Manage Camera Permissions

Connect your device to your machine with a USB data cable

If this is your first time running and debugging Android apps, follow the guidance on the Android Developer website. See Set up a device for development , and check that you have completed these steps:

1. You have followed the instructions Enable USB debugging on your device .

2. You have confirmed that you have enabled USB debugging by tapping OK on your device when the Allow USB debugging dialog appears, and that you have checked Always allow from this computer. See Figure 6.

Figure 6: Allow USB Debugging.

3. Make sure that your device model name and SDK version correctly show up in the top-right toolbar.

   Click the Run button to build and run the app.

4. After a while, you should see a notification of a successful build in Android Studio and the new app will be displayed on your Android device.

5. However, you will also see that the app shows a black screen while printing error messages in your Logcat , which looks like this:

    

        
        
2024-11-20 11:15:00.398 18782-18818 Camera2CameraImpl       com.example.holisticselfiedemo      E  Camera reopening attempted for 10000ms without success.
2024-11-20 11:30:13.560   667-707   BufferQueueProducer     pid-667                              E  [SurfaceView - com.example.holisticselfiedemo/com.example.holisticselfiedemo.MainActivity#0](id:29b00000283,api:4,p:2657,c:667) queueBuffer: BufferQueue has been abandoned
2024-11-20 11:36:13.100 20487-20499 isticselfiedem          com.example.holisticselfiedemo      E  Failed to read message from agent control socket! Retrying: Bad file descriptor
2024-11-20 11:43:03.408  2709-3807  PackageManager          pid-2709                             E  Permission android.permission.CAMERA isn't requested by package com.example.holisticselfiedemo

    

This is the expected behavior from having not yet correctly configured the app’s permissions. See Permissions on the Android Developer website. Android OS restricts the app’s access to camera features due to privacy constraints.

Request camera permission at runtime

1. Navigate to manifest.xml in your app sub-project’s src/main path.

   Declare the camera hardware, and set the permissions by inserting the following lines into the <manifest> element, ensuring that it is declared outside and above the <application> element:

    

        
        
    <uses-feature
        android:name="android.hardware.camera"
        android:required="true" />
    <uses-permission android:name="android.permission.CAMERA" />

    

2. Navigate to strings.xml in your app sub-project’s src/main/res/values path.
   Insert the following lines of text resources, which you will use at a later stage:

    

        
        
    <string name="permission_request_camera_message">Camera permission is required to recognize face and hands</string>
    <string name="permission_request_camera_rationale">To grant Camera permission to this app, please go to system settings</string>

    

3. Navigate to MainActivity.kt and add the following permission-related values to companion object:

    

        
        
        // Permissions
        private val PERMISSIONS_REQUIRED = arrayOf(Manifest.permission.CAMERA)
        private const val REQUEST_CODE_CAMERA_PERMISSION = 233

    

4. Add a new method named hasPermissions() to check on runtime whether the camera permission has been granted:

    

        
        
    private fun hasPermissions(context: Context) = PERMISSIONS_REQUIRED.all {
        ContextCompat.checkSelfPermission(context, it) == PackageManager.PERMISSION_GRANTED
    }

    

5. Add a condition check in on the onCreate() wrapping setupCamera() method, to request camera permission on runtime:

    

        
        
        if (!hasPermissions(baseContext)) {
            requestPermissions(
                arrayOf(Manifest.permission.CAMERA),
                REQUEST_CODE_CAMERA_PERMISSION
            )
        } else {
            setupCamera()
        }

    

6. Override the onRequestPermissionsResult method to handle permission request results:

    

        
        
    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        when (requestCode) {
            REQUEST_CODE_CAMERA_PERMISSION -> {
                if (PackageManager.PERMISSION_GRANTED == grantResults.getOrNull(0)) {
                    setupCamera()
                } else {
                    val messageResId =
                        if (shouldShowRequestPermissionRationale(Manifest.permission.CAMERA))
                            R.string.permission_request_camera_rationale
                        else
                            R.string.permission_request_camera_message
                    Toast.makeText(baseContext, getString(messageResId), Toast.LENGTH_LONG).show()
                }
            }
            else -> super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        }
    }

    

Verify camera permission

1. Rebuild and run the app. Now you should see a dialog pop up requesting camera permissions.

2. Depending on your Android OS version, tap Allow or While using the app().

You should then see your own face in the camera preview. Good job!

In the next section, you will learn how to integrate MediaPipe vision solutions.