NativeScript - Progress

Progress 进度条:

• value当前值
• maxValue 最大值
  下面的代码还用了下 propertyChange

  import {Component, ViewChild, ElementRef} from "angular2/core";
  import {Color}  from "color";
  import {SearchBar} from "ui/search-bar";
  import {TextField} from "ui/text-field";
  import {Switch} from "ui/switch";
  import {Slider} from "ui/slider";
  import {Progress}from"ui/progress";
  import {PropertyChangeData} from "data/observable";
  
  @Component({
      selector: "my-app",
      template: `
  <StackLayout orientation="vertical">
  <Progress #sw style="color:red"  [value]="value" maxValue="300" ></Progress>
  <Button text="add" (tap)="btn()"></Button>
  </StackLayout>
  `,
      styleUrls: ["app.css"]
  })
  export class AppComponent {
  
  
      @ViewChild('sw') ngProgress: ElementRef;
      nsProgress: Progress;
  
      value: Number = 60;
  
      constructor() {
      }
  
      ngAfterViewInit() {
          this.nsProgress = this.ngProgress.nativeElement;
  
          this.nsProgress.on("propertyChange", (e: PropertyChangeData) => {
              console.log(e.propertyName);
          })
      }
  
      btn() {
          this.nsProgress.maxValue = 200;
      }
  }

这个主要代码:
<Progress #sw style="color:red" [value]="value" maxValue="300" ></Progress>

maxValue小于value的时候会有两个propertyChange事件,因为value也跟着变小了
并且这个组件不能用ngModel,因为不是input组件