HarmonyOS @Entry页面页面如何实现全透明或者半透明效果

针对场景 ：将B页面作为一个子窗口加载然后将子窗口设置为透明背景这样来实现背景半透明效果，示例代码如下

1、EntryAbility.ets

export default class EntryAbility extends UIAbility {
  storage: LocalStorage = new LocalStorage();
  onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {
    hilog.info(0x0000, 'testTag', '%{public}s', 'Ability onCreate');
    this.storage = new LocalStorage();
  }
  …
  onWindowStageCreate(windowStage: window.WindowStage): void {
    hilog.info(0x0000, 'testTag', '%{public}s', 'Ability onWindowStageCreate');
    AppStorage.setOrCreate("windowStage", windowStage);
    windowStage.loadContent('pages/APage', this.storage, (err, data) => {
      if (err.code) {
        hilog.error(0x0000, 'testTag', 'Failed to load the content. Cause: %{public}s', JSON.stringify(err) ?? '');
        return;
      }
      hilog.info(0x0000, 'testTag', 'Succeeded in loading the content. Data: %{public}s', JSON.stringify(data) ?? '');
    });
  }
  …
}

2、APage.ets

import window from '@ohos.window';

@Entry
@Component
struct APage {
  build() {
    Row() {
      Column() {
        Button("pageA").onClick(() => {
          let windowStage_: window.WindowStage = AppStorage.get("windowStage") as window.WindowStage;
          windowStage_.createSubWindow("subWindow", (err, win) => {//创建透明子窗口并打开
            win.setUIContent('pages/BPage');
            win.showWindow();
          })
        })
      }
      .width('100%')
    }
    .height('100%')
    .backgroundColor(Color.Pink)
  }
}

3、BPage.ets

import window from '@ohos.window';

@Entry
@Component
struct BPage {
  @State message: string = 'BPage';

  aboutToAppear() {
    window.findWindow("subWindow").setWindowBackgroundColor("#00000000") //设置子窗口背景透明
  }

  onBackPress() { //关闭子窗口
    window.findWindow("subWindow").destroyWindow().then((res) => {
      console.log("destroyWindow success")
    }).catch(() => {
      console.log("destroyWindow fail")
    })
    return true
  }

  build() {
    Row() {
      Column() {
        Text(this.message)
          .fontSize(50)
          .fontWeight(FontWeight.Bold)
      }
      .width('100%')
    }
    .backgroundColor("#32ffffff") //组件背景，可以修改为#00000000透明
    .height('100%')
  }
}