Reland of more zero-length changes for svg compatibility

src/core/SkStroke.cpp

 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkStrokerPriv.h"
 #include "SkGeometry.h"
 #include "SkPathPriv.h"
@@ skipping 601 matching lines @@
     }
     *reduction = SkEvalQuadAt(quad, t);
     return kDegenerate_ReductionType;
 }
 
 void SkPathStroker::conicTo(const SkPoint& pt1, const SkPoint& pt2, SkScalar weight) {
     const SkConic conic(fPrevPt, pt1, pt2, weight);
     SkPoint reduction;
     ReductionType reductionType = CheckConicLinear(conic, &reduction);
     if (kPoint_ReductionType == reductionType) {
+        /* If the stroke consists of a moveTo followed by a degenerate curve, treat it
+            as if it were followed by a zero-length line. Lines without length
+            can have square and round end caps. */
+        this->lineTo(pt2);
         return;
     }
     if (kLine_ReductionType == reductionType) {
         this->lineTo(pt2);
         return;
     }
     if (kDegenerate_ReductionType == reductionType) {
         this->lineTo(reduction);
         SkStrokerPriv::JoinProc saveJoiner = fJoiner;
         fJoiner = SkStrokerPriv::JoinFactory(SkPaint::kRound_Join);
@@ skipping 14 matching lines @@
     (void) this->conicStroke(conic, &quadPts);
     this->setConicEndNormal(conic, normalAB, unitAB, &normalBC, &unitBC);
     this->postJoinTo(pt2, normalBC, unitBC);
 }
 
 void SkPathStroker::quadTo(const SkPoint& pt1, const SkPoint& pt2) {
     const SkPoint quad[3] = { fPrevPt, pt1, pt2 };
     SkPoint reduction;
     ReductionType reductionType = CheckQuadLinear(quad, &reduction);
     if (kPoint_ReductionType == reductionType) {
+        /* If the stroke consists of a moveTo followed by a degenerate curve, treat it
+            as if it were followed by a zero-length line. Lines without length
+            can have square and round end caps. */
+        this->lineTo(pt2);
         return;
     }
     if (kLine_ReductionType == reductionType) {
         this->lineTo(pt2);
         return;
     }
     if (kDegenerate_ReductionType == reductionType) {
         this->lineTo(reduction);
         SkStrokerPriv::JoinProc saveJoiner = fJoiner;
         fJoiner = SkStrokerPriv::JoinFactory(SkPaint::kRound_Join);
@@ skipping 495 matching lines @@
     return true;
 }
 
 void SkPathStroker::cubicTo(const SkPoint& pt1, const SkPoint& pt2,
                             const SkPoint& pt3) {
     const SkPoint cubic[4] = { fPrevPt, pt1, pt2, pt3 };
     SkPoint reduction[3];
     const SkPoint* tangentPt;
     ReductionType reductionType = CheckCubicLinear(cubic, reduction, &tangentPt);
     if (kPoint_ReductionType == reductionType) {
+        /* If the stroke consists of a moveTo followed by a degenerate curve, treat it
+            as if it were followed by a zero-length line. Lines without length
+            can have square and round end caps. */
+        this->lineTo(pt3);
         return;
     }
     if (kLine_ReductionType == reductionType) {
         this->lineTo(pt3);
         return;
     }
     if (kDegenerate_ReductionType <= reductionType && kDegenerate3_ReductionType >= reductionType) {
         this->lineTo(reduction[0]);
         SkStrokerPriv::JoinProc saveJoiner = fJoiner;
         fJoiner = SkStrokerPriv::JoinFactory(SkPaint::kRound_Join);
@@ skipping 288 matching lines @@
         default:
             break;
     }
 
     if (fWidth < SkMinScalar(rw, rh) && !fDoFill) {
         r = rect;
         r.inset(radius, radius);
         dst->addRect(r, reverse_direction(dir));
     }
 }