Аннулирование пользовательской камеры Android при возобновлении

Question

У меня есть эта пользовательская активность камеры в моем приложении, которая работает нормально, но когда я нажимаю кнопку «домой» во время действия камеры, а затем возвращаюсь в приложение, она вылетает, а лог-код говорит, что при создании представления поверхности было исключение нулевого указателя. Этот метод установки называется на onResume:

public void setup() 
    { 

    preview = new CameraPreview(this); 
    ((FrameLayout) findViewById(R.id.camera_preview)).addView(preview); 
    head=(ImageView)findViewById(R.id.head); 
     head.setX((float)(Shared.screenWidth/5*1.8)); 
     head.setY((float)(Shared.screenHeight*0.03)); 
     LayoutParams params = (LayoutParams) head.getLayoutParams(); 
     params.width = (int)((Shared.screenWidth/5*3.2)-(head.getX())); 
     params.height=(int)((Shared.screenHeight/3.8)-(head.getY())); 
     head.setLayoutParams(params); 
    body=(ImageView)findViewById(R.id.body); 
     body.setX((float)(Shared.screenWidth/7)); 
     body.setY((float)(Shared.screenHeight/3.8)); 
     LayoutParams params2 = (LayoutParams) body.getLayoutParams(); 
     params2.width = (int)((Shared.screenWidth/7*6)-(body.getX())); 
     params2.height=(int)((Shared.screenHeight)-(body.getY())); 
     body.setLayoutParams(params2); 
    go=(Button)findViewById(R.id.go); 
    again=(Button)findViewById(R.id.again); 
    stop=(ImageButton)findViewById(R.id.stop); 
    stop.setOnClickListener(new OnClickListener() { 
     public void onClick(View v) { 
      Intent i =new Intent(CamActivity.this,Main.class); 
      i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
      startActivity(i); 


     } 
    }); 
    btn = (ImageButton) findViewById(R.id.takePic); 
    btn.setOnClickListener(new OnClickListener() { 
     public void onClick(View v) { 
      preview.camera.takePicture(shutterCallback, rawCallback, jpegCallback); 
      btn.setVisibility(View.INVISIBLE); 
      btn.setEnabled(false); 
      go.setVisibility(View.VISIBLE); 
      go.setEnabled(true); 
      head.setVisibility(View.INVISIBLE); 
      body.setVisibility(View.INVISIBLE); 
      go.setOnClickListener(new OnClickListener() { 
       public void onClick(View v) { 
        Shared.bm=Bitmap.createScaledBitmap(bmp, Shared.screenWidth, Shared.screenHeight, true); 

        Intent i=new Intent(CamActivity.this,IKill.class); 
        i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
        startActivity(i); 

       } 
      }); 
      again.setVisibility(View.VISIBLE); 
      again.setEnabled(true); 
      again.setOnClickListener(new OnClickListener() { 
       public void onClick(View v) { 
        if (Build.VERSION.SDK_INT >= 11) { 
         recreate(); 
        } else { 
         Intent intent = getIntent(); 
         overridePendingTransition(0, 0); 
         intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION); 
         finish(); 

         overridePendingTransition(0, 0); 
         startActivity(intent); 
        } 

       } 
      }); 

     } 
    }); 


} 

Кроме того, на мой OnCreate метод, который я также это:

requestWindowFeature(Window.FEATURE_NO_TITLE); 

    // hide status bar 
    final Window win = getWindow(); 
    win.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
       WindowManager.LayoutParams.FLAG_FULLSCREEN); 
    setContentView(R.layout.activity_camera); 

и LogCat:

