title: zxing qr code scanner camera showing white screen
body: <p>Good day! i'm having an issue with the qr code scanner in android marshmallow and nougat using the library that i have added as dependency in my project the camera shows white screen. Code runs perfectly in lollipop and kitkat. Please let me know if there was something i have missed or something i will do to make it work. I have paste my snippets of code down below. It is my pleasure if you give me some time to notice my concern. I have seen similar topic of my issue but it did not help me work out or i have implemented it wrong. Thank you in advance. </p>
  
  <p>I have zxing jar library for generating qr code, and i used me.dm7.barcodescanner:zxing:1.8.4 for scanning qr codes:</p>
  
  <pre><code>dependency {
   compile fileTree(dir: 'libs', include: ['*.jar'])
   compile files('libs/zxing-2.1.jar')
   compile('me.dm7.barcodescanner:zxing:1.8.4'){
      exclude group: 'com.google.zxing'
     }
  }
  </code></pre>
  
  <p>The Activity for the opening of the camera:</p>
  
  <pre><code>public class ScanQRCodeActivity extends AppCompatActivity implements ZXingScannerView.ResultHandler {
  private String strDataEncrypted;
  private ZXingScannerView mScannerView;
  public static String strEncrypt;
  public static String strEncrypted;
  public static String strIV;
  public static boolean isScanSuccess = false;
  
  @Override
  public void onCreate(Bundle state) {
      super.onCreate(state);
      mScannerView = new ZXingScannerView(this);
      setContentView(mScannerView);
  }
  
  @Override
  public void onResume() {
      super.onResume();
      mScannerView.setResultHandler(this);
      mScannerView.startCamera();
  }
  
  @Override
  public void onPause() {
      super.onPause();
      mScannerView.stopCamera();
  }
  
  @Override
  public void handleResult(Result result) {
      strDataEncrypted = result.getText();
      Log.wtf("handleResult", strDataEncrypted);
      String[] strSplit = strDataEncrypted.split("\\|\\|");
      strEncrypted = strSplit[0].trim();
      strIV = strSplit[1];
      CryptLibHelper cryptLibHelper = new CryptLibHelper();
      cryptLibHelper.decrypt(strEncrypted, strIV, new CryptLibHelper.CryptLibDecryptCallback() {
          @Override
          public void onDecryptFailed(String str_message) {
              Log.wtf("onDecryptFailed", str_message);
          }
  
          @Override
          public void onDecryptSuccess(String str_message) {
              if (str_message.contains("}")) {
                  strEncrypt = str_message.replace("}", "");
                  Log.wtf("onDecryptSuccess", strEncrypt);
              }
          }
      });
      onBackPressed();
      isScanSuccess = true;
      mScannerView.resumeCameraPreview(this);
  }
  </code></pre>
  
  <p>}</p>