HarmonyOS 图片自定义分辨率问题

可以将截图后的照片通过压缩至特定大小（分辨率）后再返回储存数据。

可以先创建pixelMap获取imageInfo，计算和目标宽高的压缩比，调用pixelMap的scale方法压缩，然后在编码压缩后的pixelmap，具体参考以下代码：

// path为已获得的沙箱路径
const imageSource: image.ImageSource = image.createImageSource(path2);
let decodingOptions: image.DecodingOptions = {
  editable: true,
  desiredPixelFormat: 3,
}
this.pixelmap=await imageSource.createPixelMap(decodingOptions);
let imageInfo = await this.pixelmap.getImageInfo();
//计算压缩比
let scaleX : number = 500/imageInfo.size.width;
let scaleY : number = 500/imageInfo.size.height;
this.pixelmap.scale(scaleX,scaleY,(err : BusinessError) => {
  if (err) {
    console.error("Failed to scale pixelmap."); return;
  } else {
    console.info("Succeeded in scaling pixelmap.");
  }
});

const imagePackerApi = image.createImagePacker();
let packOpts: image.PackingOption = { format: "image/jpeg", quality: 90 };
imagePackerApi.packing( this.pixelmap, packOpts).then((data:ArrayBuffer) => {
  console.info("Succeeded in packing the image.");
}).catch((error: BusinessError) => {
  console.error("Failed to pack the image. And the error is: " + error);
})
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