sdk/android/src/java/org/webrtc/CameraCapturer.java - src.git - Git at Google

 /*
  *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */

 package org.webrtc;

 import android.content.Context;
 import android.os.Handler;
 import android.os.Looper;
 import java.util.Arrays;
 import javax.annotation.Nullable;

 @SuppressWarnings("deprecation")
 abstract class CameraCapturer implements CameraVideoCapturer {
   enum SwitchState {
     IDLE, // No switch requested.
     PENDING, // Waiting for previous capture session to open.
     IN_PROGRESS, // Waiting for new switched capture session to start.
   }

   private static final String TAG = "CameraCapturer";
   private final static int MAX_OPEN_CAMERA_ATTEMPTS = 3;
   private final static int OPEN_CAMERA_DELAY_MS = 500;
   private final static int OPEN_CAMERA_TIMEOUT = 10000;

   private final CameraEnumerator cameraEnumerator;
   @Nullable private final CameraEventsHandler eventsHandler;
   private final Handler uiThreadHandler;

   @Nullable
   private final CameraSession.CreateSessionCallback createSessionCallback =
       new CameraSession.CreateSessionCallback() {
         @Override
         public void onDone(CameraSession session) {
           checkIsOnCameraThread();
           Logging.d(TAG, "Create session done. Switch state: " + switchState);
           uiThreadHandler.removeCallbacks(openCameraTimeoutRunnable);
           synchronized (stateLock) {
             capturerObserver.onCapturerStarted(true /* success */);
             sessionOpening = false;
             currentSession = session;
             cameraStatistics = new CameraStatistics(surfaceHelper, eventsHandler);
             firstFrameObserved = false;
             stateLock.notifyAll();

             if (switchState == SwitchState.IN_PROGRESS) {
               switchState = SwitchState.IDLE;
               if (switchEventsHandler != null) {
                 switchEventsHandler.onCameraSwitchDone(cameraEnumerator.isFrontFacing(cameraName));
                 switchEventsHandler = null;
               }
             } else if (switchState == SwitchState.PENDING) {
               switchState = SwitchState.IDLE;
               switchCameraInternal(switchEventsHandler);
             }
           }
         }

         @Override
         public void onFailure(CameraSession.FailureType failureType, String error) {
           checkIsOnCameraThread();
           uiThreadHandler.removeCallbacks(openCameraTimeoutRunnable);
           synchronized (stateLock) {
             capturerObserver.onCapturerStarted(false /* success */);
             openAttemptsRemaining--;

             if (openAttemptsRemaining <= 0) {
               Logging.w(TAG, "Opening camera failed, passing: " + error);
               sessionOpening = false;
               stateLock.notifyAll();

               if (switchState != SwitchState.IDLE) {
                 if (switchEventsHandler != null) {
                   switchEventsHandler.onCameraSwitchError(error);
                   switchEventsHandler = null;
                 }
                 switchState = SwitchState.IDLE;
               }

               if (failureType == CameraSession.FailureType.DISCONNECTED) {
                 eventsHandler.onCameraDisconnected();
               } else {
                 eventsHandler.onCameraError(error);
               }
             } else {
               Logging.w(TAG, "Opening camera failed, retry: " + error);
               createSessionInternal(OPEN_CAMERA_DELAY_MS);
             }
           }
         }
       };

   @Nullable
   private final CameraSession.Events cameraSessionEventsHandler = new CameraSession.Events() {
     @Override
     public void onCameraOpening() {
       checkIsOnCameraThread();
       synchronized (stateLock) {
         if (currentSession != null) {
           Logging.w(TAG, "onCameraOpening while session was open.");
           return;
         }
         eventsHandler.onCameraOpening(cameraName);
       }
     }

     @Override
     public void onCameraError(CameraSession session, String error) {
       checkIsOnCameraThread();
       synchronized (stateLock) {
         if (session != currentSession) {
           Logging.w(TAG, "onCameraError from another session: " + error);
           return;
         }
         eventsHandler.onCameraError(error);
         stopCapture();
       }
     }

