From 0f7f9778c16d459a487dda0f476792991a92f816 Mon Sep 17 00:00:00 2001
From: "hemn.still" <hemn.still@gmail.com>
Date: Fri, 30 Jan 2015 15:16:24 +0400
Subject: [PATCH] Fix GetDeviceCoordinates. In some cases
 PresentationSource.FromVisual(this) may return null.

---
 .../NotifyIconWpf/Interop/SystemInfo.cs       | 39 +++++++++++++++++++
 .../Source/NotifyIconWpf/NotifyIconWpf.csproj |  1 +
 .../Source/NotifyIconWpf/TaskbarIcon.cs       | 20 +---------
 3 files changed, 41 insertions(+), 19 deletions(-)
 create mode 100644 Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/Interop/SystemInfo.cs

diff --git a/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/Interop/SystemInfo.cs b/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/Interop/SystemInfo.cs
new file mode 100644
index 0000000..8274196
--- /dev/null
+++ b/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/Interop/SystemInfo.cs
@@ -0,0 +1,39 @@
+using System;
+using System.Windows.Interop;
+
+namespace Hardcodet.Wpf.TaskbarNotification.Interop
+{
+  public static class SystemInfo
+  {
+    private static Tuple<double, double> dpiFactors;
+
+    private static Tuple<double, double> DpiFactors
+    {
+      get
+      {
+        if (dpiFactors == null)        
+          using (var source = new HwndSource(new HwndSourceParameters()))
+            dpiFactors = Tuple.Create(source.CompositionTarget.TransformToDevice.M11, source.CompositionTarget.TransformToDevice.M22);        
+        return dpiFactors;
+      }
+    }
+
+    public static double DpiXFactor
+    {
+      get
+      {
+        var factors = DpiFactors;
+        return factors != null ? factors.Item1 : 1;
+      }
+    }
+
+    public static double DpiYFactor
+    {
+      get
+      {
+        var factors = DpiFactors;
+        return factors != null ? factors.Item2 : 1;
+      }
+    }         
+  }
+}
diff --git a/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/NotifyIconWpf.csproj b/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/NotifyIconWpf.csproj
index 981fc5e..4e7a2af 100644
--- a/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/NotifyIconWpf.csproj
+++ b/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/NotifyIconWpf.csproj
@@ -47,6 +47,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="BalloonIcon.cs" />
+    <Compile Include="Interop\SystemInfo.cs" />
     <Compile Include="Interop\TrayInfo.cs">
       <SubType>Code</SubType>
     </Compile>
diff --git a/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/TaskbarIcon.cs b/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/TaskbarIcon.cs
index 884eedc..e59a5d5 100644
--- a/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/TaskbarIcon.cs
+++ b/Hardcodet.NotifyIcon.Wpf/Source/NotifyIconWpf/TaskbarIcon.cs
@@ -962,25 +962,7 @@ namespace Hardcodet.Wpf.TaskbarNotification
         /// <returns></returns>
         private Point GetDeviceCoordinates(Point point)
         {
-            if (double.IsNaN(scalingFactor))
-            {
-                //calculate scaling factor in order to support non-standard DPIs
-                var presentationSource = PresentationSource.FromVisual(this);
-                if (presentationSource == null)
-                {
-                    scalingFactor = 1;
-                }
-                else
-                {
-                    var transform = presentationSource.CompositionTarget.TransformToDevice;
-                    scalingFactor = 1/transform.M11;
-                }
-            }
-
-            //on standard DPI settings, just return the point
-            if (scalingFactor == 1.0) return point;
-
-            return new Point() {X = (int) (point.X*scalingFactor), Y = (int) (point.Y*scalingFactor)};
+          return new Point() { X = (int)(point.X / SystemInfo.DpiXFactor), Y = (int)(point.Y / SystemInfo.DpiYFactor) };
         }
 
         #region Dispose / Exit