如何获取base 64图像的宽度高度

Question

I want to create a helper function where i will pass the base64 image and it will return the width and height of that image, i have tried with below approach but it is always returns null. Somehow it is not updating the width and height variables.

Question: how to get the width and height of the image?

getDimensions(image : string){
   var width : number = null;
   var height : number = null;

   var img = new Image();
   img.src = image;

   img.onload = () => {
      width = img.width;
      height = img.width;
   }

   return {width, height};
}


let dimesions : any = this.getDimensions(base64Image);

Answer 1

You will have to make the function async:

getDimensions(image : string){
   return new Promise((resolve, reject)=>{

       var img = new Image();
       img.src = image;

       img.onload = () => {
          resolve({width: img.width, height: img.height})
      }

   })
}


let dimesions : Promise = await this.getDimensions(base64Image);

I would suggest trying a tutorial on promises and async programming.