[完善] 正确获取可视区域宽高

src/app/ui/collection-tools/collection-tools.component.ts

@@ -1116,8 +1116,8 @@ export class CollectionToolsComponent implements OnInit {
   //计算 可视区域内宽度, 是否缩放背景图
   backGroundScale () {
     let that = this
-    let dadWidth = document.querySelector('.canvas').clientWidth
-    let dadHeight = document.querySelector('.canvas').clientHeight
+    let dadWidth = this.element.nativeElement.querySelector('.canvas').clientWidth
+    let dadHeight = this.element.nativeElement.querySelector('.canvas').clientHeight
     let img = new Image()
     img.src = this.selectingSitePlan.imageUrl;
     img.onload = function(){