Blackberry BarcodeScanner - barcodeDecode switch to MainScreen

Question

Can somebody tell me how to close the Screen (which opened by the BarcodeScanner) and show the mainscreen again after the barcodeDecoded method was invoked?

I can't get it right. I tried a lot, one of them was this:

    public void barcodeDecoded(String rawText) {        
    final String result = rawText;
    try
    {
        final UiApplication ui = UiApplication.getUiApplication();
        final MainScreen current = (MainScreen) ui.getActiveScreen();
        System.out.println("Current: " + current.toString());

        if (UiApplication.isEventDispatchThread()) {
            getText(result);
            ui.popScreen(current);
            System.out.println("Close Window by active screen");

            ui.pushScreen(_frm);
            System.out.println("Push screen frmMain");
        }else{
            ui.invokeLater(new Runnable() {  
                public void run() {
                    getText(result);  <-- Abstract method to use within the main app.
                    ui.popScreen(current);
                    ui.pushScreen(_frm);
                }
            });
        }
    }catch(Exception err){
        System.out.println(err.getMessage());
    }

}

the abstract method when i start the Scanner

private MenuItem mnuCamera = new MenuItem("Scan", 1, 1){
    public void run(){
        frmMain f = (frmMain)getScreen();
        _decode = new BarcodeDecoderClass(f) {
            public void getText(String tekst) {
                setScannedText(tekst);
            }
        };
        _decode.Start();
    }

};

Answer 1

Ok, for the people who are stuck with the same problem. I found it out. Below you find the complete code:

The BarcodeScanner class:

public abstract class BarcodeDecoderClass implements BarcodeDecoderListener {

private Hashtable _hints;
private Vector _formats;
private BarcodeScanner _scanner;
private BarcodeDecoder _decoder;
private Field _viewFinder;
private MainScreen _screen;
public abstract void getText(String tekst, Screen screen);

public BarcodeDecoderClass(){
    _hints = new Hashtable();
    _formats = new Vector();
    _formats.addElement(BarcodeFormat.QR_CODE);
    _hints.put(DecodeHintType.POSSIBLE_FORMATS, _formats);
    _decoder = new BarcodeDecoder(_hints);

    try
    {
        _scanner = new BarcodeScanner(_decoder, this);
        _scanner.getVideoControl().setDisplayFullScreen(true);
        _viewFinder = _scanner.getViewfinder();                        

    }catch(Exception err){
        System.out.println(err.getMessage());
    }
}

public void Start(){
    try
    {
        _screen = new MainScreen();
        _screen.add(_viewFinder);
        UiApplication.getUiApplication().pushScreen(_screen);
        _scanner.startScan();
    }catch(Exception err){
        System.out.println(err.getMessage());
    }
}

public synchronized void Close(){
    if(_scanner.isScanning()){ 
        try{
            _scanner.stopScan(); 
        }catch(Exception err){
            Dialog.alert(err.getMessage());
        }
    }
    _scanner.getVideoControl().setVisible(false);
    _scanner.getPlayer().close();
}

public void barcodeDecoded(String rawText) {        
    try
    {
        getText(rawText, _screen);
    }catch(Exception err){
        System.out.println(err.getMessage());
    }
}

}

The MainScreen from which I start the BarcodeScanner (i just copied the method)

private MenuItem mnuCamera = new MenuItem("Scan", 1, 1){
    public void run(){
        final Screen f = getScreen();
        _decode = new BarcodeDecoderClass() {
            public void getText(String tekst, final Screen _screen) {
                setScannedText(tekst);
                UiApplication.getUiApplication().invokeLater(new Runnable() {
                    public void run() {
                        _decode.Close();
                        _screen.close();
                    }
                });
            }
        };
        _decode.Start();
    }        
};

Answer 2

May be help full this code.

import java.util.Hashtable;
import java.util.Vector;


import net.rim.device.api.barcodelib.BarcodeDecoder;

import net.rim.device.api.barcodelib.BarcodeDecoderListener;
import net.rim.device.api.barcodelib.BarcodeScanner;
import net.rim.device.api.system.KeyListener;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.Keypad;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.ButtonField;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.container.FullScreen;
import net.rim.device.api.ui.container.MainScreen;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.DecodeHintType;


public class BarcodeScanSample extends MainScreen{
private FullScreen _barcodeScreen;
private BarcodeScanner _scanner; 
private LabelField lblBarcodeText;
private ButtonField btnScan;

public BarcodeScanSample(String barcodeText){
    lblBarcodeText = new LabelField(barcodeText);
    add(lblBarcodeText);
    btnScan = new ButtonField("Scan");
    btnScan.setChangeListener(new FieldChangeListener() {

        public void fieldChanged(Field field, int context) {
            scanBarcode();
        }
    });
    add(btnScan);
}
private void scanBarcode() {
    // If we haven't scanned before, we will set up our barcode scanner
    if (_barcodeScreen == null) {

        // First we create a hashtable to hold all of the hints that we can
        // give the API about how we want to scan a barcode to improve speed
        // and accuracy.
        Hashtable hints = new Hashtable();

