Broke GrTessellatingPathRenderer's tessellator out into a separate file.

src/gpu/GrTessellator.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
-#include "GrTessellatingPathRenderer.h"
+#include "GrTessellator.h"
 
 #include "GrBatchFlushState.h"
 #include "GrBatchTest.h"
 #include "GrDefaultGeoProcFactory.h"
 #include "GrPathUtils.h"
 #include "GrVertices.h"
 #include "GrResourceCache.h"
 #include "GrResourceProvider.h"
-#include "SkChunkAlloc.h"
 #include "SkGeometry.h"
 
 #include "batches/GrVertexBatch.h"
 
 #include <stdio.h>
 
 /*
- * This path renderer tessellates the path into triangles, uploads the triangles to a
- * vertex buffer, and renders them with a single draw call. It does not currently do
- * antialiasing, so it must be used in conjunction with multisampling.
- *
  * There are six stages to the algorithm:
  *
  * 1) Linearize the path contours into piecewise linear segments (path_to_contours()).
  * 2) Build a mesh of edges connecting the vertices (build_edges()).
  * 3) Sort the vertices in Y (and secondarily in X) (merge_sort()).
  * 4) Simplify the mesh by inserting new vertices at intersecting edges (simplify()).
  * 5) Tessellate the simplified mesh into monotone polygons (tessellate()).
  * 6) Triangulate the monotone polygons directly into a vertex buffer (polys_to_triangles()).
  *
  * The vertex sorting in step (3) is a merge sort, since it plays well with the linked list
@@ skipping 34 matching lines @@
  * frequent. There may be other data structures worth investigating, however.
  *
  * Note that the orientation of the line sweep algorithms is determined by the aspect ratio of the
  * path bounds. When the path is taller than it is wide, we sort vertices based on increasing Y
  * coordinate, and secondarily by increasing X coordinate. When the path is wider than it is tall,
  * we sort by increasing X coordinate, but secondarily by *decreasing* Y coordinate. This is so
  * that the "left" and "right" orientation in the code remains correct (edges to the left are
  * increasing in Y; edges to the right are decreasing in Y). That is, the setting rotates 90
  * degrees counterclockwise, rather that transposing.
  */
+
 #define LOGGING_ENABLED 0
-#define WIREFRAME 0
 
 #if LOGGING_ENABLED
 #define LOG printf
 #else
 #define LOG(...)
 #endif
 
 #define ALLOC_NEW(Type, args, alloc) new (alloc.allocThrow(sizeof(Type))) Type args
 
-namespace {
+namespace GrTessellator {

[Stephen White, 2016/01/05 16:36:22]

Now that they're no longer public, can these things go back in the unnamed
namespace? (And maybe back into their original order, to
minimize diffs?)

