【每日学点鸿蒙知识】WebView代理、2D绘制矩形圆角、TextInput清理按钮、pdf滑动、icon配置问题

1、HarmonyOS Webview 支持设置代理功能吗？

使用Web的onInterceptRequest先拦截再代理来实现。具体可以参考文档：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/ts-basic-components-web-V5#ZH-CN_TOPIC_0000001930757269__oninterceptrequest9

onInterceptRequest(callback: Callback<OnInterceptRequestEvent, WebResourceResponse>)

当Web组件加载url之前触发该回调，用于拦截url并返回响应数据。
系统能力： SystemCapability.Web.Webview.Core
参数：

参数名	类型	必填	说明
callback	Callback	是	当Web组件加载url之前触发。返回值WebResourceResponse。返回响应数据则按照响应数据加载，无响应数据则返回null表示按照原来的方式加载。
示例：

// xxx.ets
import { webview } from '@kit.ArkWeb';

@Entry
@Component
struct WebComponent {
  controller: webview.WebviewController = new webview.WebviewController();
  responseWeb: WebResourceResponse = new WebResourceResponse();
  heads: Header[] = new Array();
  webData: string = "<!DOCTYPE html>\n" +
    "<html>\n" +
    "<head>\n" +
    "<title>intercept test</title>\n" +
    "</head>\n" +
    "<body>\n" +
    "<h1>intercept test</h1>\n" +
    "</body>\n" +
    "</html>";

  build() {
    Column() {
      Web({ src: 'www.example.com', controller: this.controller })
        .onInterceptRequest((event) => {
          if (event) {
            console.log('url:' + event.request.getRequestUrl());
          }
          let head1: Header = {
            headerKey: "Connection",
            headerValue: "keep-alive"
          }
          let head2: Header = {
            headerKey: "Cache-Control",
            headerValue: "no-cache"
          }
          // 将新元素追加到数组的末尾，并返回数组的新长度。
          let length = this.heads.push(head1);
          length = this.heads.push(head2);
          console.log('The response header result length is :' + length);
          const promise: Promise<String> = new Promise((resolve: Function, reject: Function) => {
            this.responseWeb.setResponseHeader(this.heads);
            this.responseWeb.setResponseData(this.webData);
            this.responseWeb.setResponseEncoding('utf-8');
            this.responseWeb.setResponseMimeType('text/html');
            this.responseWeb.setResponseCode(200);
            this.responseWeb.setReasonMessage('OK');
            resolve("success");
          })
          promise.then(() => {
            console.log("prepare response ready");
            this.responseWeb.setResponseIsReady(true);
          })
          this.responseWeb.setResponseIsReady(false);
          return this.responseWeb;
        })
    }
  }
}

2、HarmonyOS 关于使用OffscreenCanvasRenderingContext2D绘制问题？

绘制了一个矩形，但是不知道如何给这个矩形设置圆角，原始需求是绘制一个圆角是8的矩形

实现圆角就不能再用fillRect这个方法了，这是绘制长方形的，无论如何都是直角
能想到的解决方案就是用moveTo，arcTo，lineTo和stroke去绘制圆角矩形的轮廓，最后填充颜色圆角矩形的实现我这简单写了一个角，可以参考实现

@Entry
@Component
struct FillStyleExample {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  private offCanvas: OffscreenCanvas = new OffscreenCanvas(600, 600)

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() => {
          let offContext = this.offCanvas.getContext("2d", this.settings)
          offContext.fillStyle = 0x0000FF
          offContext.moveTo(100, 20)
          offContext.arcTo(300, 20, 300, 70, 8)
          offContext.lineTo(300, 80)
          offContext.stroke()
          // offContext.fill()
          let image = this.offCanvas.transferToImageBitmap()
          this.context.transferFromImageBitmap(image)
        })
    }
    .width('100%')
    .height('100%')
  }
}

3、HarmonyOS TextInput clearButton 位置问题？

TextInput 的clearButton 距离TextInput 的右边间距无法控制

目前textInput的cancelButton暂时不支持调整间距此场景可以通过自定义组件实现，以下是参考Demo：

@Entry
@Component
struct TextInputExample {
  @State text: string = ''
  @State changeType:InputType = InputType.Number
  controller: TextInputController = new TextInputController()
  build() {
    Column() {
      Flex({direction: FlexDirection.Row}){
        Stack(){
          TextInput({ text: this.text, controller: this.controller })
            .type(this.changeType)
            .placeholderFont({ size: 16, weight: 400 })
            .width('100%')
            .height(56)
            .onChange((value: string) => { this.text = value })
          Image($r('app.media.startIcon'))
            .margin({ left: 290 })
            .width(20)
            .height(20)
            .onClick(() =>{
              this.text = ''
            })
        }
      }
    }.width('100%').height('100%').backgroundColor('#F1F3F5') } }