Fix bug that prevented the line from being created by using another two existing points

src/app/components/line-segment.js

@@ -83,31 +83,19 @@ export class LineSegment {
       _this.clearState();
       return;
     }
-    let objects = Selector.getPoints();
+    const objects = Selector.getPoints();
     if (
       _this._state == undefined &&
       objects != undefined &&
       objects.length > 0
     ) {
-      let layer = App.currentLayer();
-      let p = [];
-      let ln = _this.createLine(p);
-      objects.forEach(object => {
-        object.attrs.connections.push(ln);
-        p.push(object.x());
-        p.push(object.y());
-        object.parent.on("dragmove", () => {
-          let p = [];
-          p.push(object.x());
-          p.push(object.y());
-          //object.attrs.connections[0].points(p.slice());
-          layer.batchDraw();
-        });
-        ln.points(p.slice());
-        layer.batchDraw();
-      });
-
-      _this.drawPoint(p);
+      const layer = App.currentLayer();
+      const point_groups = new Set(objects.map(object => object.parent));
+      const points_xy = objects.reduce((prev, next) => prev.concat([next.x(), next.y()]), []);
+      let ln = _this.createLine(points_xy);
+      _this.attachPoints(ln, point_groups);
+      layer.add(ln);
+      App.stage.draw();
       App.clearSelectedTool();
       _this.clearState();
       return;