 
+struct Poly;
+struct EdgeList;
 struct Vertex;
-struct Edge;
+
+struct Edge {
+    Edge(Vertex* top, Vertex* bottom, int winding)
+        : fTop(top)
+        , fBottom(bottom)
+        , fWinding(winding)
+        , fLeft(nullptr)
+        , fRight(nullptr)
+        , fPrevEdgeAbove(nullptr)
+        , fNextEdgeAbove(nullptr)
+        , fPrevEdgeBelow(nullptr)
+        , fNextEdgeBelow(nullptr)
+        , fLeftPoly(nullptr)
+        , fRightPoly(nullptr) {
+            recompute();
+        }
+    Vertex* fTop;          // The top vertex in vertex-sort-order (sweep_lt).
+    Vertex* fBottom;       // The bottom vertex in vertex-sort-order.
+    int    fWinding;       // 1 == edge goes downward; -1 = edge goes upward.
+    Edge*  fLeft;          // The linked list of edges in the active edge list.
+    Edge*  fRight;         // "
+    Edge*  fPrevEdgeAbove; // The linked list of edges in the bottom Vertex's "edges above".
+    Edge*  fNextEdgeAbove; // "
+    Edge*  fPrevEdgeBelow; // The linked list of edges in the top Vertex's "edges below".
+    Edge*  fNextEdgeBelow; // "
+    Poly*  fLeftPoly;      // The Poly to the left of this edge, if any.
+    Poly*  fRightPoly;     // The Poly to the right of this edge, if any.
+    double fDX;            // The line equation for this edge, in implicit form.
+    double fDY;            // fDY * x + fDX * y + fC = 0, for point (x, y) on the line.
+    double fC;
+    double dist(const SkPoint& p) const;
+    bool isRightOf(Vertex* v) const;
+    bool isLeftOf(Vertex* v) const;
+    void recompute();
+    bool intersect(const Edge& other, SkPoint* p);
+    bool isActive(EdgeList* activeEdges) const;
+};
+
+struct EdgeList {
+    EdgeList() : fHead(nullptr), fTail(nullptr) {}
+    Edge* fHead;
+    Edge* fTail;
+};
+
+/**
+ * Vertices are used in three ways: first, the path contours are converted into a circularly-linked 
+ * list of vertices for each contour. After edge construction, the same vertices are re-ordered by 
+ * the merge sort according to the sweep_lt comparator (usually, increasing in Y) using the same 
+ * fPrev/fNext pointers that were used for the contours, to avoid reallocation. Finally, 
+ * MonotonePolys are built containing a circularly-linked list of vertices. Currently, those 
+ * Vertices are newly-allocated for the MonotonePolys, since an individual vertex from the path mesh
+ * may belong to multiple MonotonePolys, so the original vertices cannot be re-used.
+ */
+struct Vertex {
+  Vertex(const SkPoint& point)
+    : fPoint(point), fPrev(nullptr), fNext(nullptr)
+    , fFirstEdgeAbove(nullptr), fLastEdgeAbove(nullptr)
+    , fFirstEdgeBelow(nullptr), fLastEdgeBelow(nullptr)
+    , fProcessed(false)
+#if LOGGING_ENABLED
+    , fID (-1.0f)
+#endif
+    {}
+    SkPoint fPoint;           // Vertex position
+    Vertex* fPrev;            // Linked list of contours, then Y-sorted vertices.
+    Vertex* fNext;            // "
+    Edge*   fFirstEdgeAbove;  // Linked list of edges above this vertex.
+    Edge*   fLastEdgeAbove;   // "
+    Edge*   fFirstEdgeBelow;  // Linked list of edges below this vertex.
+    Edge*   fLastEdgeBelow;   // "
+    bool    fProcessed;       // Has this vertex been seen in simplify()?
+#if LOGGING_ENABLED
+    float   fID;              // Identifier used for logging.
+#endif
+};
+
+double Edge::dist(const SkPoint& p) const {
+    return fDY * p.fX - fDX * p.fY + fC;
+}
+
+bool Edge::isRightOf(Vertex* v) const {
+    return dist(v->fPoint) < 0.0;
+}
+
+bool Edge::isLeftOf(Vertex* v) const {
+    return dist(v->fPoint) > 0.0;
+}
+
+void Edge::recompute() {
+    fDX = static_cast<double>(fBottom->fPoint.fX) - fTop->fPoint.fX;
+    fDY = static_cast<double>(fBottom->fPoint.fY) - fTop->fPoint.fY;
+    fC = static_cast<double>(fTop->fPoint.fY) * fBottom->fPoint.fX -
+         static_cast<double>(fTop->fPoint.fX) * fBottom->fPoint.fY;
+}
+
+bool Edge::intersect(const Edge& other, SkPoint* p) {
+#if LOGGING_ENABLED
+    LOG("intersecting %g -> %g with %g -> %g\n",
+           fTop->fID, fBottom->fID,
+           other.fTop->fID, other.fBottom->fID);
+#endif
+    if (fTop == other.fTop || fBottom == other.fBottom) {
+        return false;
+    }
+    double denom = fDX * other.fDY - fDY * other.fDX;
+    if (denom == 0.0) {
+        return false;
+    }
+    double dx = static_cast<double>(fTop->fPoint.fX) - other.fTop->fPoint.fX;
+    double dy = static_cast<double>(fTop->fPoint.fY) - other.fTop->fPoint.fY;
+    double sNumer = dy * other.fDX - dx * other.fDY;
+    double tNumer = dy * fDX - dx * fDY;
+    // If (sNumer / denom) or (tNumer / denom) is not in [0..1], exit early.
+    // This saves us doing the divide below unless absolutely necessary.
+    if (denom > 0.0 ? (sNumer < 0.0 || sNumer > denom || tNumer < 0.0 || tNumer > denom)
+                    : (sNumer > 0.0 || sNumer < denom || tNumer > 0.0 || tNumer < denom)) {
+        return false;
+    }
+    double s = sNumer / denom;
+    SkASSERT(s >= 0.0 && s <= 1.0);
+    p->fX = SkDoubleToScalar(fTop->fPoint.fX + s * fDX);
+    p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fDY);
+    return true;
+}
+
+bool Edge::isActive(EdgeList* activeEdges) const {
+    return activeEdges && (fLeft || fRight || activeEdges->fHead == this);
+}
+
 struct Poly;
 
 template <class T, T* T::*Prev, T* T::*Next>
 void insert(T* t, T* prev, T* next, T** head, T** tail) {
     t->*Prev = prev;
     t->*Next = next;
     if (prev) {
         prev->*Next = t;
     } else if (head) {
         *head = t;
@@ skipping 13 matching lines @@
         *head = t->*Next;
     }
     if (t->*Next) {
         t->*Next->*Prev = t->*Prev;
     } else if (tail) {
         *tail = t->*Prev;
     }
     t->*Prev = t->*Next = nullptr;
 }
 
-/**
- * Vertices are used in three ways: first, the path contours are converted into a
- * circularly-linked list of Vertices for each contour. After edge construction, the same Vertices
- * are re-ordered by the merge sort according to the sweep_lt comparator (usually, increasing
- * in Y) using the same fPrev/fNext pointers that were used for the contours, to avoid
- * reallocation. Finally, MonotonePolys are built containing a circularly-linked list of
- * Vertices. (Currently, those Vertices are newly-allocated for the MonotonePolys, since
- * an individual Vertex from the path mesh may belong to multiple
- * MonotonePolys, so the original Vertices cannot be re-used.
- */
-
-struct Vertex {
-  Vertex(const SkPoint& point)
-    : fPoint(point), fPrev(nullptr), fNext(nullptr)
-    , fFirstEdgeAbove(nullptr), fLastEdgeAbove(nullptr)
-    , fFirstEdgeBelow(nullptr), fLastEdgeBelow(nullptr)
-    , fProcessed(false)
-#if LOGGING_ENABLED
-    , fID (-1.0f)
-#endif
-    {}
-    SkPoint fPoint;           // Vertex position
-    Vertex* fPrev;            // Linked list of contours, then Y-sorted vertices.
-    Vertex* fNext;            // "
-    Edge*   fFirstEdgeAbove;  // Linked list of edges above this vertex.
-    Edge*   fLastEdgeAbove;   // "
-    Edge*   fFirstEdgeBelow;  // Linked list of edges below this vertex.
-    Edge*   fLastEdgeBelow;   // "
-    bool    fProcessed;       // Has this vertex been seen in simplify()?
-#if LOGGING_ENABLED
-    float   fID;              // Identifier used for logging.
-#endif
-};
-
 /***************************************************************************************/
 
 typedef bool (*CompareFunc)(const SkPoint& a, const SkPoint& b);
 
 struct Comparator {
     CompareFunc sweep_lt;
     CompareFunc sweep_gt;
 };
 
 bool sweep_lt_horiz(const SkPoint& a, const SkPoint& b) {
@@ skipping 11 matching lines @@
 bool sweep_gt_vert(const SkPoint& a, const SkPoint& b) {
     return a.fY == b.fY ? a.fX > b.fX : a.fY > b.fY;
 }
 
 inline SkPoint* emit_vertex(Vertex* v, SkPoint* data) {
     *data++ = v->fPoint;
     return data;
 }
 
