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, 9 insertions, 0 deletions

diff --git a/src/pdf/SkPDFCanon.h b/src/pdf/SkPDFCanon.h
index 8e89424084..6a677e9a68 100644
--- a/src/pdf/SkPDFCanon.h
+++ b/src/pdf/SkPDFCanon.h
@@ -12,9 +12,11 @@
 #include "SkTDArray.h"
 
 struct SkIRect;
+class SkBitmap;
 class SkMatrix;
 class SkPDFFont;
 class SkPDFGraphicState;
+class SkPDFBitmap;
 class SkPaint;
 
 // This class's fields and methods will eventually become part of
@@ -40,6 +42,7 @@ public:
     static SkBaseMutex& GetFontMutex();
     static SkBaseMutex& GetShaderMutex();
     static SkBaseMutex& GetPaintMutex();
+    static SkBaseMutex& GetBitmapMutex();
 
     // Returns exact match if there is one.  If not, it returns NULL.
     // If there is no exact match, but there is a related font, we
@@ -66,6 +69,10 @@ public:
     void addGraphicState(SkPDFGraphicState*);
     void removeGraphicState(SkPDFGraphicState*);
 
+    SkPDFBitmap* findBitmap(const SkBitmap&) const;
+    void addBitmap(SkPDFBitmap*);
+    void removeBitmap(SkPDFBitmap*);
+
 private:
     struct FontRec {
         SkPDFFont* fFont;
@@ -81,5 +88,7 @@ private:
     SkTDArray<SkPDFImageShader*> fImageShaderRecords;
 
     SkTDArray<SkPDFGraphicState*> fGraphicStateRecords;
+
+    SkTDArray<SkPDFBitmap*> fBitmapRecords;
 };
 #endif  // SkPDFCanon_DEFINED