08-23 08:56:20.174: E/AndroidRuntime(835): FATAL EXCEPTION: main 
08-23 08:56:20.174: E/AndroidRuntime(835): java.lang.NullPointerException 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
com.example.i_kill.CameraPreview.surfaceCreated(CameraPreview.java:38) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.SurfaceView.updateWindow(SurfaceView.java:569) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.SurfaceView.access$000(SurfaceView.java:86) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.SurfaceView$3.onPreDraw(SurfaceView.java:174) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:680) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1842) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.Choreographer.doCallbacks(Choreographer.java:562) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.Choreographer.doFrame(Choreographer.java:532) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.os.Handler.handleCallback(Handler.java:725) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.os.Handler.dispatchMessage(Handler.java:92) 
08-23 08:56:20.174: E/AndroidRuntime(835): at android.os.Looper.loop(Looper.java:137) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
android.app.ActivityThread.main(ActivityThread.java:5041) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
java.lang.reflect.Method.invokeNative(Native Method) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
java.lang.reflect.Method.invoke(Method.java:511) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
08-23 08:56:20.174: E/AndroidRuntime(835): at 
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
08-23 08:56:20.174: E/AndroidRuntime(835): at dalvik.system.NativeStart.main(Native 
Method) 
08-23 08:56:26.065: E/Trace(909): error opening trace file: No such file or directory 

и вот весь класс: упаковка com.example.i_kill;

import android.app.Activity; 
import android.content.Intent; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.hardware.Camera; 
import android.hardware.Camera.PictureCallback; 
import android.hardware.Camera.ShutterCallback; 
import android.os.Build; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.view.ViewGroup.LayoutParams; 
import android.view.Window; 
import android.view.WindowManager; 
import android.widget.Button; 
import android.widget.FrameLayout; 
import android.widget.ImageButton; 
import android.widget.ImageView; 


public class CamActivity extends Activity { 
public static final int MEDIA_TYPE_IMAGE = 1; 
public static String TAG="MainActivity"; 
private static Camera camera; 
private CameraPreview preview; 
private ImageView head,body; 
private ImageButton btn, stop; 
private Button again,go; 
private Bitmap bmp; 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 

    // hide status bar 
    final Window win = getWindow(); 
    win.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
       WindowManager.LayoutParams.FLAG_FULLSCREEN); 
    setContentView(R.layout.activity_camera); 

} 
    public void setup() 
    { 

    preview = new CameraPreview(this); 
    ((FrameLayout) findViewById(R.id.camera_preview)).addView(preview); 
    head=(ImageView)findViewById(R.id.head); 
     head.setX((float)(Shared.screenWidth/5*1.8)); 
     head.setY((float)(Shared.screenHeight*0.03)); 
     LayoutParams params = (LayoutParams) head.getLayoutParams(); 
     params.width = (int)((Shared.screenWidth/5*3.2)-(head.getX())); 
     params.height=(int)((Shared.screenHeight/3.8)-(head.getY())); 
     head.setLayoutParams(params); 
    body=(ImageView)findViewById(R.id.body); 
     body.setX((float)(Shared.screenWidth/7)); 
     body.setY((float)(Shared.screenHeight/3.8)); 
     LayoutParams params2 = (LayoutParams) body.getLayoutParams(); 
     params2.width = (int)((Shared.screenWidth/7*6)-(body.getX())); 
     params2.height=(int)((Shared.screenHeight)-(body.getY())); 
     body.setLayoutParams(params2); 
    go=(Button)findViewById(R.id.go); 
    again=(Button)findViewById(R.id.again); 
    stop=(ImageButton)findViewById(R.id.stop); 
    stop.setOnClickListener(new OnClickListener() { 
     public void onClick(View v) { 
      Intent i =new Intent(CamActivity.this,Main.class); 
      i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
      startActivity(i); 


     } 
    }); 
    btn = (ImageButton) findViewById(R.id.takePic); 
    btn.setOnClickListener(new OnClickListener() { 
     public void onClick(View v) { 
      preview.camera.takePicture(shutterCallback, rawCallback, jpegCallback); 
      btn.setVisibility(View.INVISIBLE); 
      btn.setEnabled(false); 
      go.setVisibility(View.VISIBLE); 
      go.setEnabled(true); 
      head.setVisibility(View.INVISIBLE); 
      body.setVisibility(View.INVISIBLE); 
      go.setOnClickListener(new OnClickListener() { 
       public void onClick(View v) { 
        Shared.bm=Bitmap.createScaledBitmap(bmp, Shared.screenWidth, Shared.screenHeight, true); 