 SkPoint* emit_triangle(Vertex* v0, Vertex* v1, Vertex* v2, SkPoint* data) {
-#if WIREFRAME
+#if TESSELLATOR_WIREFRAME
     data = emit_vertex(v0, data);
     data = emit_vertex(v1, data);
     data = emit_vertex(v1, data);
     data = emit_vertex(v2, data);
     data = emit_vertex(v2, data);
     data = emit_vertex(v0, data);
 #else
     data = emit_vertex(v0, data);
     data = emit_vertex(v1, data);
     data = emit_vertex(v2, data);
 #endif
     return data;
 }
 
-struct EdgeList {
-    EdgeList() : fHead(nullptr), fTail(nullptr) {}
-    Edge* fHead;
-    Edge* fTail;
-};
-
 /**
  * An Edge joins a top Vertex to a bottom Vertex. Edge ordering for the list of "edges above" and
  * "edge below" a vertex as well as for the active edge list is handled by isLeftOf()/isRightOf().
  * Note that an Edge will give occasionally dist() != 0 for its own endpoints (because floating
  * point). For speed, that case is only tested by the callers which require it (e.g.,
  * cleanup_active_edges()). Edges also handle checking for intersection with other edges.
  * Currently, this converts the edges to the parametric form, in order to avoid doing a division
  * until an intersection has been confirmed. This is slightly slower in the "found" case, but
  * a lot faster in the "not found" case.
  *
  * The coefficients of the line equation stored in double precision to avoid catastrphic
  * cancellation in the isLeftOf() and isRightOf() checks. Using doubles ensures that the result is
  * correct in float, since it's a polynomial of degree 2. The intersect() function, being
  * degree 5, is still subject to catastrophic cancellation. We deal with that by assuming its
  * output may be incorrect, and adjusting the mesh topology to match (see comment at the top of
  * this file).
  */
 
-struct Edge {
-    Edge(Vertex* top, Vertex* bottom, int winding)
-        : fWinding(winding)
-        , fTop(top)
-        , fBottom(bottom)
-        , fLeft(nullptr)
-        , fRight(nullptr)
-        , fPrevEdgeAbove(nullptr)
-        , fNextEdgeAbove(nullptr)
-        , fPrevEdgeBelow(nullptr)
-        , fNextEdgeBelow(nullptr)
-        , fLeftPoly(nullptr)
-        , fRightPoly(nullptr) {
-            recompute();
-        }
-    int      fWinding;          // 1 == edge goes downward; -1 = edge goes upward.
-    Vertex*  fTop;              // The top vertex in vertex-sort-order (sweep_lt).
-    Vertex*  fBottom;           // The bottom vertex in vertex-sort-order.
-    Edge*    fLeft;             // The linked list of edges in the active edge list.
-    Edge*    fRight;            // "
-    Edge*    fPrevEdgeAbove;    // The linked list of edges in the bottom Vertex's "edges above".
-    Edge*    fNextEdgeAbove;    // "
-    Edge*    fPrevEdgeBelow;    // The linked list of edges in the top Vertex's "edges below".
-    Edge*    fNextEdgeBelow;    // "
-    Poly*    fLeftPoly;         // The Poly to the left of this edge, if any.
-    Poly*    fRightPoly;        // The Poly to the right of this edge, if any.
-    double   fDX;               // The line equation for this edge, in implicit form.
-    double   fDY;               // fDY * x + fDX * y + fC = 0, for point (x, y) on the line.
-    double   fC;
-    double dist(const SkPoint& p) const {
-        return fDY * p.fX - fDX * p.fY + fC;
-    }
-    bool isRightOf(Vertex* v) const {
-        return dist(v->fPoint) < 0.0;
-    }
-    bool isLeftOf(Vertex* v) const {
-        return dist(v->fPoint) > 0.0;
-    }
-    void recompute() {
-        fDX = static_cast<double>(fBottom->fPoint.fX) - fTop->fPoint.fX;
-        fDY = static_cast<double>(fBottom->fPoint.fY) - fTop->fPoint.fY;
-        fC = static_cast<double>(fTop->fPoint.fY) * fBottom->fPoint.fX -
-             static_cast<double>(fTop->fPoint.fX) * fBottom->fPoint.fY;
-    }
-    bool intersect(const Edge& other, SkPoint* p) {
-        LOG("intersecting %g -> %g with %g -> %g\n",
-               fTop->fID, fBottom->fID,
-               other.fTop->fID, other.fBottom->fID);
-        if (fTop == other.fTop || fBottom == other.fBottom) {
-            return false;
-        }
-        double denom = fDX * other.fDY - fDY * other.fDX;
-        if (denom == 0.0) {
-            return false;
-        }
-        double dx = static_cast<double>(fTop->fPoint.fX) - other.fTop->fPoint.fX;
-        double dy = static_cast<double>(fTop->fPoint.fY) - other.fTop->fPoint.fY;
-        double sNumer = dy * other.fDX - dx * other.fDY;
-        double tNumer = dy * fDX - dx * fDY;
-        // If (sNumer / denom) or (tNumer / denom) is not in [0..1], exit early.
-        // This saves us doing the divide below unless absolutely necessary.
-        if (denom > 0.0 ? (sNumer < 0.0 || sNumer > denom || tNumer < 0.0 || tNumer > denom)
-                        : (sNumer > 0.0 || sNumer < denom || tNumer > 0.0 || tNumer < denom)) {
-            return false;
-        }
-        double s = sNumer / denom;
-        SkASSERT(s >= 0.0 && s <= 1.0);
-        p->fX = SkDoubleToScalar(fTop->fPoint.fX + s * fDX);
-        p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fDY);
-        return true;
-    }
-    bool isActive(EdgeList* activeEdges) const {
-        return activeEdges && (fLeft || fRight || activeEdges->fHead == this);
-    }
-};
-
 /***************************************************************************************/
 
