如何将WPF数据网格内的依赖项对象绑定到可观察的集合

Question

Background: I have a wpf datagrid that has a custom class ( CustomTextBox ) that inherits from a TextBox . I have created a dependency object ( ValueProperty ) in this custom class so I can bind to it. I also have a observable collection that I use as a DataSource for the DataGrid .

Issue: The problem is that when I bind my dependency property of my custom class to a public property in the observable collection, nothing is showing in the DataGrid .

Here is the xaml for the DataGrid TemplateColumn where the binding happens:

<DataGridTemplateColumn Header="Drawing Location"  Width="240" CellStyle="{StaticResource dataGridCellStyle}">
      <DataGridTemplateColumn.HeaderTemplate>
        <DataTemplate>
            <Label Content="Drawing Location" Width="230" HorizontalContentAlignment="Center"/>
        </DataTemplate>
    </DataGridTemplateColumn.HeaderTemplate>
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal">
                <CustomTextBox:CustomTextBox x:Name="ftbDrawingX" Value="{Binding DrawingLocationX, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
                                             Style="{StaticResource textBox}" Width="85" Behavior="DistanceCombinedFtIn"/>
                <Label Content=","/>
                <CustomTextBox:CustomTextBox x:Name="ftbDrawingY" Value="{Binding DrawingLocationY, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
                                             Style="{StaticResource textBox}" Width="85" Behavior="DistanceCombinedFtIn"/>
            </StackPanel>
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

And here is my dependency property in the custom class:

public static readonly DependencyProperty ValueProperty = DependencyProperty.Register("Value", typeof(double), typeof(CustomTextBox), 
    new FrameworkPropertyMetadata(0D, FrameworkPropertyMetadataOptions.Journal | FrameworkPropertyMetadataOptions.BindsTwoWayByDefault | FrameworkPropertyMetadataOptions.AffectsRender, new PropertyChangedCallback(ValueProperty_OnTextPropertyChanged)));

public double Value
{
    get {return (double)this.GetValue(ValueProperty);}    
    set
    {

    }
}

In the code behind:

private ObservableCollection<CustomItem> data = new ObservableCollection<CustomItem>();    
this.dgTakeoffDataGrid.ItemsSource = data;

The CustomItem object implements INotifyPropertyChanged and has two properties: DrawingLocationX and DrawingLocationY .

Can anyone please take a look and tell me what I have done wrong. My DataGrid comes up empty, I know my issue is with binding to a dependency object. Any help is appreciated here.

EDIT: I removed all logic from the setter property of Value, and I have added a callback method which handles the changes to the dependency object, and also updates it's Text property.

private static void ValueProperty_OnTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs eventArgs)
    {
        CustomTextBox box = d as CustomTextBox;
        if (box != null)
        {
            box.value = Conversions.RoundLeastSignificant(Conversions.RoundLeastSignificant((double)eventArgs.NewValue));
            box.Text = Conversions.FormatReadTextValue((double)eventArgs.NewValue, box.behavior, box.acadDocument);
        }
    }

Answer 1

I have managed to resolve this issue. The solution is in my last comment: The solution being to remove all the logic from the setter of the property, and handle setting Value in a CallBack method defined when you register the dependency property.

This is the general solution. Hope it helps others as well.