use ClipOp instead of SkRegion for clipping

include/core/SkCanvas.h

Index: include/core/SkCanvas.h
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index ff60c57fa7ec325a7678fbb8e1e28629b83e71a2..5bed56eafffedd7897f19e54a406515c5f153479 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -19,6 +19,12 @@
 #include "SkSurfaceProps.h"
 #include "SkXfermode.h"
 
+// Undefine this when we change callers to use SkClipOp or legacyClip (temporarily)
+//#define SK_SUPPORT_REGION_CLIPOPS
+
+// Undefine this when we have updated all callers to SkClipOp
+#define SK_SUPPORT_LEGACY_CLIPOPS
+
 #ifdef SK_SUPPORT_LEGACY_DRAWTEXT_VIRTUAL
     #define SK_LEGACY_DRAWTEXT_VIRTUAL  virtual
 #else
@@ -42,6 +48,11 @@ class GrRenderTarget;
 
 class SkCanvasState;
 
+enum SkClipOp {
+    kIntersect_SkClipOp,
+    kDifference_SkClipOp,
+};
+
 /** \class SkCanvas
 
     A Canvas encapsulates all of the state about drawing into a device (bitmap).
@@ -469,35 +480,68 @@ public:
     */
     void resetMatrix();
 
+#ifndef SK_SUPPORT_REGION_CLIPOPS
+private:
+#endif
+    void clipRect(const SkRect&, SkRegion::Op, bool doAntiAlias = false);
+    void clipRRect(const SkRRect&, SkRegion::Op, bool doAntiAlias = false);
+    void clipPath(const SkPath&, SkRegion::Op, bool doAntiAlias = false);
+    void clipRegion(const SkRegion&, SkRegion::Op);
+#ifndef SK_SUPPORT_REGION_CLIPOPS
+public:
+#endif
+
+/*  These support SkRegion ops, and are used in the interim until we can remove all
+ *  needs for these ops. When all callers only need Intersect or Difference, we will
+ *  remove these calls.
+ */
+#ifdef SK_SUPPORT_LEGACY_CLIPOPS
+    void legacyClipRect(const SkRect& rect, SkRegion::Op op, bool doAntiAlias = false) {
+        this->clipRect(rect, op, doAntiAlias);
+    }
+    void legacyClipRRect(const SkRRect& rrect, SkRegion::Op op, bool doAntiAlias = false) {
+        this->clipRRect(rrect, op, doAntiAlias);
+    }
+    void legacyClipPath(const SkPath& path, SkRegion::Op op, bool doAntiAlias = false) {
+        this->clipPath(path, op, doAntiAlias);
+    }
+    void legacyClipRegion(const SkRegion& deviceRgn, SkRegion::Op op) {
+        this->clipRegion(deviceRgn, op);
+    }
+#endif
+
     /**
      *  Modify the current clip with the specified rectangle.
      *  @param rect The rect to combine with the current clip
-     *  @param op The region op to apply to the current clip
+     *  @param op The ClipOp to apply to the current clip
      *  @param doAntiAlias true if the clip should be antialiased
      */
-    void clipRect(const SkRect& rect,
-                  SkRegion::Op op = SkRegion::kIntersect_Op,
-                  bool doAntiAlias = false);
+    void clipRect(const SkRect& rect, SkClipOp op, bool doAntiAlias = false);
+    void clipRect(const SkRect& rect) {
+        this->clipRect(rect, kIntersect_SkClipOp, false);
+    }
 
     /**
      *  Modify the current clip with the specified SkRRect.
      *  @param rrect The rrect to combine with the current clip
-     *  @param op The region op to apply to the current clip
+     *  @param op The ClipOp to apply to the current clip
      *  @param doAntiAlias true if the clip should be antialiased
      */
-    void clipRRect(const SkRRect& rrect,
-                   SkRegion::Op op = SkRegion::kIntersect_Op,
-                   bool doAntiAlias = false);
+    void clipRRect(const SkRRect& rrect, SkClipOp op, bool doAntiAlias = false);
+    void clipRRect(const SkRRect& rrect) {
+        this->clipRRect(rrect, kIntersect_SkClipOp, false);
+    }
 
     /**
      *  Modify the current clip with the specified path.
      *  @param path The path to combine with the current clip
-     *  @param op The region op to apply to the current clip
+     *  @param op The ClipOp to apply to the current clip
      *  @param doAntiAlias true if the clip should be antialiased
      */
-    void clipPath(const SkPath& path,
-                  SkRegion::Op op = SkRegion::kIntersect_Op,
-                  bool doAntiAlias = false);
+    void clipPath(const SkPath& path, SkClipOp op, bool doAntiAlias = false);
+    void clipPath(const SkPath& path) {
+        this->clipPath(path, kIntersect_SkClipOp, false);
+    }
 
     /** EXPERIMENTAL -- only used for testing
         Set to false to force clips to be hard, even if doAntiAlias=true is
@@ -519,10 +563,9 @@ public:
         matrix, clipRegion() assumes its argument is already in device
         coordinates, and so no transformation is performed.
         @param deviceRgn    The region to apply to the current clip
-        @param op The region op to apply to the current clip
+        @param op The ClipOp to apply to the current clip
     */
-    void clipRegion(const SkRegion& deviceRgn,
-                    SkRegion::Op op = SkRegion::kIntersect_Op);
+    void clipRegion(const SkRegion& deviceRgn, SkClipOp op = kIntersect_SkClipOp);
 
     /** Helper for clipRegion(rgn, kReplace_Op). Sets the current clip to the
         specified region. This does not intersect or in any other way account
@@ -530,7 +573,7 @@ public:
         @param deviceRgn The region to copy into the current clip.
     */
     void setClipRegion(const SkRegion& deviceRgn) {
-        this->clipRegion(deviceRgn, SkRegion::kReplace_Op);
+        this->legacyClipRegion(deviceRgn, SkRegion::kReplace_Op);
     }
 
     /** Return true if the specified rectangle, after being transformed by the