Expose FillBounds to allow GrPictureUtils::CollectLayers to be layered on top of it

src/core/SkRecordDraw.h

Index: src/core/SkRecordDraw.h
diff --git a/src/core/SkRecordDraw.h b/src/core/SkRecordDraw.h
index 75921d182fd3de1e5596114b7fce2e033cba696c..9ec554252b2c66a45dfc125680e6d3543d7032aa 100644
--- a/src/core/SkRecordDraw.h
+++ b/src/core/SkRecordDraw.h
@@ -71,6 +71,79 @@ private:
     typedef Draw INHERITED;
 };
 
+// This is an SkRecord visitor that fills an SkBBoxHierarchy.
+//
+// The interesting part here is how to calculate bounds for ops which don't
+// have intrinsic bounds.  What is the bounds of a Save or a Translate?
+//
+// We answer this by thinking about a particular definition of bounds: if I
+// don't execute this op, pixels in this rectangle might draw incorrectly.  So
+// the bounds of a Save, a Translate, a Restore, etc. are the union of the
+// bounds of Draw* ops that they might have an effect on.  For any given
+// Save/Restore block, the bounds of the Save, the Restore, and any other
+// non-drawing ("control") ops inside are exactly the union of the bounds of
+// the drawing ops inside that block.
+//
+// To implement this, we keep a stack of active Save blocks.  As we consume ops
+// inside the Save/Restore block, drawing ops are unioned with the bounds of
+// the block, and control ops are stashed away for later.  When we finish the
+// block with a Restore, our bounds are complete, and we go back and fill them
+// in for all the control ops we stashed away.
+class FillBounds : SkNoncopyable {
+public:
+    FillBounds(const SkRecord& record, SkBBoxHierarchy* bbh);

[mtklein, 2014/11/03 14:55:21]

Given that we do all the work in the constructor in one go and all the state is
private, what value do we get out of exposing this beyond what
SkRecordFillBounds gives us?

[robertphillips, 2014/11/03 15:14:17]

I guess we could move CollectLayers from GrPictureUtils.cpp to SkRecordDraw.cpp
and then add a "SkRecordCollectLayersAndFillBounds" to SkRecordDraw.h.

+
+    template <typename T> void operator()(const T& op) {
+        this->updateCTM(op);
+        this->updateClipBounds(op);
+        this->trackBounds(op);
+    }
+
+private:
+    // In FillBounds, SkRect are in local coordinates, Bounds are translated back to identity space.
+    typedef SkRect Bounds;
+
+    struct SaveBounds {
+        int controlOps;        // Number of control ops in this Save block, including the Save.
+        Bounds bounds;         // Bounds of everything in the block.
+        const SkPaint* paint;  // Unowned.  If set, adjusts the bounds of all ops in this block.
+    };
+
+    template <typename T> void updateCTM(const T&);
+    template <typename T> void updateClipBounds(const T&);
+    template <typename T> void trackBounds(const T&);
+    template <typename T> Bounds bounds(const T&) const;
+
+    void updateClipBoundsForClipOp(const SkIRect& devBounds);
+
+    void pushSaveBlock(const SkPaint* paint);
+    static bool PaintMayAffectTransparentBlack(const SkPaint* paint);
+    Bounds popSaveBlock();
+    void pushControl();
+    void popControl(const Bounds& bounds);
+    void updateSaveBounds(const Bounds& bounds);
+
+    static void AdjustTextForFontMetrics(SkRect* rect, const SkPaint& paint);
+    static bool AdjustForPaint(const SkPaint* paint, SkRect* rect);
+    bool adjustForSaveLayerPaints(SkRect* rect, int savesToIgnore = 0) const;
+    Bounds adjustAndMap(SkRect rect, const SkPaint* paint) const;
+
+    // Conservative identity-space bounds for each op in the SkRecord.
+    SkAutoTMalloc<Bounds> fBounds;
+
+    // We walk fCurrentOp through the SkRecord, as we go using updateCTM()
+    // and updateClipBounds() to maintain the exact CTM (fCTM) and conservative
+    // identity-space bounds of the current clip (fCurrentClipBounds).
+    unsigned fCurrentOp;
+    const SkMatrix* fCTM;
+    Bounds fCurrentClipBounds;
+
+    // Used to track the bounds of Save/Restore blocks and the control ops inside them.
+    SkTDArray<SaveBounds> fSaveStack;
+    SkTDArray<unsigned>   fControlIndices;
+};
+
+
 }  // namespace SkRecords
 
 #endif//SkRecordDraw_DEFINED