     @Override
     public void onCameraDisconnected(CameraSession session) {
       checkIsOnCameraThread();
       synchronized (stateLock) {
         if (session != currentSession) {
           Logging.w(TAG, "onCameraDisconnected from another session.");
           return;
         }
         eventsHandler.onCameraDisconnected();
         stopCapture();
       }
     }

     @Override
     public void onCameraClosed(CameraSession session) {
       checkIsOnCameraThread();
       synchronized (stateLock) {
         if (session != currentSession && currentSession != null) {
           Logging.d(TAG, "onCameraClosed from another session.");
           return;
         }
         eventsHandler.onCameraClosed();
       }
     }

     @Override
     public void onFrameCaptured(CameraSession session, VideoFrame frame) {
       checkIsOnCameraThread();
       synchronized (stateLock) {
         if (session != currentSession) {
           Logging.w(TAG, "onFrameCaptured from another session.");
           return;
         }
         if (!firstFrameObserved) {
           eventsHandler.onFirstFrameAvailable();
           firstFrameObserved = true;
         }
         cameraStatistics.addFrame();
         capturerObserver.onFrameCaptured(frame);
       }
     }
   };

   private final Runnable openCameraTimeoutRunnable = new Runnable() {
     @Override
     public void run() {
       eventsHandler.onCameraError("Camera failed to start within timeout.");
     }
   };

   // Initialized on initialize
   // -------------------------
   @Nullable private Handler cameraThreadHandler;
   private Context applicationContext;
   private org.webrtc.CapturerObserver capturerObserver;
   @Nullable private SurfaceTextureHelper surfaceHelper;

   private final Object stateLock = new Object();
   private boolean sessionOpening; /* guarded by stateLock */
   @Nullable private CameraSession currentSession; /* guarded by stateLock */
   private String cameraName; /* guarded by stateLock */
   private int width; /* guarded by stateLock */
   private int height; /* guarded by stateLock */
   private int framerate; /* guarded by stateLock */
   private int openAttemptsRemaining; /* guarded by stateLock */
   private SwitchState switchState = SwitchState.IDLE; /* guarded by stateLock */
   @Nullable private CameraSwitchHandler switchEventsHandler; /* guarded by stateLock */
   // Valid from onDone call until stopCapture, otherwise null.
   @Nullable private CameraStatistics cameraStatistics; /* guarded by stateLock */
   private boolean firstFrameObserved; /* guarded by stateLock */

   public CameraCapturer(String cameraName, @Nullable CameraEventsHandler eventsHandler,
       CameraEnumerator cameraEnumerator) {
     if (eventsHandler == null) {
       eventsHandler = new CameraEventsHandler() {
         @Override
         public void onCameraError(String errorDescription) {}
         @Override
         public void onCameraDisconnected() {}
         @Override
         public void onCameraFreezed(String errorDescription) {}
         @Override
         public void onCameraOpening(String cameraName) {}
         @Override
         public void onFirstFrameAvailable() {}
         @Override
         public void onCameraClosed() {}
       };
     }

     this.eventsHandler = eventsHandler;
     this.cameraEnumerator = cameraEnumerator;
     this.cameraName = cameraName;
     uiThreadHandler = new Handler(Looper.getMainLooper());

     final String[] deviceNames = cameraEnumerator.getDeviceNames();

     if (deviceNames.length == 0) {
       throw new RuntimeException("No cameras attached.");
     }
     if (!Arrays.asList(deviceNames).contains(this.cameraName)) {
       throw new IllegalArgumentException(
           "Camera name " + this.cameraName + " does not match any known camera device.");
     }
   }

   @Override
   public void initialize(@Nullable SurfaceTextureHelper surfaceTextureHelper,
       Context applicationContext, org.webrtc.CapturerObserver capturerObserver) {
     this.applicationContext = applicationContext;
     this.capturerObserver = capturerObserver;
     this.surfaceHelper = surfaceTextureHelper;
     this.cameraThreadHandler =
         surfaceTextureHelper == null ? null : surfaceTextureHelper.getHandler();
   }

