获取和设置应用内屏幕亮度值

import window from '@ohos.window'; 
import { BusinessError } from '@ohos.base'; 
import promptAction from '@ohos.promptAction'; 
  
@Entry 
@Component 
struct Page10 { 
  @State currentScreenBrightness: number = 0; 
  @State clickCount: number = 0; 
  @State baseBrightness: number = 0.1; 
  @State operation: string = 'increase'; 
  
  /** 
   * 设置应用内屏幕亮度 
   */ 
  setScreenBrightness(brightness: number) { 
    window.getLastWindow(getContext(this)).then(currentWindow => { 
      currentWindow.setWindowBrightness(brightness, (err: BusinessError) => { 
        const errCode: number = err.code; 
        if (errCode) { 
          console.error('Failed to set the brightness. Cause: ' + JSON.stringify(err)); 
          return; 
        } 
        console.info('Succeeded in setting the brightness.'); 
      }); 
    }); 
  } 
  
  /** 
   * 获取应用内屏幕亮度 
   */ 
  getScreenBrightness() { 
    window.getLastWindow(getContext(this)).then(currentWindow => { 
      let properties = currentWindow.getWindowProperties(); 
      this.currentScreenBrightness = properties.brightness; 
      console.info(`properties:${JSON.stringify(properties)}`) 
    }); 
  } 
  
  build() { 
    Column() { 
      Text(`current screen brightness: ${this.currentScreenBrightness}`) 
      Button(`click to ${this.operation} brightness`) 
        .onClick(() => { 
          if (this.operation === 'increase') { 
            this.clickCount++; 
            if (this.baseBrightness * this.clickCount <= 1.0) { 
              this.setScreenBrightness(this.baseBrightness * this.clickCount); 
            } else { 
              promptAction.showToast({ 
                message: '亮度值已达到上限！' 
              }) 
              this.operation = 'decrease'; 
            } 
          } else if (this.operation === 'decrease') { 
            this.clickCount--; 
            if (this.baseBrightness * this.clickCount >= 0.0) { 
               this.setScreenBrightness(this.baseBrightness * this.clickCount); 
            } else { 
              promptAction.showToast({ 
                message: '亮度值已达到下限！' 
              }) 
              this.operation = 'increase'; 
            } 
          } 
  
        }) 
        .margin({ 
          top: 20, 
          bottom: 20 
        }) 
  
      Button('click to get brightness') 
        .onClick(() => { 
          this.getScreenBrightness(); 
        }) 
        .margin({ 
          bottom: 20 
        }) 
    } 
  } 
}