Camera.release（）在屏幕旋轉後被調用後正在使用攝像機

Question

我有一個應用程序在定時器上拍照。通常情況下它可以正常工作，除非相機在睡眠狀態下旋轉屏幕。有誰可以告訴我爲什麼在睡眠中旋轉後無法拍照？

通常情況下，當相機進入睡眠狀態和喚醒它執行...

@Override 
protected void onPause() { 
    super.onPause(); 
    camera.stopPreview(); 
    camera.release(); 
    //camera = null; //this give me a null object message 
} 

@Override 
protected void onResume() { 
    super.onResume(); 
    camera = Camera.open(cameraId); 
    setCameraDisplayOrientation(); 
    startCameraPreview(surfaceHolder, surfaceView.getWidth(), surfaceView.getHeight()); 
} 

然而，相機在睡眠被旋轉後，當它醒來時，它首先執行的onResume（），surfaceChanged （），的onPause（），的onStop（空），的onDestroy（空），則執行下列操作：

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    surfaceView = (SurfaceView) findViewById(R.id.surface); 
    surfaceHolder = surfaceView.getHolder(); 
    surfaceHolder.addCallback(this); 
} 

@Override 
protected void onStart() { 
    super.onStart(); 
} 

@Override 
protected void onResume() { 
    super.onResume(); 
    camera = Camera.open(cameraId); 
    setCameraDisplayOrientation(); 
    startCameraPreview(surfaceHolder, surfaceView.getWidth(), surfaceView.getHeight()); 
} 

@Override 
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { 
    camera.stopPreview(); 
    setCameraDisplayOrientation(); 
    startCameraPreview(holder, w, h); 
} 

public void setCameraDisplayOrientation() { 
    deviceRotation = getWindowManager().getDefaultDisplay().getRotation(); 
    int degrees = 0; 
    switch(deviceRotation) { 
     case Surface.ROTATION_0: degrees=0; break;//vertical 
     case Surface.ROTATION_90: degrees=-90; break; //left side 
     case Surface.ROTATION_180: degrees=180; break; //upside-down 
     case Surface.ROTATION_270: degrees=90; break; //right side 
    } 
    Camera.CameraInfo info = new Camera.CameraInfo(); 
    Camera.getCameraInfo(cameraId, info); 
    displayRotation = info.orientation + degrees; 
    camera.setDisplayOrientation(displayRotation); //changes orientation of camera's display 
} 

public void startCameraPreview(SurfaceHolder holder, int w, int h) { 
    double targetRatio = 0; 
    switch(deviceRotation) { 
     case Surface.ROTATION_0: targetRatio = (double)w/(double)h; break; //vertical 
     case Surface.ROTATION_90: targetRatio = (double)h/(double)w; break; //left side 
     case Surface.ROTATION_180: targetRatio = (double)w/(double)h; break; //upside-down 
     case Surface.ROTATION_270: targetRatio = (double)h/(double)w; break; //right side 
    } 
    Camera.Parameters p = camera.getParameters(); 
    List<Camera.Size> previewSizes = p.getSupportedPreviewSizes(); 
    int optimal_h = 2; //always refers to short length in PreviewSizes 
    int optimal_w = 1; //always refers to long length in PreviewSizes 
    for(Camera.Size previewSize : previewSizes) { 
     if (Math.abs((double)previewSize.height/(double)previewSize.width - targetRatio) < 
       Math.abs((double)optimal_h/(double)optimal_w - targetRatio)) { 
      optimal_h = previewSize.height; 
      optimal_w = previewSize.width; 
     } 
    } 
    p.setPreviewSize(optimal_w, optimal_h); //defines ratio of image preview - sizes can be larger than actual display 
    p.set("rotation", displayRotation); //required to orient final jpeg file correctly 
    camera.setParameters(p); 
    ViewGroup.LayoutParams surfaceParams = surfaceView.getLayoutParams(); 
    switch(deviceRotation) { //aligns ratio of surface view to ratio of image preview 
     case Surface.ROTATION_0: 
      surfaceParams.width=ViewGroup.LayoutParams.MATCH_PARENT; 
      surfaceParams.height=(int)(w*(double)optimal_w/(double)optimal_h); 
      break; //vertical 
     case Surface.ROTATION_90: 
      surfaceParams.width=(int)(h*(double)optimal_w/(double)optimal_h); 
      surfaceParams.height=ViewGroup.LayoutParams.MATCH_PARENT; 
      break; //left side 
     case Surface.ROTATION_180: 
      surfaceParams.width=ViewGroup.LayoutParams.MATCH_PARENT; 
      surfaceParams.height=(int)(w*(double)optimal_w/(double)optimal_h); 
      break; //upside-down 
     case Surface.ROTATION_270: 
      surfaceParams.width=(int)(h*(double)optimal_w/(double)optimal_h); 
      surfaceParams.height=ViewGroup.LayoutParams.MATCH_PARENT; 
      break; //right side 
    } 
    surfaceView.setLayoutParams(surfaceParams); 
    camera.setPreviewDisplay(holder); //required to startPreview 
    camera.startPreview(); 
} 