   @Override
   public void startCapture(int width, int height, int framerate) {
     Logging.d(TAG, "startCapture: " + width + "x" + height + "@" + framerate);
     if (applicationContext == null) {
       throw new RuntimeException("CameraCapturer must be initialized before calling startCapture.");
     }

     synchronized (stateLock) {
       if (sessionOpening || currentSession != null) {
         Logging.w(TAG, "Session already open");
         return;
       }

       this.width = width;
       this.height = height;
       this.framerate = framerate;

       sessionOpening = true;
       openAttemptsRemaining = MAX_OPEN_CAMERA_ATTEMPTS;
       createSessionInternal(0);
     }
   }

   private void createSessionInternal(int delayMs) {
     uiThreadHandler.postDelayed(openCameraTimeoutRunnable, delayMs + OPEN_CAMERA_TIMEOUT);
     cameraThreadHandler.postDelayed(new Runnable() {
       @Override
       public void run() {
         createCameraSession(createSessionCallback, cameraSessionEventsHandler, applicationContext,
             surfaceHelper, cameraName, width, height, framerate);
       }
     }, delayMs);
   }

   @Override
   public void stopCapture() {
     Logging.d(TAG, "Stop capture");

     synchronized (stateLock) {
       while (sessionOpening) {
         Logging.d(TAG, "Stop capture: Waiting for session to open");
         try {
           stateLock.wait();
         } catch (InterruptedException e) {
           Logging.w(TAG, "Stop capture interrupted while waiting for the session to open.");
           Thread.currentThread().interrupt();
           return;
         }
       }

       if (currentSession != null) {
         Logging.d(TAG, "Stop capture: Nulling session");
         cameraStatistics.release();
         cameraStatistics = null;
         final CameraSession oldSession = currentSession;
         cameraThreadHandler.post(new Runnable() {
           @Override
           public void run() {
             oldSession.stop();
           }
         });
         currentSession = null;
         capturerObserver.onCapturerStopped();
       } else {
         Logging.d(TAG, "Stop capture: No session open");
       }
     }

     Logging.d(TAG, "Stop capture done");
   }

   @Override
   public void changeCaptureFormat(int width, int height, int framerate) {
     Logging.d(TAG, "changeCaptureFormat: " + width + "x" + height + "@" + framerate);
     synchronized (stateLock) {
       stopCapture();
       startCapture(width, height, framerate);
     }
   }

   @Override
   public void dispose() {
     Logging.d(TAG, "dispose");
     stopCapture();
   }

   @Override
   public void switchCamera(final CameraSwitchHandler switchEventsHandler) {
     Logging.d(TAG, "switchCamera");
     cameraThreadHandler.post(new Runnable() {
       @Override
       public void run() {
         switchCameraInternal(switchEventsHandler);
       }
     });
   }

   @Override
   public boolean isScreencast() {
     return false;
   }

   public void printStackTrace() {
     Thread cameraThread = null;
     if (cameraThreadHandler != null) {
       cameraThread = cameraThreadHandler.getLooper().getThread();
     }
     if (cameraThread != null) {
       StackTraceElement[] cameraStackTrace = cameraThread.getStackTrace();
       if (cameraStackTrace.length > 0) {
         Logging.d(TAG, "CameraCapturer stack trace:");
         for (StackTraceElement traceElem : cameraStackTrace) {
           Logging.d(TAG, traceElem.toString());
         }
       }
     }
   }

   private void reportCameraSwitchError(
       String error, @Nullable CameraSwitchHandler switchEventsHandler) {
     Logging.e(TAG, error);
     if (switchEventsHandler != null) {
       switchEventsHandler.onCameraSwitchError(error);
     }
   }

   private void switchCameraInternal(@Nullable final CameraSwitchHandler switchEventsHandler) {
     Logging.d(TAG, "switchCamera internal");

     final String[] deviceNames = cameraEnumerator.getDeviceNames();

     if (deviceNames.length < 2) {
       if (switchEventsHandler != null) {
         switchEventsHandler.onCameraSwitchError("No camera to switch to.");
       }
       return;
     }

