Android camera preview - 'no file - can't switch camera'

Question

I'm trying to create a very simple app that simply shows what the camera is viewing on the screen. I created the app with an emulator(same specification as the phone I used) which shows the black and white squared background with the grey viewing box moving over it, so I'm pretty sure I've got all code and permissions correct.

When I try to run the App on my Wildfire Phone(Android Version: 2.2.1) It force closes before anything is shown and when I check the logs this error is shown.

12-08 12:41:42.649: W/CameraSwitch(3004): open main camera
12-08 12:41:42.659: W/CameraSwitch(3004): no file - can't switch camera
12-08 12:41:43.239: D/AndroidRuntime(3004): Shutting down VM

I looked through some sites and it seems it might be a problem with the OS or the hardware. Has anyone found a work around?

I'm going to post my code just in case I've made a foolish mistake.

import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.os.Bundle;

public class InformationPassingTestActivity extends Activity {

Preview preview;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
    preview = new Preview(this);
    setContentView(preview);
    }
}

my preview class that handles the camera

class Preview extends SurfaceView implements SurfaceHolder.Callback {

SurfaceHolder mHolder;
public Camera camera;

Preview(Context context) {
    super(context);

    mHolder = getHolder();
    mHolder.addCallback(this);
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

public void surfaceCreated(SurfaceHolder holder) {

    camera = Camera.open();
    try {
        camera.setPreviewDisplay(holder);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

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

public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    Camera.Parameters parameters = camera.getParameters();
    parameters.setPreviewSize(width, height);
    camera.setParameters(parameters);
    camera.startPreview();
}   
}

Manifest.xml

<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

<uses-sdk android:minSdkVersion="8" />
<application android:icon="@drawable/ic_launcher" android:label="@string/app_name" >
<activity android:label="@string/app_name"         android:name=".InformationPassingTestActivity" >
    <intent-filter>
    <action android:name="android.intent.action.MAIN" />
    <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
    </activity>
</application>

Any help would be amazing :)

score 3 · Accepted Answer · edited Dec 13 '13 at 15:44

Your problem is probably from this line (or if it isn't yet it will be): parameters.setPreviewSize(width, height);

Actual cameras can't support every preview size. You need to choose a preview size that is close to the size of your surface and supported by the camera hardware. Here's a sample method to do that:

private  Camera.Size getBestPreviewSize(int width, int height,
                                          Camera.Parameters parameters) {
     Camera.Size result=null;

    for ( Camera.Size size : parameters.getSupportedPreviewSizes()) {
      if (size.width<=width && size.height<=height) {
        if (result==null) {
          result=size;
        }
        else {
          int resultArea=result.width*result.height;
          int newArea=size.width*size.height;

          if (newArea>resultArea) {
            result=size;
          }
        }
      }
    }

    return(result);
  }

You may also have a problem calling Camera.open() in surfaceCreated without checking whether or not the camera has already been opened. Try moving that call to your onCreate and onResume methods and adding a call to Camera.release() in your onPause method so that you don't attempt to open the camera more than once.

... and keep in mind, that even if camera advertises preview size it does not always support it. Got my @ss bitten by HTC Hero once ;) — Konstantin Pribluda, Dec 08 '11 at 13:54
Sorry it took me so long to comment/approve/rate your answer, this works perfectly. The issue was the supported sizes, while I did not use your code directly it did reveal the problem. Thank you so much :) — Michael Horsley, Apr 17 '12 at 14:39

Android camera preview - 'no file - can't switch camera'

1 Answers1