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Convert image to BASE64 with pure javascript

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  • Convert image to BASE64 with pure javascript

    If one creates a basic UX and puts an image object on a panel, is there a way to convert this to BASE64 purely within javascript?

    I content of the object is assigned to a variable, what form is that content in? Is it HTML-wrapped BASE64 already?

    If I can get the image in BASE64 without an AJAX callback then I'll be able to ship the BASE64 content to a google service quickly for some post-processing.

    I've been playing with "btoa()" and "atob()" but these don't work with binary objects.


  • #2
    Re: Convert image to BASE64 with pure javascript

    How are you "putting" the image into the image "control" in the first place?

    Then, what code are you using to assign the image to a variable?

    The Javascript debugger should show you what you're working with.


    • #3
      Re: Convert image to BASE64 with pure javascript

      Hi Dave!

      I simply created a panel and dropped in an image object and pointed it at a JPG in the webproject.

      I wanted to see if I could feed the JPG binary to a function that would convert it to BASE64 using only javascript.

      This can be done with an AJAX call and XBASIC but I'm trying to avoid a callback. Why? Because I'll then apply it to an image in a LIST and I want to do the same thing; convert the already-present image to BASE64 and ship that to the google engine without having to do an AJAX callback.

      This has more to do about how Alpha chooses to represent an image within the rendered UX component (e.g., does it simply pass the image reference to the browser component, does it auto-convert to BASE64 already on import, etc).

      I was tired and it was late so I didn't post my messy test UX.

      Selwyn got back to me this morning. I'll try to incorporate his knowledge, fix the UX, and then I'll post it as a demo.

      The technique will be useful for others I'm sure... especially once people realize how it's being used in practical form.


      • #4
        Re: Convert image to BASE64 with pure javascript

        You can use regular javascript and the html5 canvas element to do the conversion. You can also do thumbnails on the fly without having to use the server at all. I do this with a couple different mobile apps hosted on the Alpha Cloud.


        • #5
          Re: Convert image to BASE64 with pure javascript

          The challenge in my test example was that I was using a standard IMAGE object. When you pull back the covers on that object it is a simple <img> tag with a reference to a file in a directory. There's no getting around it, you have to do an AJAX callback in this case to pull the image and convert it.

          Stepping up a level, if the image is delivered to the UX in LIST element or uploaded from a mobile device, then you have the option of using a canvas element.

          I'll complete the LIST-based option and the upload option in a couple of days. Depending on time, I can potentially post the results and demonstrate how it's being used to interact with Google Visual A.I. (Google Vision API).


          • #6
            Re: Convert image to BASE64 with pure javascript

            Hi Allan,

            All you need is a URL for the image and it can be converted to base64. The image is already being delivered by the server, so no ajax callback is required. As long as the browser understands it to be an image in the first place, it doesn't matter where it's coming from. It has been months since I looked for an example of this, but it's out there.


            • #7
              Re: Convert image to BASE64 with pure javascript

              I did a fair amount of searching both within the Alpha forum and via the open net. I found pure-javascript methods for converting to Base64 as long as the image was local an in a canvas element.

              However, if the image is remote and referenced by a URL (the most simple of <img> tags), the browser may have loaded the image but I haven't been able to pick up the digital content through any object. So I've had to do a manual AJAX callback (old-school "open"), recover the digital content, and then perform a BASE64 action on it.

              As noted, I don't have to do this with a LIST or an IMAGE UPLOAD because the image content is in an object that can be referenced.

              No panic... I won't get to this until the weekend and I have a workable if inelegant solution. However, if you bump into your old references I'll happily review them.