RayHarwood - User contributions [en]

Xamarin

2016-05-23T02:49:08Z

68.98.32.163:

Best overview video ever: [https://developer.xamarin.com/videos/?v=Introduction_to_Xamarin.Forms Intro to Xamarin.Forms]

Azure Mobile Sevices: [https://developer.xamarin.com/videos/?v=Azure_Mobile_Services_and_Xamarin Overview]

Marshalling updates to a text box

2016-04-29T15:09:30Z

68.98.32.163:

When you have a text box on a form, it's typically created as part of the form's initialization code, in the main thread. If you have a background thread that needs to update the text box, you can't just "pass the text box into the thread", nor can you even respond to an Event in the thread with a handler and "just update the text box" (the event handler runs in the thread of the event).

The code isn't difficult to write, but it is ''complex'', in that it's not intuitive nor easy to simply type out when you need it.

Delegate Sub AddLogtext_Callback(TB As TextBox, Text As String)
'
Private MyTB As TextBox = Nothing
'
Sub AddLogText_Invoke(TB As TextBox, Text As String)
If TB.InvokeRequired Then
Dim AddLogText_Delegate As New AddLogtext_Callback(AddressOf AddLogText_Invoke)
MyTB = TB
Dim ParmArray() As Object = {MyTB, Text}
MyTB.Invoke(AddLogText_Delegate, ParmArray)
Else
tbInfo.Text &= Format(Now, "hh:mm:ss tt") & " " & Text & vbCrLf
tbInfo.Select(tbInfo.TextLength, 1)
tbInfo.ScrollToCaret()
Application.DoEvents()
End If
End Sub
'
Sub LogInfo(Text As String)
_TextIsDirty = True
AddLogText_Invoke(tbInfo, Text)
End Sub

'''NOTE: The code below isn't right either! Be sure to model after the above code'''

Private Delegate Sub ShowText(Text As String)
'
Sub ShowText_Invoke(Text As String)
If tbActionLog.InvokeRequired Then
Dim SHowText_Delegate As New ShowText(AddressOf ShowText_Invoke)
SHowText_Delegate(Text)
Else
tbActionLog.Text &= Format(Now, "hh:mm:ss tt") & " " & Text & vbCrLf
tbActionLog.Select(tbActionLog.TextLength, 1)
tbActionLog.ScrollToCaret()
Application.DoEvents()
End If
End Sub

Marshalling updates to a text box

2016-04-29T15:06:40Z

68.98.32.163: