Android

發(fā)表時(shí)間：2020-10-19

發(fā)布人：葵宇科技

瀏覽次數(shù)：52

Android -- Camera2(Android5.0)

Camera2

Camera2是Android5.0中的個(gè)一一個(gè)新的特點(diǎn)，新的API。與本來的camera API比擬，不合之處在于：

原生支撐RAW照片輸出
突發(fā)拍攝模式

制約拍┞氛速度的不再是軟件而是硬件。以Nexus 5為例，分辨率全開下Andorid L的連拍速度可達(dá)到30fps。

全手動控制

快門、感孤┤、對焦、測光、硬件視頻防抖等多種參數(shù)都被整合到了新的API內(nèi)。新的API中添加的手動控制功能列表：

感孤┤
手動對焦/AF開關(guān)
AE/AF/AWB模式
AE/AWB鎖
硬件視頻防抖
持續(xù)幀

干貨

Camera2 法度榜樣邏輯與原Camera有很大年夜不合。
CameraManager，體系辦事，經(jīng)由過程 CameraManager去獲得camera設(shè)備對象。CameraDevices供給描述相機(jī)硬件設(shè)備支撐可用的和輸出的參數(shù)，這些信息經(jīng)由過程 CameraCharacteristics獲得，CameraCharacteristics又是大年夜 getCameraCharacteristics（cameraId緝獲得，經(jīng)由過程freamwork中的源碼發(fā)明，其拭魅這里就是直接調(diào)用的Camera API接口。
經(jīng)由過程camera拍┞氛，應(yīng)用起重要?jiǎng)?chuàng)建由相機(jī)設(shè)備的輸出surface構(gòu)成的拍┞氛會話，createCaptureSession(List, CameraCaptureSession.StateCallback, Handler)。每個(gè)surface必須預(yù)先設(shè)置恰當(dāng)?shù)拇竽暌剐『?#26684;式去匹配相機(jī)設(shè)備的可支撐的大年夜小和格式。一個(gè)目標(biāo)surface可以大年夜不合的類中獲取，包含SurfaceView,SurfaceTexture via Surface(SurfaceTexture), MediaCodec, MediaRecorder, Allocation, and ImageReader.
一旦請求被建立，他可以交給晃蕩的拍┞氛會話：一次拍┞氛（one-shot ）或者無盡頭持續(xù)拍┞氛或預(yù)覽（Repeating）」現(xiàn)辦法都有一個(gè)其他的方法：接收一系列的請求作為burst拍┞氛/反復(fù)burst。

public void openCamera (String cameraId, CameraDevice.StateCallback callback, Handler handler)

應(yīng)用getCameraIdList()來獲得可用攝像設(shè)備的列表。一旦成功打開相機(jī),CameraDevice.StateCallback中的onOpened(CameraDevice)將被調(diào)用。相機(jī)設(shè)備可以經(jīng)由過程調(diào)用createCaptureSession()和createCaptureRequest()去設(shè)置操作。如不雅打開相機(jī)設(shè)備掉敗,那么設(shè)備回調(diào)的onError辦法將被調(diào)用,和后續(xù)調(diào)用相機(jī)設(shè)備將拋出一個(gè)CameraAccessException。

public abstract CaptureRequest.Builder createCaptureRequest (int templateType)

為請求拍┞氛創(chuàng)建一個(gè)CaptureRequest.Builder,初始化目標(biāo)用例的模板。選擇最好的設(shè)置為特定的相機(jī)設(shè)備,所以不建議為不合的相機(jī)設(shè)備重用雷同的請求,創(chuàng)建一個(gè)builder為具體的設(shè)備和模板和根據(jù)須要覆蓋的設(shè)置。
[img]http://images.cnitblog.com/blog/587773/201501/042023147478117.png

public abstract void createCaptureSession (List<Surface> outputs, CameraCaptureSession.StateCallback callback, Handler handler)

