image.createPixelMap方法与pixelMap.readPixelsToBuffer方法咨询

async createCanvasPixelMap() { 
 
  let resourceMgr: resourceManager.ResourceManager = (getContext(this) as common.UIAbilityContext).resourceManager; 
  let startIconRawDesc = await resourceMgr.getRawFd('startIcon.png'); 
  let imageSrc: image.ImageSource = image.createImageSource(startIconRawDesc); 
  // let iconMap: image.PixelMap = await imageSrc.createPixelMap(); 
  let iconMap: image.PixelMap = await imageSrc.createPixelMap({desiredPixelFormat:image.PixelMapFormat.BGRA_8888}); 
  this.defaultIcon = iconMap; 
  console.log(`${this.defaultIcon.getPixelBytesNumber()}`) 
  let iconBufSize = iconMap.getPixelBytesNumber(); 
  console.log(`${Math.sqrt(4)}`) 
  let sqr = Math.sqrt(iconBufSize / 4) 
  let opts: image.InitializationOptions = { editable: true, pixelFormat: 4, size: { height: sqr, width: sqr } } 
  let iconBuffer: ArrayBuffer = new ArrayBuffer(iconBufSize); 
  await iconMap.readPixelsToBuffer(iconBuffer) 
  this.icon = await image.createPixelMap(iconBuffer, opts); 
  // this.icon = iconMap; 
  imageSrc.release(); 
} 
}