WPF: Control Visibility from Database / Prerender Hook

Question

Hi,

we have a rather odd requirement: The visibility of any control in our WPF-Application is to be driven by a database-table.

That means we have a table which stores the name of the element and its visiblity.

Now I am looking for an elegant way to implement this feature on the client side.

I could create my own UserControl and inherit from it everywhere, providing a InitializeComponent Template Method. But what if someone programmatically adds more childcontrols?

I don't want my controls to know about this mechanism at all. I want to hook in/intercept at a certain point (pre control-rendering) and adjust the visibility of the control according to the database.

Is that somehow possible? And if not, how would you design it?

Answer 1

So here is what I did:

I inherited from UserControl and put the check in the an EventHandler for the Loaded Event.

I then let my Controls inherit from my CustomControl, this works pretty well.

The FindName() implementation won't find the FrameworkElements for some reason I don't know, although their names are defined in the xaml. So here is the routine I use to find the children by their names:

    public static T FindVisualChildByName<T>(DependencyObject parent, string name) where T : DependencyObject
    {
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        {
            var child = VisualTreeHelper.GetChild(parent, i);
            string controlName = child.GetValue(Control.NameProperty) as string;

            if (controlName == name)
            {
                return child as T;
            }
            else
            {
                T result = FindVisualChildByName<T>(child, name);
                if (result != null)
                {
                    return result;
                }
            }
        }

        return null;
    }

I don't like this solution but it works.