DirectWrite font host for skia.
https://codereview.appspot.com/5417063/


git-svn-id: http://skia.googlecode.com/svn/trunk@5128 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/utils/win/SkDWriteFontFileStream.h b/src/utils/win/SkDWriteFontFileStream.h
new file mode 100644
index 0000000..cd5787e
--- /dev/null
+++ b/src/utils/win/SkDWriteFontFileStream.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkDWriteFontFileStream_DEFINED
+#define SkDWriteFontFileStream_DEFINED
+
+#include "SkTypes.h"
+
+#include "SkStream.h"
+#include "SkTScopedComPtr.h"
+
+#include <dwrite.h>
+
+/**
+ *  An SkStream backed by an IDWriteFontFileStream.
+ *  This allows Skia code to read an IDWriteFontFileStream.
+ */
+class SkDWriteFontFileStream : public SkStream {
+public:
+    explicit SkDWriteFontFileStream(IDWriteFontFileStream* fontFileStream);
+    virtual ~SkDWriteFontFileStream();
+    
+    virtual bool rewind() SK_OVERRIDE;
+    virtual size_t read(void* buffer, size_t size) SK_OVERRIDE;
+    virtual const void* getMemoryBase() SK_OVERRIDE;
+
+private:
+    SkTScopedComPtr<IDWriteFontFileStream> fFontFileStream;
+    size_t fPos;
+    const void* fLockedMemory;
+    void* fFragmentLock;
+};
+
+/**
+ *  An IDWriteFontFileStream backed by an SkStream.
+ *  This allows DirectWrite to read an SkStream.
+ */
+class SkDWriteFontFileStreamWrapper : public IDWriteFontFileStream {
+public:
+    // IUnknown methods
+    virtual HRESULT STDMETHODCALLTYPE QueryInterface(REFIID iid, void** ppvObject);
+    virtual ULONG STDMETHODCALLTYPE AddRef();
+    virtual ULONG STDMETHODCALLTYPE Release();
+
+    // IDWriteFontFileStream methods
+    virtual HRESULT STDMETHODCALLTYPE ReadFileFragment(
+        void const** fragmentStart,
+        UINT64 fileOffset,
+        UINT64 fragmentSize,
+        void** fragmentContext);
+
+    virtual void STDMETHODCALLTYPE ReleaseFileFragment(void* fragmentContext);
+    virtual HRESULT STDMETHODCALLTYPE GetFileSize(UINT64* fileSize);
+    virtual HRESULT STDMETHODCALLTYPE GetLastWriteTime(UINT64* lastWriteTime);
+
+    static HRESULT Create(SkStream* stream, SkDWriteFontFileStreamWrapper** streamFontFileStream);
+
+private:
+    explicit SkDWriteFontFileStreamWrapper(SkStream* stream);
+
+    ULONG fRefCount;
+    SkAutoTUnref<SkStream> fStream;
+    SkMutex fStreamMutex;
+};
+#endif