Add implementation of path ops

src/pathops/SkOpEdgeBuilder.h

+/*
+ * 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 SkOpEdgeBuilder_DEFINED
+#define SkOpEdgeBuilder_DEFINED
+
+#include "SkOpContour.h"
+#include "SkPathWriter.h"
+#include "SkTDArray.h"
+#include "SkTArray.h"
+
+class SkOpEdgeBuilder {
+public:
+    SkOpEdgeBuilder(const SkPathWriter& path, SkTArray<SkOpContour>& contours)
+        : fPath(path.nativePath())
+        , fContours(contours)
+    {
+        init();
+    }
+
+    SkOpEdgeBuilder(const SkPath& path, SkTArray<SkOpContour>& contours)
+        : fPath(&path)
+        , fContours(contours)
+    {
+        init();
+    }
+
+    void complete() {
+        if (fCurrentContour && fCurrentContour->segments().count()) {
+            fCurrentContour->complete();
+            fCurrentContour = NULL;
+        }
+    }
+
+    SkPathOpsMask xorMask() const {
+        return fXorMask[fOperand];
+    }
+
+    void addOperand(const SkPath& path);
+    void finish();
+    void init();
+
+private:
+    int preFetch();
+    void walk();
+
+    const SkPath* fPath;
+    SkTDArray<SkPoint> fPathPts; // FIXME: point directly to path pts instead
+    SkTDArray<uint8_t> fPathVerbs; // FIXME: remove
+    SkOpContour* fCurrentContour;
+    SkTArray<SkOpContour>& fContours;
+    SkTDArray<SkPoint> fReducePts; // segments created on the fly
+    SkTDArray<int> fExtra; // -1 marks new contour, > 0 offsets into contour
+    SkPathOpsMask fXorMask[2];
+    int fSecondHalf;
+    bool fOperand;
+};
+
+#endif