public HRESULT GetCurrentFontFile(out IDWriteFontFile fontFile)
{
DWriteFontFile file;
try
{
file = _enumerator.Current;
}
catch (Exception e)
{
ComError.SetError(e.GetAllMessages());
fontFile = null;
return(HRESULTS.DISP_E_EXCEPTION);
}
if (file is DWriteFontStreamFile sf && sf.FilePath != null)
{
using (var mem = new ComMemory(Marshal.SizeOf <long>()))
{
if (sf.LastWriteTime.HasValue)
{
Marshal.WriteInt64(mem.Pointer, sf.LastWriteTime.Value.ToFileTime());
}
var ptr = sf.LastWriteTime.HasValue ? mem.Pointer : IntPtr.Zero;
return(_factory.CreateFontFileReference(sf.FilePath, ptr, out fontFile));
}
}
var stream = new FontFileStream(file);
_loader.AddStream(stream);
return(_factory.CreateCustomFontFileReference(stream.Key, (uint)stream.KeySize, _loader, out fontFile));
}
unsafe internal static IDWriteFontFile CreateFontFile(
IDWriteFactory factory,
IntPtr fontFileLoader, // IDWriteFontFileLoader*
Uri filePathUri
)
{
IDWriteFontFile dwriteFontFile;
bool isLocal = Factory.IsLocalUri(filePathUri);
if (isLocal)
{
// DWrite currently has a slow lookup for the last write time, which
// introduced a noticable perf regression when we switched over.
// To mitigate this scenario, we will fetch the timestamp ourselves
// and cache it for future calls.
//
// Note: we only do this if a Dispatcher exists for the current
// thread. There is a seperate cache for each thread.
FILETIME cachedTimeStamp;
IntPtr pTimeStamp = IntPtr.Zero; // If something fails, do nothing and let DWrite sort it out.
Dispatcher currentDispatcher = Dispatcher.FromThread(Thread.CurrentThread);
if (currentDispatcher != null)
{
try {
// One-time initialization per thread.
if (_timeStampCache == null)
{
_timeStampCache = new Dictionary <Uri, FILETIME>();
}
if (!_timeStampCache.TryGetValue(filePathUri, out cachedTimeStamp))
{
long longFileTime = File.GetLastWriteTime(filePathUri.LocalPath).ToFileTime();
cachedTimeStamp.dwLowDateTime = (int)(longFileTime);
cachedTimeStamp.dwHighDateTime = (int)(longFileTime >> 32);
_timeStampCache.Add(filePathUri, cachedTimeStamp);
// We don't want to hold this cached value for a long time since
// all font references will be tied to this timestamp, and any font
// update during the lifetime of the application will cause is to
// encounter errors. So we use a dispatcher operation to clear
// the cache as soon as we get back to pumping messages.
if (_timeStampCacheCleanupOp == null)
{
_timeStampCacheCleanupOp = currentDispatcher.BeginInvoke(new Action(CleanupTimeStampCache));
}
}
pTimeStamp = Marshal.AllocCoTaskMem(Marshal.SizeOf <FILETIME>());
Marshal.StructureToPtr <FILETIME>(cachedTimeStamp, pTimeStamp, false);
}
catch { }
}
try {
dwriteFontFile = factory.CreateFontFileReference(
filePathUri.LocalPath,
pTimeStamp
);
}
finally {
Marshal.FreeCoTaskMem(pTimeStamp);
}
}
else
{
string filePath = filePathUri.AbsoluteUri;
fixed(char *pFilePath = filePath)
{
dwriteFontFile = factory.CreateCustomFontFileReference(
new IntPtr(pFilePath),
(uint)(filePath.Length + 1) * 2,
fontFileLoader
);
}
}
return(dwriteFontFile);
}