 struct Poly {
     Poly(int winding)
         : fWinding(winding)
         , fHead(nullptr)
         , fTail(nullptr)
         , fActive(nullptr)
         , fNext(nullptr)
         , fPartner(nullptr)
@@ skipping 33 matching lines @@
                 fTail->fNext = newV;
                 fTail = newV;
             } else {
                 newV->fNext = fHead;
                 fHead->fPrev = newV;
                 fHead = newV;
             }
             return done;
         }
 
-        SkPoint* emit(SkPoint* data) {
+        SkPoint* emit(int winding, SkPoint* data) {
             Vertex* first = fHead;
             Vertex* v = first->fNext;
             while (v != fTail) {
                 SkASSERT(v && v->fPrev && v->fNext);
                 Vertex* prev = v->fPrev;
                 Vertex* curr = v;
                 Vertex* next = v->fNext;
                 double ax = static_cast<double>(curr->fPoint.fX) - prev->fPoint.fX;
                 double ay = static_cast<double>(curr->fPoint.fY) - prev->fPoint.fY;
                 double bx = static_cast<double>(next->fPoint.fX) - curr->fPoint.fX;
@@ skipping 53 matching lines @@
             fPartner = fPartner->fPartner = nullptr;
         }
         addVertex(v, fActive->fSide == kLeft_Side ? kRight_Side : kLeft_Side, alloc);
     }
     SkPoint* emit(SkPoint *data) {
         if (fCount < 3) {
             return data;
         }
         LOG("emit() %d, size %d\n", fID, fCount);
         for (MonotonePoly* m = fHead; m != nullptr; m = m->fNext) {
-            data = m->emit(data);
+            data = m->emit(fWinding, data);
         }
         return data;
     }
     int fWinding;
     MonotonePoly* fHead;
     MonotonePoly* fTail;
     MonotonePoly* fActive;
     Poly* fNext;
     Poly* fPartner;
     int fCount;
 #if LOGGING_ENABLED
     int fID;
 #endif
 };
 
 /***************************************************************************************/
 
 bool coincident(const SkPoint& a, const SkPoint& b) {
     return a == b;
 }
 
 Poly* new_poly(Poly** head, Vertex* v, int winding, SkChunkAlloc& alloc) {
     Poly* poly = ALLOC_NEW(Poly, (winding), alloc);
     poly->addVertex(v, Poly::kNeither_Side, alloc);
     poly->fNext = *head;
     *head = poly;
     return poly;
 }
 
-Vertex* append_point_to_contour(const SkPoint& p, Vertex* prev, Vertex** head,
-                                SkChunkAlloc& alloc) {
+Vertex* append_point_to_contour(const SkPoint& p, Vertex* prev, 
+                                Vertex** head, SkChunkAlloc& alloc) {
     Vertex* v = ALLOC_NEW(Vertex, (p), alloc);
 #if LOGGING_ENABLED
     static float gID = 0.0f;
     v->fID = gID++;
 #endif
     if (prev) {
         prev->fNext = v;
         v->fPrev = prev;
     } else {
         *head = v;
@@ skipping 54 matching lines @@
     pointsLeft >>= 1;
     prev = generate_cubic_points(p0, q[0], r[0], s, tolSqd, prev, head, pointsLeft, alloc);
     prev = generate_cubic_points(s, r[1], q[2], p3, tolSqd, prev, head, pointsLeft, alloc);
     return prev;
 }
 
 // Stage 1: convert the input path to a set of linear contours (linked list of Vertices).
 
 void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds,
                       Vertex** contours, SkChunkAlloc& alloc, bool *isLinear) {
-
     SkScalar toleranceSqd = tolerance * tolerance;
 
     SkPoint pts[4];
     bool done = false;
     *isLinear = true;
     SkPath::Iter iter(path, false);
     Vertex* prev = nullptr;
     Vertex* head = nullptr;
     if (path.isInverseFillType()) {
         SkPoint quad[4];
@@ skipping 288 matching lines @@
     }
     if (edge->fPrevEdgeBelow && (edge->fBottom == edge->fPrevEdgeBelow->fBottom ||
                                  !edge->fPrevEdgeBelow->isLeftOf(edge->fBottom))) {
         merge_edges_below(edge, edge->fPrevEdgeBelow, activeEdges, c);
     } else if (edge->fNextEdgeBelow && (edge->fBottom == edge->fNextEdgeBelow->fBottom ||
                                         !edge->isLeftOf(edge->fNextEdgeBelow->fBottom))) {
         merge_edges_below(edge, edge->fNextEdgeBelow, activeEdges, c);
     }
 }
 
-void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc);
+void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, 
+                SkChunkAlloc& alloc);
 
 void cleanup_active_edges(Edge* edge, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc) {
     Vertex* top = edge->fTop;
     Vertex* bottom = edge->fBottom;
     if (edge->fLeft) {
         Vertex* leftTop = edge->fLeft->fTop;
         Vertex* leftBottom = edge->fLeft->fBottom;
         if (c.sweep_gt(top->fPoint, leftTop->fPoint) && !edge->fLeft->isLeftOf(top)) {
             split_edge(edge->fLeft, edge->fTop, activeEdges, c, alloc);
         } else if (c.sweep_gt(leftTop->fPoint, top->fPoint) && !edge->isRightOf(leftTop)) {
@@ skipping 50 matching lines @@
         edge = next;
     }
     for (Edge* edge = src->fFirstEdgeBelow; edge;) {
         Edge* next = edge->fNextEdgeBelow;
         set_top(edge, dst, nullptr, c);
         edge = next;
     }
     remove<Vertex, &Vertex::fPrev, &Vertex::fNext>(src, head, nullptr);
 }
 
