From 1f847e76cf16c65da3a226b709901af0513d70cf Mon Sep 17 00:00:00 2001
From: glenzli <glenzli@outlook.com>
Date: Mon, 27 Apr 2020 00:28:34 +0800
Subject: [PATCH] fix null path error on offsetStroke

---
 demo/debug.js                     |  3 +++
 demo/paperjs-offset.js            | 34 ++++++++++++++++++------------
 demo/paperjs-offset.min.js        |  2 +-
 src/index.ts                      |  2 +-
 src/{Offset.ts => offset_core.ts} | 35 +++++++++++++++++++------------
 5 files changed, 48 insertions(+), 28 deletions(-)
 rename src/{Offset.ts => offset_core.ts} (95%)

diff --git a/demo/debug.js b/demo/debug.js
index a9d0f36..4026928 100644
--- a/demo/debug.js
+++ b/demo/debug.js
@@ -17,6 +17,9 @@
     cc.translate(new paper.Point(-100, -100));
 
     PaperOffset.offset(cc, 24);
+
+    const c = new paper.Path({pathData: "M4,11L5,13", strokeColor: 'rgba(156, 104, 193, 0.5)', strokeWidth: 4});
+    PaperOffset.offsetStroke(c, 10, {cap: "round", join: "round"});
   }
 
   window.onload = DebugCase;
diff --git a/demo/paperjs-offset.js b/demo/paperjs-offset.js
index bea5a93..23bcbe8 100644
--- a/demo/paperjs-offset.js
+++ b/demo/paperjs-offset.js
@@ -177,17 +177,19 @@
   }
   /** Remove self intersection when offset is negative by point direction dectection. */
   function removeIntersection(path) {
-      var newPath = path.unite(path, { insert: false });
-      if (newPath instanceof paper.CompoundPath) {
-          newPath.children.filter(function (c) {
-              if (c.segments.length > 1) {
-                  return !isSameDirection(c, path);
-              }
-              else {
-                  return true;
-              }
-          }).forEach(function (c) { return c.remove(); });
-          return reduceSingleChildCompoundPath(newPath);
+      if (path.closed) {
+          var newPath = path.unite(path, { insert: false });
+          if (newPath instanceof paper.CompoundPath) {
+              newPath.children.filter(function (c) {
+                  if (c.segments.length > 1) {
+                      return !isSameDirection(c, path);
+                  }
+                  else {
+                      return true;
+                  }
+              }).forEach(function (c) { return c.remove(); });
+              return reduceSingleChildCompoundPath(newPath);
+          }
       }
       return path;
   }
@@ -292,8 +294,14 @@
           return final;
       }
   }
+  function getNonSelfItersectionPath(path) {
+      if (path.closed) {
+          return path.unite(path, { insert: false });
+      }
+      return path;
+  }
   function offsetPath(path, offset, join, limit) {
-      var nonSIPath = path.unite(path, { insert: false });
+      var nonSIPath = getNonSelfItersectionPath(path);
       var result = nonSIPath;
       if (nonSIPath instanceof paper.Path) {
           result = offsetSimpleShape(nonSIPath, offset, join, limit);
@@ -329,7 +337,7 @@
       return result;
   }
   function offsetStroke(path, offset, join, cap, limit) {
-      var nonSIPath = path.unite(path, { insert: false });
+      var nonSIPath = getNonSelfItersectionPath(path);
       var result = nonSIPath;
