Support sharing via QR code

Another popular format is barcode but unfortunately I cannot seem to find documentations of that anywhere. Feel free to send me.

mobile/src/main/java/be/mygod/vpnhotspot/util/QRCodeDialog.kt

@@ -0,0 +1,26 @@
+package be.mygod.vpnhotspot.util
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import android.widget.ImageView
+import androidx.core.os.bundleOf
+import androidx.fragment.app.DialogFragment
+import be.mygod.vpnhotspot.R
+import net.glxn.qrgen.android.QRCode
+
+class QRCodeDialog : DialogFragment() {
+    companion object {
+        private const val KEY_ARG = "arg"
+    }
+
+    fun withArg(arg: String) = apply { arguments = bundleOf(KEY_ARG to arg) }
+    private val arg get() = arguments?.getString(KEY_ARG)
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?) =
+            ImageView(context).apply {
+                val size = resources.getDimensionPixelSize(R.dimen.qr_code_size)
+                layoutParams = ViewGroup.LayoutParams(size, size)
+                setImageBitmap((QRCode.from(arg).withSize(size, size) as QRCode).bitmap())
+            }
+}