Add base types for path ops

include/pathops/SkPathOps.h

Index: include/pathops/SkPathOps.h
===================================================================
--- include/pathops/SkPathOps.h	(revision 0)
+++ include/pathops/SkPathOps.h	(revision 0)
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#ifndef SkPathOps_DEFINED
+#define SkPathOps_DEFINED
+
+class SkPath;
+
+// FIXME: move this into SkPaths.h or just use the equivalent in SkRegion.h
+enum SkPathOp {
+    kDifference_PathOp,  //!< subtract the op path from the first path
+    kIntersect_PathOp,   //!< intersect the two paths
+    kUnion_PathOp,       //!< union (inclusive-or) the two paths
+    kXOR_PathOp,         //!< exclusive-or the two paths
+    /** subtract the first path from the op path */
+    kReverseDifference_PathOp,  // FIXME: unsupported
+    kReplace_PathOp      //!< replace the dst path with the op  FIXME: unsupported: should it be?
+};
+
+// FIXME: these functions become members of SkPath
+/**
+  *  Set this path to the result of applying the Op to this path and the
+  *  specified path: this = (this op operand). The resulting path will be constructed
+  *  from non-overlapping contours. The curve order is reduced where possible so that cubics may
+  *  be turned into quadratics, and quadratics maybe turned into lines.
+  */
+void Op(const SkPath& one, const SkPath& two, SkPathOp op, SkPath* result);
+
+/**
+  *  Set this path to a set of non-overlapping contours that describe the same
+  *  area as the original path. The curve order is reduced where possible so that cubics may
+  *  be turned into quadratics, and quadratics maybe turned into lines.
+  */
+void Simplify(const SkPath& path, SkPath* result);
+
+#endif