       if (nonSIPath instanceof paper.Path) {
           result = offsetSimpleStroke(nonSIPath, offset, join, cap, limit);
diff --git a/demo/paperjs-offset.min.js b/demo/paperjs-offset.min.js
index 0cf9172..51a8ec0 100644
--- a/demo/paperjs-offset.min.js
+++ b/demo/paperjs-offset.min.js
@@ -1 +1 @@
-!function(S){"use strict";function g(e,t,n,r){var o=e.curve===t,i=t.getNormalAtTime(o?0:1).multiply(r),a=e.point.add(i),s=new S.Segment(a),c=o?"handleOut":"handleIn";return s[c]=e[c].add(n.subtract(i).divide(2)),s}function T(e,t){return e.x*t.y-e.y*t.x}function v(e,t,n,r,o,i){var a,s,c,u,f,l,d,h,p,m,g,v,w,P,b=new S.Curve(e[0],e[1]),k=new S.Curve(t[0],t[1]),C=b.getIntersections(k),y=e[1].point.getDistance(t[0].point);if(n.isSmooth())t[0].handleOut=t[0].handleOut.project(n.handleOut),t[0].handleIn=e[1].handleIn.project(n.handleIn),t[0].point=e[1].point.add(t[0].point).divide(2),e.pop();else if(0===C.length)if(y>.1*Math.abs(o))switch(r){case"miter":var A=(d=b.point2,h=b.point2.add(b.getTangentAtTime(1)),p=k.point1,m=k.point1.add(k.getTangentAtTime(0)),g=d.subtract(h),v=p.subtract(m),w=T(d,h),P=T(p,m),new S.Point(w*v.x-g.x*P,w*v.y-g.y*P).divide(T(g,v)));Math.max(A.getDistance(b.point2),A.getDistance(k.point1))<Math.abs(o)*i&&e.push(new S.Segment(A));break;case"round":var M=(a=e[1],s=t[0],c=n.point,u=o,f=a.point.subtract(c).add(s.point.subtract(c)).normalize(Math.abs(u)).add(c),l=new S.Path.Arc({from:a.point,to:s.point,through:f,insert:!1}),a.handleOut=l.firstSegment.handleOut,s.handleIn=l.lastSegment.handleIn,3===l.segments.length?l.segments[1]:null);M&&e.push(M)}else t[0].handleIn=e[1].handleIn,e.pop();else{var O=b.divideAt(C[0]);if(O){A=O.segment1;var I=k.divideAt(k.getIntersections(b)[0]);A.handleOut=I?I.segment1.handleOut:t[0].handleOut,e.pop(),t[0]=A}else t[0].handleIn=e[1].handleIn,e.pop()}}function w(e){return 1===e.children.length&&(e=e.children[0]).remove(),e}function P(e,t){if(void 0===t&&(t=.01),e.closed){var n=Math.abs(e.area*t);if(e.clockwise||e.reverse(),(e=e.unite(e,{insert:!1}))instanceof S.CompoundPath&&(e.children.filter(function(e){return Math.abs(e.area)<n}).forEach(function(e){return e.remove()}),1===e.children.length))return w(e)}return e}function b(e,t){var n=(e.segments[0].location.offset+e.segments[Math.max(1,Math.floor(e.segments.length/2))].location.offset)/3;return t.getNearestLocation(e.getPointAt(n)).offset<t.getNearestLocation(e.getPointAt(2*n)).offset}function k(e,t){var n;((n=e)instanceof S.CompoundPath?n.children.map(function(e){return e.segments}).flat():n.segments).slice().forEach(function(e){t.contains(e.point)||e.remove()})}function h(e,t,n,r){var o,i,a,s,c;s=t,(c=(a=e).clone({insert:!1})).reduce({}),a.clockwise||(c.reverse(),s=-s),t=(o=[c,s])[1];for(var u=(i=o[0]).curves.slice().map(function(e){return function e(t,n){var r=new S.Curve(t.segment1.handleOut.add(t.segment1.point),new S.Point(0,0),new S.Point(0,0),t.segment2.handleIn.add(t.segment2.point)).getNormalAtTime(.5).multiply(n),o=g(t.segment1,t,r,n),i=g(t.segment2,t,r,n),a=new S.Curve(o,i);if(0===a.getIntersections(a).length){var s=Math.min(Math.abs(n)/10,1),c=a.getPointAtTime(.5).getDistance(t.getPointAtTime(.5));if(Math.abs(c-Math.abs(n))>s){var u=t.divideAtTime(.5);if(null!