From d48286a3ebedff8b6c64bbe8e57302a34a36c257 Mon Sep 17 00:00:00 2001
From: Mike Griese <migrie@microsoft.com>
Date: Thu, 3 Apr 2025 06:44:10 -0500
Subject: [PATCH] Scale the toast window for DPI (#38198)

Ah of course, AppWindow.Resize doesn't use DIPs. Why would it? It's not like literally everything else in XAML does.

Related to half of https://github.com/zadjii-msft/PowerToys/issues/508
---
 .../Microsoft.CmdPal.UI/NativeMethods.txt     |  1 +
 .../Microsoft.CmdPal.UI/ToastWindow.xaml.cs   | 27 ++++++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/modules/cmdpal/Microsoft.CmdPal.UI/NativeMethods.txt b/src/modules/cmdpal/Microsoft.CmdPal.UI/NativeMethods.txt
index 6186b45ef8..566f459c65 100644
--- a/src/modules/cmdpal/Microsoft.CmdPal.UI/NativeMethods.txt
+++ b/src/modules/cmdpal/Microsoft.CmdPal.UI/NativeMethods.txt
@@ -19,6 +19,7 @@ SetFocus
 SetActiveWindow
 MonitorFromWindow
 GetMonitorInfo
+GetDpiForMonitor
 SHCreateStreamOnFileEx
 CoAllowSetForegroundWindow
 SHCreateStreamOnFileEx
diff --git a/src/modules/cmdpal/Microsoft.CmdPal.UI/ToastWindow.xaml.cs b/src/modules/cmdpal/Microsoft.CmdPal.UI/ToastWindow.xaml.cs
index e21c8dd55d..47ecf96975 100644
--- a/src/modules/cmdpal/Microsoft.CmdPal.UI/ToastWindow.xaml.cs
+++ b/src/modules/cmdpal/Microsoft.CmdPal.UI/ToastWindow.xaml.cs
@@ -4,6 +4,7 @@
 
 using CommunityToolkit.Mvvm.Messaging;
 using CommunityToolkit.WinUI;
+using ManagedCommon;
 using Microsoft.CmdPal.UI.Helpers;
 using Microsoft.CmdPal.UI.ViewModels;
 using Microsoft.CmdPal.UI.ViewModels.Messages;
@@ -13,6 +14,8 @@ using Microsoft.UI.Xaml;
 using Windows.Graphics;
 using Windows.Win32;
 using Windows.Win32.Foundation;
+using Windows.Win32.Graphics.Gdi;
+using Windows.Win32.UI.HiDpi;
 using Windows.Win32.UI.WindowsAndMessaging;
 using RS_ = Microsoft.CmdPal.UI.Helpers.ResourceLoaderInstance;
 
@@ -44,6 +47,21 @@ public sealed partial class ToastWindow : Window,
         WeakReferenceMessenger.Default.Register<QuitMessage>(this);
     }
 
+    private static double GetScaleFactor(HWND hwnd)
+    {
+        try
+        {
+            var monitor = PInvoke.MonitorFromWindow(hwnd, MONITOR_FROM_FLAGS.MONITOR_DEFAULTTONEAREST);
+            _ = PInvoke.GetDpiForMonitor(monitor, MONITOR_DPI_TYPE.MDT_EFFECTIVE_DPI, out var dpiX, out _);
+            return dpiX / 96.0;
+        }
+        catch (Exception ex)
+        {
+            Logger.LogError($"Failed to get scale factor, error: {ex.Message}");
+            return 1.0;
+        }
+    }
+
     private void PositionCentered()
     {
         var intSize = new SizeInt32
@@ -51,7 +69,14 @@ public sealed partial class ToastWindow : Window,
             Width = Convert.ToInt32(ToastText.ActualWidth),
             Height = Convert.ToInt32(ToastText.ActualHeight),
         };
-        AppWindow.Resize(intSize);
+
+        var scaleAdjustment = GetScaleFactor(_hwnd);
+        var scaled = new SizeInt32
+        {
+            Width = (int)Math.Round(intSize.Width * scaleAdjustment),
+            Height = (int)Math.Round(intSize.Height * scaleAdjustment),
+        };
+        AppWindow.Resize(scaled);
 
         var displayArea = DisplayArea.GetFromWindowId(AppWindow.Id, DisplayAreaFallback.Nearest);
         if (displayArea is not null)