B4J Question Delay label text update

bdunkleysmith · Aug 8, 2017

I have a UI app which reads in serial data and updates a label (GameClock) based on a certain element in that data stream. In part the code is:

B4X:

Sub btnOpen_Action
    sp.Open(cmbPort.Value)
    sp.SetParams(115200,8,1,0)
    ast.Initialize(Me, "ast", sp.GetInputStream, sp.GetOutputStream)
    btnOpen.Enabled = False
    lblStatus.Text = "Status: Open"
End Sub

Sub ast_NewText(Text As String)
    Select js.left(Text,1)
        Case "T"           
            GameClock.Text = js.Mid(Text,2,5)           
    End Select
End Sub

My problem is that I need to delay each label update by say 150ms, however given the nature of the data stream, ast_NewText may be called every 100ms. So it seems I can't just simply put a 150ms delay ahead of the label update:

B4X:

GameClock.Text = js.Mid(Text,2,5)

but instead need to put the updates into a queue and execute each update 150ms after it has entered the queue.

Any suggestions how to achieve that in code?

Erel · Aug 8, 2017

There is really no reason to use jStringFunctions. Learn the built-in string methods. They are not more complicated.

bdunkleysmith said:
My problem is that I need to delay each label update by say 150ms, however given the nature of the data stream, ast_NewText may be called every 100ms.

Do you want to skip some of the updates? Or queue them and show them in a slower rate?

bdunkleysmith · Aug 8, 2017

No, I don't want to skip any updates. I want to queue them and update at the same rate, but with just a fixed delay of 150ms. I may want to adjust the fixed delay to between 100 and 200ms, and that would mean there would only be up to say three updates in the queue.

As background, my UI app is displaying a sports game clock as well as other scoreboard details and when I mix it with video from a venue camera, it is around 150ms ahead of the camera video due to delay induced by the camera capture digital processing path.

Erel · Aug 8, 2017

Create a global List with the messages.

B4X:

Sub UpdateLabel
 Do While True
   If ListOfMessages.Size > 0 Then
     Label1.Text = ListOfMessages.Get(0)
     ListOfMessages.RemoveAt(0)
  End If
  Sleep (UpdateInterval) 'global variable set to 150. You can change it whenever you want.
 Loop
End Sub

Call UpdateLabel once when the program starts.
Add messages to ListOfMessages from ast_NewText.

bdunkleysmith · Aug 9, 2017

Thanks for the pointer Erel.

Now I've gone to implement it I realise I may need to deal with a couple of other related issues, but the principle of your suggestion will remain the basis for the solution.

Thanks again for your great support . . .

B4J Question Delay label text update

bdunkleysmith

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Erel

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bdunkleysmith

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Erel

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bdunkleysmith

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B4J Question Delay label text update

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