCAMERA, true);
        config.putBoolean(TangoConfig.KEY_BOOLEAN_DEPTH, true);
        config.putInt(TangoConfig.KEY_INT_DEPTH_MODE, TangoConfig.TANGO_DEPTH_MODE_POINT_CLOUD);
        // Drift correction allows motion tracking to recover after it loses tracking.
        // The drift-corrected pose is available through the frame pair with
        // base frame AREA_DESCRIPTION and target frame DEVICE.
        config.putBoolean(TangoConfig.KEY_BOOLEAN_DRIFT_CORRECTION, true);

        return config;
    }

    /**
     * Set up the callback listeners for the Tango Service and obtain other parameters required
     * after Tango connection.
     * Listen to updates from the RGB camera and point cloud.
     */
    private void startupTango() {
        // No need to add any coordinate frame pairs since we are not
        // using pose data. So just initialize.
        ArrayList<TangoCoordinateFramePair> framePairs = new ArrayList<TangoCoordinateFramePair>();
        mTango.connectListener(framePairs, new OnTangoUpdateListener() {
            @Override
            public void onPoseAvailable(TangoPoseData pose) {
                // We are not using OnPoseAvailable for this app.
            }

            @Override
            public void onFrameAvailable(int cameraId) {
                // Check if the frame available is for the camera we want and update its frame
                // on the view.
                if (cameraId == TangoCameraIntrinsics.TANGO_CAMERA_COLOR) {
                    // Mark a camera frame as available for rendering in the OpenGL thread.
                    mIsFrameAvailableTangoThread.set(true);
                    mSurfaceView.requestRender();
                }
            }

            @Override
            public void onXyzIjAvailable(TangoXyzIjData xyzIj) {
                // We are not using onXyzIjAvailable for this app.
            }

            @Override
            public void onPointCloudAvailable(TangoPointCloudData pointCloud) {
                // Save the cloud and point data for later use.
                mPointCloudManager.updatePointCloud(pointCloud);
            }

            @Override
            public void onTangoEvent(TangoEvent event) {
                // We are not using OnPoseAvailable for this app.
            }
        });
        mTango.experimentalConnectOnFrameListener(TangoCameraIntrinsics.TANGO_CAMERA_COLOR,
                new Tango.OnFrameAvailableListener() {
                    @Override
                    public void onFrameAvailable(TangoImageBuffer tangoImageBuffer, int i) {
                        mCurrentImageBuffer = copyImageBuffer(tangoImageBuffer);
                    }

                    TangoImageBuffer copyImageBuffer(TangoImageBuffer imageBuffer) {
                        ByteBuffer clone = ByteBuffer.allocateDirect(imageBuffer.data.capacity());
                        imageBuffer.data.rewind();
                        clone.put(imageBuffer.data);
                        imageBuffer.data.rewind();
                        clone.flip();
                        return new TangoImageBuffer(imageBuffer.width, imageBuffer.height, imageBuffer.stride,
                                imageBuffer.frameNumber, imageBuffer.timestamp, imageBuffer.format, clone);
                    }
                });
    }

    /**
     * Connects the view and renderer to the color camara and callbacks.
     */
    private void connectRenderer() {
        // Register a Rajawali Scene Frame Callback to update the scene camera pose whenever a new
        // RGB frame is rendered.
        // (@see https://github.com/Rajawali/Rajawali/wiki/Scene-Frame-Callbacks)
        mRenderer.getCurrentScene().registerFrameCallback(new ASceneFrameCallback() {
            @Override
            public void onPreFrame(long sceneTime, double deltaTime) {
                // NOTE: This is called from the OpenGL render thread, after all the renderer
                // onRender callbacks have a chance to run and before scene objects are rendered
                // into the scene.

                try {
                    // Prevent concurrent access to {@code mIsFrameAvailableTangoThread} from the
                    // Tango callback thread and service disconnection from an onPause event.
                    synchronized (PointToPointActivity.this) {
                        // Don't execute any tango API actions if we're not connected to the
                        // service.
                        if (!mIsConnected) {
                            return;
                        }

                        // Set up scene camera projection to match RGB camera intrinsics.
                        if (!mRenderer.isSceneCameraConfigured()) {
                            TangoCameraIntrinsics intrinsics = TangoSupport
                                    .getCameraIntrinsicsBasedOnDisplayRotation(
                                            TangoCameraIntrinsics.TANGO_CAMERA_COLOR, mDisplayRotation);
                            mRenderer.setProjectionMatrix(projectionMatrixFromCameraIntrinsics(intrinsics));
                        }

