From ca7ca983ca48afcae95515280f36e004ce262494 Mon Sep 17 00:00:00 2001
From: David Hall <dahall68@gmail.com>
Date: Thu, 5 Apr 2018 13:25:38 -0600
Subject: [PATCH] Changed GetIcon to GetSystemIcon and added GetFileIcon.

---
 Windows.Shell/ShellImageList.cs | 63 +++++++++++++++++++++++++++--------------
 1 file changed, 41 insertions(+), 22 deletions(-)

diff --git a/Windows.Shell/ShellImageList.cs b/Windows.Shell/ShellImageList.cs
index 1ac94f45..c078e859 100644
--- a/Windows.Shell/ShellImageList.cs
+++ b/Windows.Shell/ShellImageList.cs
@@ -1,39 +1,58 @@
 using System;
 using System.Drawing;
-using System.IO;
-using System.Runtime.InteropServices;
 using static Vanara.PInvoke.ComCtl32;
 using static Vanara.PInvoke.Shell32;
-using static Vanara.PInvoke.User32_Gdi;
 
 namespace Vanara.Windows.Shell
 {
+	/// <summary>Used to determine the size of the icon returned by <see cref="ShellImageList.GetSystemIcon"/>.</summary>
+	public enum ShellImageSize
+	{
+		/// <summary>
+		/// The image size is normally 32x32 pixels. However, if the Use large icons option is selected from the Effects section of the Appearance tab in
+		/// Display Properties, the image is 48x48 pixels.
+		/// </summary>
+		Large = SHIL.SHIL_LARGE,
+		/// <summary>The image is the Shell standard small icon size of 16x16, but the size can be customized by the user.</summary>
+		Small = SHIL.SHIL_SMALL,
+		/// <summary>The image is the Shell standard extra-large icon size. This is typically 48x48, but the size can be customized by the user.</summary>
+		ExtraLarge = SHIL.SHIL_EXTRALARGE,
+		/// <summary>Windows Vista and later. The image is normally 256x256 pixels.</summary>
+		Jumbo = SHIL.SHIL_JUMBO
+	}
+
+	/// <summary>Represents the System Image List holding images for all shell icons.</summary>
 	public static class ShellImageList
 	{
-		private static IntPtr largeImageListHandle;
-		private static IntPtr smallImageListHandle;
+		private static int shfiSz = SHFILEINFO.Size;
 
-		static ShellImageList()
+		/// <summary>Gets the system icon for the given file name or extension.</summary>
+		/// <param name="fileNameOrExtension">The file name or extension.</param>
+		/// <param name="iconSize">Size of the icon.</param>
+		/// <returns>An <see cref="Icon"/> instance if found; otherwise <see langword="null"/>.</returns>
+		public static Icon GetSystemIcon(string fileNameOrExtension, ShellImageSize iconSize = ShellImageSize.Large)
 		{
-			const SHGFI baseFlags = SHGFI.SHGFI_USEFILEATTRIBUTES | SHGFI.SHGFI_SYSICONINDEX;
-
-			var shfiSz = Marshal.SizeOf(typeof(SHFILEINFO));
-
-			var shfiSmall = new SHFILEINFO();
-			smallImageListHandle = SHGetFileInfo(".txt", FileAttributes.Normal, ref shfiSmall, shfiSz, baseFlags | SHGFI.SHGFI_SMALLICON);
-			
-			var shfiLarge = new SHFILEINFO();
-			largeImageListHandle = SHGetFileInfo(".txt", FileAttributes.Normal, ref shfiLarge, shfiSz, baseFlags | SHGFI.SHGFI_LARGEICON);
+			var shfi = new SHFILEINFO();
+			var hImageList = SHGetFileInfo(fileNameOrExtension, 0, ref shfi, shfiSz, SHGFI.SHGFI_SYSICONINDEX | (iconSize == ShellImageSize.Small ? SHGFI.SHGFI_SMALLICON : 0));
+			if (hImageList == IntPtr.Zero) return null;
+			if (iconSize <= ShellImageSize.Small)
+				return IconLocation.GetClonedIcon(ImageList_GetIcon(hImageList, shfi.iIcon, IMAGELISTDRAWFLAGS.ILD_TRANSPARENT));
+			SHGetImageList((SHIL)iconSize, typeof(IImageList).GUID, out var il).ThrowIfFailed();
+			return IconLocation.GetClonedIcon(il.GetIcon(shfi.iIcon, IMAGELISTDRAWFLAGS.ILD_TRANSPARENT));
 		}
 
-		public static Icon GetIcon(int index, bool small = true)
+		/// <summary>Gets the Shell icon for the given file name or extension.</summary>
+		/// <param name="fileNameOrExtension">The file name or extension .</param>
+		/// <param name="iconType">Flags to specify the type of the icon to retrieve. This uses the <see cref="SHGetFileInfo(string, System.IO.FileAttributes, ref SHFILEINFO, int, SHGFI)"/> method and can only retrieve small or large icons.</param>
+		/// <returns>An <see cref="Icon"/> instance if found; otherwise <see langword="null"/>.</returns>
+		public static Icon GetFileIcon(string fileNameOrExtension, ShellIconType iconType = ShellIconType.Large)
 		{
-			var hIcon = ImageList_GetIcon(small ? smallImageListHandle : largeImageListHandle, index, IMAGELISTDRAWFLAGS.ILD_NORMAL);
-			if (hIcon == IntPtr.Zero) return null;
-			var icon = Icon.FromHandle(hIcon);
-			var ret = (Icon)icon.Clone();
-			DestroyIcon(hIcon);
-			return ret;
+			const SHGFI baseFlags = SHGFI.SHGFI_USEFILEATTRIBUTES | SHGFI.SHGFI_ICON;
+			var shfi = new SHFILEINFO();
+			var ret = SHGetFileInfo(fileNameOrExtension, 0, ref shfi, shfiSz, baseFlags | (SHGFI)iconType);
+			if (ret == IntPtr.Zero)
+				ret = SHGetFileInfo(fileNameOrExtension, 0, ref shfi, shfiSz, SHGFI.SHGFI_ICON | (SHGFI)iconType);
+			return ret == IntPtr.Zero ? null : IconLocation.GetClonedIcon(shfi.hIcon);
 		}
 	}
 }