From 62ebe4176f867fb7616cbe5f9858d7bfce7e9d8b Mon Sep 17 00:00:00 2001
From: Andy McFadden <thefadden@gmail.com>
Date: Mon, 1 Oct 2018 10:44:24 -0700
Subject: [PATCH] Replace BUILD_FOR_WINDOWS with a runtime check

Mono runs the same executable, so #if isn't useful.
---
 CommonWinForms/CommonWinForms.csproj |  4 +--
 CommonWinForms/NativeMethods.cs      |  2 --
 CommonWinForms/WinFormsExtensions.cs | 50 +++++++++++++++++++---------
 3 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/CommonWinForms/CommonWinForms.csproj b/CommonWinForms/CommonWinForms.csproj
index ea54c28..10e868e 100644
--- a/CommonWinForms/CommonWinForms.csproj
+++ b/CommonWinForms/CommonWinForms.csproj
@@ -18,7 +18,7 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
     <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>TRACE;DEBUG;BUILD_FOR_WINDOWS</DefineConstants>
+    <DefineConstants>TRACE;DEBUG</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
   </PropertyGroup>
@@ -26,7 +26,7 @@
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
     <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE;BUILD_FOR_WINDOWS</DefineConstants>
+    <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
   </PropertyGroup>
diff --git a/CommonWinForms/NativeMethods.cs b/CommonWinForms/NativeMethods.cs
index dc5847e..90700a5 100644
--- a/CommonWinForms/NativeMethods.cs
+++ b/CommonWinForms/NativeMethods.cs
@@ -17,7 +17,6 @@ using System;
 using System.Runtime.InteropServices;
 using System.Windows.Forms;
 
-#if BUILD_FOR_WINDOWS   // I don't know if other platforms will emulate the LVITEM stuff
 namespace CommonWinForms {
     // From https://stackoverflow.com/questions/1019388/
 
@@ -82,4 +81,3 @@ namespace CommonWinForms {
         }
     }
 }
-#endif //BUILD_FOR_WINDOWS
diff --git a/CommonWinForms/WinFormsExtensions.cs b/CommonWinForms/WinFormsExtensions.cs
index 9f54ea0..662e08b 100644
--- a/CommonWinForms/WinFormsExtensions.cs
+++ b/CommonWinForms/WinFormsExtensions.cs
@@ -37,6 +37,26 @@ namespace CommonWinForms {
     /// Add functions to select and deselect all items.
     /// </summary>
     public static class ListViewExtensions {
+        // I don't know if NativeMethods is going to work on other platforms, but I assume
+        // not.  I'm not sure how expensive the runtime check is, so cache the result.
+        private enum DNY { Dunno = 0, No, Yes };
+        private static DNY IsPlatformWindows;
+        private static bool IsWindows {
+            get {
+                if (IsPlatformWindows == DNY.Dunno) {
+                    // This is the .NET framework 4.6 way.  Later versions (4.7, netcommon)
+                    // prefer the RuntimeInformation.IsOSPlatform() approach.
+                    OperatingSystem os = Environment.OSVersion;
+                    if (os.Platform == PlatformID.Win32NT) {
+                        IsPlatformWindows = DNY.Yes;
+                    } else {
+                        IsPlatformWindows = DNY.No;
+                    }
+                }
+                return (IsPlatformWindows == DNY.Yes);
+            }
+        }
+
         /// <summary>
         /// Selects all items in the list view.
         /// </summary>
@@ -50,23 +70,23 @@ namespace CommonWinForms {
             // https://stackoverflow.com/questions/9039989/
             // https://stackoverflow.com/questions/1019388/
 
-#if BUILD_FOR_WINDOWS   // defined in our project properties
-            NativeMethods.SelectAllItems(listView);
-#else
-            try {
-                Application.UseWaitCursor = true;
-                Cursor.Current = Cursors.WaitCursor;
-                listView.BeginUpdate();
-                int max = listView.VirtualListSize;
-                for (int i = 0; i < max; i++) {
-                    //codeListView.Items[i].Selected = true;
-                    listView.SelectedIndices.Add(i);
+            if (IsWindows) {
+                NativeMethods.SelectAllItems(listView);
+            } else {
+                try {
+                    Application.UseWaitCursor = true;
+                    Cursor.Current = Cursors.WaitCursor;
+                    listView.BeginUpdate();
+                    int max = listView.VirtualListSize;
+                    for (int i = 0; i < max; i++) {
+                        //codeListView.Items[i].Selected = true;
+                        listView.SelectedIndices.Add(i);
+                    }
+                } finally {
+                    listView.EndUpdate();
+                    Application.UseWaitCursor = false;
                 }
-            } finally {
-                listView.EndUpdate();
-                Application.UseWaitCursor = false;
             }
-#endif
         }
 
         /// <summary>