Prerequisite:
• Android 4.2.2+
• Latest Android SDK
• Google Play Services 7.8+ (Rev. 26.0 in SDK)
• compile 'com.android.support:appcompat-v7:22.0.0'
• compile 'com.google.android.gms:play-services:7.8+'
Download the code sample code from this link,import the barcode-reader project in android studio. Add the google play services 7.8+ & add the mentioned support library in your app gradle. Now modified the BarcodeTrackerFactory.java and MultiTrackerActivity.java class.
BarcodeTrackerFactory.java
import android.app.Activity;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.Log;
import com.google.android.gms.samples.vision.face.multitracker.ui.camera.GraphicOverlay;
import com.google.android.gms.vision.MultiProcessor;
import com.google.android.gms.vision.Tracker;
import com.google.android.gms.vision.barcode.Barcode;
/**
* Factory for creating a tracker and associated graphic to be associated with a new barcode. The
* multi-processor uses this factory to create barcode trackers as needed -- one for each barcode.
*/
class BarcodeTrackerFactory implements MultiProcessor.Factory<Barcode> {
public Activity context;
private GraphicOverlay mGraphicOverlay;
BarcodeTrackerFactory(GraphicOverlay graphicOverlay) {
mGraphicOverlay = graphicOverlay;
}
BarcodeTrackerFactory(GraphicOverlay graphicOverlay ,Activity ctx) {
mGraphicOverlay = graphicOverlay;
this.context =ctx;
}
@Override
public Tracker<Barcode> create(Barcode barcode) {
BarcodeGraphic graphic = new BarcodeGraphic(mGraphicOverlay,context);
return new GraphicTracker<>(mGraphicOverlay, graphic);
}
}
/**
* Graphic instance for rendering barcode position, size, and ID within an associated graphic
* overlay view.
*/
class BarcodeGraphic extends TrackedGraphic<Barcode> {
private static final int COLOR_CHOICES[] = {
Color.BLUE,
Color.CYAN,
Color.GREEN
};
private static int mCurrentColorIndex = 0;
private Paint mRectPaint;
private Paint mTextPaint;
private volatile Barcode mBarcode;
private Activity context;
private boolean isFirstScandetaction=true;
BarcodeGraphic(GraphicOverlay overlay ,Activity context) {
super(overlay);
this.context=context;
mCurrentColorIndex = (mCurrentColorIndex + 1) % COLOR_CHOICES.length;
final int selectedColor = COLOR_CHOICES[mCurrentColorIndex];
mRectPaint = new Paint();
mRectPaint.setColor(selectedColor);
mRectPaint.setStyle(Paint.Style.STROKE);
mRectPaint.setStrokeWidth(4.0f);
mTextPaint = new Paint();
mTextPaint.setColor(selectedColor);
mTextPaint.setTextSize(36.0f);
}
/**
* Updates the barcode instance from the detection of the most recent frame. Invalidates the
* relevant portions of the overlay to trigger a redraw.
*/
void updateItem(Barcode barcode) {
mBarcode = barcode;
if (isFirstScandetaction) {
postInvalidate();
if (null != mBarcode) {
isFirstScandetaction = false;
Intent intent = new Intent();
intent.putExtra("SCAN_RESULT", barcode.rawValue.toString());
intent.putExtra("SCAN_RESULT_FORMAT",String.valueOf( barcode.format));
context.setResult(Activity.RESULT_OK, intent);
context.finish();
}
}
}
/**
* Draws the barcode annotations for position, size, and raw value on the supplied canvas.
*/
@Override
public void draw(Canvas canvas) {
Barcode barcode = mBarcode;
if (barcode == null) {
return;
}
// Draws the bounding box around the barcode.