        Intent i=new Intent(CamActivity.this,IKill.class); 
        i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
        startActivity(i); 

       } 
      }); 
      again.setVisibility(View.VISIBLE); 
      again.setEnabled(true); 
      again.setOnClickListener(new OnClickListener() { 
       public void onClick(View v) { 
        if (Build.VERSION.SDK_INT >= 11) { 
         recreate(); 
        } else { 
         Intent intent = getIntent(); 
         overridePendingTransition(0, 0); 
         intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION); 
         finish(); 

         overridePendingTransition(0, 0); 
         startActivity(intent); 
        } 

       } 
      }); 

     } 
    }); 


} 

ShutterCallback shutterCallback = new ShutterCallback() { 
    public void onShutter() { 
     Log.d(TAG, "onShutter'd"); 
    } 
}; 

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) { 
     bmp=BitmapFactory.decodeByteArray(data, 0, data.length); 
     System.out.println(bmp.getHeight()); 
     System.out.println(bmp.getWidth()); 
}; 
}; 


public void onPause(){ 
super.onPause(); 
if(camera!=null){ 
    camera.stopPreview(); 
    camera.setPreviewCallback(null); 

    camera.release(); 
    camera = null; 
} 


} 


public void onResume() 
{ 
super.onResume(); 
setup(); 
    } 
} 

и камеры предварительного просмотра Класс:

package com.example.i_kill; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.util.List; 

import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.hardware.Camera; 
import android.hardware.Camera.PreviewCallback; 
import android.hardware.Camera.Size; 
import android.util.Log; 
import android.view.SurfaceHolder; 
import android.view.SurfaceView; 


public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback { 
private SurfaceHolder holder; 
public Camera camera; 
public static String TAG="CameraPreview"; 
public CameraPreview(Context context) { 
    super(context); 

    holder=getHolder(); 
    holder.addCallback(this); 
    holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 
} 
public void surfaceCreated(SurfaceHolder holder) { 
// The Surface has been created, now tell the camera where to draw the preview. 

camera = getCameraInstance(); 

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

} 

public void surfaceDestroyed(SurfaceHolder holder) { 

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

    camera.release(); 
    camera = null; 
} 

} 
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { 
Camera.Parameters parameters = camera.getParameters(); 
    List<Size> previewSizes = parameters.getSupportedPreviewSizes(); 
    Size bestSize = null; 
    int bestDiff = 0; 
int diff = 0; 
    for (Size size : previewSizes) { 
     diff = Math.abs(h - size.height) + Math.abs(w - size.width); 
    if (bestSize == null || diff < bestDiff) { 
      bestSize = size; 
      bestDiff = diff; 
    } 
    parameters.setPreviewSize(bestSize.width, bestSize.height); 
    camera.setParameters(parameters); 
    } 

     //start preview of camera 
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); 
} 

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

Спасибо за вашу помощь :)

Answer 1

Я решил это, позвонив по телефону setContentView в резюме. Спасибо вам всем!

Answer 2

Если не призыв к getHolder() быть сделано в surfaceCreated? Найдено ниже в documentation:

Доступ к подстилающей поверхности обеспечивается через интерфейс SurfaceHolder , которые могут быть извлечены с помощью вызова getHolder().

Поверхность будет создана для вас, пока окно SurfaceView будет visible; вы должны реализовать surfaceCreated (SurfaceHolder) и surfaceDestroyed (SurfaceHolder), чтобы обнаружить, когда поверхность создана и уничтожена при показе и скрытии окна.

Answer 3

Это мое решение.

public void onResume(){ 
    super.onResume(); 

    if(mCamera ==null){ 

    setContentView(R.layout.activity_capture_local_plates);  
    autoFocusHandler = new Handler(); 
    mCamera = getCameraInstance();  

    mPreview = new CameraPreview(this, mCamera, previewCb, autoFocusCB); 
    FrameLayout preview = (FrameLayout)findViewById(R.id.cameraPreview); 
    preview.addView(mPreview); 

    } 

}