                        // Connect the camera texture to the OpenGL Texture if necessary
                        // NOTE: When the OpenGL context is recycled, Rajawali may regenerate the
                        // texture with a different ID.
                        if (mConnectedTextureIdGlThread != mRenderer.getTextureId()) {
                            mTango.connectTextureId(TangoCameraIntrinsics.TANGO_CAMERA_COLOR,
                                    mRenderer.getTextureId());
                            mConnectedTextureIdGlThread = mRenderer.getTextureId();
                            Log.d(TAG, "connected to texture id: " + mRenderer.getTextureId());
                        }

                        // If there is a new RGB camera frame available, update the texture with
                        // it.
                        if (mIsFrameAvailableTangoThread.compareAndSet(true, false)) {
                            mRgbTimestampGlThread = mTango.updateTexture(TangoCameraIntrinsics.TANGO_CAMERA_COLOR);
                        }

                        // If a new RGB frame has been rendered, update the camera pose to match.
                        if (mRgbTimestampGlThread > mCameraPoseTimestamp) {
                            // Calculate the camera color pose at the camera frame update time in
                            // OpenGL engine.
                            //
                            // When drift correction mode is enabled in config file, we need
                            // to query the device with respect to Area Description pose in
                            // order to use the drift-corrected pose.
                            //
                            // Note that if you don't want to use the drift corrected pose, the
                            // normal device with respect to start of service pose is still
                            // available.
                            //
                            // Also, we used mColorCameraToDipslayRotation to rotate the
                            // transformation to align with the display frame. The reason we use
                            // color camera instead depth camera frame is because the
                            // getDepthAtPointNearestNeighbor transformed depth point to camera
                            // frame.
                            TangoPoseData lastFramePose = TangoSupport.getPoseAtTime(mRgbTimestampGlThread,
                                    TangoPoseData.COORDINATE_FRAME_AREA_DESCRIPTION,
                                    TangoPoseData.COORDINATE_FRAME_CAMERA_COLOR,
                                    TangoSupport.TANGO_SUPPORT_ENGINE_OPENGL,
                                    TangoSupport.TANGO_SUPPORT_ENGINE_OPENGL, mDisplayRotation);
                            if (lastFramePose.statusCode == TangoPoseData.POSE_VALID) {
                                // Update the camera pose from the renderer.
                                mRenderer.updateRenderCameraPose(lastFramePose);
                                mCameraPoseTimestamp = lastFramePose.timestamp;
                            } else {
                                // When the pose status is not valid, it indicates the tracking has
                                // been lost. In this case, we simply stop rendering.
                                //
                                // This is also the place to display UI to suggest the user walk
                                // to recover tracking.
                                Log.w(TAG, "Can't get device pose at time: " + mRgbTimestampGlThread);
                            }
                        }
                    }
                    // Avoid crashing the application due to unhandled exceptions.
                } catch (TangoErrorException e) {
                    Log.e(TAG, "Tango API call error within the OpenGL render thread", e);
                } catch (Throwable t) {
                    Log.e(TAG, "Exception on the OpenGL thread", t);
                }
            }

            @Override
            public void onPreDraw(long sceneTime, double deltaTime) {

            }

            @Override
            public void onPostFrame(long sceneTime, double deltaTime) {

            }

            @Override
            public boolean callPreFrame() {
                return true;
            }
        });
    }

    /**
     * Use Tango camera intrinsics to calculate the projection Matrix for the Rajawali scene.
     */
    private static float[] projectionMatrixFromCameraIntrinsics(TangoCameraIntrinsics intrinsics) {
        // Uses frustumM to create a projection matrix taking into account calibrated camera
        // intrinsic parameter.
        // Reference: http://ksimek.github.io/2013/06/03/calibrated_cameras_in_opengl/
        float near = 0.1f;
        float far = 100;

        double cx = intrinsics.cx;
        double cy = intrinsics.cy;
        double width = intrinsics.width;
        double height = intrinsics.height;
        double fx = intrinsics.fx;
        double fy = intrinsics.fy;

        double xscale = near / fx;
        double yscale = near / fy;

        double xoffset = (cx - (width / 2.0)) * xscale;
        // Color camera's coordinates has y pointing downwards so we negate this term.
        double yoffset = -(cy - (height / 2.0)) * yscale;

        float m[] = new float[16];
        Matrix.frustumM(m, 0, (float) (xscale * -width / 2.0 - xoffset), (float) (xscale * width / 2.0 - xoffset),
                (float) (yscale * -height / 2.0 - yoffset), (float) (yscale * height / 2.0 - yoffset), near, far);
        return m;
    }