RectF rect = new RectF(barcode.getBoundingBox());
rect.left = translateX(rect.left);
rect.top = translateY(rect.top);
rect.right = translateX(rect.right);
rect.bottom = translateY(rect.bottom);
canvas.drawRect(rect, mRectPaint);
// Draws a label at the bottom of the barcode indicate the barcode value that was detected.
canvas.drawText(barcode.rawValue, rect.left, rect.bottom, mTextPaint);
Log.v("On Draw", "called");
}
}
MultiTrackerActivity.java
import java.io.IOException;
import android.Manifest;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GoogleApiAvailability;
import com.google.android.gms.samples.vision.face.multitracker.ui.camera.CameraSourcePreview;
import com.google.android.gms.samples.vision.face.multitracker.ui.camera.GraphicOverlay;
import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.MultiProcessor;
import com.google.android.gms.vision.barcode.BarcodeDetector;
/**
* Activity for the multi-tracker app. This app detects faces and barcodes with the rear facing
* camera, and draws overlay graphics to indicate the position, size, and ID of each face and
* barcode.
*/
public final class MultiTrackerActivity extends AppCompatActivity {
private static final String TAG = "MultiTracker";
private static final int RC_HANDLE_GMS = 9001;
// permission request codes need to be < 256
private static final int RC_HANDLE_CAMERA_PERM = 2;
private CameraSource mCameraSource = null;
private CameraSourcePreview mPreview;
private GraphicOverlay mGraphicOverlay;
/**
* Initializes the UI and creates the detector pipeline.
*/
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
mPreview = (CameraSourcePreview) findViewById(R.id.preview);
mGraphicOverlay = (GraphicOverlay) findViewById(R.id.faceOverlay);
// Check for the camera permission before accessing the camera. If the
// permission is not granted yet, request permission.
int rc = ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA);
if (rc == PackageManager.PERMISSION_GRANTED) {
createCameraSource();
} else {
requestCameraPermission();
}
}
/**
* Handles the requesting of the camera permission. This includes
* showing a "Snackbar" message of why the permission is needed then
* sending the request.
*/
private void requestCameraPermission() {
Log.w(TAG, "Camera permission is not granted. Requesting permission");
final String[] permissions = new String[]{Manifest.permission.CAMERA};
if (!ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.CAMERA)) {
ActivityCompat.requestPermissions(this, permissions, RC_HANDLE_CAMERA_PERM);
return;
}
final Activity thisActivity = this;
View.OnClickListener listener = new View.OnClickListener() {
@Override
public void onClick(View view) {
ActivityCompat.requestPermissions(thisActivity, permissions,
RC_HANDLE_CAMERA_PERM);
}
};
Snackbar.make(mGraphicOverlay, R.string.permission_camera_rationale,
Snackbar.LENGTH_INDEFINITE)
.setAction(R.string.ok, listener)
.show();
}
/**
* Creates and starts the camera. Note that this uses a higher resolution in comparison
* to other detection examples to enable the barcode detector to detect small barcodes
* at long distances.
*/
private void createCameraSource() {
Context context = getApplicationContext();
// A barcode detector is created to track barcodes. An associated multi-processor instance
// is set to receive the barcode detection results, track the barcodes, and maintain
// graphics for each barcode on screen. The factory is used by the multi-processor to
// create a separate tracker instance for each barcode.
BarcodeDetector barcodeDetector = new BarcodeDetector.Builder(context).build();
BarcodeTrackerFactory barcodeFactory = new BarcodeTrackerFactory(mGraphicOverlay,this);
barcodeDetector.setProcessor(
new MultiProcessor.Builder<>(barcodeFactory).build());
if (!barcodeDetector.isOperational()) {
// Note: The first time that an app using the barcode or face API is installed on a
// device, GMS will download a native libraries to the device in order to do detection.
// Usually this completes before the app is run for the first time. But if that
// download has not yet completed, then the above call will not detect any barcodes
// and/or faces.
//
// isOperational() can be used to check if the required native libraries are currently
// available. The detectors will automatically become operational once the library
// downloads complete on device.
Log.w(TAG, "Detector dependencies are not yet available.");
}
// Creates and starts the camera. Note that this uses a higher resolution in comparison
// to other detection examples to enable the barcode detector to detect small barcodes
// at long distances.
mCameraSource = new CameraSource.Builder(getApplicationContext(), barcodeDetector)
.setFacing(CameraSource.CAMERA_FACING_BACK)
.setRequestedPreviewSize(1600, 1024)
.setRequestedFps(15.0f)
.build();
}
/**
* Restarts the camera.
