Getting dpi from presentationsource

Change dpi getting logic

Author: l1pton17

MaterialDesignThemes.Wpf/ComboBoxPopup.cs

@@ -105,17 +105,19 @@ private CustomPopupPlacement[] ComboBoxCustomPopupPlacementCallback(Size popupSi
             Point offset)
         {
             var locationFromScreen = this.PlacementTarget.PointToScreen(new Point(0, 0));
-
+            
             int locationX = (int)locationFromScreen.X % (int)DpiHelper.TransformToDeviceX(SystemParameters.PrimaryScreenWidth);
             int locationY = (int)locationFromScreen.Y % (int)DpiHelper.TransformToDeviceY(SystemParameters.PrimaryScreenHeight);
-            double realOffsetX = (popupSize.Width - targetSize.Width) / 2.0;
 
-            double offsetX = DpiHelper.TransformToDeviceX(offset.X);
-            double defaultVerticalOffsetIndepent = DpiHelper.TransformToDeviceY(DefaultVerticalOffset);
-            double upVerticalOffsetIndepent = DpiHelper.TransformToDeviceY(UpVerticalOffset);
-            double downVerticalOffsetIndepent = DpiHelper.TransformToDeviceY(DownVerticalOffset);
+            var mainVisual = TreeHelper.FindMainTreeVisual(this.PlacementTarget);
+            double realOffsetX = (popupSize.Width - targetSize.Width) / 2.0;
+            double offsetX = DpiHelper.TransformToDeviceX(mainVisual, offset.X);
+            double defaultVerticalOffsetIndepent = DpiHelper.TransformToDeviceY(mainVisual, DefaultVerticalOffset);
+            double upVerticalOffsetIndepent = DpiHelper.TransformToDeviceY(mainVisual, UpVerticalOffset);
+            double downVerticalOffsetIndepent = DpiHelper.TransformToDeviceY(mainVisual, DownVerticalOffset);
 
-            if (locationX + popupSize.Width - realOffsetX > SystemParameters.PrimaryScreenWidth || locationX + realOffsetX < 0)
+            if (locationX + popupSize.Width - realOffsetX > SystemParameters.PrimaryScreenWidth
+                || locationX + realOffsetX < 0)
             {
                 SetChildTemplateIfNeed(DefaultContentTemplate);
 

MaterialDesignThemes.Wpf/DpiHelper.cs

@@ -5,6 +5,7 @@
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
+using System.Windows.Media;
 
 namespace MaterialDesignThemes.Wpf
 {
@@ -25,6 +26,28 @@ static DpiHelper()
             _dpiY = (int)dpiYProperty.GetValue(null, null);
         }
 
+        public static double TransformToDeviceY(Visual visual, double y)
+        {
+            var source = PresentationSource.FromVisual(visual);
+            if (source != null)
+            {
+                return y * source.CompositionTarget.TransformToDevice.M22;
+            }
+
+            return TransformToDeviceY(y);
+        }
+
+        public static double TransformToDeviceX(Visual visual, double x)
+        {
+            var source = PresentationSource.FromVisual(visual);
+            if (source != null)
+            {
+                return x * source.CompositionTarget.TransformToDevice.M11;
+            }
+
+            return TransformToDeviceX(x);
+        }
+
         public static double TransformToDeviceY(double y)
         {
             return y * _dpiY / StandartDpiY;

MaterialDesignThemes.Wpf/MaterialDesignThemes.Wpf.csproj

@@ -277,6 +277,7 @@
     <Compile Include="RippleAssist.cs" />
     <Compile Include="Ripple.cs" />
     <Compile Include="TransitionAssist.cs" />
+    <Compile Include="TreeHelper.cs" />
     <Compile Include="Underline.cs" />
     <Compile Include="ValidationAssist.cs" />
     <EmbeddedResource Include="Properties\Resources.resx">

MaterialDesignThemes.Wpf/TreeHelper.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls.Primitives;
+using System.Windows.Media;
+
+namespace MaterialDesignThemes.Wpf
+{
+    internal static class TreeHelper
+    {
+        public static Visual FindMainTreeVisual(Visual visual)
+        {
+            DependencyObject root = null;
+            DependencyObject dependencyObject = visual;
+
+            while (dependencyObject != null)
+            {
+                root = dependencyObject;
+                dependencyObject = VisualTreeHelper.GetParent(dependencyObject);
+            }
+
+            return root as Visual;
+        }
+    }
+}