Getting Image height and width from base64 Image string in GoJS

Question

I am trying to get the Image height and width from a base64 string representation of the image and I am using GoJS.

What I eventually want to do is to add that image to a PDF using jspdf library.

Here is what I have done so far:

download() {
    let imgData = this.diagram.makeImageData({background: "white", returnType: "string"}); 
    let pdf = new jspdf('p', 'mm', 'a4'); // A4 size page of PDF  
      var position = 0;
      var imgWidth = imgData.width; //Reading width from Image Data
      var imgHeight = imgData.height; //Reading height from Image Data
      pdf.setFontSize(30);
      pdf.text("Diagram", 100, 20, 'center');
      pdf.addImage(imgData, 'PNG', 1, 25, position, imgWidth, imgHeight);  
      pdf.save("Diagram.pdf');
  }

In that imgData.width and imgData.height, the visual studio intellisense is showing "Property 'height' and 'width' does not exist on type 'string'.

How can I get the height and width property of the image?

Walter Northwoods · Accepted Answer · 2018-08-31 21:45:20Z

1

Create an HTMLImageElement using that image data, and then get its naturalWidth and naturalHeight once it has been loaded:

var imgData = myDiagram.makeImageData(. . .);
var img = document.createElement("img");
img.addEventListener('load', function(e) {
  console.log(img.naturalWidth + " " + img.naturalHeight);
});
img.src = imgData;

edited Aug 31, 2018 at 21:45

answered Aug 31, 2018 at 15:13

Walter Northwoods

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1 Comment

s4tr2 Over a year ago

What if the image type is blob?

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