=u)return e(t,n).concat(e(u,n))}}return[o,i]}(e,t)}).flat(),f=[],l=0;l<u.length;l+=2)f.push(u.slice(l,l+2));var d,h,p=function(e,t,n,r,o){for(var i=n.segments,a=e[0].slice(),s=0;s<e.length-1;++s)v(e[s],e[s+1],i[s+1],t,r,o);return n.closed&&(v(e[e.length-1],a,i[0],t,r,o),e[0][0]=a[0]),e}(f,n,i,t,r).flat(),m=(d=new S.Path({segments:p,insert:!1,closed:e.closed}),(h=d.unite(d,{insert:!1}))instanceof S.CompoundPath?(h.children.filter(function(e){return!(1<e.segments.length&&b(e,d))}).forEach(function(e){return e.remove()}),w(h)):d);return m.reduce({}),i.closed&&(i.clockwise&&t<0||!i.clockwise&&0<t)&&k(m,e),i.clockwise!==e.clockwise&&m.reverse(),P(m)}function p(e,t,n){var r=e.point.add(t.point).divide(2),o=t.point.subtract(e.point).rotate(-90,new S.Point(0,0)).normalize(n),i=r.add(o);return new S.Path.Arc({from:e.point,to:t.point,through:i,insert:!1}).segments}function l(e,t,n,r,o){var i=h(e,t=e.clockwise?t:-t,n,o),a=h(e,-t,n,o);if(e.closed)return i.subtract(a,{insert:!1});var s=a,c=new Array;a instanceof S.CompoundPath&&((c=a.children.filter(function(e){return e.closed})).forEach(function(e){return e.remove()}),s=a.children[0]),s.reverse();var u=function(e,t,n,r){if(e instanceof S.CompoundPath){var o=e.children.map(function(e){return{c:e,a:Math.abs(e.area)}});e=(o=o.sort(function(e,t){return t.a-e.a}))[0].c}var i=e.segments.slice(),a=t.segments.slice();switch(r){case"round":var s=p(a[a.length-1],i[0],n),c=p(i[i.length-1],a[0],n),u=new S.Path({segments:s.concat(i,c,a),closed:!0,insert:!1});return u.reduce({}),u;default:return new S.Path({segments:i.concat(a),closed:!0,insert:!1})}}(i,s,t,r);if(0<c.length)for(var f=0,l=c;f<l.length;f++){var d=l[f];u=u.subtract(d,{insert:!1})}return u}S=S&&Object.prototype.hasOwnProperty.call(S,"default")?S.default:S;var e,n=(t.offset=function(e,t,n){var r=function(n,r,o,i){var e=n.unite(n,{insert:!1}),t=e;if(e instanceof S.Path)t=h(e,r,o,i);else{var a=e.children.map(function(e){if(1<e.segments.length){b(e,n)||e.reverse();var t=h(e,r,o,i);return(t=P(t)).clockwise!==e.clockwise&&t.reverse(),t instanceof S.CompoundPath?(t.applyMatrix=!0,t.children):t}return null}).flat().filter(function(e){return!!e});t=new S.CompoundPath({children:a,insert:!1})}return t.copyAttributes(e,!1),t.remove(),t}(e,t,(n=n||{}).join||"miter",n.limit||10);return void 0===n.insert&&(n.insert=!0),n.insert&&(e.parent||S.project.activeLayer).addChild(r),r},t.offsetStroke=function(e,t,n){var r,o,i,a,s,c,u,f=(r=e,o=t,i=(n=n||{}).join||"miter",a=n.cap||"butt",s=n.limit||10,c=r.unite(r,{insert:!1}),(u=(u=c)instanceof S.Path?l(c,o,i,a,s):c.children.flatMap(function(e){return l(e,o,i,a,s)}).reduce(function(e,t){return e.unite(t,{insert:!1})})).strokeWidth=0,u.fillColor=c.strokeColor,u.shadowBlur=c.shadowBlur,u.shadowColor=c.shadowColor,u.shadowOffset=c.shadowOffset,u);return void 0===n.insert&&(n.insert=!0),n.insert&&(e.parent||S.project.activeLayer).addChild(f),f},t);function t(){}(e=S).Path.prototype.offset=function(e,t){return n.offset(this,e,t)},e.Path.prototype.offsetStroke=function(e,t){return n.offsetStroke(this,e,t)},e.CompoundPath.prototype.offset=function(e,t){return n.offset(this,e,t)},e.CompoundPath.prototype.offsetStroke=function(e,t){return n.offsetStroke(this,e,t)},window.PaperOffset={offset:n.offset,offsetStroke:n.offsetStroke}}(paper);
