hotfix(canvasDirective): fixed reset grid

src/app/app.component.html

@@ -12,8 +12,6 @@
 <ul>
   <li><b>Static Configuration</b></li>
   <li *ngIf="canvasConfig"><pre>{{canvasConfig | json}}</pre></li>
-  <li><b>Changeable Parameters</b></li>
-  <li><pre>{{canvasParam | json}}</pre></li>
 
   <li>
     <label>

src/app/canvas/canvas.directive.ts

@@ -289,7 +289,7 @@ export class CanvasDirective implements OnChanges {
   private resetGrid() {
     const group = Selection.select('g#grid');
 
-    if (!group.size() && this.param.showGrid) {
+    if (group.size() && this.param.showGrid) {
       Selection.selectAll('g#grid').remove();
     }
   }