HarmonyOS 鸿蒙Next 如何将应用沙箱内的图片生成PixelMap

生成PixelMap可以参考：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-image-V5#createpixelmapsync12

可以使用packing对图片进行压缩，参考文档：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-image-V5#packing

图片压缩到指定大小参考：https://gitee.com/harmonyos-cases/cases/tree/master/CommonAppDevelopment/feature/imagecompression#%E5%9B%BE%E7%89%87%E5%8E%8B%E7%BC%A9%E6%96%B9%E6%A1%88

packingToBase64() {

    const context: Context = getContext();

    const imagePackerApi = image.createImagePacker();

    //此处'test.jpg'仅作示例，请开发者自行替换，否则imageSource会创建失败导致后续无法正常执行。

    let filePath: string = context.cacheDir + "/test.jpg";

    const imageSourceApi: image.ImageSource = image.createImageSource(filePath);

    let packOpts: image.PackingOption = { format: "image/jpeg", quality: 98 };

    imagePackerApi.packing(imageSourceApi, packOpts, (err: BusinessError, data: ArrayBuffer) => {

      if (err) {

        console.error(`Failed to pack the image.code ${err.code},message is ${err.message}`);

      } else {

        let buf: buffer.Buffer = buffer.from(data);

        let base64  = 'data:image/jpeg;base64,' + buf.toString('base64', 0, buf.length);

        console.info('base64: ' + base64);

      }

    })

  }