Camera2 打开相机预览界面
camera2 是21之后的api用于代替Camera，提供更加牛X的对相机hardware操作的api
参考资料:http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2015/0428/2811.html
http://www.tuicool.com/articles/6b67Nra
此篇笔记主要是记录打开预览界面
后面会记录Camera打开相机预览的代码，对比一下
界面布局
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.arvin.camera3.view.AutoFitTextureView
android:id="@+id/surface"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<Button
android:id="@+id/capturebtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:text="拍照" />
<ImageView
android:id="@+id/preview"
android:layout_width="120dp"
android:layout_height="120dp"
android:layout_alignParentBottom="true" />
RelativeLayout>AutoFitTextureView 继承自 TextureVeiw
1.首先要初始化view，就是一些findviewbyid
2.示例代码是在onResume中，能否有更好方式？？？？
if (surfaceView.isAvailable()) {
// FIXME: 2016/6/13
try {
openCamera(surfaceView.getWidth(), surfaceView.getHeight());
} catch (Exception e) {
e.printStackTrace();
}
} else {
surfaceView.setSurfaceTextureListener(mSurfaceTextureListener);
}surfaceView即TextureView
判断TextureView状态
可用，打开相机，否则设置相应的回调
先看打开相机的代码
private void openCamera(int width, int height) throws Exception {
Activity activity = getActivity();
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
if (mCameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
manager.openCamera(mCameraId,deviceStateCallback,mPreviewHandler );
}
}首先调用getSystemService(Context.CAMERA_SERVICE),拿到CameraManager实例，
注：Api 21 新增的，无兼容包，估计也不会发布兼容包吧，21之后 Camera已弃用
然后通过CameraManager实例的 openCamera()方法打开相机预览
我们看下openCamera的声明
@RequiresPermission(android.Manifest.permission.CAMERA)
public void openCamera(@NonNull String cameraId,
@NonNull final CameraDevice.StateCallback callback, @Nullable Handler handler)
throws CameraAccessException {
if (cameraId == null) {
throw new IllegalArgumentException("cameraId was null");
} else if (callback == null) {
throw new IllegalArgumentException("callback was null");
} else if (handler == null) {
if (Looper.myLooper() != null) {
handler = new Handler();
} else {
throw new IllegalArgumentException(
"Handler argument is null, but no looper exists in the calling thread");
}
}
openCameraDeviceUserAsync(cameraId, callback, handler);
}@RequiresPermission(android.Manifest.permission.CAMERA)
需要camera权限，在camera声明，android 6.0之后需要请求，属于runtime permission
需要传入三个参数
cameraId ： “0”表示后置摄像头，“1”表示前置摄像头
callback : CameraDevice.StateCallback 相机状态回调
注：CameraDevice 实例代表一个相机
handler : hanlder
回头看如果TextureView不可用的状态下
surfaceView.setSurfaceTextureListener(mSurfaceTextureListener);
看下 mSurfaceTextureListener是个什么东西
private final TextureView.SurfaceTextureListener mSurfaceTextureListener = new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
try {
openCamera(width, height);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
return false;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture surface) {
}
};这个有点和SurfaceView的回调相似了
设置回调，然后当surface可用的时候openCamera(),回到上面的流程去了
包含四个方法，分别对应可用，尺寸发生变化，TextureView销毁，以及更新的时候回调
继续看manager.openCamera();
已经说了第一个参数camreaId，“0”代表后置摄像头，“1”代表前置摄像头
第二个参数CameraDevice.StateCallback， 直接看
CameraDevice.StateCallback deviceStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(CameraDevice camera) {
mCameraOpenCloseLock.release();
mCameraDevice = camera;
try {
createCameraPreviewSession();
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onDisconnected(CameraDevice camera) {
mCameraOpenCloseLock.release();
camera.close();
mCameraDevice = null;
}
@Override
public void onError(CameraDevice camera, int error) {
mCameraOpenCloseLock.release();
camera.close();
mCameraDevice = null;
Toast.makeText(getActivity(), "onError,error--->" + error, Toast.LENGTH_SHORT).show();
}
};通过代码可知，CameraDevice.StateCallback 提供了三个回调方法，分别对应于camrea打开，失去连接，打开错误的时候回调，
在打开的时候会调用createCameraPreviewSession() ，看一下方法定义
private void createCameraPreviewSession() throws CameraAccessException {
initSurface();
mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewBuilder.addTarget(mSurface);
mCameraDevice.createCaptureSession(Arrays.asList(mSurface), mCaptureSessionStateCallback, mPreviewHandler);
}
private void initSurface() {
SurfaceTexture sufaceTexture = surfaceView.getSurfaceTexture();
assert sufaceTexture != null;
sufaceTexture.setDefaultBufferSize(surfaceView.getWidth(), surfaceView.getHeight());
mSurface = new Surface(sufaceTexture);
}首先通过TextureView的getSurfaceTexture() 拿到 对应 SurfaceTexture 是不是SurfaceView的getSurfaceHolder()很像
设置显示大小，创建Surface实例