     synchronized (stateLock) {
       if (switchState != SwitchState.IDLE) {
         reportCameraSwitchError("Camera switch already in progress.", switchEventsHandler);
         return;
       }
       if (!sessionOpening && currentSession == null) {
         reportCameraSwitchError("switchCamera: camera is not running.", switchEventsHandler);
         return;
       }

       this.switchEventsHandler = switchEventsHandler;
       if (sessionOpening) {
         switchState = SwitchState.PENDING;
         return;
       } else {
         switchState = SwitchState.IN_PROGRESS;
       }

       Logging.d(TAG, "switchCamera: Stopping session");
       cameraStatistics.release();
       cameraStatistics = null;
       final CameraSession oldSession = currentSession;
       cameraThreadHandler.post(new Runnable() {
         @Override
         public void run() {
           oldSession.stop();
         }
       });
       currentSession = null;

       int cameraNameIndex = Arrays.asList(deviceNames).indexOf(cameraName);
       cameraName = deviceNames[(cameraNameIndex + 1) % deviceNames.length];

       sessionOpening = true;
       openAttemptsRemaining = 1;
       createSessionInternal(0);
     }
     Logging.d(TAG, "switchCamera done");
   }

   private void checkIsOnCameraThread() {
     if (Thread.currentThread() != cameraThreadHandler.getLooper().getThread()) {
       Logging.e(TAG, "Check is on camera thread failed.");
       throw new RuntimeException("Not on camera thread.");
     }
   }

   protected String getCameraName() {
     synchronized (stateLock) {
       return cameraName;
     }
   }

   abstract protected void createCameraSession(
       CameraSession.CreateSessionCallback createSessionCallback, CameraSession.Events events,
       Context applicationContext, SurfaceTextureHelper surfaceTextureHelper, String cameraName,
       int width, int height, int framerate);
 }
	/*
	* Copyright 2016 The WebRTC project authors. All Rights Reserved.
	*
	* Use of this source code is governed by a BSD-style license
	* that can be found in the LICENSE file in the root of the source
	* tree. An additional intellectual property rights grant can be found
	* in the file PATENTS. All contributing project authors may
	* be found in the AUTHORS file in the root of the source tree.
	*/

	package org.webrtc;

	import android.content.Context;
	import android.os.Handler;
	import android.os.Looper;
	import java.util.Arrays;
	import javax.annotation.Nullable;

	@SuppressWarnings("deprecation")
	abstract class CameraCapturer implements CameraVideoCapturer {
	enum SwitchState {
	IDLE, // No switch requested.
	PENDING, // Waiting for previous capture session to open.
	IN_PROGRESS, // Waiting for new switched capture session to start.
	}

	private static final String TAG = "CameraCapturer";
	private final static int MAX_OPEN_CAMERA_ATTEMPTS = 3;
	private final static int OPEN_CAMERA_DELAY_MS = 500;
	private final static int OPEN_CAMERA_TIMEOUT = 10000;

	private final CameraEnumerator cameraEnumerator;
	@Nullable private final CameraEventsHandler eventsHandler;
	private final Handler uiThreadHandler;

	@Nullable
	private final CameraSession.CreateSessionCallback createSessionCallback =
	new CameraSession.CreateSessionCallback() {
	@Override
	public void onDone(CameraSession session) {
	checkIsOnCameraThread();
	Logging.d(TAG, "Create session done. Switch state: " + switchState);
	uiThreadHandler.removeCallbacks(openCameraTimeoutRunnable);
	synchronized (stateLock) {
	capturerObserver.onCapturerStarted(true /* success */);
	sessionOpening = false;
	currentSession = session;
	cameraStatistics = new CameraStatistics(surfaceHelper, eventsHandler);
	firstFrameObserved = false;
	stateLock.notifyAll();

	if (switchState == SwitchState.IN_PROGRESS) {
	switchState = SwitchState.IDLE;
	if (switchEventsHandler != null) {
	switchEventsHandler.onCameraSwitchDone(cameraEnumerator.isFrontFacing(cameraName));
	switchEventsHandler = null;
	}
	} else if (switchState == SwitchState.PENDING) {
	switchState = SwitchState.IDLE;
	switchCameraInternal(switchEventsHandler);
	}
	}
	}

