move annotations to canvas virtual

include/core/SkCanvas.h

Index: include/core/SkCanvas.h
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index c23d748e7817735328108bf6de3d6029b008b79a..1b4571a09c9c65b9b3fdcfde71431636a1d39736 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -22,6 +22,7 @@ class GrRenderTarget;
 class SkBaseDevice;
 class SkCanvasClipVisitor;
 class SkClipStack;
+class SkData;
 class SkDraw;
 class SkDrawable;
 class SkDrawFilter;
@@ -1072,6 +1073,18 @@ public:
     void drawDrawable(SkDrawable* drawable, const SkMatrix* = NULL);
     void drawDrawable(SkDrawable*, SkScalar x, SkScalar y);
 
+    /**
+     *  Send an "annotation" to the canvas. The annotation is a key/value pair, where the key is
+     *  a null-terminated utf8 string, and the value is a blob of data stored in an SkData
+     *  (which may be null). The annotation is associated with the specified rectangle.
+     *
+     *  The caller still retains its ownership of the data (if any).
+     *
+     *  Note: on may canvas types, this information is ignored, but some canvases (e.g. recording
+     *  a picture or drawing to a PDF document) will pass on this information.
+     */
+    void drawAnnotation(const SkRect&, const char key[], SkData* value);

[hal.canary, 2016/02/29 14:53:31]

I propose this:

    enum class AnnotationKey {
        kURL,
        kDefineNamedDestination,
        kLinkNamedDestination,
    };
    void drawAnnotation(const SkRect&, SkCanvas::AnnotationKey, SkData* value);

[reed1, 2016/03/03 15:01:33]

Possibly, but I'd like to be conservative for the moment, and just focus on
moving from paint to canvas. Using strings may prove valuable if we want to
reused these for other purposes (e.g. comments).

+
     //////////////////////////////////////////////////////////////////////////
 #ifdef SK_INTERNAL
 #ifndef SK_SUPPORT_LEGACY_DRAWFILTER
@@ -1221,6 +1234,7 @@ protected:
     virtual void didConcat(const SkMatrix&) {}
     virtual void didSetMatrix(const SkMatrix&) {}
 
+    virtual void onDrawAnnotation(const SkRect&, const char key[], SkData* value);
     virtual void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&);
 
     virtual void onDrawText(const void* text, size_t byteLength, SkScalar x,