Add onDrawBitmapLattice(), avoid unnecessary bitmap->image copy

src/pdf/SkPDFCanvas.cpp

Index: src/pdf/SkPDFCanvas.cpp
diff --git a/src/pdf/SkPDFCanvas.cpp b/src/pdf/SkPDFCanvas.cpp
index 1d3138541d796207287ba69afd2ca3e3995956a2..4ef1922a58fff23c86b315d6454d59208b769c9d 100644
--- a/src/pdf/SkPDFCanvas.cpp
+++ b/src/pdf/SkPDFCanvas.cpp
@@ -95,3 +95,15 @@ void SkPDFCanvas::onDrawImageLattice(const SkImage* image,
         this->drawImageRect(image, srcR, dstR, paint);
     }
 }
+
+void SkPDFCanvas::onDrawBitmapLattice(const SkBitmap& bitmap,

[reed1, 2016/08/16 11:28:47]

General question for PDF canvas (not strictly related to this CL)

- can it fold bitmaps->images at this level, to reduce the number of internal
methods? (as pictures do)?

[hal.canary, 2016/08/16 14:57:33]

No!

You need to keep the bitmaps until we get to the de-duplication stage.  As long
as out clients are using bitmaps, we need to keep de-duping them.

+                                      const Lattice& lattice,
+                                      const SkRect& dst,
+                                      const SkPaint* paint) {
+    SkLatticeIter iter(bitmap.width(), bitmap.height(), lattice, dst);
+    SkRect srcR, dstR;
+    while (iter.next(&srcR, &dstR)) {
+        this->drawBitmapRect(bitmap, srcR, dstR, paint);
+    }
+}
+