Question

我制作的应用程序使用相机将数据发送到surfaceHolder。但是当我调用addCallBack（）时，我的应用程序崩溃了。这是代码：

public class Cam_View extends Activity implements SurfaceHolder.Callback{

private SurfaceView camView;
private SurfaceHolder camHolder;
private boolean previewRunning;

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.camera);

camView = (SurfaceView)findViewById(R.id.sview);
camHolder = camView.getHolder();
camHolder.addCallback(this);
camHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}}

未实现的方法：

 @Override
  public void surfaceChanged(SurfaceHolder holder, int format, int width,
    int height) {
if(previewRunning){
    camera.stopPreview();
}
Camera.Parameters camParams = camera.getParameters();
camParams.setPreviewFormat(PixelFormat.JPEG);
camera.setParameters(camParams);
try{
    camera.setPreviewDisplay(holder);
    camera.startPreview();
    previewRunning=true;
}catch(IOException e){
    e.printStackTrace();
}
 }


 public void surfaceCreated(SurfaceHolder holder) {
try{
    camera=Camera.open();
}catch(Exception e){
    e.printStackTrace();
    Toast.makeText(getApplicationContext(),"Error",Toast.LENGTH_LONG).show();
    finish();
}
 }

  @Override
  public void surfaceDestroyed(SurfaceHolder holder) {
camera.stopPreview();
camera.release();
camera=null;
  }

为什么我打电话时应用程序崩溃了 camHolder.addCallback（本）; ？我的代码中还有其他问题吗？

Answer 1

我尝试了上面的代码。它在我的设备上工作正常。我成功地启动了相机。我不认为他们的问题在camHolder.addCallback（this）;

问题在线

camParams.setPreviewFormat（PixelFormat.JPEG）;

用

更新它

Camera.Size size = camParams.getSupportedPreviewSizes（）。get（0）; camParams.setPreviewSize（size.width，size.height）;

您的代码将有效。

还要确保正确添加以下内容。

1）名为SurfaceView的sview退出你的布局

2）添加相机权限 - “android.permission.CAMERA”

如果问题仍然存在，请分享日志。

Answer 2

检查此代码，这对我有用。

FIRST CameraDemo活动

public class CameraDemo extends Activity {
    private static final String TAG = "CameraDemo";
    Camera camera;
    Preview preview;
    Button buttonClick;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera_demo);

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

        buttonClick = (Button) findViewById(R.id.buttonClick);
        buttonClick.setOnClickListener( new OnClickListener() {
            public void onClick(View v) {
                preview.camera.takePicture(shutterCallback, rawCallback, jpegCallback);
            }
        });

        Log.d(TAG, "onCreate'd");
    }


    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;
            long time = 0;
            try {
                // write to local sandbox file system
//                outStream = CameraDemo.this.openFileOutput(String.format("%d.jpg", System.currentTimeMillis()), 0);    
                // Or write to sdcard
                time =  System.currentTimeMillis();
                outStream = new FileOutputStream(String.format("/sdcard/%d.jpg",time));    
                outStream.write(data);
                outStream.close();
                Log.d(TAG, "onPictureTaken - wrote bytes: " + data.length);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {



            }
            Log.d(TAG, "onPictureTaken - jpeg");
        }
    };

}

AND预览课程为：

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

    SurfaceHolder mHolder;
    public static Camera camera;

    Preview(Context context) {
        super(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);
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, acquire the camera and tell it where
        // to draw.



        /*  camera =  getCameraInstance();

        camera = Camera.open();*/

        //int cameraType = 1; // front
        camera = Camera.open(CameraInfo.CAMERA_FACING_BACK);



        try {
            camera.setPreviewDisplay(holder);


            camera.setPreviewCallback(new PreviewCallback() {

                public void onPreviewFrame(byte[] data, Camera arg1) {
                    FileOutputStream outStream = null;
                    try {
                        outStream = new FileOutputStream(String.format("/sdcard/%d.jpg", System.currentTimeMillis()));    
                        outStream.write(data);
                        outStream.close();
                        Log.d(TAG, "onPreviewFrame - wrote bytes: " + data.length);
                    } catch (FileNotFoundException e) {

                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    } finally {
                    }
                        Preview.this.invalidate();
                }
            });
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static Camera getCameraInstance(){
        camera = null;
        try {
            camera = Camera.open(); // attempt to get a Camera instance
        }
        catch (Exception e){
            // Camera is not available (in use or does not exist)
        }
        return camera; // returns null if camera is unavailable
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // Surface will be destroyed when we return, so stop the preview.
        // Because the CameraDevice object is not a shared resource, it's very
        // important to release it when the activity is paused.
        camera.stopPreview();

        camera.release();
        camera = null;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // Now that the size is known, set up the camera parameters and begin
        // the preview.
        Camera.Parameters parameters = camera.getParameters();
//        parameters.setPreviewSize(w, h);
        camera.setParameters(parameters);
        camera.startPreview();
    }

    @Override
    public void draw(Canvas canvas) {
            super.draw(canvas);
            Paint p= new Paint(Color.RED);
            Log.d(TAG,"draw");
            canvas.drawText("PREVIEW", canvas.getWidth()/2, canvas.getHeight()/2, p );
    }
}

使用手机的相机

2 个答案: