PDF: Add (low-memory) SkPDFBitmap class

src/pdf/SkDeflateWStream.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkDeflateWStream_DEFINED
+#define SkDeflateWStream_DEFINED
+
+#include "SkStream.h"
+// https://skia.org/dev/contrib/style#no-define-before-sktypes
+
+#ifndef SK_NO_FLATE  // Clients of this class should be guarded.
+
+/**
+ * Wrap a stream in this class to compress the information written to
+ * this stream using the Deflate algorithm.  Uses Zlib's
+ * Z_DEFAULT_COMPRESSION level.
+ *
+ * See http://en.wikipedia.org/wiki/DEFLATE
+ */
+class SkDeflateWStream : public SkWStream {
+public:
+    /** Does not take ownership of the stream. */
+    SkDeflateWStream(SkWStream*);
+
+    /** The destructor calls finalize(). */
+    ~SkDeflateWStream();
+
+    /** Write the end of the compressed stream.  All subsequent calls to
+        write() will fail. Subsequent calls to finalize() do nothing. */
+    void finalize();
+
+    // The SkWStream interface:
+    bool write(const void*, size_t) SK_OVERRIDE;
+    size_t bytesWritten() const SK_OVERRIDE;
+
+private:
+    struct Impl;
+    SkAutoTDelete<Impl> fImpl;
+};
+#endif  // SK_NO_FLATE
+
+#endif  // SkDeflateWStream_DEFINED