HarmonyOS 鸿蒙Next应用亮度获取第一次值错误，为-1

import { promptAction, router, window } from '@kit.ArkUI';
import settings from '@ohos.settings';
import { BusinessError } from '@ohos.base';

@Entry
@Component
export struct Index {
  @State windowClass: window.Window | undefined = undefined;

  /** 获取跟随系统的亮度数值 */
  getLightWithoutSetting() {
    let context = this;
    let value = settings.getValueSync(context, settings.display.SCREEN_BRIGHTNESS_STATUS, '10');
    console.log(`当前屏幕的亮度为： ${JSON.stringify(value)}`);
  }

  /** 只有设置窗口亮度后再获取，亮度信息才不会是-1 */
  getLight() {
    let brightness: number = 0.78;
    let windowStage: window.WindowStage | undefined = AppStorage.get('windowStage') as window.WindowStage
    windowStage.getMainWindow((err: BusinessError, data) => {
      const errCode: number = err.code;
      if (errCode) {
        console.error('Failed to obtain the main window. Cause: ' + JSON.stringify(err));
        return;
      }
      this.windowClass = data;
      this.windowClass.setWindowBrightness(brightness, (err: BusinessError) => {
        const errCode: number = err.code;
        if (errCode) {
          console.error('Failed to set the brightness. Cause: ' + JSON.stringify(err));
          return;
        }
        let screenLight = this.windowClass?.getWindowProperties().brightness
        console.info('Succeeded in setting the brightness.');
        console.info(`Succeeded in getting the light:${screenLight}`);
      });
    });
  }

  build() {
    Column({ space: 10 }) {
      Button('获取亮度').onClick(() => {
        this.getLightWithoutSetting()
      })
      Button('点击设置并获取亮度').onClick(() => {
        this.getLight()
      })
    }.width('100%').height("100%").justifyContent(FlexAlign.Center)
  }
}

运行上述代码前需替换EntryAbility.ets文件中的onWindowStageCreate方法,替换代码如下：

  onWindowStageCreate(windowStage: window.WindowStage): void {
    hilog.info(0x0000, 'testTag', '%{public}s', 'Ability onWindowStageCreate');
    windowStage.loadContent('pages/Index', (err) => {
      AppStorage.setOrCreate('windowStage', windowStage)
      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.');
    }
    );
  }