*/
@Override
protected void onResume() {
super.onResume();
startCameraSource();
}
/**
* Stops the camera.
*/
@Override
protected void onPause() {
super.onPause();
mPreview.stop();
}
/**
* Releases the resources associated with the camera source, the associated detectors, and the
* rest of the processing pipeline.
*/
@Override
protected void onDestroy() {
super.onDestroy();
if (mCameraSource != null) {
mCameraSource.release();
}
}
/**
* Callback for the result from requesting permissions. This method
* is invoked for every call on {@link #requestPermissions(String[], int)}.
* <p>
* <strong>Note:</strong> It is possible that the permissions request interaction
* with the user is interrupted. In this case you will receive empty permissions
* and results arrays which should be treated as a cancellation.
* </p>
*
* @param requestCode The request code passed in {@link #requestPermissions(String[], int)}.
* @param permissions The requested permissions. Never null.
* @param grantResults The grant results for the corresponding permissions
* which is either {@link PackageManager#PERMISSION_GRANTED}
* or {@link PackageManager#PERMISSION_DENIED}. Never null.
* @see #requestPermissions(String[], int)
*/
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
if (requestCode != RC_HANDLE_CAMERA_PERM) {
Log.d(TAG, "Got unexpected permission result: " + requestCode);
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
return;
}
if (grantResults.length != 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Log.d(TAG, "Camera permission granted - initialize the camera source");
// we have permission, so create the camerasource
createCameraSource();
return;
}
Log.e(TAG, "Permission not granted: results len = " + grantResults.length +
" Result code = " + (grantResults.length > 0 ? grantResults[0] : "(empty)"));
DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
finish();
}
};
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Multitracker sample")
.setMessage(R.string.no_camera_permission)
.setPositiveButton(R.string.ok, listener)
.show();
}
/**
* Starts or restarts the camera source, if it exists. If the camera source doesn't exist yet
* (e.g., because onResume was called before the camera source was created), this will be called
* again when the camera source is created.
*/
private void startCameraSource() {
// check that the device has play services available.
int code = GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(
getApplicationContext());
if (code != ConnectionResult.SUCCESS) {
Dialog dlg =
GoogleApiAvailability.getInstance().getErrorDialog(this, code, RC_HANDLE_GMS);
dlg.show();
}
if (mCameraSource != null) {
try {
mPreview.start(mCameraSource, mGraphicOverlay);
} catch (IOException e) {
Log.e(TAG, "Unable to start camera source.", e);
mCameraSource.release();
mCameraSource = null;
}
}
}
}
Now to call the scan code and recieve the result-
BarCodeReader.java
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class BarCodeReader extends FragmentActivity {
String QR_CODE = "256";
private Button btnscan;
@Override
protected void onCreate(Bundle bundle) {
super.onCreate(bundle);
setContentView(R.layout.scanlayout);
btnscan = (Button) findViewById(R.id.scanbtn);
btnscan.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(BarCodeReader.this,
MultiTrackerActivity.class);
startActivityForResult(intent, 0);
}
});
}
public void onActivityResult(int requestCode, int resultCode, Intent intent) {
if (requestCode == 0) {
if (resultCode == RESULT_OK) {
String contents = intent.getStringExtra("SCAN_RESULT");
String format = intent.getStringExtra("SCAN_RESULT_FORMAT");
if (format.equals(QR_CODE)) {
Toast.makeText(
BarCodeReader.this,
"content is : " + contents + " \n Format is: "
+ format, Toast.LENGTH_LONG).show();
} else {
Toast.makeText(BarCodeReader.this, "wrong format",
Toast.LENGTH_LONG).show();
}
} else if (resultCode == RESULT_CANCELED) {
// To Handle cancel
Log.i("App", "Scan unsuccessful");
}
}
}
}
