Add implementation of path ops

src/pathops/SkPathWriter.cpp

Index: src/pathops/SkPathWriter.cpp
===================================================================
--- src/pathops/SkPathWriter.cpp	(revision 0)
+++ src/pathops/SkPathWriter.cpp	(revision 0)
@@ -0,0 +1,157 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "SkPathOpsTypes.h"
+#include "SkPathWriter.h"
+
+// wrap path to keep track of whether the contour is initialized and non-empty
+SkPathWriter::SkPathWriter(SkPath& path)
+    : fPathPtr(&path)
+    , fCloses(0)
+    , fMoves(0)
+{
+    init();
+}
+
+void SkPathWriter::close() {
+    if (!fHasMove) {
+        return;
+    }
+    bool callClose = isClosed();
+    lineTo();
+    if (fEmpty) {
+        return;
+    }
+    if (callClose) {
+#if DEBUG_PATH_CONSTRUCTION
+        SkDebugf("path.close();\n");
+#endif
+        fPathPtr->close();
+        fCloses++;
+    }
+    init();
+}
+
+void SkPathWriter::cubicTo(const SkPoint& pt1, const SkPoint& pt2, const SkPoint& pt3) {
+    lineTo();
+    moveTo();
+    fDefer[1] = pt3;
+    nudge();
+    fDefer[0] = fDefer[1];
+#if DEBUG_PATH_CONSTRUCTION
+    SkDebugf("path.cubicTo(%1.9g,%1.9g, %1.9g,%1.9g, %1.9g,%1.9g);\n",
+            pt1.fX, pt1.fY, pt2.fX, pt2.fY, fDefer[1].fX, fDefer[1].fY);
+#endif
+    fPathPtr->cubicTo(pt1.fX, pt1.fY, pt2.fX, pt2.fY, fDefer[1].fX, fDefer[1].fY);
+    fEmpty = false;
+}
+
+void SkPathWriter::deferredLine(const SkPoint& pt) {
+    if (pt == fDefer[1]) {
+        return;
+    }
+    if (changedSlopes(pt)) {
+        lineTo();
+        fDefer[0] = fDefer[1];
+    }
+    fDefer[1] = pt;
+}
+
+void SkPathWriter::deferredMove(const SkPoint& pt) {
+    fMoved = true;
+    fHasMove = true;
+    fEmpty = true;
+    fDefer[0] = fDefer[1] = pt;
+}
+
+void SkPathWriter::deferredMoveLine(const SkPoint& pt) {
+    if (!fHasMove) {
+        deferredMove(pt);
+    }
+    deferredLine(pt);
+}
+
+bool SkPathWriter::hasMove() const {
+    return fHasMove;
+}
+
+void SkPathWriter::init() {
+    fEmpty = true;
+    fHasMove = false;
+    fMoved = false;
+}
+
+bool SkPathWriter::isClosed() const {
+    return !fEmpty && fFirstPt == fDefer[1];
+}
+
+void SkPathWriter::lineTo() {
+    if (fDefer[0] == fDefer[1]) {
+        return;
+    }
+    moveTo();
+    nudge();
+    fEmpty = false;
+#if DEBUG_PATH_CONSTRUCTION
+    SkDebugf("path.lineTo(%1.9g,%1.9g);\n", fDefer[1].fX, fDefer[1].fY);
+#endif
+    fPathPtr->lineTo(fDefer[1].fX, fDefer[1].fY);
+    fDefer[0] = fDefer[1];
+}
+
+const SkPath* SkPathWriter::nativePath() const {
+    return fPathPtr;
+}
+
+void SkPathWriter::nudge() {
+    if (fEmpty || !AlmostEqualUlps(fDefer[1].fX, fFirstPt.fX)
+            || !AlmostEqualUlps(fDefer[1].fY, fFirstPt.fY)) {
+        return;
+    }
+    fDefer[1] = fFirstPt;
+}
+
+void SkPathWriter::quadTo(const SkPoint& pt1, const SkPoint& pt2) {
+    lineTo();
+    moveTo();
+    fDefer[1] = pt2;
+    nudge();
+    fDefer[0] = fDefer[1];
+#if DEBUG_PATH_CONSTRUCTION
+    SkDebugf("path.quadTo(%1.9g,%1.9g, %1.9g,%1.9g);\n",
+            pt1.fX, pt1.fY, fDefer[1].fX, fDefer[1].fY);
+#endif
+    fPathPtr->quadTo(pt1.fX, pt1.fY, fDefer[1].fX, fDefer[1].fY);
+    fEmpty = false;
+}
+
+bool SkPathWriter::someAssemblyRequired() const {
+    return fCloses < fMoves;
+}
+
+bool SkPathWriter::changedSlopes(const SkPoint& pt) const {
+    if (fDefer[0] == fDefer[1]) {
+        return false;
+    }
+    SkScalar deferDx = fDefer[1].fX - fDefer[0].fX;
+    SkScalar deferDy = fDefer[1].fY - fDefer[0].fY;
+    SkScalar lineDx = pt.fX - fDefer[1].fX;
+    SkScalar lineDy = pt.fY - fDefer[1].fY;
+    return deferDx * lineDy != deferDy * lineDx;
+}
+
+void SkPathWriter::moveTo() {
+    if (!fMoved) {
+        return;
+    }
+    fFirstPt = fDefer[0];
+#if DEBUG_PATH_CONSTRUCTION
+    SkDebugf("path.moveTo(%1.9g,%1.9g);\n", fDefer[0].fX, fDefer[0].fY);
+#endif
+    fPathPtr->moveTo(fDefer[0].fX, fDefer[0].fY);
+    fMoved = false;
+    fMoves++;
+}