B4A Library [class] Google Code Scanner - no permission, very simple to use, barcode scanning

Erel · Apr 24, 2024

This solution is based on ML Kit (https://developers.google.com/ml-kit/vision/barcode-scanning/code-scanner).

Instructions:
1. Add to main module:

B4X:

#AdditionalJar: com.google.android.gms:play-services-code-scanner
#MultiDex: True

2. Add to manifest editor:

B4X:

CreateResourceFromFile(Macro, FirebaseAnalytics.GooglePlayBase) 'add if not already there

'******* google code scanner
AddApplicationText(
<meta-data
      android:name="com.google.mlkit.vision.DEPENDENCIES"
      android:value="barcode_ui"/>
 <activity
            android:name="com.google.mlkit.vision.codescanner.internal.GmsBarcodeScanningDelegateActivity"
            android:exported="false"
            android:screenOrientation="portrait"
           >
  </activity>
)
'*****************

'*********  ML kit **********
AddApplicationText(
 <activity
            android:name="com.google.mlkit.vision.documentscanner.internal.GmsDocumentScanningDelegateActivity"
            android:exported="false"
            android:screenOrientation="portrait"
            android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"
             >
        </activity>
         <provider
            android:name="com.google.mlkit.common.internal.MlKitInitProvider"
            android:authorities="${applicationId}.mlkitinitprovider"
            android:exported="false"
            android:initOrder="99" />

        <service
            android:name="com.google.mlkit.common.internal.MlKitComponentDiscoveryService"
            android:directBootAware="true"
            android:exported="false"
             >
            <meta-data
                android:name="com.google.firebase.components:com.google.mlkit.common.internal.CommonComponentRegistrar"
                android:value="com.google.firebase.components.ComponentRegistrar" />
        </service>
)
'******************************

Usage:

B4X:

Private Sub Button1_Click
    Dim formats As List = Array(Scanner.FORMAT_ALL_FORMATS) 'For better performance pass the specific formats needed.
    Wait For (Scanner.Scan(formats)) Complete (Result As ScannerResult)
    If Result.Success Then
        Log(Result.Value)
    End If
End Sub

See attached project.

Beja · Mar 25, 2025

Erel said:
When the app crashes there is always a stack trace in the logs. Please post it.

Strange behaviour>> Now working normally.

*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create (first time) **
Call B4XPages.GetManager.LogEvents = True to enable logging B4XPages events.
** Activity (main) Resume **

Beja · May 25, 2025

Hi Erel,
Today I went back to this app example and got this error:

B4A Version: 13.10
Parsing code. (0.01s)
Java Version: 8
Building folders structure. (0.01s)
Running custom action. (0.04s)
Compiling code. (0.07s)
Compiling layouts code. (0.02s)
Organizing libraries. Error
Maven artifact not found: com.google.android.gms/play-services-code-scanner
Source: com.google.android.gmslay-services-code-scanner

Any meaning appreciated

Erel · May 26, 2025

You need to install this component with B4A Sdk Manager.

It will be included in the prepackaged SDK when it is next updated.

Jota21 · Jun 24, 2025

Hi, I'm using this library and something very strange is happening. I used it a couple of times a few days ago and it worked perfectly on my Android device (INFINIX HOT 20 with Android 12). I used it to scan a few QR codes and everything worked fine.

Then I continued developing the rest of the app and testing, and everything else worked as expected. But when I went back to use the scanner, it just wouldn’t launch. It made a kind of movement as if it was about to open, but the scanner never actually started.

At first, I thought it might have been a mistake on my part, so I commented out the new code and tried again — same issue. Then I decided to run the example provided with the library to rule out an error in my implementation, but even the example didn’t work.

So I ran it on my emulator (MEMU PLAY with Android 9), and to my surprise, it worked perfectly there. But on my actual Android device, it still doesn’t work.

If anyone else has experienced this issue or knows how to fix it, please let me know. I’ve already restarted my phone, uninstalled the app completely, and reinstalled it, but nothing worked.

I’m attaching a video showing what’s happening on my device, a working test from the emulator, and also the page logs — though there’s not even an error showing up.

Thank you in advance!

Link of Videos:

Videos - Google Drive

drive.google.com

Magma · Jun 24, 2025

In some devices i have the same problem - before was working but not now at all devices... is there a way to somehow reset somehow the MLKIT... Exception Not Initialize

may be is a manifest problem ?

extra for mlkit (have also ocr and qrcode - may be is better to combine them - but i don't know how):

B4X:

...

'******* google code scanner
AddApplicationText(
<meta-data
      android:name="com.google.mlkit.vision.DEPENDENCIES"
      android:value="barcode_ui"/>
 <activity
            android:name="com.google.mlkit.vision.codescanner.internal.GmsBarcodeScanningDelegateActivity"
            android:exported="false"
            android:screenOrientation="portrait"
           >
  </activity>
)
'*****************

'*********  ML kit **********
AddApplicationText(
 <activity
            android:name="com.google.mlkit.vision.documentscanner.internal.GmsDocumentScanningDelegateActivity"
            android:exported="false"
            android:screenOrientation="portrait"
            android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"
             >
        </activity>
         <provider
            android:name="com.google.mlkit.common.internal.MlKitInitProvider"
            android:authorities="${applicationId}.mlkitinitprovider"
            android:exported="false"
            android:initOrder="99" />

        <service
            android:name="com.google.mlkit.common.internal.MlKitComponentDiscoveryService"
            android:directBootAware="true"
            android:exported="false"
             >
            <meta-data
                android:name="com.google.firebase.components:com.google.mlkit.common.internal.CommonComponentRegistrar"
                android:value="com.google.firebase.components.ComponentRegistrar" />
        </service>
)
'******************************

'****** text recognition *****
AddApplicationText(
 <meta-data
          android:name="com.google.mlkit.vision.DEPENDENCIES"
          android:value="ocr" />
)
'**********

'*********  ML kit + subject segmentation +  text recognition **********
AddApplicationText(
 <activity
            android:name="com.google.mlkit.vision.documentscanner.internal.GmsDocumentScanningDelegateActivity"
            android:exported="false"
            android:screenOrientation="portrait"
            android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"
             >
        </activity>
         <provider
            android:name="com.google.mlkit.common.internal.MlKitInitProvider"
            android:authorities="${applicationId}.mlkitinitprovider"
            android:exported="false"
            android:initOrder="99" />

        <service
            android:name="com.google.mlkit.common.internal.MlKitComponentDiscoveryService"
            android:directBootAware="true"
            android:exported="false"
             >
            <meta-data
                android:name="com.google.firebase.components:com.google.mlkit.common.internal.CommonComponentRegistrar"
                android:value="com.google.firebase.components.ComponentRegistrar" />
             <meta-data
                android:name="com.google.firebase.components:com.google.mlkit.vision.segmentation.subject.internal.SubjectSegmentationRegistrar"
                android:value="com.google.firebase.components.ComponentRegistrar" />
            <meta-data
                android:name="com.google.firebase.components:com.google.mlkit.vision.text.internal.TextRegistrar"
                android:value="com.google.firebase.components.ComponentRegistrar" />
        </service>
)
'******************************

AddPermission(android.permission.CAMERA)

...

Erel · Jun 25, 2025

please start a new thread. Don't post screenshots. Post code and logs as text. And find the error message. There should be one if the app crashes. It might be in the unfiltered logs.

B4A Library [class] Google Code Scanner - no permission, very simple to use, barcode scanning

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