    @Override
    public boolean onTouch(View view, MotionEvent motionEvent) {
        if (motionEvent.getAction() == MotionEvent.ACTION_UP) {
            // Calculate click location in u,v (0;1) coordinates.
            float u = motionEvent.getX() / view.getWidth();
            float v = motionEvent.getY() / view.getHeight();

            try {
                // Place point near the clicked point using the latest point cloud data.
                // Synchronize against concurrent access to the RGB timestamp in the OpenGL thread
                // and a possible service disconnection due to an onPause event.
                float[] rgbPoint;
                synchronized (this) {
                    rgbPoint = getDepthAtTouchPosition(u, v);
                }
                if (rgbPoint != null) {
                    // Update a line endpoint to the touch location.
                    // This update is made thread-safe by the renderer.
                    updateLine(rgbPoint);
                    mRenderer.setLine(generateEndpoints());
                } else {
                    Log.w(TAG, "Point was null.");
                }

            } catch (TangoException t) {
                Toast.makeText(getApplicationContext(), R.string.failed_measurement, Toast.LENGTH_SHORT).show();
                Log.e(TAG, getString(R.string.failed_measurement), t);
            } catch (SecurityException t) {
                Toast.makeText(getApplicationContext(), R.string.failed_permissions, Toast.LENGTH_SHORT).show();
                Log.e(TAG, getString(R.string.failed_permissions), t);
            }
        }
        return true;
    }

    /**
     * Use the Tango Support Library with point cloud data to calculate the depth
     * of the point closest to where the user touches the screen. It returns a
     * Vector3 in OpenGL world space.
     */
    private float[] getDepthAtTouchPosition(float u, float v) {
        TangoPointCloudData pointCloud = mPointCloudManager.getLatestPointCloud();
        if (pointCloud == null) {
            return null;
        }

        double rgbTimestamp;
        TangoImageBuffer imageBuffer = mCurrentImageBuffer;
        if (mBilateralBox.isChecked()) {
            rgbTimestamp = imageBuffer.timestamp; // CPU.
        } else {
            rgbTimestamp = mRgbTimestampGlThread; // GPU.
        }

        // Get pose transforms for openGL to depth/color cameras.
        TangoPoseData oglTdepthPose = TangoSupport.getPoseAtTime(pointCloud.timestamp,
                TangoPoseData.COORDINATE_FRAME_AREA_DESCRIPTION, TangoPoseData.COORDINATE_FRAME_CAMERA_DEPTH,
                TangoSupport.TANGO_SUPPORT_ENGINE_OPENGL, TangoSupport.TANGO_SUPPORT_ENGINE_TANGO,
                TangoSupport.ROTATION_IGNORED);
        if (oglTdepthPose.statusCode != TangoPoseData.POSE_VALID) {
            Log.w(TAG, "Could not get depth camera transform at time " + pointCloud.timestamp);
            return null;
        }
        TangoPoseData oglTcolorPose = TangoSupport.getPoseAtTime(rgbTimestamp,
                TangoPoseData.COORDINATE_FRAME_AREA_DESCRIPTION, TangoPoseData.COORDINATE_FRAME_CAMERA_COLOR,
                TangoSupport.TANGO_SUPPORT_ENGINE_OPENGL, TangoSupport.TANGO_SUPPORT_ENGINE_TANGO,
                TangoSupport.ROTATION_IGNORED);
        if (oglTcolorPose.statusCode != TangoPoseData.POSE_VALID) {
            Log.w(TAG, "Could not get color camera transform at time " + rgbTimestamp);
            return null;
        }

        float[] openglPoint;
        if (mBilateralBox.isChecked()) {
            openglPoint = TangoSupport.getDepthAtPointBilateral(pointCloud, oglTdepthPose.translation,
                    oglTdepthPose.rotation, imageBuffer, u, v, mDisplayRotation, oglTcolorPose.translation,
                    oglTcolorPose.rotation);
        } else {
            openglPoint = TangoSupport.getDepthAtPointNearestNeighbor(pointCloud, oglTdepthPose.translation,
                    oglTdepthPose.rotation, u, v, mDisplayRotation, oglTcolorPose.translation,
                    oglTcolorPose.rotation);
        }
        if (openglPoint == null) {
            return null;
        }
        return openglPoint;
    }

    /**
     * Update the oldest line endpoint to the value passed into this function.
     * This will also flag the line for update on the next render pass.
     */
    private synchronized void updateLine(float[] worldPoint) {
        if (mPointSwitch) {
            mPointSwitch = !mPointSwitch;
            mLinePoints[0] = worldPoint;
            return;
        }
        mPointSwitch = !mPointSwitch;
        mLinePoints[1] = worldPoint;
    }

