Improve Permission Request and QR Code Decoding in ScannerActivity (#3776)

Streamlined the permission request process using RxPermissions and improved error handling for file selection and QR code decoding in ScannerActivity. Enhanced user feedback for decoding failures and file processing errors.

V2rayNG/app/src/main/kotlin/com/v2ray/ang/ui/ScannerActivity.kt

@@ -74,19 +74,17 @@ class ScannerActivity : BaseActivity() {
             }
             RxPermissions(this)
                 .request(permission)
-                .subscribe {
-                    if (it) {
-                        try {
-                            showFileChooser()
-                        } catch (e: Exception) {
-                            e.printStackTrace()
-                        }
-                    } else
+                .subscribe { granted ->
+                    if (granted) {
+                        showFileChooser()
+                    } else {
                         toast(R.string.toast_permission_denied)
+                    }
                 }
             true
         }
 
+
         else -> super.onOptionsItemSelected(item)
     }
 
@@ -107,13 +105,21 @@ class ScannerActivity : BaseActivity() {
         val uri = it.data?.data
         if (it.resultCode == RESULT_OK && uri != null) {
             try {
-                val bitmap = BitmapFactory.decodeStream(contentResolver.openInputStream(uri))
+                val inputStream = contentResolver.openInputStream(uri)
+                val bitmap = BitmapFactory.decodeStream(inputStream)
+                inputStream?.close()
+
                 val text = QRCodeDecoder.syncDecodeQRCode(bitmap)
-                finished(text.orEmpty())
+                if (text.isNullOrEmpty()) {
+                    toast(R.string.toast_decoding_failed)
+                } else {
+                    finished(text)
+                }
             } catch (e: Exception) {
                 e.printStackTrace()
-                toast(e.message.toString())
+                toast(R.string.toast_decoding_failed)
             }
         }
     }
+
 }