Fix 634 (antvis#642)

* fix: getPointAtLength failed on an empty path

* fix: add test case for antvis#634

packages/g-svg/src/shape/path.ts

@@ -73,6 +73,10 @@ class Path extends ShapeBase {
   getPoint(ratio: number): Point {
     const el = this.get('el');
     const totalLength = this.getTotalLength();
+    // @see https://github.com/antvis/g/issues/634
+    if (totalLength === 0) {
+      return null;
+    }
     const point = el ? el.getPointAtLength(ratio * totalLength) : null;
     return point
       ? {

packages/g-svg/tests/bugs/issue-634-spec.js

@@ -0,0 +1,30 @@
+const expect = require('chai').expect;
+import Canvas from '../../../g-svg/src/canvas';
+import Path from '../../../g-svg/src/shape/path';
+
+const dom = document.createElement('div');
+document.body.appendChild(dom);
+dom.id = 'c1';
+
+describe('#634', () => {
+  const canvas = new Canvas({
+    container: dom,
+    width: 400,
+    height: 400,
+  });
+
+  it('should get null point on an empty path', () => {
+    const path = new Path({
+      attrs: {
+        path: [
+          ['M', 0, 0],
+          ['L', 0, 0],
+        ],
+        lineWidth: 1,
+        stroke: 'red',
+      },
+    });
+    canvas.add(path);
+    expect(path.getPoint(0)).eqls(null);
+  });
+});

packages/g-svg/tests/mocha.opts

@@ -1,3 +1,4 @@
 --require source-map-support/register
 --recursive
 tests/unit
+tests/bugs