+!function(S){"use strict";function p(e,t,n,r){var o=e.curve===t,i=t.getNormalAtTime(o?0:1).multiply(r),a=e.point.add(i),s=new S.Segment(a),c=o?"handleOut":"handleIn";return s[c]=e[c].add(n.subtract(i).divide(2)),s}function T(e,t){return e.x*t.y-e.y*t.x}function m(e,t,n,r,o,i){var a,s,c,u,f,l,d,h,p,m,g,v,w,P,b=new S.Curve(e[0],e[1]),k=new S.Curve(t[0],t[1]),C=b.getIntersections(k),y=e[1].point.getDistance(t[0].point);if(n.isSmooth())t[0].handleOut=t[0].handleOut.project(n.handleOut),t[0].handleIn=e[1].handleIn.project(n.handleIn),t[0].point=e[1].point.add(t[0].point).divide(2),e.pop();else if(0===C.length)if(y>.1*Math.abs(o))switch(r){case"miter":var A=(d=b.point2,h=b.point2.add(b.getTangentAtTime(1)),p=k.point1,m=k.point1.add(k.getTangentAtTime(0)),g=d.subtract(h),v=p.subtract(m),w=T(d,h),P=T(p,m),new S.Point(w*v.x-g.x*P,w*v.y-g.y*P).divide(T(g,v)));Math.max(A.getDistance(b.point2),A.getDistance(k.point1))<Math.abs(o)*i&&e.push(new S.Segment(A));break;case"round":var M=(a=e[1],s=t[0],c=n.point,u=o,f=a.point.subtract(c).add(s.point.subtract(c)).normalize(Math.abs(u)).add(c),l=new S.Path.Arc({from:a.point,to:s.point,through:f,insert:!1}),a.handleOut=l.firstSegment.handleOut,s.handleIn=l.lastSegment.handleIn,3===l.segments.length?l.segments[1]:null);M&&e.push(M)}else t[0].handleIn=e[1].handleIn,e.pop();else{var O=b.divideAt(C[0]);if(O){A=O.segment1;var I=k.divideAt(k.getIntersections(b)[0]);A.handleOut=I?I.segment1.handleOut:t[0].handleOut,e.pop(),t[0]=A}else t[0].handleIn=e[1].handleIn,e.pop()}}function g(e){return 1===e.children.length&&(e=e.children[0]).remove(),e}function v(e,t){if(void 0===t&&(t=.01),e.closed){var n=Math.abs(e.area*t);if(e.clockwise||e.reverse(),(e=e.unite(e,{insert:!1}))instanceof S.CompoundPath&&(e.children.filter(function(e){return Math.abs(e.area)<n}).forEach(function(e){return e.remove()}),1===e.children.length))return g(e)}return e}function w(e,t){var n=(e.segments[0].location.offset+e.segments[Math.max(1,Math.floor(e.segments.length/2))].location.offset)/3;return t.getNearestLocation(e.getPointAt(n)).offset<t.getNearestLocation(e.getPointAt(2*n)).offset}function P(e,t){var n;((n=e)instanceof S.CompoundPath?n.children.map(function(e){return e.segments}).flat():n.segments).slice().forEach(function(e){t.contains(e.point)||e.remove()})}function h(e,t,n,r){var o,i,a,s,c;s=t,(c=(a=e).clone({insert:!1})).reduce({}),a.clockwise||(c.reverse(),s=-s),t=(o=[c,s])[1];for(var u=(i=o[0]).curves.slice().map(function(e){return function e(t,n){var r=new S.Curve(t.segment1.handleOut.add(t.segment1.point),new S.Point(0,0),new S.Point(0,0),t.segment2.handleIn.add(t.segment2.point)).getNormalAtTime(.5).multiply(n),o=p(t.segment1,t,r,n),i=p(t.segment2,t,r,n),a=new S.Curve(o,i);if(0===a.getIntersections(a).length){var s=Math.min(Math.abs(n)/10,1),c=a.getPointAtTime(.5).getDistance(t.getPointAtTime(.5));if(Math.abs(c-Math.abs(n))>s){var u=t.divideAtTime(.5);if(null!