Why zebra InputScannerPlugin stops react to sended broadcast?

Question

I am creating an Android apk on ZEBRA MC3300 - this device have preinstalled DataWedge, in my app I use Zebra InputScannerPlugin to disable/enable scanner depending on activity. I have code for disable/enable methods from Zebra guide it looks like that:

    static String scannerInputPlugin = "com.symbol.datawedge.api.ACTION";
    static String extraData = "com.symbol.datawedge.api.SCANNER_INPUT_PLUGIN";

public static void enableScanner(Activity activity){
        try {            
            if(!scannerEnabled) {
                Intent i = new Intent();
                i.setAction(scannerInputPlugin);
                i.putExtra(extraData, "ENABLE_PLUGIN");
                activity.sendBroadcast(i);
            }
            scannerEnabled = true;
        }catch(Exception e){
            Log.d("TERMINALPROP", e.toString());
        }
}
public static void disableScanner(Activity activity){
        try {            
            if(!scannerEnabled) {
                Intent i = new Intent();
                i.setAction(scannerInputPlugin);
                i.putExtra(extraData, "DISABLE_PLUGIN");
                activity.sendBroadcast(i);
            }
            scannerEnabled = true;
        }catch(Exception e){
            Log.d("TERMINALPROP", e.toString());
        }
}

I am using disableScanner and enableScanner at onResumie methods, and it works fine, but also I am using them at my AsyncTask at onPreExecute and onPostExecute methods.

Sometimes I got problem that my scanner do not react to enable/disable. It looks like datawedge runtime stops working, I send there broadcast and nothing changes - scanner stays disabled, but it not happens every time.

I was able to recreate problem several times. It looks like that:

I have Activity A and B. At activity A at method onResumie I am disabling scanner, before I start activity B, I am using AsyncTask (it disable on preExecute, and enable Scanner on postExecute), and I am switching to activity B and there onResume method I call enableScanner again.

And if I switch activities very fast, sometimes my scanner stays disabled, and stops react to all my enableScanner calls. It happens randomly, sometimes after 3 switches of activity, sometimes I have to switch it 20 times etc.

Any idea what I am doing wrong?

@EDIT It probably something with Datawedge InputScanner plugin - (I removed if(!scannerEnabled) from methods) and just added result codes to my apk, and when scanner is 'blocked' it returns me SCANNER_ALREADY_ENABLED when I call enableScanner but scanner is disabled :/

Have you checked the `Log.d("TERMINALPROP", e.toString());` `postExecute()` runs on UI thread but if the Activity is dead it will not work. `. The `Activity activity` context will not work if Activity is closed using back button — Erik, Mar 15 '19 at 13:31
It probably something with Datawedge InputScanner plugin - (I removed if(!scannerEnabled) from methods) and just added result codes to my apk, and when scanner is 'blocked' it returns me SCANNER_ALREADY_ENABLED when I call enableScanner but scanner is disabled :/ — Cerveza, Mar 15 '19 at 14:49

score 0 · Answer 1 · answered Mar 18 '19 at 08:38

If you never want the scanner to be enabled in Activity A then create a new DataWedge profile, associate it with Activity A and disable the barcode input plugin. You would have another profile associated with Activity B with the barcode input plugin enabled. You can then remove all the code logic around enabling / disabling the scanner when either activity gets focus as DataWedge will handle that automatically.

score 0 · Answer 2 · answered Feb 26 '20 at 14:40

I have noticed the same behavior with DataWedge with small differences between versions.

6.7 will totally stop sending broadcast events or notice the trigger button on my TC20.
6.6 will only stop for a certain time. Also switching apps / activities might work.

I found out that (on 6.7.47 at least) the following looks to work;

Every time you want to enable the scanner to scan do:

Use a profile linked with your whole app. (not only specific activities)
Disable Datawegde by intent (and delay a little)
Enable DataWedge by intent (and delay a little)
Enable the scanner plugin by intent

With this approach my app will not end up with a disabled scanner.

Why zebra InputScannerPlugin stops react to sended broadcast?

2 Answers2