	@Override
	public void onFailure(CameraSession.FailureType failureType, String error) {
	checkIsOnCameraThread();
	uiThreadHandler.removeCallbacks(openCameraTimeoutRunnable);
	synchronized (stateLock) {
	capturerObserver.onCapturerStarted(false /* success */);
	openAttemptsRemaining--;

	if (openAttemptsRemaining <= 0) {
	Logging.w(TAG, "Opening camera failed, passing: " + error);
	sessionOpening = false;
	stateLock.notifyAll();

	if (switchState != SwitchState.IDLE) {
	if (switchEventsHandler != null) {
	switchEventsHandler.onCameraSwitchError(error);
	switchEventsHandler = null;
	}
	switchState = SwitchState.IDLE;
	}

	if (failureType == CameraSession.FailureType.DISCONNECTED) {
	eventsHandler.onCameraDisconnected();
	} else {
	eventsHandler.onCameraError(error);
	}
	} else {
	Logging.w(TAG, "Opening camera failed, retry: " + error);
	createSessionInternal(OPEN_CAMERA_DELAY_MS);
	}
	}
	}
	};

	@Nullable
	private final CameraSession.Events cameraSessionEventsHandler = new CameraSession.Events() {
	@Override
	public void onCameraOpening() {
	checkIsOnCameraThread();
	synchronized (stateLock) {
	if (currentSession != null) {
	Logging.w(TAG, "onCameraOpening while session was open.");
	return;
	}
	eventsHandler.onCameraOpening(cameraName);
	}
	}

	@Override
	public void onCameraError(CameraSession session, String error) {
	checkIsOnCameraThread();
	synchronized (stateLock) {
	if (session != currentSession) {
	Logging.w(TAG, "onCameraError from another session: " + error);
	return;
	}
	eventsHandler.onCameraError(error);
	stopCapture();
	}
	}

	@Override
	public void onCameraDisconnected(CameraSession session) {
	checkIsOnCameraThread();
	synchronized (stateLock) {
	if (session != currentSession) {
	Logging.w(TAG, "onCameraDisconnected from another session.");
	return;
	}
	eventsHandler.onCameraDisconnected();
	stopCapture();
	}
	}

	@Override
	public void onCameraClosed(CameraSession session) {
	checkIsOnCameraThread();
	synchronized (stateLock) {
	if (session != currentSession && currentSession != null) {
	Logging.d(TAG, "onCameraClosed from another session.");
	return;
	}
	eventsHandler.onCameraClosed();
	}
	}

	@Override
	public void onFrameCaptured(CameraSession session, VideoFrame frame) {
	checkIsOnCameraThread();
	synchronized (stateLock) {
	if (session != currentSession) {
	Logging.w(TAG, "onFrameCaptured from another session.");
	return;
	}
	if (!firstFrameObserved) {
	eventsHandler.onFirstFrameAvailable();
	firstFrameObserved = true;
	}
	cameraStatistics.addFrame();
	capturerObserver.onFrameCaptured(frame);
	}
	}
	};

	private final Runnable openCameraTimeoutRunnable = new Runnable() {
	@Override
	public void run() {
	eventsHandler.onCameraError("Camera failed to start within timeout.");
	}
	};