-Vertex* check_for_intersection(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c,
+Vertex* check_for_intersection(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c, 
                                SkChunkAlloc& alloc) {
     SkPoint p;
     if (!edge || !other) {
         return nullptr;
     }
     if (edge->intersect(*other, &p)) {
         Vertex* v;
         LOG("found intersection, pt is %g, %g\n", p.fX, p.fY);
         if (p == edge->fTop->fPoint || c.sweep_lt(p, edge->fTop->fPoint)) {
             split_edge(other, edge->fTop, activeEdges, c, alloc);
@@ skipping 209 matching lines @@
                     if (check_for_intersection(edge, leftEnclosingEdge, &activeEdges, c, alloc)) {
                         restartChecks = true;
                         break;
                     }
                     if (check_for_intersection(edge, rightEnclosingEdge, &activeEdges, c, alloc)) {
                         restartChecks = true;
                         break;
                     }
                 }
             } else {
-                if (Vertex* pv = check_for_intersection(leftEnclosingEdge, rightEnclosingEdge,
+                if (Vertex* pv = check_for_intersection(leftEnclosingEdge, rightEnclosingEdge, 
                                                         &activeEdges, c, alloc)) {
                     if (c.sweep_lt(pv->fPoint, v->fPoint)) {
                         v = pv;
                     }
                     restartChecks = true;
                 }
 
             }
         } while (restartChecks);
         for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) {
@@ skipping 121 matching lines @@
             LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID,
                 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1);
         }
 #endif
     }
     return polys;
 }
 
 // This is a driver function which calls stages 2-5 in turn.
 
-Poly* contours_to_polys(Vertex** contours, int contourCnt, Comparator& c, SkChunkAlloc& alloc) {
+Poly* contours_to_polys(Vertex** contours, int contourCnt, SkRect pathBounds, SkChunkAlloc& alloc) {
+    Comparator c;
+    if (pathBounds.width() > pathBounds.height()) {
+        c.sweep_lt = sweep_lt_horiz;
+        c.sweep_gt = sweep_gt_horiz;
+    } else {
+        c.sweep_lt = sweep_lt_vert;
+        c.sweep_gt = sweep_gt_vert;
+    }
 #if LOGGING_ENABLED
     for (int i = 0; i < contourCnt; ++i) {
         Vertex* v = contours[i];
         SkASSERT(v);
         LOG("path.moveTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY);
         for (v = v->fNext; v != contours[i]; v = v->fNext) {
             LOG("path.lineTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY);
         }
     }
 #endif
     sanitize_contours(contours, contourCnt);
     Vertex* vertices = build_edges(contours, contourCnt, c, alloc);
     if (!vertices) {
         return nullptr;
     }
 
     // Sort vertices in Y (secondarily in X).
     merge_sort(&vertices, c);
     merge_coincident_vertices(&vertices, c, alloc);
 #if LOGGING_ENABLED
     for (Vertex* v = vertices; v != nullptr; v = v->fNext) {
         static float gID = 0.0f;
         v->fID = gID++;
     }
 #endif
     simplify(vertices, c, alloc);
     return tessellate(vertices, alloc);
 }
 
+Poly* path_to_polys(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 
+                    bool* isLinear) {
+    int contourCnt;
+    int maxPts = GrPathUtils::worstCasePointCount(path, &contourCnt, tolerance);
+    if (maxPts <= 0) {
+        return nullptr;
+    }
+    if (maxPts > ((int)SK_MaxU16 + 1)) {
+        SkDebugf("Path not rendered, too many verts (%d)\n", maxPts);
+        return nullptr;
+    }
+    SkPath::FillType fillType = path.getFillType();
+    if (SkPath::IsInverseFillType(fillType)) {
+        contourCnt++;
+    }
+    SkAutoTDeleteArray<Vertex*> contours(new Vertex* [contourCnt]);
+
+    // For the initial size of the chunk allocator, estimate based on the point count:
+    // one vertex per point for the initial passes, plus two for the vertices in the
+    // resulting Polys, since the same point may end up in two Polys.  Assume minimal
+    // connectivity of one Edge per Vertex (will grow for intersections).
+    SkChunkAlloc alloc(maxPts * (3 * sizeof(Vertex) + sizeof(Edge)));
+    path_to_contours(path, tolerance, clipBounds, contours.get(), alloc, isLinear);
+    return contours_to_polys(contours.get(), contourCnt, path.getBounds(), alloc);

[Stephen White, 2016/01/05 16:36:22]

We're now returning a pointer to Polys which were allocated by the chunk
allocator, which goes out of scope at the end of this function (along with its
memory). This doesn't look right. I think the chunk allocator
should be allocated by the caller.

+}
+
 // Stage 6: Triangulate the monotone polygons into a vertex buffer.
 
