Binding error when binding to Width Property of MainView Window

Question

I have a MainView Window whose width and height I'm trying to bind from its Code-Behind class.

<Window x:Class="RpP25.MainView"
   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
   xmlns:shared="http://schemas.actiprosoftware.com/winfx/xaml/shared"     
   xmlns:docking="http://schemas.actiprosoftware.com/winfx/xaml/docking"
   xmlns:themes="http://schemas.actiprosoftware.com/winfx/xaml/themes"
   xmlns:RpWin="clr-namespace:RpP25"
   xmlns:RpWinCmds="clr-namespace:RpP25.Commands"
   xmlns:diagnostics="clr-namespace:System.Diagnostics;assembly=WindowsBase"
   Title="{Binding Path=FileName, Converter={StaticResource WindowTitleNameConverter}}"
   Height="{Binding Path=WindowHeight, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}"
   Width="{Binding Path=WindowWidth, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}"
   Icon="images/CobWhite.ico"
   Loaded="Window_Loaded"
   Closing="Window_Closing">

The Code behind has the properties and also sets the datacontext to by ViewModel MainVM.

public partial class MainView : Window, INotifyPropertyChanged
{
    // Constant Fields
    private const double windowDefaultWidth_ = 720;
    private const double windowDefaultHeight_ = 400;

    // Private Fields
    private RegistryKey RegKey_;                                // Registry Key to hold Registry Subkey
    private WindowState windowState_ = WindowState.Normal;   // Display State of the MainWindow (Min,Max or Normal)
    private double windowWidth_ = windowDefaultWidth_;    // Width of the MainWindow
    private double windowHeight_ = windowDefaultHeight_;  // Height of the MainWindow

    #region Constructors

    public MainView()
    {
        InitializeComponent();
        DataContext = new MainVM();

        // Get the state of the window and the width/height from the registry
        ReadRegistryValues();

    /// <summary>
    /// Gets the Width of the Window
    /// </summary>
    public double WindowWidth
    {
        get { return windowWidth_; }
        set { windowWidth_ = value; NotifyPropertyChanged("WindowWidth"); }
    }

    /// <summary>
    /// Gets the Height of the Window
    /// </summary>
    public double WindowHeight
    {
        get { return windowHeight_; }
        set { windowHeight_ = value; NotifyPropertyChanged("windowHeight"); }
    }

    ...
}

This window is created from App::OnStartup().

When I run the code the debugger throws the following error in the output window.

Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Window', AncestorLevel='1''. BindingExpression:Path=WindowHeight; DataItem=null; target element is 'MainView' (Name=''); target property is 'Height' (type 'Double')

and a similar one for WindowWidth.

I thought I understood the binding modes, but I guess I was wrong :(

I was thinking that using FindAncestor looking for a Window would cause it to look up the visual tree until it found the MainView window that had my properties on it.

Any help would be MUCH appreciated.

Steck Steck · Accepted Answer · 2012-01-13T06:08:03

try

Width="{Binding Path=WindowWidth, RelativeSource={RelativeSource Self}}"

Codebehind is the same element that your window. So use Self binding.

Binding error when binding to Width Property of MainView Window

1 Answers