WPF 为每个屏幕创建一个 Window，并将它们居中放置在每个屏幕上

Question

编辑： 我解决了。在下面的答案中查看我的修复。

我正在开发一个应用程序，该应用程序应在连接到运行它的计算机的每个屏幕上打开一个小弹出窗口 window。在单个屏幕上很简单（使用 WindowStartupLocation = CenterScreen），但在多个屏幕上却非常困难。

我目前的代码是这样的：

        foreach (var s in Screen.AllScreens) //System.Windows.Forms.Screen
        {
            var b = s.Bounds;
            var w = new PopupWindow();

            var oW = w.Width; //Keep track of original size ...
            var oH = w.Height;

            w.Width = 0; //then set the size to 0, to avoid that the 
            w.Height = 0;//popup shows before it is correctly positioned

            w.Show(); //Now show it, so that we can place it (when I
                      //tried to place it before showing, the window
                      //was always repositioned when Show() was called)

            double dpiX = 1, dpiY = 1;
            var presentationsource = PresentationSource.FromVisual(w);

            if (presentationsource != null)
            {
                dpiX = presentationsource.CompositionTarget.TransformToDevice.M11;
                dpiY = presentationsource.CompositionTarget.TransformToDevice.M22;
            }

            var aW = oW*dpiX; //Calculate the actual size of the window
            var aH = oH*dpiY;

            //***** THIS IS WRONG, SEE ANSWER *****
            w.Left = (b.X + (b.Width / dpiX - aW) / 2); //Place it
            w.Top = (b.Y + (b.Height / dpiY - aH) / 2);
            //*************************************

            w.Width = oW; //And set the size back to the original size
            w.Height = oH;
        }

这似乎只适用于主屏幕。在其他屏幕上，windows 没有正确居中。

我猜这是因为我对 WPF 和 DPI 的了解非常有限，而且我可能做错了什么。有人能给我指出正确的方向吗？

Answer 1

当然，我在这里发布后设法解决了它。看起来我在尝试用 DPI 划分整个位置时做错了其他事情，这导致我走上了上面发布的错误路径。

放置表单的正确行应该是这样的（所有其他代码都有效）：

                w.Left = (b.X + (b.Width - aW) / 2) / dpiX;
                w.Top = (b.Y + (b.Height - aH) / 2) / dpiX;

但是，我仍然认为这是一个简单任务的大量代码，所以如果有人有更好的想法，请告诉我！

所以这是我现在使用的（工作）代码：

    foreach (var s in Screen.AllScreens) //System.Windows.Forms.Screen
    {
        var b = s.Bounds;
        var w = new PopupWindow();

        var oW = w.Width; //Keep track of original size ...
        var oH = w.Height;

        w.Width = 0; //then set the size to 0, to avoid that the 
        w.Height = 0;//popup shows before it is correctly positioned

        w.Show(); //Now show it, so that we can place it (when I
                  //tried to place it before showing, the window
                  //was always repositioned when Show() was called)

        double dpiX = 1, dpiY = 1;
        var ps = PresentationSource.FromVisual(w);
        if (ps != null)
        {
            dpiX = ps.CompositionTarget.TransformToDevice.M11;
            dpiY = ps.CompositionTarget.TransformToDevice.M22;
        }

        var aW = oW*dpiX; //Calculate the actual size of the window
        var aH = oH*dpiY;

        w.Left = (b.X + (b.Width - aW) / 2) / dpiX;
        w.Top = (b.Y + (b.Height - aH) / 2) / dpiX;

        w.Width = oW; //And set the size back to the original size
        w.Height = oH;
    }

Answer 2

        var centers =
            System.Windows.Forms.Screen.AllScreens.Select(
                s =>
                    new
                    {
                        Left = s.Bounds.X + (s.WorkingArea.Right - s.WorkingArea.Left)/2,
                        Top = s.Bounds.Y + (s.WorkingArea.Bottom - s.WorkingArea.Top)/2
                    });

        foreach (var c in centers)
        {
            var w = new Window1();

            w.Left = c.Left - w.Width/2;
            w.Top = c.Top - w.Height/2;

            w.Show();
        }

WPF 为每个屏幕创建一个 Window，并将它们居中放置在每个屏幕上

WPF create one Window for each screen, and center them on each screen

c#

wpf

multiple-monitors

centering