Android相机 - 有时当我拍照时,应用程序冻结,相机无法使用

Question

我已经构建了一个应用程序,可以在您触摸预览时拍照.我可以拍很多照片,但有时当我触摸预览拍照时,没有快门声,整个应用都冻结了.此外,在那之后,如果我尝试启动内置相机应用程序,我收到一条消息,说明相机无法使用.

我不知道这种行为的原因,它是随机发生的,当它发生时我必须重新启动设备(三星Galaxy S)才能再次使用相机.

在DDM中,崩溃后我可以看到以下行:keyDispatchingTimedOut

以下是相关代码:CameraActivity类:

public class CameraActivity extends Activity {
  private static final String TAG = "CameraDemo";
  Preview preview;

  public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    preview = new Preview(this);
    ((FrameLayout) findViewById(R.id.preview)).addView(preview);
    ((FrameLayout) findViewById(R.id.preview)).setOnTouchListener(preview); 

    Log.d(TAG, "Camera Activity Created.");

  }
}

预览课程:

    class Preview extends SurfaceView implements SurfaceHolder.Callback, OnTouchListener {
    private static final String TAG = "Preview";

    SurfaceHolder mHolder;
    public Camera camera;
    Context ctx;
    boolean previewing = false;

    Preview(Context context) {
        super(context);
        ctx = context;
        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }


    // Called once the holder is ready
    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, acquire the camera and tell it where
        // to draw.
        camera = Camera.open();
    }

    // Called when the holder is destroyed
    public void surfaceDestroyed(SurfaceHolder holder) {

        if (camera != null) {
            camera.setPreviewCallback(null);
            camera.stopPreview();  
            camera.release();
            camera = null;
        }

        previewing = false;
    }

    // Called when holder has changed
    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {

        if(previewing){
             camera.stopPreview();
             previewing = false;
        }

        if (camera != null){
            try {

                camera.setDisplayOrientation(90);
                camera.setPreviewDisplay(holder);
                camera.setPreviewCallback(new PreviewCallback() {
                    // Called for each frame previewed
                    public void onPreviewFrame(byte[] data, Camera camera) {
                        Log.d(TAG, "onPreviewFrame called at: " + System.currentTimeMillis());  
                        Preview.this.invalidate();
                    }
                });
                camera.startPreview();
                previewing = true;
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    public boolean onTouch(View v, MotionEvent event) {
        camera.takePicture(shutterCallback, rawCallback, jpegCallback);
        return false;
    }


    // Called when shutter is opened
    ShutterCallback shutterCallback = new ShutterCallback() {
        public void onShutter() {
            Log.d(TAG, "onShutter'd");
        }
    };

    // Handles data for raw picture
    PictureCallback rawCallback = new PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            Log.d(TAG, "onPictureTaken - raw");
        }
    };

    // Handles data for jpeg picture
    PictureCallback jpegCallback = new PictureCallback() {

        public void onPictureTaken(byte[] data, Camera camera) {
            FileOutputStream outStream = null;
            try {
                // Write to SD Card
                outStream = new FileOutputStream(String.format("/sdcard/TVguide/Detection/detected.jpg", System.currentTimeMillis())); // <9>
                outStream.write(data);
                outStream.close();
                Log.d(TAG, "onPictureTaken - wrote bytes: " + data.length);
            } catch (FileNotFoundException e) { // <10>
                //Toast.makeText(ctx, "Exception #2", Toast.LENGTH_LONG).show();
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {}
            Log.d(TAG, "onPictureTaken - jpeg");
            Toast.makeText(ctx, "SAVED", Toast.LENGTH_SHORT).show();

            camera.startPreview();
        }
    };

}

请帮助,我试着几天了解问题所在并没有成功

的Eyal

Answer 1

我在三星Galaxy SII上测试我的应用程序时遇到了这个问题.您只需在拍照前删除预览回调:

mCamera.setPreviewCallback(null);
mCamera.takePicture(null, null, mPictureCallback);

Answer 2

我不知道导致该错误的原因,如果您从发生此错误的时间开始发布loggcat输出,这将非常有用.

但是,我可以做一些保护.它看起来像相机被锁定(内置相机不起作用).如果您的应用程序强制关闭,相机锁定可能是由三星相机HAL中的错误处理错误引起的.特别是在像Galaxy S这样的旧款手机中,他们在处理错误或非标准API调用时并没有做得最好.

以下是可能导致此行为的一些建议:

1. 你应该为拍照添加一个警卫.现在,如果您触摸屏幕并拍照,则可以在照片完成拍摄之前再次触摸屏幕.因此,camera.takePicture()将被调用两次.第二个将失败.这是我最好的猜测.

   添加一些boolean isTakingPicture = false变量,然后:

   public boolean onTouch(View v, MotionEvent event) {
     if (!isTakingPicture) {
       camera.takePicture(shutterCallback, rawCallback, jpegCallback);
       isTakingPicture = true;
     }
     return false;
   }
   ...
   public void onPictureTaken(byte[] data, Camera camera) {
     isTakingPicture = false;
     ...
   

2. 你使用previewCallback做什么？我这里没有做任何有用的事情.虽然你的代码看起来很好,但有时预览回调有时会引起一些痛苦.你可以尝试删除它并检查是否有帮助.