    /**
     * Return the endpoints of the line as a Stack of Vector3 objects. Returns
     * null if the line is not visible.
     */
    private synchronized Stack<Vector3> generateEndpoints() {

        // Place the line based on the two points.
        if (mLinePoints[0] != null && mLinePoints[1] != null) {
            Stack<Vector3> points = new Stack<Vector3>();
            points.push(new Vector3(mLinePoints[0][0], mLinePoints[0][1], mLinePoints[0][2]));
            points.push(new Vector3(mLinePoints[1][0], mLinePoints[1][1], mLinePoints[1][2]));
            return points;
        }
        return null;
    }

    /*
     * Remove all the points from the Scene.
     */
    private synchronized void clearLine() {
        mLinePoints[0] = null;
        mLinePoints[1] = null;
        mPointSwitch = true;
        mRenderer.setLine(null);
    }

    /**
     * Create a String containing a human-readable description of the
     * distance between endpoints.
     */
    private synchronized String getPointSeparation() {
        if (mLinePoints[0] == null || mLinePoints[1] == null) {
            return "Null";
        }
        float[] p1 = mLinePoints[0];
        float[] p2 = mLinePoints[1];
        double separation = Math
                .sqrt(Math.pow(p1[0] - p2[0], 2) + Math.pow(p1[1] - p2[1], 2) + Math.pow(p1[2] - p2[2], 2));
        return String.format("%.2f", separation) + " meters";
    }

    // Debug text UI update loop, updating at 10Hz.
    private Runnable mUpdateUiLoopRunnable = new Runnable() {
        public void run() {
            updateUi();
            mHandler.postDelayed(this, UPDATE_UI_INTERVAL_MS);
        }
    };

    private synchronized void updateUi() {
        try {
            mDistanceMeasure.setText(getPointSeparation());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Set the color camera background texture rotation and save the display rotation.
     */
    private void setDisplayRotation() {
        Display display = getWindowManager().getDefaultDisplay();
        mDisplayRotation = display.getRotation();

        // We also need to update the camera texture UV coordinates. This must be run in the OpenGL
        // thread.
        mSurfaceView.queueEvent(new Runnable() {
            @Override
            public void run() {
                if (mIsConnected) {
                    mRenderer.updateColorCameraTextureUvGlThread(mDisplayRotation);
                }
            }
        });
    }

    /**
     * Check to see if we have the necessary permissions for this app; ask for them if we don't.
     *
     * @return True if we have the necessary permissions, false if we don't.
     */
    private boolean checkAndRequestPermissions() {
        if (!hasCameraPermission()) {
            requestCameraPermission();
            return false;
        }
        return true;
    }

    /**
     * Check to see if we have the necessary permissions for this app.
     */
    private boolean hasCameraPermission() {
        return ContextCompat.checkSelfPermission(this, CAMERA_PERMISSION) == PackageManager.PERMISSION_GRANTED;
    }

    /**
     * Request the necessary permissions for this app.
     */
    private void requestCameraPermission() {
        if (ActivityCompat.shouldShowRequestPermissionRationale(this, CAMERA_PERMISSION)) {
            showRequestPermissionRationale();
        } else {
            ActivityCompat.requestPermissions(this, new String[] { CAMERA_PERMISSION }, CAMERA_PERMISSION_CODE);
        }
    }

    /**
     * If the user has declined the permission before, we have to explain that the app needs this
     * permission.
     */
    private void showRequestPermissionRationale() {
        final AlertDialog dialog = new AlertDialog.Builder(this)
                .setMessage("Java Point to point Example requires camera permission")
                .setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        ActivityCompat.requestPermissions(PointToPointActivity.this,
                                new String[] { CAMERA_PERMISSION }, CAMERA_PERMISSION_CODE);
                    }
                }).create();
        dialog.show();
    }

    /**
     * Display toast on UI thread.
     *
     * @param resId The resource id of the string resource to use. Can be formatted text.
     */
    private void showsToastAndFinishOnUiThread(final int resId) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(PointToPointActivity.this, getString(resId), Toast.LENGTH_LONG).show();
                finish();
            }
        });
    }

    /**
     * Result for requesting camera permission.
     */
    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        if (hasCameraPermission()) {
            bindTangoService();
        } else {
            Toast.makeText(this, "Java Point to point Example requires camera permission", Toast.LENGTH_LONG)
                    .show();
        }
    }
}