绑定WindowStartupLocation

Question

我正在尝试让我的主窗口记住并恢复启动时的位置和大小.所以我尝试将我的窗口的启动位置绑定到我的viewmodel中的属性,如下所示:

<Window x:Class="MyApp.Views.MainWindow"
    ...
    Width="{Binding Width}"
    Height="{Binding Height}"
    WindowStartupLocation="{Binding WindowStartupLocation}"
    WindowState="{Binding WindowState}"
    MinHeight="600"
    MinWidth="800"
    Closing="OnWindowClosing"
    Closed="OnWindowClosed"
    ContentRendered="OnMainWindowReady"
    ...>

我的viewmodel:

        ...

        // Default settings
        WindowState = (WindowState)FormWindowState.Normal;
        this.WindowStartupLocation = WindowStartupLocation.CenterScreen;
        Width = 800;
        Height = 600;

        // check if the saved bounds are nonzero and is visible on any screen
        if (Properties.Settings.Default.WindowStartupLocation != Rectangle.Empty &&
            IsVisibleOnAnyScreen(Properties.Settings.Default.WindowStartupLocation))
        {
            this.WindowStartupLocation = WindowStartupLocation.Manual;
            this.WindowState = (WindowState)Properties.Settings.Default.WindowState;
            Height = Properties.Settings.Default.WindowStartupLocation.Size.Height;
            Width = Properties.Settings.Default.WindowStartupLocation.Size.Width;
            Left = Properties.Settings.Default.WindowStartupLocation.Left;
            Top = Properties.Settings.Default.WindowStartupLocation.Top;
        }
        ...

当我运行应用程序时,我得到一个System.Windows.Markup.XamlParseException和附加信息:无法在'MainWindow'类型的'WindowStartupLocation'属性上设置'绑定'.'绑定'只能在DependencyObject的DependencyProperty上设置.

我该怎么纠正这个？

Answer 1

尝试使用附加行为来绑定WindowStartupLocation属性:

namespace YourProject.PropertiesExtension
{
    public static class WindowExt
    {
        public static readonly DependencyProperty WindowStartupLocationProperty;

        public static void SetWindowStartupLocation(DependencyObject DepObject, WindowStartupLocation value)
        {
            DepObject.SetValue(WindowStartupLocationProperty, value);
        }

        public static WindowStartupLocation GetWindowStartupLocation(DependencyObject DepObject)
        {
            return (WindowStartupLocation)DepObject.GetValue(WindowStartupLocationProperty);
        }

        static WindowExt() 
        {            
            WindowStartupLocationProperty = DependencyProperty.RegisterAttached("WindowStartupLocation",
                                                      typeof(WindowStartupLocation),
                                                      typeof(WindowExt),
                                                      new UIPropertyMetadata(WindowStartupLocation.Manual, OnWindowStartupLocationChanged));
        }

        private static void OnWindowStartupLocationChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        {
            Window window = sender as Window; 

            if (window != null) 
            {
                window.WindowStartupLocation = GetWindowStartupLocation(window);
            }
        }
    }
}

用法:

<Window
  PropertiesExtension:WindowExt.WindowStartupLocation="{Binding ..}" />

正如错误所述,WindowStartupLocation不是依赖性,这意味着你无法绑定它.解决方案可以是派生自Window,也可以创建依赖属性,或者使用附加行为.