如何从图像onLoad中返回变量

Question

  export class AttachmentComponent {
   imageWidth: number;
   imageHeight: number;
   ngOnInit() {
    this.imgSize(imagePath);
   }
   getImageSize(url) {
    const img = new Image();
    img.src = imgurl;
    img.onload = (event) => {
      const  loadedImage: any = event.currentTarget;
      const width = loadedImage.width;
      const height = loadedImage.height;
    }
   }
 }

[这里，我要使用在getImageSize中的onLoad内部计算的宽度和高度来填充类的'imageWidth'和'imageHeight'属性。帮助吗？

Answer 1

如果我对您的问题的理解是正确的，您想将loadedImage.width的值分配给imageWidth属性，并用height赋值。

您可以通过引用this（它是AttachmentComponent实例）来做到这一点。

export class AttachmentComponent {
   imageWidth: number;
   imageHeight: number;
   ngOnInit() {
    this.imgSize(imagePath);
   }
   getImageSize(url) {
    const img = new Image();
    img.src = imgurl;
    img.onload = (event) => {
      const  loadedImage: any = event.currentTarget;
      // => here is what I've changed
      this.imageWidth = loadedImage.width;
      this.imageHeight = loadedImage.height;
    }
   }
 }