Add helper method "ScaleSmallIconToDpi"

Author: LeafShi1

src/System.Windows.Forms.Primitives/src/System/Windows/Forms/Internals/ScaleHelper.cs

@@ -421,6 +421,16 @@ internal static HighDpiMode GetThreadHighDpiMode()
         return HighDpiMode.DpiUnaware;
     }
 
+    /// <summary>
+    ///  Get X, Y metrics at DPI, IF icon is not already that size, create and return a new one.
+    /// </summary>
+    internal static Icon ScaleSmallIconToDpi(Icon icon, int dpi)
+    {
+        return new(icon,
+            PInvoke.GetCurrentSystemMetrics(SYSTEM_METRICS_INDEX.SM_CXSMICON, (uint)dpi),
+            PInvoke.GetCurrentSystemMetrics(SYSTEM_METRICS_INDEX.SM_CXSMICON, (uint)dpi));
+    }
+
     /// <summary>
     ///  Sets the requested DPI mode. If the current OS does not support the requested mode,
     /// </summary>

src/System.Windows.Forms/src/System/Windows/Forms/ErrorProvider/ErrorProvider.ErrorWindow.cs

@@ -456,9 +456,8 @@ protected override void WmDpiChangedBeforeParent(ref Message m)
 
             double factor = ((double)currentDpi) / _parent._deviceDpi;
             using Icon icon = _provider.Icon;
-            _provider.Icon = new Icon(icon, (int)(icon.Width * factor), (int)(icon.Height * factor));
-            _provider.DisposeRegion();
             _provider._currentDpi = currentDpi;
+            _provider.Icon = new Icon(icon, (int)(icon.Width * factor), (int)(icon.Height * factor));
         }
     }
 }

src/System.Windows.Forms/src/System/Windows/Forms/ErrorProvider/ErrorProvider.IconRegion.cs

@@ -15,11 +15,9 @@ internal class IconRegion : IHandle<HICON>
         private Region? _region;
         private readonly Icon _icon;
 
-        public IconRegion(int currentDpi, Icon icon)
+        public IconRegion(Icon icon, int currentDpi)
         {
-            _icon = new(icon,
-                PInvoke.GetCurrentSystemMetrics(SYSTEM_METRICS_INDEX.SM_CXSMICON, (uint)currentDpi),
-                PInvoke.GetCurrentSystemMetrics(SYSTEM_METRICS_INDEX.SM_CXSMICON, (uint)currentDpi));
+            _icon = ScaleHelper.ScaleSmallIconToDpi(icon, currentDpi);
         }
 
         /// <summary>

src/System.Windows.Forms/src/System/Windows/Forms/ErrorProvider/ErrorProvider.cs

@@ -549,10 +549,7 @@ private static Icon DefaultIcon
                 {
                     // Error provider uses small Icon.
                     using Icon defaultIcon = new(typeof(ErrorProvider), "Error");
-                    int currentDpi = (int)PInvoke.GetDpiForSystem();
-                    t_defaultIcon = new(defaultIcon,
-                        PInvoke.GetCurrentSystemMetrics(SYSTEM_METRICS_INDEX.SM_CXSMICON, (uint)currentDpi),
-                        PInvoke.GetCurrentSystemMetrics(SYSTEM_METRICS_INDEX.SM_CXSMICON, (uint)currentDpi));
+                    t_defaultIcon = ScaleHelper.ScaleSmallIconToDpi(defaultIcon, (int)PInvoke.GetDpiForSystem());
                 }
             }
 
@@ -589,7 +586,7 @@ public Icon Icon
     /// <summary>
     ///  Create the icon region on demand.
     /// </summary>
-    internal IconRegion Region => _region ??= new IconRegion(_currentDpi, Icon);
+    internal IconRegion Region => _region ??= new IconRegion(Icon, _currentDpi);
 
     /// <summary>
     ///  Begin bulk member initialization - deferring binding to data source until EndInit is reached