IDWriteFontFileStream::ReadFileFragment Method

Reads a fragment from a font file.

Syntax

virtual HRESULT ReadFileFragment(
  [out]  const void ** fragmentStart,
  UINT64  fileOffset,
  UINT64  fragmentSize,
  [out]  void ** fragmentContext
) = 0;

Parameter

• fragmentStart [out]
  When this method returns, contains an address of a pointer to the start of the font file fragment. This parameter is passed uninitialized.

• fileOffset
  The offset of the fragment, in bytes, from the beginning of the font file.

• fragmentSize
  The size of the file fragment, in bytes.

• fragmentContext [out]
  When this method returns, contains the address of a pointer to a pointer to the client-defined context to be passed to ReleaseFileFragment.

Rückgabewert

Ist Methode erfolgreich, wird "S_OK" zurückgegeben. Andernfalls wird ein HRESULT-Fehlercode zurückgegeben.

Hinweise

Note that ReadFileFragment implementations must check whether the requested font file fragment is within the file bounds. Otherwise, an error should be returned from ReadFileFragment.

DirectWrite may invoke IDWriteFontFileStream methods on the same object from multiple threads simultaneously. Therefore, ReadFileFragment implementations that rely on internal mutable state must serialize access to such state across multiple threads. For example, an implementation that uses separate Seek and Read operations to read a file fragment must place the code block containing Seek and Read calls under a lock or a critical section.

Anforderungen

Mindestens unterstützter Client	Windows 7, Windows Vista with SP2 and Platform Update for Windows Vista
Mindestens unterstützter Server	Windows Server 2008 R2, Windows Server 2008 with SP2 and Platform Update for Windows Server 2008
Header	Dwrite.h
Bibliothek	Dwrite.lib
DLL	Dwrite.dll

Siehe auch

IDWriteFontFileStream