Barcode - Object reference not set to an instance of an object.

[Unknown]

I am creating SfBarcode generator from user input text. User choose type of code, then write text and generate it by button. Code is in attach file

1) I can´t use these characters in QRCode: š,č,ř,ž,... (diacritic) but standard qrcode and datamatrix alow these characters

2) I don't know how to write try, catch if user insert not supported characters by barcode (for now I do manually control in code)

3) 

On iOS is everything ok (work as I want), but on android i get this message:

"Object reference not set to an instance of an object."

{System.NullReferenceException: Object reference not set to an instance of an object.

  at Syncfusion.SfBarcode.XForms.Android.SfBarcodeMapping.OnSfBarcodePropertyChanged (System.String propertyName, Syncfusion.SfBarcode.XForms.SfBarcode barcode, Com.Syncfusion.Barcode.SfBarcode nativeBarcode) [0x004cb] in <e5b50884afa840daa78448e5114ae941>:0 

  at Syncfusion.SfBarcode.XForms.Android.SfBarcodeRenderer.OnElementPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs e) [0x00014] in <e5b50884afa840daa78448e5114ae941>:0 

  at (wrapper delegate-invoke) <Module>.invoke_void_object_PropertyChangedEventArgs(object,System.ComponentModel.PropertyChangedEventArgs)

  at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:150 

  at Xamarin.Forms.Element.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:370 

  at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00114] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:623 

  at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0015b] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:417 

  at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value, System.Boolean fromStyle, System.Boolean checkAccess) [0x0003d] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:573 

  at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:99 

  at Syncfusion.SfBarcode.XForms.SfBarcode.set_SymbologySettings (Syncfusion.SfBarcode.XForms.BarcodeSettings value) [0x00000] in <25124daea36445bba3d101f15dac02fc>:0 

  at Syncfusion.SfBarcode.XForms.SfBarcode.Dispose () [0x00008] in <25124daea36445bba3d101f15dac02fc>:0 

  at Syncfusion.SfBarcode.XForms.Android.SfBarcodeRenderer.Dispose () [0x00008] in <e5b50884afa840daa78448e5114ae941>:0 

  at Xamarin.Forms.Platform.Android.VisualElementPackager.RemoveChild (Xamarin.Forms.VisualElement view) [0x00072] in D:\a\1\s\Xamarin.Forms.Platform.Android\VisualElementPackager.cs:203 

  at Xamarin.Forms.Platform.Android.VisualElementPackager.OnChildRemoved (System.Object sender, Xamarin.Forms.ElementEventArgs e) [0x00021] in D:\a\1\s\Xamarin.Forms.Platform.Android\VisualElementPackager.cs:175 

  at Xamarin.Forms.Element.OnChildRemoved (Xamarin.Forms.Element child) [0x00007] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:355 

  at Xamarin.Forms.VisualElement.OnChildRemoved (Xamarin.Forms.Element child) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\VisualElement.cs:751 

  at Xamarin.Forms.Layout.OnInternalRemoved (Xamarin.Forms.View view) [0x00012] in D:\a\1\s\Xamarin.Forms.Core\Layout.cs:461 

  at Xamarin.Forms.Layout.InternalChildrenOnCollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x0002f] in D:\a\1\s\Xamarin.Forms.Core\Layout.cs:425 

  at System.Collections.ObjectModel.ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00018] in <3e9b3e26c4694baab3f689687ad40612>:0 

  at System.Collections.ObjectModel.ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedAction action, System.Object item, System.Int32 index) [0x00009] in <3e9b3e26c4694baab3f689687ad40612>:0 

  at System.Collections.ObjectModel.ObservableCollection`1[T].RemoveItem (System.Int32 index) [0x00021] in <3e9b3e26c4694baab3f689687ad40612>:0 

  at System.Collections.ObjectModel.Collection`1[T].RemoveAt (System.Int32 index) [0x0002b] in <d4a23bbd2f544c30a48c44dd622ce09f>:0 

  at Xamarin.Forms.TemplateUtilities.OnContentChanged (Xamarin.Forms.BindableObject bindable, System.Object oldValue, System.Object newValue) [0x00018] in D:\a\1\s\Xamarin.Forms.Core\TemplateUtilities.cs:63 

  at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00120] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:625 

  at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0015b] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:417 

  at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value, System.Boolean fromStyle, System.Boolean checkAccess) [0x0003d] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:573 

  at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:99 

  at Xamarin.Forms.ContentView.set_Content (Xamarin.Forms.View value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\ContentView.cs:11 

  at FlowerMobileTrends.Views.PageBarcodeCreator+<OnButtonBarcodeCreate_Click>d__7.MoveNext () [0x000c0] in D:\Projekty\FlowerMobileTrends\FlowerMobileTrends\FlowerMobileTrends\Views\PageBarcodeCreator.xaml.cs:232 }

Attachment: barcode_8e457b09.zip

[Karthikeyan Chandrasekar]

Hi Tomas, 

Query	Response
1)    I can´t use these characters in QRCode: š,č,ř,ž,... (diacritic) but standard qrcode and datamatrix alow these characters.       3)     On iOS is everything ok (work as I want), but on android i get this message:    "Object reference not set to an instance of an object."	We have tried creating QR Barcode using SfBarcode in Xamarin forms android with the inputs which you have given.   The barcode is generated without any exception but when we tried to read the barcode using barcode scanner.   It was not scanned properly. We have attached the sample for the same in below link. We are analyzing this issue we will let you know more about this on 20-Feb-19.  Sample link:  http://www.syncfusion.com/downloads/support/forum/142705/ze/SampleXamarin-2035077047  Please modify this sample with code the exceptions issue is reproduced. So that we can provide you better solution in this.
I don't know how to write try, catch if user insert not supported characters by barcode (for now I do manually control in code)	Since the exception is thrown while rendering we cannot implement try/catch block. But this can be achieved if there is a EventHandler triggered while saving the barcode.   At present we do not have API for event handler while saving barcode.   We will analyze the feasibility and let you know about this on 20-Feb-19

Regards, 

Karthikeyan  

[Prakash Viswanathan]

Hi Tomas, 

Thanks for the patience. 

Query	Response
The barcode is generated without any exception but when we tried to read the barcode using barcode scanner it was not scanned properly.	We confirm this to be a bug and we will include the fix for this issue in our upcoming 2019 Volume 1 SP1 release.
Since the exception is thrown while rendering we cannot implement try/catch block. But this can be achieved if there is a EventHandler triggered while saving the barcode.      At present we do not have API for event handler while saving barcode.      We will analyze the feasibility and let you know about this on 20-Feb-19	We have analyzed the feasibility for implementing event handler while rendering the barcode in Xamarin platform.  We will notify you know when this feature is implemented.

Regards, 

Prakash V 

[Unknown]

Hi, thank you for your reply. I will look forward to a new update.

I've tried your demo, but:

1) If I use your demo with a diacritic ("š,č,ř,ž") I get the following exceptions:

Unhandled Exception:

Com.Syncfusion.Barcode.BarcodeException: Input text contains non-convertable characters

or

Com.Syncfusion.Barcode.BarcodeException: <Timeout exceeded getting exception details>

2) If I tried on iOS - QRCode is not displayed - only gray screen (on Android is everything ok)

3) I've modified your demo and added a button to change barcode. On Android: When I click the button I get the following message: (On iOS is everything OK)

Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.

Attachment: sx_4824c835.zip