图片填充整个页面，如何用图片填充整个页面，上面有白色的区域？

// EntryAbility.ets  
export default class EntryAbility extends UIAbility {  
  onWindowStageCreate(windowStage: window.WindowStage): void {  
    try {  
      window.getLastWindow(this.context, (err: BusinessError, data: window.Window) => {  
        data.setWindowLayoutFullScreen(true)  
      })  
    } catch {}  
    windowStage.loadContent('pages/Index', (err) => {  
      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.');  
    });  
  }  
}