c# / WPF:获取shell使用的图标

我正在尝试开发一个应用程序，可以向您展示目录的内容，如Windows资源管理器(带文件名和图标)。我目前正在使用这个代码:

public class IconManager
{
    public static ImageSource GetIcon(string path, bool smallIcon, bool isDirectory)
    {
        uint flags = SHGFI_ICON | SHGFI_USEFILEATTRIBUTES;
        if (smallIcon)
            flags |= SHGFI_SMALLICON;
        uint attributes = FILE_ATTRIBUTE_NORMAL;
        if (isDirectory)
            attributes |= FILE_ATTRIBUTE_DIRECTORY;
        SHFILEINFO shfi;
        if (0 != SHGetFileInfo(path, attributes, out shfi, (uint)Marshal.SizeOf(typeof(SHFILEINFO)), flags))
        {
            return System.Windows.Interop.Imaging.CreateBitmapSourceFromHIcon(shfi.hIcon, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());
        }
        return null;
    }
    [StructLayout(LayoutKind.Sequential)]
    private struct SHFILEINFO
    {
        public IntPtr hIcon;
        public int iIcon;
        public uint dwAttributes;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
        public string szDisplayName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
        public string szTypeName;
    }
    [DllImport("shell32")]
    private static extern int SHGetFileInfo(string pszPath, uint dwFileAttributes, out SHFILEINFO psfi, uint cbFileInfo, uint flags);
    private const uint FILE_ATTRIBUTE_READONLY = 0x00000001;
    private const uint FILE_ATTRIBUTE_HIDDEN = 0x00000002;
    private const uint FILE_ATTRIBUTE_SYSTEM = 0x00000004;
    private const uint FILE_ATTRIBUTE_DIRECTORY = 0x00000010;
    private const uint FILE_ATTRIBUTE_ARCHIVE = 0x00000020;
    private const uint FILE_ATTRIBUTE_DEVICE = 0x00000040;
    private const uint FILE_ATTRIBUTE_NORMAL = 0x00000080;
    private const uint FILE_ATTRIBUTE_TEMPORARY = 0x00000100;
    private const uint FILE_ATTRIBUTE_SPARSE_FILE = 0x00000200;
    private const uint FILE_ATTRIBUTE_REPARSE_POINT = 0x00000400;
    private const uint FILE_ATTRIBUTE_COMPRESSED = 0x00000800;
    private const uint FILE_ATTRIBUTE_OFFLINE = 0x00001000;
    private const uint FILE_ATTRIBUTE_NOT_CONTENT_INDEXED = 0x00002000;
    private const uint FILE_ATTRIBUTE_ENCRYPTED = 0x00004000;
    private const uint FILE_ATTRIBUTE_VIRTUAL = 0x00010000;
    private const uint SHGFI_ICON = 0x000000100;
    private const uint SHGFI_DISPLAYNAME = 0x000000200;
    private const uint SHGFI_TYPENAME = 0x000000400;
    private const uint SHGFI_ATTRIBUTES = 0x000000800;
    private const uint SHGFI_ICONLOCATION = 0x000001000;
    private const uint SHGFI_EXETYPE = 0x000002000;
    private const uint SHGFI_SYSICONINDEX = 0x000004000;
    private const uint SHGFI_LINKOVERLAY = 0x000008000;
    private const uint SHGFI_SELECTED = 0x000010000;
    private const uint SHGFI_ATTR_SPECIFIED = 0x000020000;
    private const uint SHGFI_LARGEICON = 0x000000000;
    private const uint SHGFI_SMALLICON = 0x000000001;
    private const uint SHGFI_OPENICON = 0x000000002;
    private const uint SHGFI_SHELLICONSIZE = 0x000000004;
    private const uint SHGFI_PIDL = 0x000000008;
    private const uint SHGFI_USEFILEATTRIBUTES = 0x000000010;
}

我使用以下代码来获取带有图标的文件和目录:

foreach (string d in Directory.GetDirectories(Path))
        {
            string name = "";
            foreach (string p in d.Split(''''))
                name = p;
            ImageSource icon = IconManager.GetIcon(d + "''", false, true);
            colDesktopItems.Add(new DesktopItem() { ItemName = name, ItemPath = d });
        }
        foreach (string f in Directory.GetFiles(Path))
        {
            if (File.GetAttributes(f) != FileAttributes.Hidden && File.GetAttributes(f) != FileAttributes.System)
            {
                string name = "";
                foreach (string p in f.Split(''''))
                    if (p.Contains("."))
                        name = p;
                ImageSource icon = IconManager.GetIcon(f, false, false);
                if (name != "desktop.ini" && name != "Thumbs.db")
                    colDesktopItems.Add(new DesktopItem() { ItemName = name.Split('.')[0], ItemPath = f, ItemIcon = icon });
            }
        }

我还使用DispatcherTimer进行自动刷新(间隔= 5秒):

private void dpt_Tick(object sender, EventArgs e)
    {
        if (dPath != null)
        {
            if (GetContent(dPath).ToString() != diCollection.ToString())
            {
                diCollection.Clear();
                foreach (DesktopItem i in GetContent(dPath))
                    diCollection.Add(i);
            }
        }
    }

diCollection是包含要显示的元素的集合，dPath是要显示文件的目录路径。

但是有两个问题:

• 当我设置isDirectory为true时，它只是返回一个空图标。
过了一会儿，它抛出一个异常:

该值不能为NULL。

异常发生在这一行:

return System.Windows.Interop.Imaging.CreateBitmapSourceFromHIcon(shfi.hIcon, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());

public static class ImageUtilities
{
    public static System.Drawing.Icon GetRegisteredIcon(string filePath)
    {
        var shinfo = new SHfileInfo();
        Win32.SHGetFileInfo(filePath, 0, ref shinfo, (uint)Marshal.SizeOf(shinfo), Win32.SHGFI_ICON | Win32.SHGFI_SMALLICON);
        return System.Drawing.Icon.FromHandle(shinfo.hIcon);
    }
}
[StructLayout(LayoutKind.Sequential)]
public struct SHfileInfo
{
    public IntPtr hIcon;
    public int iIcon;
    public uint dwAttributes;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
    public string szDisplayName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
    public string szTypeName;
}

internal sealed class Win32
{
    public const uint SHGFI_ICON = 0x100;
    public const uint SHGFI_LARGEICON = 0x0; // large
    public const uint SHGFI_SMALLICON = 0x1; // small
    [System.Runtime.InteropServices.DllImport("shell32.dll")]
    public static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes, ref SHfileInfo psfi, uint cbSizeFileInfo, uint uFlags);
}

var icon = ImageUtilites.GetRegisteredIcon(string path)

public static System.Windows.Media.ImageSource ToImageSource(this System.Drawing.Bitmap bitmap, int width, int height)
{
    var hBitmap = bitmap.GetHbitmap();
    System.Windows.Media.ImageSource wpfBitmap = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
        hBitmap,
        IntPtr.Zero,
        System.Windows.Int32Rect.Empty,
        System.Windows.Media.Imaging.BitmapSizeOptions.FromWidthAndHeight(width, height));
    if (!DeleteObject(hBitmap))
    {
        throw new System.ComponentModel.Win32Exception();
    }
    return wpfBitmap;
}

 [DllImport("gdi32.dll", SetLastError = true)]
 private static extern bool DeleteObject(IntPtr hObject);