之后，调用 CameraDevice createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW) 创建预览请求
并设置target, CaptureRequest.Builder addTarget(Surface surface)
然后调用CameraDevice createCaptureSession()，创建一个相机回话
createCaptureSession()需要传入三个参数
看下声明
public abstract void createCaptureSession(@NonNull List outputs,
@NonNull CameraCaptureSession.StateCallback callback, @Nullable Handler handler) List outputs 我的理解是预览的输出载体列表，在上面的代码中，我们传入了new Surface(TextureView.getSurface()) 对象
ImageReader 也有 getSurface()方法，ImageReader也可以作为输出载体
第二个参数CameraCaptureSession.StateCallback 摄像头采集状态回调
直接看代码
private CameraCaptureSession.StateCallback mCaptureSessionStateCallback = new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(CameraCaptureSession session) {
if (null == mCameraDevice) {
return;
}
mSession = session;
mPreviewBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
mPreviewBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
try {
session.setRepeatingRequest(mPreviewBuilder.build(), mSessionCaptureCallback, mPreviewHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(CameraCaptureSession session) {
}
};设置拍摄模式，这里设置了连拍，flash，其他的模式嘛，我也不清楚了
mPreviewBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
mPreviewBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
session.setRepeatingRequest(mPreviewBuilder.build(), mSessionCaptureCallback, mPreviewHandler);设置重复请求，字面上这么理解
同样是三个参数
第一个是CaptureRequest.Builder buildI() 这个是前面采集请求builder 通过CameraDevice createCaptureRequest创建的
第二个是摄像头采集回话采集状态的回调
private CameraCaptureSession.CaptureCallback mSessionCaptureCallback = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
}
@Override
public void onCaptureProgressed(CameraCaptureSession session, CaptureRequest request, CaptureResult partialResult) {
super.onCaptureProgressed(session, request, partialResult);
}
};包含两个状态，采集进行，采集完成
可以在这里面去做处理，
贴上一段代码
private CameraCaptureSession.CaptureCallback mSessionCaptureCallback = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
mSession = session;
if (!PreferenceHelper.getCameraFormat(getActivity()).equals("DNG")) {
checkState(result);
}
}
@Override
public void onCaptureProgressed(CameraCaptureSession session, CaptureRequest request, CaptureResult partialResult) {
mSession = session;
if (!PreferenceHelper.getCameraFormat(getActivity()).equals("DNG")) {
checkState(partialResult);
}
}
private void checkState(CaptureResult result) {
// mFrameBitmap = mPreviewView.getBitmap();
// mMainHandler.sendEmptyMessage(1);
switch (mState) {
case STATE_PREVIEW:
// NOTHING
break;
case STATE_WAITING_CAPTURE:
int afState = result.get(CaptureResult.CONTROL_AF_STATE);
Log.i("checkState", "afState--->" + afState);
if (CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED == afState || CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED == afState
|| CaptureResult.CONTROL_AF_STATE_PASSIVE_FOCUSED == afState || CaptureResult.CONTROL_AF_STATE_PASSIVE_UNFOCUSED == afState) {
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
Log.i("checkState", "进来了一层,aeState--->" + aeState);
if (aeState == null || aeState == CaptureResult.CONTROL_AE_STATE_CONVERGED) {
Log.i("checkState", "进来了第二层");
mState = STATE_TRY_DO_CAPTURE;
doStillCapture();
} else {
mState = STATE_TRY_CAPTURE_AGAIN;
tryCaptureAgain();
}
}
break;
case STATE_TRY_CAPTURE_AGAIN:
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null ||
aeState == CaptureResult.CONTROL_AE_STATE_PRECAPTURE ||
aeState == CaptureRequest.CONTROL_AE_STATE_FLASH_REQUIRED) {
mState = STATE_TRY_DO_CAPTURE;
}
break;
case STATE_TRY_DO_CAPTURE:
aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null || aeState != CaptureResult.CONTROL_AE_STATE_PRECAPTURE) {
mState = STATE_TRY_DO_CAPTURE;
doStillCapture();
}
break;
}
}
};至此,打开相机预览的代码就结束了，后续比如拍照，录像什么的以后再分析啦，这里的api还没在学习中
最后附上Camera打开预览的代码，感觉要简单好多呀
//布局文件
"@+id/surface"
android:layout_width="match_parent"
android:layout_height="match_parent" />
Camera camera;
surfaceView = (SurfaceView) findViewById(R.id.surface);
holder = surfaceView.getHolder();
holder.addCallback(this); //设置回调
@Override
public void surfaceCreated(SurfaceHolder holder) {
camera = Camera.open();
try {
camera.setPreviewDisplay(holder);
} catch (IOException e) {
e.printStackTrace();
}
camera.startPreview();
}
//将camera预览界面绑定到SurfaceView
//startPreview()
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
} 代码是不是比camera2简单多了，不过这个预览界面挺难看的，其他设置也没有仔细研究，用到的时候再说吧
文中参考了
Android实战技巧之三十三：android.hardware.camera2使用指南
再此对原作者表示感谢