mCamera.takePicture(null, null, mPicture) 不起作用

Question

我跟随https://developer.android.com/guide/topics/media/camera.html 激活了android 4 的自定义相机，但我的捕捉功能完全不起作用。以下是我的代码：

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;
    }
}
}

我在清单中添加了权限 uses-permission android:name="android.permission.CAMERA",uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"

但是从上面的代码它可以让我打开相机但是当我点击屏幕时它变成错误并且无法存储图像。所以任何人都可以分享我的想法吗？

错误：

Answer 1

您看到的失败可能是因为您没有设置图片大小。有些设备需要这个。

请注意，您必须选择支持的尺寸之一，并确保图片尺寸和预览尺寸同步（即具有相同的纵横比）。

您不能设置从表面视图大小派生的预览大小……实际上，您没有：您的电话

parameters.setPreviewSize(w, h);

后面没有

mCamera.setParameters(parameters);