-SkPoint* polys_to_triangles(Poly* polys, SkPath::FillType fillType, SkPoint* data) {
-    SkPoint* d = data;
+int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 
+                    GrResourceProvider* resourceProvider, 
+                    SkAutoTUnref<GrVertexBuffer>& vertexBuffer, bool canMapVB, bool* isLinear) {
+    Poly* polys = path_to_polys(path, tolerance, clipBounds, isLinear);
+    SkPath::FillType fillType = path.getFillType();
+    int count = 0;
+    for (Poly* poly = polys; poly; poly = poly->fNext) {
+        if (apply_fill_type(fillType, poly->fWinding) && poly->fCount >= 3) {
+            count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3);
+        }
+    }
+    if (0 == count) {
+        return 0;
+    }
+
+    size_t size = count * sizeof(SkPoint);
+    if (!vertexBuffer.get() || vertexBuffer->gpuMemorySize() < size) {
+        vertexBuffer.reset(resourceProvider->createVertexBuffer(
+            size, GrResourceProvider::kStatic_BufferUsage, 0));
+    }
+    if (!vertexBuffer.get()) {
+        SkDebugf("Could not allocate vertices\n");
+        return 0;
+    }
+    SkPoint* verts;
+    if (canMapVB) {
+        verts = static_cast<SkPoint*>(vertexBuffer->map());
+    } else {
+        verts = new SkPoint[count];
+    }
+    SkPoint* end = verts;
     for (Poly* poly = polys; poly; poly = poly->fNext) {
         if (apply_fill_type(fillType, poly->fWinding)) {
-            d = poly->emit(d);
+            end = poly->emit(end);
         }
     }
-    return d;
+    int actualCount = static_cast<int>(end - verts);
+    LOG("actual count: %d\n", actualCount);
+    SkASSERT(actualCount <= count);
+    if (canMapVB) {
+        vertexBuffer->unmap();
+    } else {
+        vertexBuffer->updateData(verts, actualCount * sizeof(SkPoint));
+        delete[] verts;
+    }
+
+    return actualCount;
 }
 
-struct TessInfo {
-    SkScalar  fTolerance;
-    int       fCount;
-};
+int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 
+                   WindingVertex** verts) {
+    bool isLinear;
+    Poly* polys = path_to_polys(path, tolerance, clipBounds, &isLinear);
+    SkPath::FillType fillType = path.getFillType();
+    int count = 0;
+    for (Poly* poly = polys; poly; poly = poly->fNext) {
+        if (apply_fill_type(fillType, poly->fWinding) && poly->fCount >= 3) {
+            count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3);
+        }
+    }
+    if (0 == count) {
+        *verts = nullptr;
+        return 0;
+    }
 
-bool cache_match(GrVertexBuffer* vertexBuffer, SkScalar tol, int* actualCount) {
-    if (!vertexBuffer) {
-        return false;
+    *verts = new WindingVertex[count];
+    WindingVertex* vertsEnd = *verts;
+    SkPoint* points = new SkPoint[count];
+    SkPoint* pointsEnd = points;
+    for (Poly* poly = polys; poly; poly = poly->fNext) {
+        if (apply_fill_type(fillType, poly->fWinding)) {
+            SkPoint* start = pointsEnd;
+            pointsEnd = poly->emit(pointsEnd);
+            while (start != pointsEnd) {
+                vertsEnd->fPos = *start;
+                vertsEnd->fWinding = poly->fWinding;
+                ++start;
+                ++vertsEnd;
+            }
+        }
     }
-    const SkData* data = vertexBuffer->getUniqueKey().getCustomData();
-    SkASSERT(data);
-    const TessInfo* info = static_cast<const TessInfo*>(data->data());
-    if (info->fTolerance == 0 || info->fTolerance < 3.0f * tol) {
-        *actualCount = info->fCount;
-        return true;
-    }
-    return false;
+    int actualCount = static_cast<int>(vertsEnd - *verts);
+    SkASSERT(actualCount <= count);
+    SkASSERT(pointsEnd - points == actualCount);
+    delete[] points;
+    return actualCount;
 }
 
