Read-only PropertyGrid [C#]

This example demonstrates how to implement a read only property grid.

The default PropertyGrid control provided by WinForms doesn't support a read-only functionality. You can only disable the default PropertyGrid by setting the Enable property to false, but then a user won't be able to fully inspect all the properties of the selected object. The way to go is to add the class-level ReadOnlyAttribute, which is provided by .NET, to the selected object.

The main problem is how to add and remove class-level ReadOnly attribute to an object at runtime.

This code shows how to add ReadOnlyAttribute at runtime.

[C#]

TypeDescriptor.AddAttributes(this.SelectedObject, new Attribute[] { new ReadOnlyAttribute(_readOnly) });

The following code shows how to implement ReadOnlyPropertyGrid.

[C#]

public class ReadOnlyPropertyGrid : PropertyGrid
{
  private bool _readOnly;
  public bool ReadOnly
  {
    get { return _readOnly; }
    set
    {
      _readOnly = value;
      this.SetObjectAsReadOnly(this.SelectedObject, _readOnly);
    }
  }

  protected override void OnSelectedObjectsChanged(EventArgs e)
  {
    this.SetObjectAsReadOnly(this.SelectedObject, this._readOnly);
    base.OnSelectedObjectsChanged(e);
  }

  private void SetObjectAsReadOnly(object selectedObject, bool isReadOnly)
  {
    if (this.SelectedObject != null)
    {
      TypeDescriptor.AddAttributes(this.SelectedObject, new Attribute[] { new ReadOnlyAttribute(_readOnly) });
      this.Refresh();
    }
  }
}

Note: In the previous code we actually do not remove the ReadOnly attribute. If you want to remove the attribute, you have to store the TypeDescriptorProvider and then use the RemoveProvider method as shows the following code.

[C#]

// store the provider
TypeDescriptionProvider provider = TypeDescriptor.AddAttributes(this.SelectedObject,
new Attribute[] { new ReadOnlyAttribute(_readOnly) });

// remove the provider
TypeDescriptor.RemoveProvider(provider, this.SelectedObject);

Note: The property grid in this example can inspect only classes which implements IComponent interface.

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Read-only PropertyGrid [C#]

See also