WPF中的Adorner，isEnabled无法正常工作吗？

Question

I'm using an adorner layer to make a grid (like, boxes across the entire screen) across my grid (WPF grid).

I want this to be shown ONLY when a checkbox is marked. However, when I bind the "IsEnabled" property, nothing happens. Even if I set the IsEnabled to false, the grid overlay is still shown!

This is how I do from my mainWindow.xaml, note the IsEnabled is set to false, but it is still showing up:

<Grid>
        <!--Adornerdecorator is made to make sure the adorner is in the background, and not the foreground-->
        <AdornerDecorator>
          <View:GridWithRulerxaml IsEnabled="False" />
        </AdornerDecorator>
        <ItemsControl ItemsSource="{Binding Classes}"/>
        <ItemsControl ItemsSource="{Binding Edges}"/>
    </Grid>

this is the adorner usercontrol:

namespace UMLDesigner.View
{
/// <summary>
/// Interaction logic for GridWithRulerxaml.xaml
/// </summary>
public partial class GridWithRulerxaml : UserControl
{
    public GridWithRulerxaml()
    {
        InitializeComponent();

        //Loaded event is necessary as Adorner is null until control is shown.
        Loaded += GridWithRulerxaml_Loaded;

    }

    void GridWithRulerxaml_Loaded(object sender, RoutedEventArgs e)
    {
        var adornerLayer = AdornerLayer.GetAdornerLayer(this);
        var rulerAdorner = new AlignmentAdorner(this);
        adornerLayer.Add(rulerAdorner);
    }
}
}

And finally the adorner itself:

namespace UMLDesigner.Utilities
{
public class AlignmentAdorner : Adorner
{
    private FrameworkElement element;
    public AlignmentAdorner(UIElement el)
        : base(el)
    {
        element = el as FrameworkElement;
    }

    protected override void OnRender(System.Windows.Media.DrawingContext drawingContext)
    {
        base.OnRender(drawingContext);

        double height = element.ActualHeight;
        double width = element.ActualWidth;

        double linesHorizontal = height / 50;
        double linesVertical = width / 50;

        var pen = new Pen(Brushes.LightGray, 1) { StartLineCap = PenLineCap.Triangle,     EndLineCap = PenLineCap.Triangle };

        int offset = 0;

        for (int i = 0; i <= linesVertical; ++i)
        {
            offset = offset + 50;
            drawingContext.DrawLine(pen, new Point(offset, 0), new Point(offset, height));
        }

        offset = 0;

        for (int i = 0; i <= linesHorizontal; ++i)
        {
            offset = offset + 50;
            drawingContext.DrawLine(pen, new Point(0, offset), new Point(width, offset));
        }
    }
}
}

I really hope you can help me out here guys.

Answer 1

The IsEnabled property only enables/disables interaction with the element, and has nothing to do with the Visibility.

What you should do is set the Visibility property of the GridWithRulerxaml to Collapsed or Hidden when you want to hide it, and set it to Visible when you want it shown.

Edit: Tested it, setting the visiblity to Hidden of the GridWithRulerxaml usercontrol inside the AdornerDecorator doesn't hide the adorner.

And thinking some more about it, if this isn't what you want, it might be possible to do this with the IsEnabled property, watching for changes in it and adding/removing the adorner depending on the value.