Ways to retrieve base64 encoded information from an image within an HTML document

Question

Ways to retrieve base64 encoded information from an image within an HTML document

On my registration form, users have the option to select an avatar from 2 choices:

Select a default avatar
Upload their own custom avatar

This is how I have implemented it in my HTML page.

<img id="preview" src="img/default_1.png">

The chosen avatar is displayed accordingly. I have integrated the File Api to allow users to upload their unique image. This results in the src attribute of the HTML image changing to something like this.

<img id="preview" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgA... />

Upon submission of the registration form, the data is transmitted to a REST service. For instances where a user has uploaded a custom avatar, I can easily send the base64 encoded data. However, I am looking for guidance on how to manage the default avatar as it is represented by a URL instead of base64 encoded data.

javascript html image base64

Answer 1

Answer №1

If you're looking to experiment with some code, feel free to check out this sample: http://jsfiddle.net/xKJB8/3/

<img id="preview" src="http://www.gravatar.com/avatar/0e39d18b89822d1d9871e0d1bc839d06?s=128&d=identicon&r=PG">
<canvas id="myCanvas" />

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
var img = document.getElementById("preview");
ctx.drawImage(img, 10, 10);
alert(c.toDataURL());

Answer 2

If you're looking to experiment with some code, feel free to check out this sample: http://jsfiddle.net/xKJB8/3/

<img id="preview" src="http://www.gravatar.com/avatar/0e39d18b89822d1d9871e0d1bc839d06?s=128&d=identicon&r=PG">
<canvas id="myCanvas" />

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
var img = document.getElementById("preview");
ctx.drawImage(img, 10, 10);
alert(c.toDataURL());

Answer 3

Answer №2

Another method to read files is by utilizing the FileReader class:

    var fileReader = new FileReader();
    fileReader.onload = function (e) {
        var fileData = this.result;
    }
    fileReader.readAsDataURL( file );

Answer 4

Another method to read files is by utilizing the FileReader class:

    var fileReader = new FileReader();
    fileReader.onload = function (e) {
        var fileData = this.result;
    }
    fileReader.readAsDataURL( file );

Answer 5

Answer №3

A straightforward solution can be achieved using a JavaScript function

function convertImageToBase64(imageSelector){
  var selectedImage = document.querySelector(imageSelector);
  var canvasElement = document.createElement("canvas");
  canvasElement.width = selectedImage.naturalWidth;
  canvasElement.height = selectedImage.naturalHeight;
  var context = canvasElement.getContext("2d");  
  context.drawImage(selectedImage, 0, 0);
  return canvasElement.toDataURL();
}

Answer 6

A straightforward solution can be achieved using a JavaScript function

function convertImageToBase64(imageSelector){
  var selectedImage = document.querySelector(imageSelector);
  var canvasElement = document.createElement("canvas");
  canvasElement.width = selectedImage.naturalWidth;
  canvasElement.height = selectedImage.naturalHeight;
  var context = canvasElement.getContext("2d");  
  context.drawImage(selectedImage, 0, 0);
  return canvasElement.toDataURL();
}

Ways to retrieve base64 encoded information from an image within an HTML document

Answer №1

Answer №2

Answer №3

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