Move the GraphicsPath type to SafeHandles.

And rename some parameter names in the manually marshalled P/Invoke definitions.

src/libraries/System.Drawing.Common/src/Microsoft/Win32/SafeHandles/SafeGraphicsPathHandle.cs

@@ -0,0 +1,22 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using Gdip = System.Drawing.SafeNativeMethods.Gdip;
+
+namespace Microsoft.Win32.SafeHandles
+{
+    internal class SafeGraphicsPathHandle : SafeGdiPlusHandle
+    {
+        public SafeGraphicsPathHandle(IntPtr preexistingHandle, bool ownsHandle) : base(ownsHandle)
+        {
+            SetHandle(preexistingHandle);
+        }
+
+        public SafeGraphicsPathHandle() : base(true)
+        {
+        }
+
+        protected override int ReleaseHandleImpl() => Gdip.GdipDeletePath(handle);
+    }
+}

src/libraries/System.Drawing.Common/src/System.Drawing.Common.csproj

@@ -33,8 +33,10 @@ Unix support is disabled by default. See https://aka.ms/systemdrawingnonwindows
   <ItemGroup Condition="'$(TargetsAnyOS)' != 'true'">
     <Compile Include="Microsoft\Win32\SafeHandles\SafeBrushHandle.cs" />
     <Compile Include="Microsoft\Win32\SafeHandles\SafeGdiPlusHandle.cs" />
+    <Compile Include="Microsoft\Win32\SafeHandles\SafeGraphicsPathHandle.cs" />
     <Compile Include="Microsoft\Win32\SafeHandles\SafeMatrixHandle.cs" />
     <Compile Include="Microsoft\Win32\SafeHandles\SafePenHandle.cs" />
+    <Compile Include="Microsoft\Win32\SafeHandles\SafeRegionHandle.cs" />
     <Compile Include="System\Drawing\Bitmap.cs" />
     <Compile Include="System\Drawing\BitmapSuffixInSameAssemblyAttribute.cs" />
     <Compile Include="System\Drawing\BitmapSuffixInSatelliteAssemblyAttribute.cs" />
@@ -84,6 +86,7 @@ Unix support is disabled by default. See https://aka.ms/systemdrawingnonwindows
     <Compile Include="System\Drawing\Drawing2D\FillMode.cs" />
     <Compile Include="System\Drawing\Drawing2D\FlushIntention.cs" />
     <Compile Include="System\Drawing\Drawing2D\GraphicsContainer.cs" />
+    <Compile Include="System\Drawing\Drawing2D\GraphicsPath.cs" />
     <Compile Include="System\Drawing\Drawing2D\HatchBrush.cs" />
     <Compile Include="System\Drawing\Drawing2D\HatchStyle.cs" />
     <Compile Include="System\Drawing\Drawing2D\InterpolationMode.cs" />

src/libraries/System.Drawing.Common/src/System/Drawing/Drawing2D/CustomLineCap.cs

@@ -28,8 +28,8 @@ public CustomLineCap(GraphicsPath? fillPath, GraphicsPath? strokePath, LineCap b
         {
             IntPtr nativeLineCap;
             int status = Gdip.GdipCreateCustomLineCap(
-                                new HandleRef(fillPath, (fillPath == null) ? IntPtr.Zero : fillPath._nativePath),
-                                new HandleRef(strokePath, (strokePath == null) ? IntPtr.Zero : strokePath._nativePath),
+                                fillPath?.SafeGraphicsPathHandle,
+                                strokePath?.SafeGraphicsPathHandle,
                                 baseCap, baseInset, out nativeLineCap);
 
             if (status != Gdip.Ok)