	// Initialized on initialize
	// -------------------------
	@Nullable private Handler cameraThreadHandler;
	private Context applicationContext;
	private org.webrtc.CapturerObserver capturerObserver;
	@Nullable private SurfaceTextureHelper surfaceHelper;

	private final Object stateLock = new Object();
	private boolean sessionOpening; /* guarded by stateLock */
	@Nullable private CameraSession currentSession; /* guarded by stateLock */
	private String cameraName; /* guarded by stateLock */
	private int width; /* guarded by stateLock */
	private int height; /* guarded by stateLock */
	private int framerate; /* guarded by stateLock */
	private int openAttemptsRemaining; /* guarded by stateLock */
	private SwitchState switchState = SwitchState.IDLE; /* guarded by stateLock */
	@Nullable private CameraSwitchHandler switchEventsHandler; /* guarded by stateLock */
	// Valid from onDone call until stopCapture, otherwise null.
	@Nullable private CameraStatistics cameraStatistics; /* guarded by stateLock */
	private boolean firstFrameObserved; /* guarded by stateLock */

	public CameraCapturer(String cameraName, @Nullable CameraEventsHandler eventsHandler,
	CameraEnumerator cameraEnumerator) {
	if (eventsHandler == null) {
	eventsHandler = new CameraEventsHandler() {
	@Override
	public void onCameraError(String errorDescription) {}
	@Override
	public void onCameraDisconnected() {}
	@Override
	public void onCameraFreezed(String errorDescription) {}
	@Override
	public void onCameraOpening(String cameraName) {}
	@Override
	public void onFirstFrameAvailable() {}
	@Override
	public void onCameraClosed() {}
	};
	}

	this.eventsHandler = eventsHandler;
	this.cameraEnumerator = cameraEnumerator;
	this.cameraName = cameraName;
	uiThreadHandler = new Handler(Looper.getMainLooper());

	final String[] deviceNames = cameraEnumerator.getDeviceNames();

	if (deviceNames.length == 0) {
	throw new RuntimeException("No cameras attached.");
	}
	if (!Arrays.asList(deviceNames).contains(this.cameraName)) {
	throw new IllegalArgumentException(
	"Camera name " + this.cameraName + " does not match any known camera device.");
	}
	}

	@Override
	public void initialize(@Nullable SurfaceTextureHelper surfaceTextureHelper,
	Context applicationContext, org.webrtc.CapturerObserver capturerObserver) {
	this.applicationContext = applicationContext;
	this.capturerObserver = capturerObserver;
	this.surfaceHelper = surfaceTextureHelper;
	this.cameraThreadHandler =
	surfaceTextureHelper == null ? null : surfaceTextureHelper.getHandler();
	}

	@Override
	public void startCapture(int width, int height, int framerate) {
	Logging.d(TAG, "startCapture: " + width + "x" + height + "@" + framerate);
	if (applicationContext == null) {
	throw new RuntimeException("CameraCapturer must be initialized before calling startCapture.");
	}

	synchronized (stateLock) {
	if (sessionOpening \|\| currentSession != null) {
	Logging.w(TAG, "Session already open");
	return;
	}

	this.width = width;
	this.height = height;
	this.framerate = framerate;

	sessionOpening = true;
	openAttemptsRemaining = MAX_OPEN_CAMERA_ATTEMPTS;
	createSessionInternal(0);
	}
	}

	private void createSessionInternal(int delayMs) {
	uiThreadHandler.postDelayed(openCameraTimeoutRunnable, delayMs + OPEN_CAMERA_TIMEOUT);
	cameraThreadHandler.postDelayed(new Runnable() {
	@Override
	public void run() {
	createCameraSession(createSessionCallback, cameraSessionEventsHandler, applicationContext,
	surfaceHelper, cameraName, width, height, framerate);
	}
	}, delayMs);
	}

	@Override
	public void stopCapture() {
	Logging.d(TAG, "Stop capture");

	synchronized (stateLock) {
	while (sessionOpening) {
	Logging.d(TAG, "Stop capture: Waiting for session to open");
	try {
	stateLock.wait();
	} catch (InterruptedException e) {
	Logging.w(TAG, "Stop capture interrupted while waiting for the session to open.");
	Thread.currentThread().interrupt();
	return;
	}
	}

	if (currentSession != null) {
	Logging.d(TAG, "Stop capture: Nulling session");
	cameraStatistics.release();
	cameraStatistics = null;
	final CameraSession oldSession = currentSession;
	cameraThreadHandler.post(new Runnable() {
	@Override
	public void run() {
	oldSession.stop();
	}
	});
	currentSession = null;
	capturerObserver.onCapturerStopped();
	} else {
	Logging.d(TAG, "Stop capture: No session open");
	}
	}

