Custom control binding not working when parent control visibility changed

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C#

WPF

custom-controls

Binding

Hello all.

I have a WPF custom control placed to grid. There is some standard wpf controls placed to same grid. My custom control has a binded dependency property. Parent grid have a datatrigger on Property Visibility and triggered when DataContext is not null.

Using my custom control:

<Grid Margin="5" DataContext="{Binding DetailedView}" >
    <Grid.Resources>
        <Style TargetType="{x:Type Grid}">
            <Setter Property="Visibility" Value="Visible"/>
                <Style.Triggers>
                     <DataTrigger Binding="{Binding}" Value="{x:Null}">
                          <Setter Property="Visibility" Value="Collapsed"/>
                     </DataTrigger>
                </Style.Triggers>
            </Style>
    </Grid.Resources>
    <!- ... -->
    <!-- Grid layout -->
    <!-- ... -->
    <Grid Grid.Column="1" Grid.Row="0">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="320"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="32"/>
            <RowDefinition Height="32"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <!-- My Custom control -->
        <controls:RatingControl x:Name="RcMangaRating" Grid.Column="1" Grid.Row="0" Value="{Binding Rating}" Size="24" Maximum="10" HorizontalAlignment="Right"/>
        <!-- Standard WPF control which have same binding as custom control -->
        <TextBlock Grid.Column="1" Grid.Row="1" FontSize="12" VerticalAlignment="Top" Text="{Binding Rating, StringFormat='{}Rating: {0:F2} from 10'}" Margin="0,5,5,0" HorizontalAlignment="Right"/>
    </Grid>
</Grid>

So, when visibility changed from Collapsed to Visible the binding for custom control not working but for standard control binding works normally. http://i.stack.imgur.com/bzZc7.png[^]

But when grid visibility set to Visible and not changing the binding for custom control works normally. http://i.stack.imgur.com/ny5EH.png[^]

Region of custom control style:

<Rectangle Grid.Row="0" Height="{TemplateBinding Width}" Width="{TemplateBinding Height}">
    <Rectangle.Style>
        <Style>
             <Setter Property="Rectangle.OpacityMask">
                <Setter.Value>
                    <LinearGradientBrush StartPoint="0,0" EndPoint="1,0">
                        <GradientStop Color="Black" Offset="{Binding Value, RelativeSource={RelativeSource TemplatedParent}}"/>
                        <GradientStop Color="Transparent" Offset="{Binding Value, RelativeSource={RelativeSource TemplatedParent}}"/>
                    </LinearGradientBrush>
                </Setter.Value>
            </Setter>
        </Style>
    </Rectangle.Style>
</Rectangle>

What I have tried:

I delete trigger on Visibility property and all bindings works normally

<Grid Margin="5" DataContext="{Binding DetailedView}" >
    <!-- ... -->
    <!-- Grid layout -->
    <!-- ... -->
    <Grid Grid.Column="1" Grid.Row="0">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="320"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="32"/>
            <RowDefinition Height="32"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <!-- My Custom control -->
        <controls:RatingControl x:Name="RcMangaRating" Grid.Column="1" Grid.Row="0" Value="{Binding Rating}" Size="24" Maximum="10" HorizontalAlignment="Right"/>
        <!-- Standard WPF control which have same binding as custom control -->
        <TextBlock Grid.Column="1" Grid.Row="1" FontSize="12" VerticalAlignment="Top" Text="{Binding Rating, StringFormat='{}Rating: {0:F2} from 10'}" Margin="0,5,5,0" HorizontalAlignment="Right"/>
    </Grid>
</Grid>

Have you any ideas what is problem?

--
Thanks you in advance.

Problem solved

Solution:

So, at first, there is the problem was in OnApplyTemplate in my control. I get TemplatePart in this method and initialize some fields in control:

public override void OnApplyTemplate()
{
    base.OnApplyTemplate();

    _starItems = (ItemsControl)GetTemplateChild("PART_StarItems");
    if (_starItems == null) return;

    var values = Enumerable.Range(0, (int)Maximum).Select(r => 0.0).ToList();
    _starValues = new ObservableCollection<double>(values);
}

Then in callback OnChangeValue applyes _starValues to _starItems. But at first time OnApplyTemplate after initializing is not calling (it calls after OnChangeValue and etc.) and _starItems was null:

RatingControl control = d as RatingControl;
if (control == null) return;
if (control._starItems == null) return; // Here was problem

/* Update values in _starValues */
_starItems.ItemsSource = _starValues;

So, I created new private DependecyProperty Values (same as _starValues) and bind it to ItemsSource of my control and removed TemplatePart and needless fields.

Source code[^]

Control template style[^]

Sorry, the problem was not in control template (how i originally thought), and there is implementation of binding for ItemsSource in my code. By this reason i originally post only XAML code. Thank you.

Thanks to my leader for the help and advice