1     /// <summary>
 2     /// 窗口显示变更触发时机
 3     /// </summary>
 4     public enum WindowLocationInvokeOccasion
 5     {
 6         /// <summary>
 7         /// 只要Activated就显示在中间
 8         /// </summary>
 9         Activated = 0,
10 
11         /// <summary>
12         /// 只在第一次Activated时，显示在中间一次，之后的变化就不修改
13         /// </summary>
14         FirstActivated,
15 
16         /// <summary>
17         /// 窗口每次显示时，窗口居中
18         /// <para>可以解决单实例窗口弹出不居中问题</para>
19         /// </summary>
20         Visibile,
21 
22         /// <summary>
23         /// 窗口每次显示时，如父窗口与当前窗口不在同一屏幕时，窗口居中
24         /// <para>可以解决单实例窗口弹出不居中问题</para>
25         /// </summary>
26         VisibileInDifferentScreen,
27 
28         /// <summary>
29         /// 不触发
30         /// </summary>
31         Defatult
32     }

1 /// <summary>
2 /// 窗口显示居中触发时机
3 /// <para>另：居中显示设置，请使用<see cref="Window"/>的<see cref="WindowStartupLocation"/>属性</para>
4 /// </summary>
5 public static readonly DependencyProperty InvokeOccasionProperty = DependencyProperty.RegisterAttached(
6     "InvokeOccasion", typeof(WindowLocationInvokeOccasion), typeof(WindowLocationOptions),
7     new PropertyMetadata(default(WindowLocationInvokeOccasion), InvokeOccasionProperty_ChangedCallback));

 1 var screen = Screen.FromHandle(new WindowInteropHelper(parentWindow).Handle);
 2 
 3 Graphics currentGraphics = Graphics.FromHwnd(new WindowInteropHelper(parentWindow).Handle);
 4 double dpiXRatio = currentGraphics.DpiX / 96;
 5 double dpiYRatio = currentGraphics.DpiY / 96;
 6 
 7 //当子窗口与父窗口所在屏幕相同时，不作处理
 8 var isSubWindowInSameScreen = subWindow.Left > screen.Bounds.Left / dpiXRatio &&
 9                                 subWindow.Left < screen.Bounds.Left / dpiXRatio + screen.Bounds.Width / dpiXRatio &&
10                                 subWindow.Top > screen.Bounds.Top / dpiYRatio &&
11                                 subWindow.Top < screen.Bounds.Top / dpiYRatio + screen.Bounds.Height / dpiYRatio;
12 return isSubWindowInSameScreen;

 1 /// <summary>
 2 /// 在主窗口中居中显示
 3 /// </summary>
 4 /// <param name="subWindow"></param>
 5 /// <param name="parentWindow"></param>
 6 private static void SetWindowInCenterOwner(Window subWindow, Window parentWindow)
 7 {
 8     //最大化窗口，固定的弹出到主屏幕，因此需额外处理
 9     if (subWindow.WindowState == WindowState.Maximized)
10     {
11         //子窗口最大化时，需要根据屏幕设置位置；
12         var screen = Screen.FromHandle(new WindowInteropHelper(parentWindow).Handle);
13 
14         Graphics currentGraphics = Graphics.FromHwnd(new WindowInteropHelper(parentWindow).Handle);
15         double dpiXRatio = currentGraphics.DpiX / 96;
16         double dpiYRatio = currentGraphics.DpiY / 96;
17 
18         subWindow.Left = screen.Bounds.Left / dpiXRatio;
19         subWindow.Top = screen.Bounds.Top / dpiYRatio;
20     }
21     if (parentWindow.WindowState == WindowState.Maximized)
22     {
23         //父窗口最大化时，父窗口的location,因窗口设置margin，有可能不准确，故取屏幕位置
24         var screen = Screen.FromHandle(new WindowInteropHelper(parentWindow).Handle);
25 
26         Graphics currentGraphics = Graphics.FromHwnd(new WindowInteropHelper(parentWindow).Handle);
27         double dpiXRatio = currentGraphics.DpiX / 96;
28         double dpiYRatio = currentGraphics.DpiY / 96;
29 
30         //窗口居中显示
31         subWindow.Left = screen.Bounds.Left / dpiXRatio +
32                             (screen.Bounds.Width / dpiXRatio - subWindow.ActualWidth) / 2;
33         subWindow.Top = screen.Bounds.Top / dpiYRatio +
34                         (screen.Bounds.Height / dpiYRatio - subWindow.ActualHeight) / 2;
35     }
36     else
37     {
38         //窗口居中显示
39         subWindow.Left = parentWindow.Left + (parentWindow.ActualWidth - subWindow.ActualWidth) / 2;
40         subWindow.Top = parentWindow.Top + (parentWindow.ActualHeight - subWindow.ActualHeight) / 2;
41     }
42 }

 1 /// <summary>
 2 /// 在父窗口所在屏幕居中显示
 3 /// </summary>
 4 /// <param name="subWindow"></param>
 5 /// <param name="parentWindow"></param>
 6 private static void SetWindowInCenterScreen(Window subWindow, Window parentWindow)
 7 {
 8     SetWindowLocationInScreen(subWindow, parentWindow, subWindow.WindowState);
 9 }
10 
11 private const int DpiPercent = 96;
12 
13 private static void SetWindowLocationInScreen(Window subWindow, Window parentWindow, WindowState windowState)
14 {
15     var intPtr = new WindowInteropHelper(parentWindow).Handle;
16     var screen = Screen.FromHandle(intPtr);
17 
18     using (Graphics currentGraphics = Graphics.FromHwnd(intPtr))
19     {
20         double dpiXRatio = currentGraphics.DpiX / DpiPercent;
21         double dpiYRatio = currentGraphics.DpiY / DpiPercent;
22 
23         if (windowState == WindowState.Maximized)
24         {
25             //设置全屏Location
26             subWindow.Left = screen.Bounds.Left / dpiXRatio;
27             subWindow.Top = screen.Bounds.Top / dpiYRatio;
28         }
29         else
30         {
31             //设置居中Location
32             subWindow.Left = screen.Bounds.Left / dpiXRatio +
33                                 (screen.Bounds.Width / dpiXRatio - subWindow.ActualWidth) / 2;
34             subWindow.Top = screen.Bounds.Top / dpiYRatio +
35                             (screen.Bounds.Height / dpiYRatio - subWindow.ActualHeight) / 2;
36         }
37     }
38 }