=u)return e(t,n).concat(e(u,n))}}return[o,i]}(e,t)}).flat(),f=[],l=0;l<u.length;l+=2)f.push(u.slice(l,l+2));var d=function(e,t,n,r,o){for(var i=n.segments,a=e[0].slice(),s=0;s<e.length-1;++s)m(e[s],e[s+1],i[s+1],t,r,o);return n.closed&&(m(e[e.length-1],a,i[0],t,r,o),e[0][0]=a[0]),e}(f,n,i,t,r).flat(),h=function(t){if(t.closed){var e=t.unite(t,{insert:!1});if(e instanceof S.CompoundPath)return e.children.filter(function(e){return!(1<e.segments.length)||!w(e,t)}).forEach(function(e){return e.remove()}),g(e)}return t}(new S.Path({segments:d,insert:!1,closed:e.closed}));return h.reduce({}),i.closed&&(i.clockwise&&t<0||!i.clockwise&&0<t)&&P(h,e),i.clockwise!==e.clockwise&&h.reverse(),v(h)}function b(e,t,n){var r=e.point.add(t.point).divide(2),o=t.point.subtract(e.point).rotate(-90,new S.Point(0,0)).normalize(n),i=r.add(o);return new S.Path.Arc({from:e.point,to:t.point,through:i,insert:!1}).segments}function l(e,t,n,r,o){var i=h(e,t=e.clockwise?t:-t,n,o),a=h(e,-t,n,o);if(e.closed)return i.subtract(a,{insert:!1});var s=a,c=new Array;a instanceof S.CompoundPath&&((c=a.children.filter(function(e){return e.closed})).forEach(function(e){return e.remove()}),s=a.children[0]),s.reverse();var u=function(e,t,n,r){if(e instanceof S.CompoundPath){var o=e.children.map(function(e){return{c:e,a:Math.abs(e.area)}});e=(o=o.sort(function(e,t){return t.a-e.a}))[0].c}var i=e.segments.slice(),a=t.segments.slice();switch(r){case"round":var s=b(a[a.length-1],i[0],n),c=b(i[i.length-1],a[0],n),u=new S.Path({segments:s.concat(i,c,a),closed:!0,insert:!1});return u.reduce({}),u;default:return new S.Path({segments:i.concat(a),closed:!0,insert:!1})}}(i,s,t,r);if(0<c.length)for(var f=0,l=c;f<l.length;f++){var d=l[f];u=u.subtract(d,{insert:!1})}return u}function d(e){return e.closed?e.unite(e,{insert:!1}):e}S=S&&Object.prototype.hasOwnProperty.call(S,"default")?S.default:S;var e,n=(t.offset=function(e,t,n){var r=function(n,r,o,i){var e=d(n),t=e;if(e instanceof S.Path)t=h(e,r,o,i);else{var a=e.children.map(function(e){if(1<e.segments.length){w(e,n)||e.reverse();var t=h(e,r,o,i);return(t=v(t)).clockwise!==e.clockwise&&t.reverse(),t instanceof S.CompoundPath?(t.applyMatrix=!0,t.children):t}return null}).flat().filter(function(e){return!!e});t=new S.CompoundPath({children:a,insert:!1})}return t.copyAttributes(e,!1),t.remove(),t}(e,t,(n=n||{}).join||"miter",n.limit||10);return void 0===n.insert&&(n.insert=!0),n.insert&&(e.parent||S.project.activeLayer).addChild(r),r},t.offsetStroke=function(e,t,n){var r,o,i,a,s,c,u,f=(r=e,o=t,i=(n=n||{}).join||"miter",a=n.cap||"butt",s=n.limit||10,c=d(r),(u=(u=c)instanceof S.Path?l(c,o,i,a,s):c.children.flatMap(function(e){return l(e,o,i,a,s)}).reduce(function(e,t){return e.unite(t,{insert:!1})})).strokeWidth=0,u.fillColor=c.strokeColor,u.shadowBlur=c.shadowBlur,u.shadowColor=c.shadowColor,u.shadowOffset=c.shadowOffset,u);return void 0===n.insert&&(n.insert=!0),n.insert&&(e.parent||S.project.activeLayer).addChild(f),f},t);function t(){}(e=S).Path.prototype.offset=function(e,t){return n.offset(this,e,t)},e.Path.prototype.offsetStroke=function(e,t){return n.offsetStroke(this,e,t)},e.CompoundPath.prototype.offset=function(e,t){return n.offset(this,e,t)},e.CompoundPath.prototype.offsetStroke=function(e,t){return n.offsetStroke(this,e,t)},window.PaperOffset={offset:n.offset,offsetStroke:n.offsetStroke}}(paper);