-};
-
-GrTessellatingPathRenderer::GrTessellatingPathRenderer() {
 }
-
-namespace {
-
-// When the SkPathRef genID changes, invalidate a corresponding GrResource described by key.
-class PathInvalidator : public SkPathRef::GenIDChangeListener {
-public:
-    explicit PathInvalidator(const GrUniqueKey& key) : fMsg(key) {}
-private:
-    GrUniqueKeyInvalidatedMessage fMsg;
-
-    void onChange() override {
-        SkMessageBus<GrUniqueKeyInvalidatedMessage>::Post(fMsg);
-    }
-};
-
-}  // namespace
-
-bool GrTessellatingPathRenderer::onCanDrawPath(const CanDrawPathArgs& args) const {
-    // This path renderer can draw all fill styles, all stroke styles except hairlines, but does
-    // not do antialiasing. It can do convex and concave paths, but we'll leave the convex ones to
-    // simpler algorithms.
-    return !IsStrokeHairlineOrEquivalent(*args.fStroke, *args.fViewMatrix, nullptr) &&
-           !args.fAntiAlias && !args.fPath->isConvex();
-}
-
-class TessellatingPathBatch : public GrVertexBatch {
-public:
-    DEFINE_BATCH_CLASS_ID
-
-    static GrDrawBatch* Create(const GrColor& color,
-                               const SkPath& path,
-                               const GrStrokeInfo& stroke,
-                               const SkMatrix& viewMatrix,
-                               SkRect clipBounds) {
-        return new TessellatingPathBatch(color, path, stroke, viewMatrix, clipBounds);
-    }
-
-    const char* name() const override { return "TessellatingPathBatch"; }
-
-    void computePipelineOptimizations(GrInitInvariantOutput* color, 
-                                      GrInitInvariantOutput* coverage,
-                                      GrBatchToXPOverrides* overrides) const override {
-        color->setKnownFourComponents(fColor);
-        coverage->setUnknownSingleComponent();
-        overrides->fUsePLSDstRead = false;
-    }
-
-private:
-    void initBatchTracker(const GrXPOverridesForBatch& overrides) override {
-        // Handle any color overrides
-        if (!overrides.readsColor()) {
-            fColor = GrColor_ILLEGAL;
-        }
-        overrides.getOverrideColorIfSet(&fColor);
-        fPipelineInfo = overrides;
-    }
-
-    int tessellate(GrUniqueKey* key,
-                   GrResourceProvider* resourceProvider,
-                   SkAutoTUnref<GrVertexBuffer>& vertexBuffer,
-                   bool canMapVB) const {
-        SkPath path;
-        GrStrokeInfo stroke(fStroke);
-        if (stroke.isDashed()) {
-            if (!stroke.applyDashToPath(&path, &stroke, fPath)) {
-                return 0;
-            }
-        } else {
-            path = fPath;
-        }
-        if (!stroke.isFillStyle()) {
-            stroke.setResScale(SkScalarAbs(fViewMatrix.getMaxScale()));
-            if (!stroke.applyToPath(&path, path)) {
-                return 0;
-            }
-            stroke.setFillStyle();
-        }
-        SkRect pathBounds = path.getBounds();
-        Comparator c;
-        if (pathBounds.width() > pathBounds.height()) {
-            c.sweep_lt = sweep_lt_horiz;
-            c.sweep_gt = sweep_gt_horiz;
-        } else {
-            c.sweep_lt = sweep_lt_vert;
-            c.sweep_gt = sweep_gt_vert;
-        }
-        SkScalar screenSpaceTol = GrPathUtils::kDefaultTolerance;
-        SkScalar tol = GrPathUtils::scaleToleranceToSrc(screenSpaceTol, fViewMatrix, pathBounds);
-        int contourCnt;
-        int maxPts = GrPathUtils::worstCasePointCount(path, &contourCnt, tol);
-        if (maxPts <= 0) {
-            return 0;
-        }
-        if (maxPts > ((int)SK_MaxU16 + 1)) {
-            SkDebugf("Path not rendered, too many verts (%d)\n", maxPts);
-            return 0;
-        }
-        SkPath::FillType fillType = path.getFillType();
-        if (SkPath::IsInverseFillType(fillType)) {
-            contourCnt++;
-        }
-
-        LOG("got %d pts, %d contours\n", maxPts, contourCnt);
-        SkAutoTDeleteArray<Vertex*> contours(new Vertex* [contourCnt]);
-
-        // For the initial size of the chunk allocator, estimate based on the point count:
-        // one vertex per point for the initial passes, plus two for the vertices in the
-        // resulting Polys, since the same point may end up in two Polys.  Assume minimal
-        // connectivity of one Edge per Vertex (will grow for intersections).
-        SkChunkAlloc alloc(maxPts * (3 * sizeof(Vertex) + sizeof(Edge)));
-        bool isLinear;
-        path_to_contours(path, tol, fClipBounds, contours.get(), alloc, &isLinear);
-        Poly* polys;
-        polys = contours_to_polys(contours.get(), contourCnt, c, alloc);
-        int count = 0;
-        for (Poly* poly = polys; poly; poly = poly->fNext) {
-            if (apply_fill_type(fillType, poly->fWinding) && poly->fCount >= 3) {
-                count += (poly->fCount - 2) * (WIREFRAME ? 6 : 3);
-            }
-        }
-        if (0 == count) {
-            return 0;
-        }
-
-        size_t size = count * sizeof(SkPoint);
-        if (!vertexBuffer.get() || vertexBuffer->gpuMemorySize() < size) {
-            vertexBuffer.reset(resourceProvider->createVertexBuffer(
-                size, GrResourceProvider::kStatic_BufferUsage, 0));
-        }
-        if (!vertexBuffer.get()) {
-            SkDebugf("Could not allocate vertices\n");
-            return 0;
-        }
-        SkPoint* verts;
-        if (canMapVB) {
-            verts = static_cast<SkPoint*>(vertexBuffer->map());
-        } else {
-            verts = new SkPoint[count];
-        }
-        SkPoint* end = polys_to_triangles(polys, fillType, verts);
-        int actualCount = static_cast<int>(end - verts);
-        LOG("actual count: %d\n", actualCount);
-        SkASSERT(actualCount <= count);
-        if (canMapVB) {
-            vertexBuffer->unmap();
-        } else {
-            vertexBuffer->updateData(verts, actualCount * sizeof(SkPoint));
-            delete[] verts;
-        }
-
-
-        if (!fPath.isVolatile()) {
-            TessInfo info;
-            info.fTolerance = isLinear ? 0 : tol;
-            info.fCount = actualCount;
-            SkAutoTUnref<SkData> data(SkData::NewWithCopy(&info, sizeof(info)));
-            key->setCustomData(data.get());
