internal static string?GetShellFileTypeAndIcon(string fileName, bool useExistingFile, IconOptions iconOptions, Action <IntPtr>?useIconHandle)
{
Conditions.RequireString(fileName, nameof(fileName));
Conditions.RequireArgument(
(iconOptions == IconOptions.None && useIconHandle == null) || (iconOptions != IconOptions.None && useIconHandle != null),
"The iconOptions and useIconHandle arguments must be compatible.");
SHFILEINFO info = default;
int cbFileInfo = Marshal.SizeOf(info);
SHGFI flags = SHGFI.TypeName;
int fileAttributes = 0;
if (!useExistingFile)
{
flags |= SHGFI.UseFileAttributes;
const int FILE_ATTRIBUTE_NORMAL = 128;
const int FILE_ATTRIBUTE_DIRECTORY = 16;
// http://stackoverflow.com/questions/1599235/how-do-i-fetch-the-folder-icon-on-windows-7-using-shell32-shgetfileinfo
fileAttributes = iconOptions.HasFlag(IconOptions.Folder) ? FILE_ATTRIBUTE_DIRECTORY : FILE_ATTRIBUTE_NORMAL;
}
bool useIcon = iconOptions != IconOptions.None;
if (useIcon)
{
flags |= SHGFI.Icon;
// The Small and Large options are mutually exclusive. If they specify neither or both, then we'll default to small.
if (iconOptions.HasFlag(IconOptions.Small) || !iconOptions.HasFlag(IconOptions.Large))
{
flags |= SHGFI.SmallIcon;
}
else
{
flags |= SHGFI.LargeIcon;
}
if (iconOptions.HasFlag(IconOptions.ShellSize))
{
flags |= SHGFI.ShellIconSize;
}
if (iconOptions.HasFlag(IconOptions.Open))
{
flags |= SHGFI.OpenIcon;
}
if (iconOptions.HasFlag(IconOptions.Shortcut))
{
flags |= SHGFI.LinkOverlay;
}
if (iconOptions.HasFlag(IconOptions.Selected))
{
flags |= SHGFI.Selected;
}
}
string?result = null;
if (SHGetFileInfo(fileName, fileAttributes, out info, (uint)cbFileInfo, flags) != IntPtr.Zero)
{
result = info.szTypeName;
if (useIcon && useIconHandle != null)
{
// The caller has to make a copy (e.g., Icon.FromHandle(hIcon).Clone()).
useIconHandle(info.hIcon);
DestroyIcon(info.hIcon);
}
}
return(result);
}