	Logging.d(TAG, "Stop capture done");
	}

	@Override
	public void changeCaptureFormat(int width, int height, int framerate) {
	Logging.d(TAG, "changeCaptureFormat: " + width + "x" + height + "@" + framerate);
	synchronized (stateLock) {
	stopCapture();
	startCapture(width, height, framerate);
	}
	}

	@Override
	public void dispose() {
	Logging.d(TAG, "dispose");
	stopCapture();
	}

	@Override
	public void switchCamera(final CameraSwitchHandler switchEventsHandler) {
	Logging.d(TAG, "switchCamera");
	cameraThreadHandler.post(new Runnable() {
	@Override
	public void run() {
	switchCameraInternal(switchEventsHandler);
	}
	});
	}

	@Override
	public boolean isScreencast() {
	return false;
	}

	public void printStackTrace() {
	Thread cameraThread = null;
	if (cameraThreadHandler != null) {
	cameraThread = cameraThreadHandler.getLooper().getThread();
	}
	if (cameraThread != null) {
	StackTraceElement[] cameraStackTrace = cameraThread.getStackTrace();
	if (cameraStackTrace.length > 0) {
	Logging.d(TAG, "CameraCapturer stack trace:");
	for (StackTraceElement traceElem : cameraStackTrace) {
	Logging.d(TAG, traceElem.toString());
	}
	}
	}
	}

	private void reportCameraSwitchError(
	String error, @Nullable CameraSwitchHandler switchEventsHandler) {
	Logging.e(TAG, error);
	if (switchEventsHandler != null) {
	switchEventsHandler.onCameraSwitchError(error);
	}
	}

	private void switchCameraInternal(@Nullable final CameraSwitchHandler switchEventsHandler) {
	Logging.d(TAG, "switchCamera internal");

	final String[] deviceNames = cameraEnumerator.getDeviceNames();

	if (deviceNames.length < 2) {
	if (switchEventsHandler != null) {
	switchEventsHandler.onCameraSwitchError("No camera to switch to.");
	}
	return;
	}

	synchronized (stateLock) {
	if (switchState != SwitchState.IDLE) {
	reportCameraSwitchError("Camera switch already in progress.", switchEventsHandler);
	return;
	}
	if (!sessionOpening && currentSession == null) {
	reportCameraSwitchError("switchCamera: camera is not running.", switchEventsHandler);
	return;
	}

	this.switchEventsHandler = switchEventsHandler;
	if (sessionOpening) {
	switchState = SwitchState.PENDING;
	return;
	} else {
	switchState = SwitchState.IN_PROGRESS;
	}

	Logging.d(TAG, "switchCamera: Stopping session");
	cameraStatistics.release();
	cameraStatistics = null;
	final CameraSession oldSession = currentSession;
	cameraThreadHandler.post(new Runnable() {
	@Override
	public void run() {
	oldSession.stop();
	}
	});
	currentSession = null;

	int cameraNameIndex = Arrays.asList(deviceNames).indexOf(cameraName);
	cameraName = deviceNames[(cameraNameIndex + 1) % deviceNames.length];

	sessionOpening = true;
	openAttemptsRemaining = 1;
	createSessionInternal(0);
	}
	Logging.d(TAG, "switchCamera done");
	}

	private void checkIsOnCameraThread() {
	if (Thread.currentThread() != cameraThreadHandler.getLooper().getThread()) {
	Logging.e(TAG, "Check is on camera thread failed.");
	throw new RuntimeException("Not on camera thread.");
	}
	}

	protected String getCameraName() {
	synchronized (stateLock) {
	return cameraName;
	}
	}

	abstract protected void createCameraSession(
	CameraSession.CreateSessionCallback createSessionCallback, CameraSession.Events events,
	Context applicationContext, SurfaceTextureHelper surfaceTextureHelper, String cameraName,
	int width, int height, int framerate);
	}