code: package me.dm7.barcodescanner.zbar;
  
  import android.content.Context;
  import android.content.res.Configuration;
  import android.graphics.Rect;
  import android.hardware.Camera;
  import android.os.Handler;
  import android.os.Looper;
  import android.text.TextUtils;
  import android.util.AttributeSet;
  import android.util.Log;
  
  import net.sourceforge.zbar.Config;
  import net.sourceforge.zbar.Image;
  import net.sourceforge.zbar.ImageScanner;
  import net.sourceforge.zbar.Symbol;
  import net.sourceforge.zbar.SymbolSet;
  
  import java.nio.charset.StandardCharsets;
  import java.util.Collection;
  import java.util.List;
  
  import me.dm7.barcodescanner.core.BarcodeScannerView;
  import me.dm7.barcodescanner.core.DisplayUtils;
  
  public class ZBarScannerView extends BarcodeScannerView {
      private static final String TAG = "ZBarScannerView";
  
      public interface ResultHandler {
          public void handleResult(Result rawResult);
      }
  
      static {
          System.loadLibrary("iconv");
      }
  
      private ImageScanner mScanner;
      private List<BarcodeFormat> mFormats;
      private ResultHandler mResultHandler;
  
      public ZBarScannerView(Context context) {
          super(context);
          setupScanner();
      }
  
      public ZBarScannerView(Context context, AttributeSet attributeSet) {
          super(context, attributeSet);
          setupScanner();
      }
  
      public void setFormats(List<BarcodeFormat> formats) {
          mFormats = formats;
          setupScanner();
      }
  
      public void setResultHandler(ResultHandler resultHandler) {
          mResultHandler = resultHandler;
      }
  
      public Collection<BarcodeFormat> getFormats() {
          if(mFormats == null) {
              return BarcodeFormat.ALL_FORMATS;
          }
          return mFormats;
      }
  
      public void setupScanner() {
          mScanner = new ImageScanner();
          mScanner.setConfig(0, Config.X_DENSITY, 3);
          mScanner.setConfig(0, Config.Y_DENSITY, 3);
  
          mScanner.setConfig(Symbol.NONE, Config.ENABLE, 0);
          for(BarcodeFormat format : getFormats()) {
              mScanner.setConfig(format.getId(), Config.ENABLE, 1);
          }
      }
  
      @Override
      public void onPreviewFrame(byte[] data, Camera camera) {
          if(mResultHandler == null) {
              return;
          }
  
          try {
              Camera.Parameters parameters = camera.getParameters();
              Camera.Size size = parameters.getPreviewSize();
              int width = size.width;
              int height = size.height;
  
              if (DisplayUtils.getScreenOrientation(getContext()) == Configuration.ORIENTATION_PORTRAIT) {
                  int rotationCount = getRotationCount();
                  if (rotationCount == 1 || rotationCount == 3) {
                      int tmp = width;
                      width = height;
                      height = tmp;
                  }
                  data = getRotatedData(data, camera);
              }
  
              Rect rect = getFramingRectInPreview(width, height);
              Image barcode = new Image(width, height, "Y800");
              barcode.setData(data);
              barcode.setCrop(rect.left, rect.top, rect.width(), rect.height());
  
              int result = mScanner.scanImage(barcode);
  
              if (result != 0) {
                  SymbolSet syms = mScanner.getResults();
                  final Result rawResult = new Result();
                  for (Symbol sym : syms) {
                      // In order to retreive QR codes containing null bytes we need to
                      // use getDataBytes() rather than getData() which uses C strings.
                      // Weirdly ZBar transforms all data to UTF-8, even the data returned
                      // by getDataBytes() so we have to decode it as UTF-8.
                      String symData;
                      if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {
                          symData = new String(sym.getDataBytes(), StandardCharsets.UTF_8);
                      } else {
                          symData = sym.getData();
                      }
                      if (!TextUtils.isEmpty(symData)) {
                          rawResult.setContents(symData);
                          rawResult.setBarcodeFormat(BarcodeFormat.getFormatById(sym.getType()));
                          break;
                      }
                  }
  
                  Handler handler = new Handler(Looper.getMainLooper());
                  handler.post(new Runnable() {
                      @Override
                      public void run() {
                          // Stopping the preview can take a little long.
                          // So we want to set result handler to null to discard subsequent calls to
                          // onPreviewFrame.
                          ResultHandler tmpResultHandler = mResultHandler;
                          mResultHandler = null;
                          
                          stopCameraPreview();
                          if (tmpResultHandler != null) {
                              tmpResultHandler.handleResult(rawResult);
                          }
                      }
                  });
              } else {
                  camera.setOneShotPreviewCallback(this);
              }
          } catch(RuntimeException e) {
              // TODO: Terrible hack. It is possible that this method is invoked after camera is released.
              Log.e(TAG, e.toString(), e);
          }
      }
  
      public void resumeCameraPreview(ResultHandler resultHandler) {
          mResultHandler = resultHandler;
          super.resumeCameraPreview();
      }
  }
  