Google Chrome Extension to upload a locally stored image to imgurl API service.

## background.html
<!DOCTYPE html>
<html>
  <head>
  <script>

  const API_KEY = 'SOME_KEY';

  /**
   * Use HTML5 Canvas to get the image data
   * @param {HTMLImageElement} img An Image Tag
   */
  function getBase64Image(img) {
    var canvas = document.createElement('canvas');
    canvas.width = img.width;
    canvas.height = img.height;
    var ctx = canvas.getContext('2d');
    ctx.drawImage(img, 0, 0);
    var dataURL = canvas.toDataURL('image/png');
    return dataURL.replace(/data:image\/png;base64,/, '');
 }

  /**
   * Quick way to url encode a string.
   */
  function encode_utf8(s) {
    return unescape(encodeURIComponent(s));
  }

  /**
   * BrowserAction click.
   */
  chrome.browserAction.onClicked.addListener(function(tab) {
    // Store the local image in a buffer so we can draw it to the canvas,
    // and have some kind of preloader to know when it has done loading.
    var image_buffer = document.createElement('img');
    image_buffer.src = chrome.extension.getURL('uploader.png');
    image_buffer.onload = function() {
      // Do an ASYNC request to send the POST data.
      var xhr = new XMLHttpRequest();
      xhr.open('POST', 'http://api.imgur.com/2/upload.json?key=' + API_KEY, true);
      xhr.setRequestHeader('Cache-Control', 'no-cache');
      xhr.onreadystatechange = function() {
        if (this.readyState == 4) {
          var response = JSON.parse(xhr.response);

          // Check for error.
          if (response.error) {
            alert('Error: ' + response.error.message);
            return;
          }

          // Retrieve the image url.
          alert('Image URL: ' + response.upload.links.original);
        }
      };

      // Get the base64 image using HTML5 Canvas.
      var image64 = getBase64Image(image_buffer);

      // Properly escape the contents of the image. And post it.
      var post_data =  encode_utf8(image64);
      xhr.send(post_data);
    };

  });

  </script>
  </head>
</html>

## manifest.json
{
  "name": "imgurl uploader",
  "version": "0.1",
  "description": "imgurl uploader",
  "permissions": [
   "tabs",
   "http://*/*"
  ],
  "background_page": "background.html",
  "browser_action": {
   "default_icon": "uploader.png"
  }
}