晃蕩著的會話決定了相機(jī)的output Surfaces 為每個(gè)拍┞氛的請求。給定請求可以應(yīng)用全部或只有部分的output Surfaces。一旦CameraCaptureSession創(chuàng)建,可以提交capture請求、captureBurst請求,setRepeatingRequest請求或setRepeatingBurst請求。

權(quán)限

<uses-permission android:name="android.permission.CAMERA"/>

構(gòu)造

[img]http://common.cnblogs.com/images/copycode.gif

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical">

    <TextureView
        android:id="@+id/textureview"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"/>

</LinearLayout>

[img]http://common.cnblogs.com/images/copycode.gif

核心代碼

[img]http://common.cnblogs.com/images/copycode.gif

public class CameraFragment extends Fragment implements TextureView.SurfaceTextureListener {

    private TextureView mPreviewView;
    private Handler mHandler;
    private HandlerThread mThreadHandler;
    private Size mPreviewSize;
    private CaptureRequest.Builder mPreviewBuilder;

    public static CameraFragment newInstance() {
        return new CameraFragment();
    }

    @SuppressWarnings("ResourceType")
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.camera_frag, null);
        initLooper();
        initUIAndListener(v);
        return v;
    }
    //很多過程都變成了異步的了，所以這里須要一個(gè)子線程的looper
    private void initLooper() {
        mThreadHandler = new HandlerThread("CAMERA2");
        mThreadHandler.start();
        mHandler = new Handler(mThreadHandler.getLooper());
    }
    //可以經(jīng)由過程TextureView或者SurfaceView
    private void initUIAndListener(View v) {
        mPreviewView = (TextureView) v.findViewById(R.id.textureview);
        mPreviewView.setSurfaceTextureListener(this);
    }

    @SuppressWarnings("ResourceType")
    @Override
    public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
        try {
            //獲得CameraManager
            CameraManager cameraManager = (CameraManager) getActivity().getSystemService(Context.CAMERA_SERVICE);
            //獲得屬性
            CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics("0");
            //支撐的STREAM CONFIGURATION
            StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
            //顯示的size
            mPreviewSize = map.getOutputSizes(SurfaceTexture.class)[0];
            //打開相機(jī)
            cameraManager.openCamera("0", mCameraDeviceStateCallback, mHandler);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {

    }

    @Override
    public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
        return false;
    }

    //TextureView.SurfaceTextureListener
    @Override
    public void onSurfaceTextureUpdated(SurfaceTexture surface) {

    }

    private CameraDevice.StateCallback mCameraDeviceStateCallback = new CameraDevice.StateCallback() {

        @Override
        public void onOpened(CameraDevice camera) {
            try {
                startPreview(camera);
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onDisconnected(CameraDevice camera) {

        }

        @Override
        public void onError(CameraDevice camera, int error) {

        }
    };
    //開端預(yù)覽，主如果camera.createCaptureSession這段代碼很重要，創(chuàng)建會話
    private void startPreview(CameraDevice camera) throws CameraAccessException {
        SurfaceTexture texture = mPreviewView.getSurfaceTexture();
        texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
        Surface surface = new Surface(texture);
        try {
            mPreviewBuilder = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
        mPreviewBuilder.addTarget(surface);
        camera.createCaptureSession(Arrays.asList(surface), mSessionStateCallback, mHandler);
    }

    private CameraCaptureSession.StateCallback mSessionStateCallback = new CameraCaptureSession.StateCallback() {

        @Override
        public void onConfigured(CameraCaptureSession session) {
            try {
                updatePreview(session);
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onConfigureFailed(CameraCaptureSession session) {

        }
    };

    private void updatePreview(CameraCaptureSession session) throws CameraAccessException {
        session.setRepeatingRequest(mPreviewBuilder.build(), null, mHandler);
    }
}

[img]http://common.cnblogs.com/images/copycode.gif