PDF: Add (low-memory) SkPDFBitmap class

Also: Add SkDeflateWStream and associated unit tests.

SkPDFBitmap is a replacement for SkPDFImage.  As of now, it only
supports 8888 bitmaps (the most common case).

SkPDFBitmap takes very little extra memory (aside from refing the
bitmap's pixels), and its emitObject() does not cache any data.

The SkPDFBitmap::Create function will check the canon for duplicates.
This can reduce the size of the output PDF.

Motivation:  this gives another ~40% decrease in PDF memory overhead

TODO: Support other ColorTypes and scrap SkPDFImage.

BUG=skia:3030

Review URL: https://codereview.chromium.org/918813002

1 files changed, 45 insertions, 0 deletions

diff --git a/src/pdf/SkPDFBitmap.h b/src/pdf/SkPDFBitmap.h
new file mode 100644
index 0000000000..922db8f1c1
--- /dev/null
+++ b/src/pdf/SkPDFBitmap.h
@@ -0,0 +1,45 @@
+/*
+ * 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 SkPDFBitmap_DEFINED
+#define SkPDFBitmap_DEFINED
+
+#include "SkPDFTypes.h"
+#include "SkBitmap.h"
+
+/**
+ * SkPDFBitmap wraps a SkBitmap and serializes it as an image Xobject.
+ * It is designed to use a minimal amout of memory, aside from refing
+ * the bitmap's pixels, and its emitObject() does not cache any data.
+ *
+ * As of now, it only supports 8888 bitmaps (the most common case).
+ *
+ * The SkPDFBitmap::Create function will check the canon for duplicates.
+ */
+class SkPDFBitmap : public SkPDFObject {
+public:
+    // Returns NULL on unsupported bitmap;
+    // TODO(halcanary): support other bitmap colortypes and replace
+    // SkPDFImage.
+    static SkPDFBitmap* Create(const SkBitmap&, const SkIRect& subset);
+    ~SkPDFBitmap();
+    void emitObject(SkWStream*, SkPDFCatalog*) SK_OVERRIDE;
+    void addResources(SkTSet<SkPDFObject*>* resourceSet,
+                      SkPDFCatalog* catalog) const SK_OVERRIDE;
+    bool equals(const SkBitmap& other) const {
+        return fBitmap.getGenerationID() == other.getGenerationID() &&
+               fBitmap.pixelRefOrigin() == other.pixelRefOrigin() &&
+               fBitmap.dimensions() == other.dimensions();
+    }
+
+private:
+    const SkBitmap fBitmap;
+    const SkAutoTUnref<SkPDFObject> fSMask;
+    SkPDFBitmap(const SkBitmap&, SkPDFObject*);
+    void emitDict(SkWStream*, SkPDFCatalog*, size_t, bool) const;
+};
+
+#endif  // SkPDFBitmap_DEFINED