WIP RasterCanvasLayerAllocator

include/core/SkCanvas.h

Index: include/core/SkCanvas.h
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index ec14829ca85296d12d79d27a04073c6ee587c20e..e2cfa5ebf632372f21f82675c42cf92bd9ea4f41 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -33,6 +33,7 @@ class SkPath;
 class SkPicture;
 class SkPixmap;
 class SkRasterClip;
+class SkRasterCanvasLayerAllocator;
 class SkRRect;
 struct SkRSXform;
 class SkSurface;
@@ -1219,6 +1220,12 @@ public:
      */
     void replayClips(ClipVisitor*) const;
 
+    /**
+     *  Returns any OS-specific native context backing this SkCanvas,
+     *  or nullptr.
+     */
+    void* getTopLayerNative() const;
+
     ///////////////////////////////////////////////////////////////////////////
 
     // don't call
@@ -1413,7 +1420,7 @@ private:
     enum {
         kMCRecSize      = 128,  // most recent measurement
         kMCRecCount     = 32,   // common depth for save/restores
-        kDeviceCMSize   = 176,  // most recent measurement
+        kDeviceCMSize   = 192,  // most recent measurement
     };
     intptr_t fMCRecStorage[kMCRecSize * kMCRecCount / sizeof(intptr_t)];
     intptr_t fDeviceCMStorage[kDeviceCMSize / sizeof(intptr_t)];
@@ -1450,6 +1457,7 @@ private:
     friend class SkPictureImageFilter;  // SkCanvas(SkBaseDevice*, SkSurfaceProps*, InitFlags)
     friend class SkPictureRecord;   // predrawNotify (why does it need it? <reed>)
     friend class SkPicturePlayback; // SaveFlagsToSaveLayerFlags
+    friend class SkRasterCanvasLayerAllocator;
 
     enum InitFlags {
         kDefault_InitFlags                  = 0,
@@ -1457,6 +1465,7 @@ private:
     };
     SkCanvas(const SkIRect& bounds, InitFlags);
     SkCanvas(SkBaseDevice* device, InitFlags);
+    SkCanvas(const SkBitmap& bitmap, sk_sp<SkRasterCanvasLayerAllocator>);

[tomhudson, 2016/05/26 16:36:17]

Figuring out lifetime here is a little awkward - the RasterCanvasLayerAllocator
constructs a smart pointer around (this) to pass here so that the Canvas can own
it?

Perhaps we should instead copy in the Allocator, since we really don't want to
have one instance shared between multiple canvases. That is itself awkward to
code, although we can hide the awkwardness from the API user I *think*.

Or perhaps that's not so important, and we can share these; if we don't share
these, we could simplify the API a bit.

[reed1, 2016/07/12 19:52:39]

I think unique_ptr as a parameter type is fine. No need to make it sharable (at
least not right now).

 
     void resetForNextPicture(const SkIRect& bounds);
 
@@ -1468,7 +1477,7 @@ private:
     //  - internalSaveLayer
     void setupDevice(SkBaseDevice*);
 
-    SkBaseDevice* init(SkBaseDevice*, InitFlags);
+    SkBaseDevice* init(SkBaseDevice*, InitFlags, sk_sp<SkRasterCanvasLayerAllocator>);
 
     /**
      * Gets the bounds of the top level layer in global canvas coordinates. We don't want this
@@ -1543,6 +1552,8 @@ private:
     void validateClip() const {}
 #endif
 
+    sk_sp<SkRasterCanvasLayerAllocator> fAllocator;
+
     typedef SkRefCnt INHERITED;
 };