        // The first thing going in is a list of formats. We could look for
        // more than one at a time, but it's much slower. and set Barcode Format.
        Vector formats = new Vector();
        formats.addElement(BarcodeFormat.QR_CODE);
        formats.addElement(BarcodeFormat.CODE_128);
        formats.addElement(BarcodeFormat.CODE_39);
        formats.addElement(BarcodeFormat.DATAMATRIX);
        formats.addElement(BarcodeFormat.EAN_13);
        formats.addElement(BarcodeFormat.EAN_8);
        formats.addElement(BarcodeFormat.ITF);
        formats.addElement(BarcodeFormat.PDF417);
        formats.addElement(BarcodeFormat.UPC_A);
        formats.addElement(BarcodeFormat.UPC_E);

        hints.put(DecodeHintType.POSSIBLE_FORMATS, formats);

        // We will also use the "TRY_HARDER" flag to make sure we get an
        // accurate scan
        hints.put(DecodeHintType.TRY_HARDER, Boolean.TRUE);

        // We create a new decoder using those hints
        BarcodeDecoder decoder = new BarcodeDecoder(hints);

        // Finally we can create the actual scanner with a decoder and a
        // listener that will handle the data stored in the barcode. We put
        // that in our view screen to handle the display.
        try {
            _scanner = new BarcodeScanner(decoder, new MyBarcodeDecoderListener());
            _barcodeScreen = new MyBarcodeScannerViewScreen(_scanner);

        } catch (Exception e) {
            System.out.println("Could not initialize barcode scanner: " + e);
            return;
        }
    }

    // If we get here, all the barcode scanning infrastructure should be set
    // up, so all we have to do is start the scan and display the viewfinder
    try {
        _scanner.startScan();
        UiApplication.getUiApplication().pushScreen(_barcodeScreen);
    } catch (Exception e) {
        System.out.println("Could not start scan: " + e);
    }

}
/***
 * MyBarcodeScannerViewScreen
 * <p>
 * This view screen is simply an extension of MainScreen that will hold our
 * scanner's viewfinder, and handle cleanly stopping the scan if the user
 * decides they want to abort via the back button.
 * 
 * @author PBernhardt
 * 
 */
private class MyBarcodeScannerViewScreen extends MainScreen {

    public MyBarcodeScannerViewScreen(BarcodeScanner scanner) {
        super();
        try {
            // Get the viewfinder and add it to the screen
            _scanner.getVideoControl().setDisplayFullScreen(true);
            Field viewFinder = _scanner.getViewfinder();
            this.add(viewFinder);

            // Create and add our key listener to the screen
            this.addKeyListener(new MyKeyListener());

        } catch (Exception e) {
            System.out.println("Error creating view screen: " + e);
        }

    }

    /***
     * MyKeyListener
     * <p>
     * This KeyListener will stop the current scan cleanly when the back
     * button is pressed, and then pop the viewfinder off the stack.
     * 
     * @author PBernhardt
     * 
     */
    private class MyKeyListener implements KeyListener {

        public boolean keyDown(int keycode, int time) {

            // First convert the keycode into an actual key event, taking
            // modifiers into account
            int key = Keypad.key(keycode);

            // From there we can compare against the escape key constant. If
            // we get it, we stop the scan and pop this screen off the stack
            if (key == Keypad.KEY_ESCAPE) {
                try {
                    _scanner.stopScan();
                } catch (Exception e) {
                    System.out.println("Error stopping scan: " + e);
                }
                UiApplication.getUiApplication().invokeLater(new Runnable() {
                    public void run() {
                        UiApplication.getUiApplication().popScreen(_barcodeScreen);

                    }
                });

                return true;

            }
            // Otherwise, we'll return false so as not to consume the
            // keyDown event
            return false;
        }

        // We will only act on the keyDown event
        public boolean keyChar(char key, int status, int time) {
            return false;
        }

        public boolean keyRepeat(int keycode, int time) {
            return false;
        }

        public boolean keyStatus(int keycode, int time) {
            return false;
        }

        public boolean keyUp(int keycode, int time) {
            return false;
        }

    }
}
/***
 * MyBarcodeDecoderListener
 * <p>
 * This BarcodeDecoverListener implementation tries to open any data encoded
 * in a barcode in the browser.
 * 
 * @author PBernhardt
 * 
 **/
private class MyBarcodeDecoderListener implements BarcodeDecoderListener {

    public void barcodeDecoded(final String rawText) {

        // First pop the viewfinder screen off of the stack so we can see
        // the main app
        UiApplication.getUiApplication().invokeLater(new Runnable() {
            public void run() {
                UiApplication.getUiApplication().popScreen(_barcodeScreen);
            }
        });

        _barcodeScreen.invalidate();
        //Display this barcode on LabelField on BarcodeScanSample MainScreen we can also set whatever field here.
        UiApplication.getUiApplication().invokeLater(new Runnable() {
            public void run() {
                    UiApplication.getUiApplication().popScreen();
                    UiApplication.getUiApplication().pushScreen(new BarcodeScanSample(rawText));
                    _barcodeScreen.close();
                    _barcodeScreen=null;
            }
        });
    }

}

}