Android Camera2入门
Android Camera2入门系列1 – Camera2在textureView预览
Android Camera2入门系列2 – ImageReader取得预览数据
Android Camera2入门系列3 – Image中取得YUV数据及YUV格式了解
Android Camera2入门系列4 – libyuv的编译和运用
本文供给最easy的Camera2的入门，供入门查看，意在精简，深化内容看后续文章。
The android.hardware.camera2 package provides an interface to individual camera devices connected to an Android device. It replaces the deprecated
[Camera]class. camera2给Android的给个Camera设备供给了接口，并且deprecated掉了Camera类
下面是翻译了部分Camera2的API描述：基本上涉及了咱们运用camera2的一切的API：
经过CameraManager能查询本设备有多少个available的Camera设备。
每个CameraDevice设备供给了一系列静态参数去描述当时的Camera设备，比方设置或许输出参数，这些参数经过[CameraCharacteristics]供给出来，经过[getCameraCharacteristics(cameraId)]获取。
从相机设备获取一个或许多个image，首要有必要创立一个CameraCaptureSession并输出到一个或多个方针Surface上。每个Surface有必要预先设置适宜的预览尺度，这个尺度有必要是Camera支撑的尺度。方针Surface能够被一系列的类所持有，比方SurfaceView,SurfaceTexture,MediaCodec,MediaRecorder,Allocation和ImageReader。也便是说Camera的输出能够被分发到多个Surface上面。
通常，相机预览图画能够被发送到SurfaceView或许TextureView上面，像摄影的时候去单独获取某一帧或许特效相机类的App取得要处理的RAW数据流能够经过ImageReader来获取JPEG格式或许YUV格式的图画数据。比方要用RenderScript, OpenGL ES或许直接在native处理的数据就引荐运用YUV_420_888数据格式来承载。
假如相机设备要获取Image(也便是获取图画的raw数据:JPEG或许YUV数据)，咱们需求创立一个界说了相机需求的参数的CaptureRequest，CameraDevice有工厂办法去创立一个request builder。
一旦request被创立出来，它能够被一个active状况的session拿去得到一个Image(one-shot)或许多个Image(endless)，也便是说session经过request去得到一张图或许多张图。
//得到一个Image
session.capture(request, null, mCameraHandler);
//一向回调回来Image
session.setRepeatingRequest(request, null, mCameraHandler);
API运用流程大体如下:
- 经过context.getSystemService(Context.CAMERA_SERVICE) 获取CameraManager.
- 调用CameraManager .open()办法在回调中得到CameraDevice.
- 经过CameraDevice.createCaptureSession() 在回调中获取CameraCaptureSession.
- 构建CaptureRequest, 有三种形式可选 预览/摄影/录像.
- 经过 CameraCaptureSession发送CaptureRequest, capture表明只发一次恳求, setRepeatingRequest表明不断发送恳求.
- 摄影数据能够在ImageReader.OnImageAvailableListener回调中获取, CaptureCallback中则可获取摄影实践的参数和Camera当时状况.
上文提到了Camera2的某些必要的API。其实单纯的去看某个类或某些类的责任，只是看这些API的功能描述只会看的头大，由于camera2确实供给了许多API来操控。还不如直接来看一个demo来的愈加直观，引荐咱们不要复制，哪怕看着自己敲一遍，形象会深入许多。
public class Camera2Provider {
private Activity mContext;
private String mCameraId;
private Handler mCameraHandler;
private CameraDevice mCameraDevice;
private TextureView mTextureView;
private CaptureRequest.Builder mPreviewBuilder;
private Size previewSize;
public Camera2Provider(Activity mContext) {
this.mContext = mContext;
//创立了一个Thread来供Camera运行运用，运用HandlerThread而不运用Thread是由于HandlerThread给咱们创立了Looper，不必咱们自己创立了。
HandlerThread handlerThread = new HandlerThread("camera");
handlerThread.start();
mCameraHandler = new Handler(handlerThread.getLooper());
}
/**
* 设置预览view
*
* @param textureView 需求预览的TextureView
*/
public void initTexture(TextureView textureView) {
mTextureView = textureView;
textureView.setSurfaceTextureListener(new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
openCamera(width, height);
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {return false;}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture surface) {}
});
}
/**
* surface ready的时候敞开Camera
*
* @param width surface的宽
* @param height surface的高
*/
private void openCamera(int width, int height) {
CameraManager cameraManager = (CameraManager) mContext.getSystemService(Context.CAMERA_SERVICE);
try {
for (String cameraId : cameraManager.getCameraIdList()) {
//描述相机设备的属性类
CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
//获取是前置还是后置摄像头
Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
//运用后置摄像头
if (facing != null && facing == CameraCharacteristics.LENS_FACING_BACK) {
StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
if (map != null) {
previewSize = CameraUtil.getOptimalSize(map.getOutputSizes(SurfaceTexture.class), width, height);
mCameraId = cameraId;
}
}
}
String[] params = new String[]{Manifest.permission.CAMERA};
if (!PermissionUtil.checkPermission(mContext, params)) {
PermissionUtil.requestPermission(mContext, "", 0, params);
}
cameraManager.openCamera(mCameraId, mStateCallback, mCameraHandler);
} catch (CameraAccessException r) {}
}
/**
* 状况回调
*/
private CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(CameraDevice camera) {
mCameraDevice = camera;
SurfaceTexture surfaceTexture = mTextureView.getSurfaceTexture();
surfaceTexture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());
Surface previewSurface = new Surface(surfaceTexture);
try {
mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
//假如需求多个surface能够add多个
mPreviewBuilder.addTarget(previewSurface);
mCameraDevice.createCaptureSession(Arrays.asList(previewSurface), mStateCallBack, mCameraHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onDisconnected(CameraDevice camera) {
camera.close();
}
@Override
public void onError(CameraDevice camera, int error) {
camera.close();
}
};
private CameraCaptureSession.StateCallback mStateCallBack = new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(CameraCaptureSession session) {
CaptureRequest request = mPreviewBuilder.build();
try {
//获取一个Image，one-shot
// session.capture(request, null, mCameraHandler);
//敞开获取Image，repeat形式
session.setRepeatingRequest(request, null, mCameraHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(CameraCaptureSession session) {}
};
/**
* 记住关掉Camera
*/
public void closeCamera() {
mCameraDevice.close();
}
}
需求留意的几个问题：
- 记住增加权限，并自己完成动态恳求权限。
- 创立一个Thread供Camera2运用。
- 留意预览尺度和Camera能供给的尺度。
github代码：Camera2Provider.java 欢迎star/follow
接着看下一篇怎么获取回调的数据Android Camera系列2 – ImageReader取得预览数据
