fix null path error on offsetStroke

glenzli · Apr 26, 2020 · 1f847e7 · 1f847e7
1 parent 7f57473
commit 1f847e7
Show file tree

Hide file tree

Showing 5 changed files with 48 additions and 28 deletions.
diff --git 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
@@ -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
diff --git 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 → src/offset_core.ts b/src/Offset.ts → 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 {