mCamera.take图片（null， null， mPicture）不工作

Question

我按照https://developer.android.com/guide/topics/media/camera.html激活Android 4的自定义相机，但我的捕捉功能完全不起作用。下面是我的代码：

cameraf.java：

public class cameraf extends AppCompatActivity{
private Preview mPreview;
private Camera mCamera;
private static final String TAG = "Myact";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_cameraf);
    mCamera = getCameraInstance();
    mPreview = new Preview(this, mCamera);
    FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
   preview.setOnTouchListener(new View.OnTouchListener(){
        public boolean onTouch(View v, MotionEvent event){
            Log.v(TAG, "will now take picture");
            mCamera.takePicture(null, null, mPicture);
            return true;
        }
    });
    preview.addView(mPreview);
}
private Camera.PictureCallback mPicture = new Camera.PictureCallback() {
    @Override
    public void onPictureTaken(byte[] data, Camera camera) {
        Log.v(TAG, "Getting output media file");
        File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
        if (pictureFile == null) {
            Log.v(TAG, "Error creating output file");
            return;}
        try {
            FileOutputStream fos = new FileOutputStream(pictureFile);
            fos.write(data);
            fos.close();
        } catch (FileNotFoundException e) {
            Log.v(TAG, e.getMessage());
        } catch (IOException e) {
            Log.v(TAG, e.getMessage());}
    }
};
public static final int MEDIA_TYPE_IMAGE = 1;
private static File getOutputMediaFile(int type){
        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_PICTURES), "MyCameraApp");
    if (! mediaStorageDir.exists()){
        if (! mediaStorageDir.mkdirs()){
            Log.d("MyCameraApp", "failed to create directory");
            return null;}
    }
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    File mediaFile;
    if (type == MEDIA_TYPE_IMAGE){
        mediaFile = new File(mediaStorageDir.getPath() + File.separator +
                "IMG_"+ timeStamp + ".jpg");
    } else {
        return null;}
    return mediaFile;
}
public static Camera getCameraInstance(){
    Camera c = null;
    try {
        c = Camera.open(); // attempt to get a Camera instance
    }
    catch (Exception e){
    }
    return c; // returns null if camera is unavailable
}
public class Preview extends SurfaceView implements SurfaceHolder.Callback {
    private SurfaceHolder mHolder;
    private Camera mCamera;
    public Preview(Context context, Camera camera) {
        super(context);
        mCamera = camera;
        mHolder = getHolder();
        mHolder.addCallback(this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }
    public void surfaceCreated(SurfaceHolder holder) {
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.setDisplayOrientation(90);
            Camera.Parameters params = mCamera.getParameters();
            params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
            params.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
            mCamera.setParameters(params);
        } catch (IOException exception) {
            mCamera.release();
            mCamera = null;}
    }
    public void surfaceDestroyed(SurfaceHolder holder) {
        mCamera.stopPreview();
        mCamera.release();
        mCamera = null;
    }
    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        Camera.Parameters parameters = mCamera.getParameters();
        parameters.setPreviewSize(w, h);
        mCamera.startPreview();
    }
}
private void releaseCamera(){
    if (mCamera != null){
        mCamera.release();        // release the camera for other applications
        mCamera = null;
    }
}
}

我已经添加了清单中的权限，这是使用权限Android：名称="android.permission.相机"，使用权限Android：名称="android.permission.WRITE_EXTERNAL_STORAGE"

但从上面的代码可以让我打开相机，但当我在屏幕上点击它成为错误，无法存储图像。所以有人能和我分享想法吗？

Answer 1

您看到的故障可能会发生，因为您没有设置图片大小。有些设备需要这样做。

请注意，您必须选择一种支持的大小，并确保图片大小和预览大小同步（即具有相同的纵横比）。

您无法设置从曲面视图大小派生的预览大小…实际上，您没有：您的调用

parameters.setPreviewSize(w, h);

后面不是

mCamera.setParameters(parameters);