如何在ionic 4中缩小缩放图像？

ionic cordova plugin add cordova-plugin-camera
npm install @ionic-native/camera

import { Camera, CameraOptions } from '@ionic-native/camera/ngx';
import { Platform } from '@ionic/angular';

constructor(private camera: Camera, private platform: Platform) { }

async selectImage() {
  const options: CameraOptions = {
    quality: 100,
    destinationType: this.camera.DestinationType.DATA_URL,
    sourceType: this.camera.PictureSourceType.PHOTOLIBRARY,
    mediaType: this.camera.MediaType.PICTURE
  };

  const imageData = await this.camera.getPicture(options);
}

const canvas = document.createElement('canvas');
const ctx = canvas.getContext('2d');

const image = new Image();
image.src = 'data:image/jpeg;base64,' + imageData;
image.onload = () => {
  canvas.width = image.width / 2; // 缩小图像的宽度
  canvas.height = image.height / 2; // 缩小图像的高度
  ctx.drawImage(image, 0, 0, canvas.width, canvas.height);
};

const resizedImageData = canvas.toDataURL('image/jpeg');
// 进一步处理缩小和缩放后的图像数据