這不是完整代碼。此代碼確實會產生一些較小的圖像格式錯誤，但它仍然表明此問題。爲了簡單起見，我已經刪除了一些內容。主要問題是當它在睡眠中旋轉後嘗試拍照時，它會返回一個錯誤「Camera.release（）被調用後正在使用相機」。爲什麼是這樣？

Answer 1

這實在是過期了，但是因爲我在一分鐘前解決了類似的問題，所以我認爲我會爲自己和任何可能拼命搜索Stack的人提供幫助。

因此，當您旋轉設備時，您正在調用onPause和onDestroy，您正在釋放相機。我注意到你的onResume中有camera.open（），而沒有看到我無法評論的與表面相關的代碼。繼承人什麼對我有效。

首先，cameraPreview

`

public void surfaceChanged(SurfaceHolder surfaceHolder, int format, int width, int height) { 
    try { 
     this.mCamera.setPreviewDisplay(surfaceHolder); 
     this.mCamera.startPreview(); 
    } catch (Exception e) { 
    } 
} 


public void surfaceCreated(SurfaceHolder surfaceHolder) { 
    try { 
     //TODO we need this here too because on SurfaceCreated we always need to open the camera, in case its released 

     this.mCamera.setPreviewDisplay(surfaceHolder); 
     this.mCamera.setDisplayOrientation(90); 
     //this.mCamera.startPreview(); 
    } catch (IOException e) { 
    } 
} 

接下來，CameraActivity的生命週期代碼

@Override 
public void onResume() { 
    super.onResume(); 
    try{ 
     mCamera = openFrontFacingCameraGingerbread(); 
     // Add to Framelayout 
     this.mCameraPreview = new CameraPreview(this, this.mCamera); 
     mImage.removeAllViews(); 
     this.mImage.addView(this.mCameraPreview); 

    }catch (RuntimeException ex){ 

    } 



} 


@Override 
public void onPause() { 
    super.onPause(); 
    captureButton.setText("Begin Capture"); 
    if(CameraActivity.this.timer !=null) { 
     CameraActivity.this.timer.cancel(); 
     CameraActivity.this.timer.purge(); 
     CameraActivity.this.timer = null; 
    } 
    if (mCamera != null) { 
     mCamera.setPreviewCallback(null); 
     mCameraPreview.getHolder().removeCallback(mCameraPreview); 
     mCamera.release(); 
     mCamera = null; 
    } 


} 


@Override 
protected void onDestroy(){ 
    super.onDestroy(); 
    releaseCameraAndPreview(); 
} 

private void releaseCameraAndPreview() { 

    if (mCamera != null) { 
     mCamera.stopPreview(); 
     mCamera.release(); 
     mCamera = null; 
    } 
    if(mCameraPreview != null){ 
     mCameraPreview.destroyDrawingCache(); 
     mCameraPreview.mCamera = null; 
    } 
}