Determine if an open WPF window is visible on any monitor

Question

Is there a way to determine if an open WPF window is currently visible in any of the desktop's connected monitors? By visible I mean that the window's bounds rectangle intersects with the desktop rectangle of any of the monitors.

I need this functionality to determine if a window needs to be repositioned because the monitor configuration (working areas bounds, monitor count) changed between restarts of my application (which saves window positions).

I have come up with the code below and it seems to work, but it has several problems:

1. I need to reference windows forms.
2. I need the desktop's DPI settings and transform the windows forms actual pixels to WPF virtual pixels.
3. I need an acutal Visual instance that already has been rendered to perform the transformation.

Do you know of a solution that gets rid of some or all of the 3 issues above?

using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Forms;
using System.Windows.Media;

internal static class Desktop
{
    private static Size dpiFactor = new Size(1.0, 1.0);
    private static bool isInitialized;

    public static IEnumerable<Rect> WorkingAreas
    {
        get
        {
            return
                Screen.AllScreens.Select(
                    screen =>
                    new Rect(
                        screen.WorkingArea.Left * dpiFactor.Width,
                        screen.WorkingArea.Top * dpiFactor.Height,
                        screen.WorkingArea.Width * dpiFactor.Width,
                        screen.WorkingArea.Height * dpiFactor.Height));
        }
    }

    public static void TryInitialize(Visual visual)
    {
        if (isInitialized)
        {
            return;
        }

        var ps = PresentationSource.FromVisual(visual);
        if (ps == null)
        {
            return;
        }

        var ct = ps.CompositionTarget;
        if (ct == null)
        {
            return;
        }

        var m = ct.TransformToDevice;
        dpiFactor = new Size(m.M11, m.M22);
        isInitialized = true;
    }
}

Usage of the (initialized) Desktop class:

    private bool IsLocationValid(Rect windowRectangle)
    {
        foreach (var workingArea in Desktop.WorkingAreas)
        {
            var intersection = Rect.Intersect(windowRectangle, workingArea);
            var minVisible = new Size(10.0, 10.0);
            if (intersection.Width >= minVisible.Width && 
                intersection.Height >= minVisible.Height)
            {
                return true;
            }
        }

        return false;
    }

Update

Using the virtual screen (SystemParameters.VirtualScreen*) does not work because when using multiple monitors the "desktop" is not a simple rectangle. It might be a polygon. There will be blind spots in the virtual screen because

1. the connected screens can have different resolutions
2. you can configure the position of each screen.

Answer 1

The code we use to do something similar uses information from SystemParameters, in particular SystemParameter.VirtualScreenLeft, Top, Width and Height.

If we have a saved Location and Size then we determine if the window is out of bounds like this:

bool outOfBounds =
    (location.X <= SystemParameters.VirtualScreenLeft - size.Width) ||
    (location.Y <= SystemParameters.VirtualScreenTop - size.Height) ||
    (SystemParameters.VirtualScreenLeft + 
        SystemParameters.VirtualScreenWidth <= location.X) ||
    (SystemParameters.VirtualScreenTop + 
        SystemParameters.VirtualScreenHeight <= location.Y);

Answer 2

I use this code snipped in my WPF project on startup; it's written in vb.net:

If My.Settings.RememberWindowPositionAndSize Then
    If My.Settings.winMainWinState > 2 Then My.Settings.winMainWinState = WindowState.Normal
    If My.Settings.winMainWinState = WindowState.Minimized Then My.Settings.winMainWinState = WindowState.Normal
    Me.WindowState = My.Settings.winMainWinState
    If My.Settings.winMainWinState = WindowState.Normal Then
        Dim winBounds As New System.Drawing.Rectangle(CInt(My.Settings.winMainPosX), CInt(My.Settings.winMainPosY),
                                                      CInt(My.Settings.winMainSizeB), CInt(My.Settings.winMainSizeH))
        For Each scr As System.Windows.Forms.Screen In System.Windows.Forms.Screen.AllScreens
            If winBounds.IntersectsWith(scr.Bounds) Then
                Me.Width = My.Settings.winMainSizeB
                Me.Height = My.Settings.winMainSizeH
                Me.Top = My.Settings.winMainPosY
                Me.Left = My.Settings.winMainPosX
                Exit For
            End If
        Next
    End If
End If

and here is same (converted) code in C#

if (My.Settings.RememberWindowPositionAndSize) {
    if (My.Settings.winMainWinState > 2)
        My.Settings.winMainWinState = WindowState.Normal;
    if (My.Settings.winMainWinState == WindowState.Minimized)
        My.Settings.winMainWinState = WindowState.Normal;
    this.WindowState = My.Settings.winMainWinState;

    if (My.Settings.winMainWinState == WindowState.Normal) {
        System.Drawing.Rectangle winBounds = new System.Drawing.Rectangle(Convert.ToInt32(My.Settings.winMainPosX), Convert.ToInt32(My.Settings.winMainPosY), Convert.ToInt32(My.Settings.winMainSizeB), Convert.ToInt32(My.Settings.winMainSizeH));

        foreach (System.Windows.Forms.Screen scr in System.Windows.Forms.Screen.AllScreens) {
            if (winBounds.IntersectsWith(scr.Bounds)) {
                this.Width = My.Settings.winMainSizeB;
                this.Height = My.Settings.winMainSizeH;
                this.Top = My.Settings.winMainPosY;
                this.Left = My.Settings.winMainPosX;
                break;
            }
        }
    }
}