fix hair fuzz

src/core/SkScan_Hairline.cpp

 /*
  * Copyright 2006 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 "SkScan.h"
 #include "SkBlitter.h"
 #include "SkRasterClip.h"
@@ skipping 410 matching lines @@
     if (SkPath::kMove_Verb == prevVerb) {
         SkPoint* first = pts;
         SkPoint* ctrl = first;
         int controls = ptCount - 1;
         SkVector tangent;
         do {
             tangent = *first - *++ctrl;
         } while (tangent.isZero() && --controls > 0);
         if (tangent.isZero()) {
             tangent.set(1, 0);
+            controls = ptCount - 1;  // If all points are equal, move all but one
         } else {
             tangent.normalize();
         }
-        first->fX += tangent.fX * capOutset;
-        first->fY += tangent.fY * capOutset;
+        do {    // If the end point and control points are equal, loop to move them in tandem.
+            first->fX += tangent.fX * capOutset;
+            first->fY += tangent.fY * capOutset;
+            ++first;
+        } while (++controls < ptCount);
     }
     if (SkPath::kMove_Verb == nextVerb || SkPath::kDone_Verb == nextVerb) {
         SkPoint* last = &pts[ptCount - 1];
         SkPoint* ctrl = last;
         int controls = ptCount - 1;
         SkVector tangent;
         do {
             tangent = *last - *--ctrl;
         } while (tangent.isZero() && --controls > 0);
         if (tangent.isZero()) {
             tangent.set(-1, 0);
+            controls = ptCount - 1;
         } else {
             tangent.normalize();
         }
-        last->fX += tangent.fX * capOutset;
-        last->fY += tangent.fY * capOutset;
+        do {
+            last->fX += tangent.fX * capOutset;
+            last->fY += tangent.fY * capOutset;
+            --last;
+        } while (++controls < ptCount);
     }
 }
 
 template <SkPaint::Cap capStyle>
 void hair_path(const SkPath& path, const SkRasterClip& rclip, SkBlitter* blitter,
                       SkScan::HairRgnProc lineproc) {
     if (path.isEmpty()) {
         return;
     }
 
     SkAAClipBlitterWrapper wrap;
     const SkRegion* clip = nullptr;
     SkRect insetStorage, outsetStorage;
     const SkRect* insetClip = nullptr;
     const SkRect* outsetClip = nullptr;
 
     {
-        const SkIRect ibounds = path.getBounds().roundOut().makeOutset(1, 1);
-
+        const int capOut = SkPaint::kButt_Cap == capStyle ? 1 : 2;
+        const SkIRect ibounds = path.getBounds().roundOut().makeOutset(capOut, capOut);
         if (rclip.quickReject(ibounds)) {
             return;
         }
         if (!rclip.quickContains(ibounds)) {
             if (rclip.isBW()) {
                 clip = &rclip.bwRgn();
             } else {
                 wrap.init(rclip, blitter);
                 blitter = wrap.getBlitter();
                 clip = &wrap.getRgn();
@@ skipping 192 matching lines @@
 
         SkAAClipBlitterWrapper wrap;
         if (!clip.quickContains(r.roundOut().makeOutset(1, 1))) {
             wrap.init(clip, blitter);
             blitter = wrap.getBlitter();
             clipRgn = &wrap.getRgn();
         }
         AntiHairLineRgn(pts, count, clipRgn, blitter);
     }
 }