【WPF】UpdateSourceTrigger

UpdateSourceTrigger： Gets or sets a value , Determine when to update the binding source . The default value is Default

Default ： Bind the default value of the target property System.Windows.Data.UpdateSourceTrigger value . The default value for most dependent properties is UpdateSourceTrigger.PropertyChanged, and TextBox.Text The default value of the property is UpdateSourceTrigger.LostFocus.     

PropertyChanged： Whenever the binding target property changes , Will update the binding source .   
LostFocus ： Whenever the binding target element loses focus , Will update the binding source .      
Explicit： Only when calling BindingExpression.UpdateSource Method to update the binding source .

        <WrapPanel Grid.Row="1" Margin="10">
            <TextBlock Text="window title"/>
            <TextBox x:Name="txtTitle" Text="{Binding Title,UpdateSourceTrigger=Default}" Width="100" Margin="5 0 5 0"/>
            <Button x:Name="_btnUpdateSource" Content="update source" Click="_btnUpdateSource_Click"/>
        </WrapPanel>
        <WrapPanel Grid.Row="2" Margin="10">
            <TextBlock Text="window dimensions:"/>
            <TextBox x:Name="txtWidth" Text="{Binding Width,UpdateSourceTrigger=LostFocus}" Width="50"/>
            <TextBlock Text="x"/>
            <TextBox x:Name="txtHeigth" Text="{Binding Height,UpdateSourceTrigger=PropertyChanged}" Width="50"/>
        </WrapPanel>

        private void _btnUpdateSource_Click(object sender, RoutedEventArgs e)
        {
            BindingExpression binding = _txtwindow.GetBindingExpression(TextBox.TextProperty);// Get the binding of the target control 
            binding.UpdateSource();
        }

  modify txtTitle Then click update source Button , forms Title change

  modify txtWidth Change the mouse focus after , Form width update

modify txtHeight, Form height update