-            resourceProvider->assignUniqueKeyToResource(*key, vertexBuffer.get());
-            SkPathPriv::AddGenIDChangeListener(fPath, new PathInvalidator(*key));
-        }
-        return actualCount;
-    }
-
-    void onPrepareDraws(Target* target) const override {
-        // construct a cache key from the path's genID and the view matrix
-        static const GrUniqueKey::Domain kDomain = GrUniqueKey::GenerateDomain();
-        GrUniqueKey key;
-        int clipBoundsSize32 =
-            fPath.isInverseFillType() ? sizeof(fClipBounds) / sizeof(uint32_t) : 0;
-        int strokeDataSize32 = fStroke.computeUniqueKeyFragmentData32Cnt();
-        GrUniqueKey::Builder builder(&key, kDomain, 2 + clipBoundsSize32 + strokeDataSize32);
-        builder[0] = fPath.getGenerationID();
-        builder[1] = fPath.getFillType();
-        // For inverse fills, the tessellation is dependent on clip bounds.
-        if (fPath.isInverseFillType()) {
-            memcpy(&builder[2], &fClipBounds, sizeof(fClipBounds));
-        }
-        fStroke.asUniqueKeyFragment(&builder[2 + clipBoundsSize32]);
-        builder.finish();
-        GrResourceProvider* rp = target->resourceProvider();
-        SkAutoTUnref<GrVertexBuffer> vertexBuffer(rp->findAndRefTByUniqueKey<GrVertexBuffer>(key));
-        int actualCount;
-        SkScalar screenSpaceTol = GrPathUtils::kDefaultTolerance;
-        SkScalar tol = GrPathUtils::scaleToleranceToSrc(
-            screenSpaceTol, fViewMatrix, fPath.getBounds());
-        if (!cache_match(vertexBuffer.get(), tol, &actualCount)) {
-            bool canMapVB = GrCaps::kNone_MapFlags != target->caps().mapBufferFlags();
-            actualCount = this->tessellate(&key, rp, vertexBuffer, canMapVB);
-        }
-
-        if (actualCount == 0) {
-            return;
-        }
-
-        SkAutoTUnref<const GrGeometryProcessor> gp;
-        {
-            using namespace GrDefaultGeoProcFactory;
-
-            Color color(fColor);
-            LocalCoords localCoords(fPipelineInfo.readsLocalCoords() ?
-                                    LocalCoords::kUsePosition_Type :
-                                    LocalCoords::kUnused_Type);
-            Coverage::Type coverageType;
-            if (fPipelineInfo.readsCoverage()) {
-                coverageType = Coverage::kSolid_Type;
-            } else {
-                coverageType = Coverage::kNone_Type;
-            }
-            Coverage coverage(coverageType);
-            gp.reset(GrDefaultGeoProcFactory::Create(color, coverage, localCoords,
-                                                     fViewMatrix));
-        }
-
-        target->initDraw(gp, this->pipeline());
-        SkASSERT(gp->getVertexStride() == sizeof(SkPoint));
-
-        GrPrimitiveType primitiveType = WIREFRAME ? kLines_GrPrimitiveType
-                                                  : kTriangles_GrPrimitiveType;
-        GrVertices vertices;
-        vertices.init(primitiveType, vertexBuffer.get(), 0, actualCount);
-        target->draw(vertices);
-    }
-
-    bool onCombineIfPossible(GrBatch*, const GrCaps&) override { return false; }
-
-    TessellatingPathBatch(const GrColor& color,
-                          const SkPath& path,
-                          const GrStrokeInfo& stroke,
-                          const SkMatrix& viewMatrix,
-                          const SkRect& clipBounds)
-      : INHERITED(ClassID())
-      , fColor(color)
-      , fPath(path)
-      , fStroke(stroke)
-      , fViewMatrix(viewMatrix) {
-        const SkRect& pathBounds = path.getBounds();
-        fClipBounds = clipBounds;
-        // Because the clip bounds are used to add a contour for inverse fills, they must also
-        // include the path bounds.
-        fClipBounds.join(pathBounds);
-        if (path.isInverseFillType()) {
-            fBounds = fClipBounds;
-        } else {
-            fBounds = path.getBounds();
-        }
-        if (!stroke.isFillStyle()) {
-            SkScalar radius = SkScalarHalf(stroke.getWidth());
-            if (stroke.getJoin() == SkPaint::kMiter_Join) {
-                SkScalar scale = stroke.getMiter();
-                if (scale > SK_Scalar1) {
-                    radius = SkScalarMul(radius, scale);
-                }
-            }
-            fBounds.outset(radius, radius);
-        }
-        viewMatrix.mapRect(&fBounds);
-    }
-
-    GrColor                 fColor;
-    SkPath                  fPath;
-    GrStrokeInfo            fStroke;
-    SkMatrix                fViewMatrix;
-    SkRect                  fClipBounds; // in source space
-    GrXPOverridesForBatch   fPipelineInfo;
-
-    typedef GrVertexBatch INHERITED;
-};
-
-bool GrTessellatingPathRenderer::onDrawPath(const DrawPathArgs& args) {
-    SkASSERT(!args.fAntiAlias);
-    const GrRenderTarget* rt = args.fPipelineBuilder->getRenderTarget();
-    if (nullptr == rt) {
-        return false;
-    }
-
-    SkIRect clipBoundsI;
-    args.fPipelineBuilder->clip().getConservativeBounds(rt->width(), rt->height(), &clipBoundsI);
-    SkRect clipBounds = SkRect::Make(clipBoundsI);
-    SkMatrix vmi;
-    if (!args.fViewMatrix->invert(&vmi)) {
-        return false;
-    }
-    vmi.mapRect(&clipBounds);
-    SkAutoTUnref<GrDrawBatch> batch(TessellatingPathBatch::Create(args.fColor, *args.fPath,
-                                                                  *args.fStroke, *args.fViewMatrix,
-                                                                  clipBounds));
-    args.fTarget->drawBatch(*args.fPipelineBuilder, batch);
-
-    return true;
-}
-
-///////////////////////////////////////////////////////////////////////////////////////////////////
-
-#ifdef GR_TEST_UTILS
-
-DRAW_BATCH_TEST_DEFINE(TesselatingPathBatch) {
-    GrColor color = GrRandomColor(random);
-    SkMatrix viewMatrix = GrTest::TestMatrixInvertible(random);
-    SkPath path = GrTest::TestPath(random);
-    SkRect clipBounds = GrTest::TestRect(random);
-    SkMatrix vmi;
-    bool result = viewMatrix.invert(&vmi);
-    if (!result) {
-        SkFAIL("Cannot invert matrix\n");
-    }
-    vmi.mapRect(&clipBounds);
-    GrStrokeInfo strokeInfo = GrTest::TestStrokeInfo(random);
-    return TessellatingPathBatch::Create(color, path, strokeInfo, viewMatrix, clipBounds);
-}
-
-#endif