綁定窗口啓動位置

Question

我試圖讓我的主窗口在啓動時記住並恢復位置和大小。所以，我想我的窗口的啓動位置綁定到我的視圖模型一個屬性如下：

<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" 
    ...> 

我的視圖模型：

 ... 

     // 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; 
     } 
     ... 

當我運行該應用程序，我得到一個System.Windows.Markup .XamlParseException和附加信息：無法在「MainWindow」類型的「WindowStartupLocation」屬性上設置「綁定」。 '綁定'只能在DependencyObject的DependencyProperty上設置。

我應該如何糾正？

Answer 1

嘗試使用附加的行爲，它可以讓你綁定WindowStartupLocation性質：

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 ..}" /> 

正如錯誤所述，WindowStartupLocation不是依賴性屬性，這意味着你不能綁定它。解決方案可以是從Window派生，並創建依賴項屬性，或使用附加的行爲。

Answer 2

不能綁定WindowsStartupLocation，此行生成錯誤：

WindowStartupLocation="{Binding WindowStartupLocation}" 

你可以將它設置爲某個特定的值，這樣的：

WindowStartupLocation="CenterScreen"