diff --git a/src/index.ts b/src/index.ts
index dcc5933..8c0bf7d 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,5 +1,5 @@
 import paper from 'paper';
-import { StrokeJoinType, PathType, StrokeCapType, offsetPath, offsetStroke } from './offset';
+import { StrokeJoinType, PathType, StrokeCapType, offsetPath, offsetStroke } from './offset_core';
 
 export interface OffsetOptions {
   join?: StrokeJoinType;
diff --git a/src/Offset.ts b/src/offset_core.ts
similarity index 95%
rename from src/Offset.ts
rename to src/offset_core.ts
index 1740004..949f6df 100644
--- a/src/Offset.ts
+++ b/src/offset_core.ts
@@ -188,16 +188,18 @@ function isSameDirection(partialPath: paper.Path, fullPath: PathType) {
 
 /** Remove self intersection when offset is negative by point direction dectection. */
 function removeIntersection(path: PathType) {
-  const newPath = path.unite(path, { insert: false }) as PathType;
-  if (newPath instanceof paper.CompoundPath) {
-    (newPath.children as paper.Path[]).filter((c) => {
-      if (c.segments.length > 1) {
-        return !isSameDirection(c, path);
-      } else {
-        return true;
-      }
-    }).forEach((c) => c.remove());
-    return reduceSingleChildCompoundPath(newPath);
+  if (path.closed) {
+    const newPath = path.unite(path, { insert: false }) as PathType;
+    if (newPath instanceof paper.CompoundPath) {
+      (newPath.children as paper.Path[]).filter((c) => {
+        if (c.segments.length > 1) {
+          return !isSameDirection(c, path);
+        } else {
+          return true;
+        }
+      }).forEach((c) => c.remove());
+      return reduceSingleChildCompoundPath(newPath);
+    }
   }
   return path;
 }
@@ -306,8 +308,15 @@ function offsetSimpleStroke(path: paper.Path, offset: number, join: StrokeJoinTy
   }
 }
 
+function getNonSelfItersectionPath(path: PathType) {
+  if (path.closed) {
+    return path.unite(path, { insert: false }) as PathType;
+  }
+  return path;
+}
+
 export function offsetPath(path: PathType, offset: number, join: StrokeJoinType, limit: number): PathType {
-  const nonSIPath = path.unite(path, { insert: false }) as PathType;
+  const nonSIPath = getNonSelfItersectionPath(path);
   let result = nonSIPath;
   if (nonSIPath instanceof paper.Path) {
     result = offsetSimpleShape(nonSIPath, offset, join, limit);
@@ -341,8 +350,8 @@ export function offsetPath(path: PathType, offset: number, join: StrokeJoinType,
 }
 
 export function offsetStroke(path: PathType, offset: number, join: StrokeJoinType, cap: StrokeCapType, limit: number): PathType {
-  const nonSIPath = path.unite(path, { insert: false }) as PathType;
-  let result = nonSIPath as PathType;
+  const nonSIPath = getNonSelfItersectionPath(path);
+  let result = nonSIPath;
   if (nonSIPath instanceof paper.Path) {
     result = offsetSimpleStroke(nonSIPath, offset, join, cap, limit);
   } else {