How to refresh a Binding from another thread ?

Using Microsoft Windows Presentation Foundation and Syncfusion WPF Libraries

How to refresh a Binding from another thread ?

Postby PGilbert on Thu Aug 03, 2017 11:50 pm

If you fix the following two functions in a )CLEAR WS:

      test;binding;str;types;xaml;xml;⎕USING

⎕USING←'System.IO'
⎕USING,←⊂'System'
⎕USING,←⊂'System.Windows.Markup'
⎕USING,←⊂'System.Xml,system.xml.dll'
⎕USING,←⊂'System.Windows.Controls,WPF/PresentationFramework.dll'

xaml←'<Window '
xaml,←' xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"'
xaml,←' xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" '
xaml,←' xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"'
xaml,←' xmlns:local="clr-namespace:testlibrary" '
xaml,←' Title="Window" Height="300" Width="300"> '
xaml,←' <Grid > '
xaml,←' <StackPanel DataContext="{Binding MyValues}"> '
xaml,←' <TextBox Text="{Binding TextValue, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"></TextBox> '
xaml,←' </StackPanel> '
xaml,←' </Grid> '
xaml,←'</Window>'

str←⎕NEW StringReader(⊂xaml)
xml←⎕NEW XmlTextReader str
win←XamlReader.Load xml

props←⎕NS''
props.MyValues←⎕NS''
props.MyValues.TextValue←'this is working'

binding←(2015⌶)'props'

win.DataContext←binding
win.Show


      refreshBind ra
props.MyValues.TextValue←ra


Then if you execute the function 'test' you get a WPF window as expected with the TextBox text as: 'this is working'. After that if you execute the function 'refreshBind' you can change the value of the TextBox as expected. But if you try to refresh the namespace with 'refreshBind&' from another thread it is not working. Is there a way to make this work ?

      test
refreshBind 'this is working'
refreshBind& 'this is NOT working'


Thanks in advance,

Pierre Gilbert
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PGilbert
 
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Location: Montréal, Québec, Canada

Re: How to refresh a Binding from another thread ?

Postby JohnD|Dyalog on Mon Aug 21, 2017 12:07 pm

Hello Pierre,

This looks like a bug, but there's an easy workaround. Just add another line after the assignment in the function - it doesn't even have to do anything:

Code: Select all
refreshBind ra
props.MyValues.TextValue←ra
⍝hello


The problem is that the binding notifications are kept in a thread-specific queue, and in your code the thread ends before the queue is processed. The extra line gives the interpreter a chance to process the queue before thread termination.

I'll look into a proper fix.

Best Regards,
John Daintree.
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Re: How to refresh a Binding from another thread ?

Postby PGilbert on Mon Aug 21, 2017 12:15 pm

Thanks John, its working for me too.
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