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Eliminate memory copy when reading font data #6254

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Merged
merged 1 commit into from
Jul 13, 2022
Merged

Eliminate memory copy when reading font data #6254

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41 changes: 6 additions & 35 deletions src/Microsoft.DotNet.Wpf/src/DirectWriteForwarder/CPP/DWriteWrapper/FontFileStream.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,17 +17,15 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
// guarantee that this problem will be fixed so we will use the GetUnmanagedStream(). Note: This path will only
// be taken for embedded fonts among which XPS is a main scenario. For local fonts we use DWrite's APIs.
_fontSourceStream = fontSource->GetUnmanagedStream();
_fontSourcePointer = _fontSourceStream->PositionPointer - _fontSourceStream->Position;
try
{
_lastWriteTime = fontSource->GetLastWriteTimeUtc().ToFileTimeUtc();
}
}
catch(System::ArgumentOutOfRangeException^) //The resulting file time would represent a date and time before 12:00 midnight January 1, 1601 C.E. UTC.
{
_lastWriteTime = -1;
}

// Create lock to control access to font source stream.
_fontSourceStreamLock = gcnew Object();
}
}

FontFileStream::~FontFileStream()
Expand Down Expand Up @@ -61,31 +59,9 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
return E_INVALIDARG;
}

int fragmentSizeInt = (int)fragmentSize;
array<byte>^ buffer = gcnew array<byte>(fragmentSizeInt);

// DWrite may call this method from multiple threads. We need to ensure thread safety by making Seek and Read atomic.
System::Threading::Monitor::Enter(_fontSourceStreamLock);
try
{
_fontSourceStream->Seek(fileOffset, //long
System::IO::SeekOrigin::Begin);

_fontSourceStream->Read(buffer, //byte[]
0, //int
fragmentSizeInt //int
);
}
finally
{
System::Threading::Monitor::Exit(_fontSourceStreamLock);
}

GCHandle gcHandle = GCHandle::Alloc(buffer, GCHandleType::Pinned);

*fragmentStart = (byte*)(gcHandle.AddrOfPinnedObject().ToPointer());

*fragmentContext = GCHandle::ToIntPtr(gcHandle).ToPointer();
// Return a pointer to the font data that is already loaded in memory (because the font source resource is mmapped into the process' address space).
*fragmentStart = _fontSourcePointer + fileOffset;
*fragmentContext = nullptr;
}
catch(System::Exception^ exception)
{
Expand All @@ -102,11 +78,6 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
void* fragmentContext
)
{
if (fragmentContext != NULL)
{
GCHandle gcHandle = GCHandle::FromIntPtr(IntPtr(fragmentContext));
gcHandle.Free();
}
}

[ComVisible(true)]
Expand Down
4 changes: 2 additions & 2 deletions src/Microsoft.DotNet.Wpf/src/DirectWriteForwarder/CPP/DWriteWrapper/FontFileStream.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,9 +20,9 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
private ref class FontFileStream : public IDWriteFontFileStreamMirror
{
private:
Stream^ _fontSourceStream;
UnmanagedMemoryStream^ _fontSourceStream;
Byte* _fontSourcePointer;
INT64 _lastWriteTime;
Object^ _fontSourceStreamLock;

public:

Expand Down