java - Camera.takePicture(null, null, mPicture) 不起作用

Question

我关注https://developer.android.com/guide/topics/media/camera.html激活 android 4 的自定义相机，但我的拍摄功能完全不起作用。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;
    }
}
}

我已经在 list 中添加了权限，即 uses-permission android:name="android.permission.CAMERA",uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"

但是从上面的代码来看，它可以让我打开相机，但是当我点击屏幕时，它会出错并且无法存储图像。那么有人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而发生的。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(即具有相同的宽高比)。

您无法设置从表面 View 尺寸派生的预览尺寸……实际上，您不这样做:您的电话

parameters.setPreviewSize(w, h);

后面没有

mCamera.setParameters(parameters);