【每日学点鸿蒙知识】人脸活体检测、NodeController刷新、自动关闭输入框、Row设置中间最大宽、WebView单例
1、HarmonyOS 人脸活体检测调用？
H5调用应用侧方法可参考以下demo：
index.ets
Web()//注册方法.javaScriptProxy({object: this.testObj,name: "testObjName",methodList: ["getLocationTS"],controller: this.webController})class testClass {constructor() {}async getLocationTS(): Promise<string> {//应用侧方法逻辑}
H5页面
<!DOCTYPE html>
<html>
<head><link rel="stylesheet" type="text/css"><meta charset="UTF-8"><title>获取定位信息</title><style>#prize {border-radius: 16px 16px 16px 16px;background-image: linear-gradient(180deg, #A2DAFF 0%, #EAF5FF 100%);margin-left: 1.82%;margin-top: 1.43%;width: 96.5%;height: 96.7%;}</style>
</head>
<body>
<div style="width:1000px;height:500px"><input style="width:1000px;height:100px;font-size:30px" id="inputText"/><p style="width:1000px;height:100px;font-size:30px" id="demo">p1</p><button style="width:1000px;height:100px" onclick="getLocation()"><span style="font-size:30px">获取定位</span></button>
</div><script>function getLocation() {
<!-- ArtTS侧返回的如果是 promise对象，使用改方法处理 -->
<!-- 具体可参考前端页面调用应用侧函数API，包含简单类型和复杂类型-->
<!-- https://developer.huawei.com/consumer/cn/doc/harmonyos-guides/web-in-page-app-function-invoking-0000001844832802--><!-- H5侧方法调用 -->testObjName.getLocationTS().then((param)=>{ document.getElementById("demo").innerHTML = "testObjName.getLocationTS()--"+JSON.stringify(param) }).catch((param)=>{ document.getElementById("demo").innerHTML = "testObjName.getLocationTS()--"+JSON.stringify(param) })}
</script>
</body>
</html>
}
2、HarmonyOS NodeController调用this.rebuild()后，画面没有刷新？
使用NodeController，首次进入页面，makeNode被自动回调，绘制出了3个题目框。之后外部调用onSelectBoxChange，更新了nodeArray并手动调用this.rebuild()，makeNode再次被回调，但是页面上并没有出现新绘制的框。
参考demo：
import { RenderNode, DrawContext, FrameNode, NodeController } from "@ohos.ArkUI.node"
import drawing from "@ohos.graphics.drawing"class TextRenderNode extends RenderNode {async draw(context: DrawContext) {const canvas = context.canvas;const pen = new drawing.Pen();pen.setStrokeWidth(5);pen.setColor({alpha: 255, red: 255, green: 0, blue: 0});let path = new drawing.Path();path.moveTo(10,10);path.arcTo(10, 10, 200, 200, 0, 150);path.close();canvas.attachPen(pen);canvas.drawPath(path);canvas.detachPen();}
}class MyNodeController extends NodeController {private rootNode: FrameNode | null = null;private nodeArray: Array<TextRenderNode> = []addMyNode(item:TextRenderNode){this.nodeArray.push(item)}makeNode(uiContext: UIContext): FrameNode | null {this.rootNode = new FrameNode(uiContext);const renderNode = this.rootNode.getRenderNode();if (renderNode === null) {return this.rootNode;}if (renderNode) {renderNode.clearChildren()this.nodeArray.forEach((item) => {renderNode.appendChild(item)})}return this.rootNode;}// onTouchEvent(event: TouchEvent): void {// this.nodeArray.forEach((node, index) => { // this是undefined，无法获取到当前类的一些参数<---------// console.log(JSON.stringify(this.nodeArray) + '德玛西亚')// })// }
}@Entry
@Component
struct Index {@State newNode:TextRenderNode = new TextRenderNode();@State nodeCV:MyNodeController = new MyNodeController()tempY = 0build() {Column() {Column() {NodeContainer(this.nodeCV).width('100%').height(200)Button('Invalidate').onClick(() => {let newNode = new TextRenderNode()newNode.frame = { x: 0, y: this.tempY, width: 200, height: 100 }this.nodeCV.addMyNode(newNode)this.nodeCV.rebuild()this.tempY += 100})}.width('100%').height('100%')}.height('100%')}
}
3、HarmonyOS TextInput输入的时候，当文字达到一定数量的时候，自动关闭输入框？
设置TextInput输入字符数量达到设定长度时自动关闭demo
@Entry
@Component
struct FirstTest {@State message1: string = 'Hello World';private controller:TextInputController = new TextInputController();build() {Column() {Text("FirstTest：" + this.message1).fontSize(25).fontWeight(FontWeight.Bold)TextInput({placeholder:'Waiting for input',text:$$this.message1,controller:this.controller}).fontSize(25).fontWeight(FontWeight.Bold).onChange(()=>{if(this.message1.length >= 20){this.controller.stopEditing()}})}}
}
4、HarmonyOS Row 怎么设置中间最大宽度？
Row 怎么设置中间最大宽度
使用constraintSize({maxWidth: Infinity})来对尺寸范围限制
5、HarmonyOS 如何创建单例的WebView组件？
只可以创建单例的对象，示例:
export class GlobalContext {private constructor() {}private static instance: GlobalContext;private _objects = new Map<string, Object>();public static getContext(): GlobalContext {if (!GlobalContext.instance) {GlobalContext.instance = new GlobalContext();}return GlobalContext.instance;}getObject(value: string): Object | undefined {return this._objects.get(value);}setObject(key: string, objectClass: Object): void {this._objects.set(key, objectClass);}
}