Android Camera实现毫秒级拍照

我们知道自定义Camera需要以下几步

• 打开相机，即实例化Camera对象

Camera camera = Camera.open();

• 设置Camera的相关参数

Camera.Parameters parameters = camera.getParameters();

• 打开预览

camera.setPreviewDisplay(surfaceholder);
camera.startPreview();

• 获取图片，这里只是从预览中获取因此使用

camera.setPreviewCallback(new Camera.PreviewCallback(){……..});

• 停止预览，释放相机

camera.stopPreview();
camera.release();

1、打开相机

public static Camera openFacingBackCamera() {
        Camera cam = null;
        Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
        for (int camIdx = 0, cameraCount = Camera.getNumberOfCameras(); camIdx < cameraCount; camIdx++) {
            Camera.getCameraInfo(camIdx, cameraInfo);
            if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
                try {
                    //打开相应的摄像头，目前是前置摄像头
                    cam = Camera.open(camIdx);
                } catch (RuntimeException e) {
                    e.printStackTrace();
                    if (cam!=null){
                        cam.stopPreview();
                        cam.release();
                    }
                    cam = null;
                }
            }
        }
        return cam;
    }
````````
2、设置相关参数和预览
````````
//定义SurfaceView
private SurfaceView localSurface;
 // 为surfaceHolder添加一个回调监听器
        localSurface.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {

            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                camera = CameraUtil.openFacingBackCamera();
                //设置相机预览旋转角度
                camera.setDisplayOrientation(180);
                if (camera != null) {
                    Camera.Parameters parameters = camera.getParameters();// 获得相机参数
                    List sizes = parameters.getSupportedPreviewSizes();
                    List sizes_pic = parameters.getSupportedPictureSizes();
                    Camera.Size cs = sizes.get(0);
                    int mWidth = cs.width;
                    int mHeight = cs.height;
                    parameters.setPreviewSize(mWidth, mHeight);
                    parameters.setPictureSize(sizes_pic.get(0).width, sizes_pic.get(0).height);
                    parameters.setJpegQuality(85);//
                    parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
                    parameters.setPictureFormat(ImageFormat.JPEG);
                    camera.setParameters(parameters);
                    try {
                        camera.setPreviewDisplay(localSurface.getHolder());
                        camera.startPreview(); // 开始预览
                        camera.autoFocus(null); // 自动对焦
                    } catch (IOException e) {
                        e.printStackTrace();
                        camera.stopPreview();
                        camera.release();
                        camera = null;
                    }
                }
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                if (camera!=null){
                    camera.stopPreview();
                    camera.release();
                    camera = null;
                }
            }
        } );
        // 设置该SurfaceView自己不维护缓冲
        localSurface.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
````````
3、获取图片
```````
 private void getViewImage() {
      //设置监听
        camera.setPreviewCallback(new Camera.PreviewCallback(){

            @Override
            public void onPreviewFrame(byte[] data, Camera camera) {
                Camera.Size size = camera.getParameters().getPreviewSize();
                try{
                    YuvImage image = new YuvImage(data, ImageFormat.NV21, size.width, size.height, null);
                    if(image!=null){
                        ByteArrayOutputStream stream = new ByteArrayOutputStream();
                        image.compressToJpeg(new Rect(0, 0, size.width, size.height), 80, stream);
                        Bitmap bmp = BitmapFactory.decodeByteArray(stream.toByteArray(), 0, stream.size());
                        //因为图片会放生旋转，因此要对图片进行旋转到和手机在一个方向上
                        rotateBitmap(bmp);
                        stream.close();
                    }
                }catch(Exception ex){
                    Log.e("Sys","Error:"+ex.getMessage());
                }
            }
        });
    }
```````
旋转图片的方法
```````
public void rotateMyBitmap(Bitmap bmp){
        Matrix matrix = new Matrix();
        matrix.postScale(-1, 1); // 镜像水平翻转(如果左右颠倒)
        matrix.postRotate(180);
        Bitmap nbmp = Bitmap.createBitmap(bmp, 0,0, bmp.getWidth(),  bmp.getHeight(), matrix, true);
        imageView.setImageBitmap(nbmp);
    };
```````
自定义时间拍照
```````
    private Handler mHandler = new Handler() {
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case 101:
                    getViewImage();
                    Log.e(TAG, "handleMessage: 拍照" );
                    mHandler.sendEmptyMessageDelayed(102, 100);
                    break;
                case 102:
                    camera.setPreviewCallback(null);
                    break ;
            }
        }
    };
````````
然后点击按钮调用
`
 mHandler.sendEmptyMessageDelayed(101, 100);
`