/// <summary>
/// Creates a font file reference object from a local font file.
/// </summary>
/// <param name="factory">A reference to a DirectWrite factory <see cref="Factory"/></param>
/// <param name="filePath">An array of characters that contains the absolute file path for the font file. Subsequent operations on the constructed object may fail if the user provided filePath doesn't correspond to a valid file on the disk. </param>
/// <param name="lastWriteTime">The last modified time of the input file path. If the parameter is omitted, the function will access the font file to obtain its last write time. You should specify this value to avoid extra disk access. Subsequent operations on the constructed object may fail if the user provided lastWriteTime doesn't match the file on the disk. </param>
/// <unmanaged>HRESULT IDWriteFactory::CreateFontFileReference([In] const wchar_t* filePath,[In, Optional] const __int64* lastWriteTime,[Out] IDWriteFontFile** fontFile)</unmanaged>
public FontFile(Factory factory, string filePath, long?lastWriteTime)
{
factory.CreateFontFileReference(filePath, lastWriteTime, this);
}