utils修改

src/jlgraphic/utils/GraphicUtils.ts

@@ -695,33 +695,30 @@ export function splitLineEvenly(
     });
 }
 
-/** 计算折线的平行线 */
-export function getParallelOfPolyline(
+/** 计算直线的平行线 */
+export function getParallelOfLine(
   points: IPointData[],
   direction: 'L' | 'R',
   offset: number
 ) {
-  if (points.length < 2) throw Error('折线点不能少于2个');
+  if (points.length !== 2) throw Error('直线点的个数需为2');
   const normalVecs = points.map((p, i) => {
-    if (points[i - 1] && points[i + 1]) {
+    let point;
+    if (points[i + 1]) {
+      point = new Vector2([
+        points[i + 1].x - p.x,
+        points[i + 1].y - p.y,
+      ]).normalize();
     } else {
-      let point;
-      if (points[i + 1]) {
-        point = new Vector2([
-          points[i + 1].x - p.x,
-          points[i + 1].y - p.y,
-        ]).normalize();
-      } else {
-        point = new Vector2([
-          p.x - points[i - 1].x,
-          p.y - points[i - 1].y,
-        ]).normalize();
-      }
-      const rotate = new Matrix().rotate(
-        (direction === 'L' ? Math.PI : -Math.PI) / 2
-      );
-      return rotate.apply(point);
+      point = new Vector2([
+        p.x - points[i - 1].x,
+        p.y - points[i - 1].y,
+      ]).normalize();
     }
+    const rotate = new Matrix().rotate(
+      (direction === 'L' ? Math.PI : -Math.PI) / 2
+    );
+    return rotate.apply(point);
   });
   return points.map((p, i) => ({
     x: p.x + offset * normalVecs[i]?.x,