Binary Fetch Example

const {PNG} = require('bundle.js');
const {Button, ImageView, ui} = require('tabris');
const base64 = require('base-64');

function _arrayBufferToBase64( buffer ) {
    var binary = '';
    var bytes = new Uint8Array( buffer );
    var len = bytes.byteLength;
    for (var i = 0; i < len; i++) {
        binary += String.fromCharCode( bytes[ i ] );
    }
    return base64.encode( binary );
}

new Button({
  left: 16, right: 16, top: 'prev() 12',
  text: 'load'
}).on('select', loadData).appendTo(ui.contentView);

let imageView = new ImageView({
  left: 16, right: 16, top: 'prev() 12'
}).appendTo(ui.contentView);

function loadData() {
  fetch('https://tabrisjs.com/assets/public-content/img/iphone-cropped-small.png')
    .then(response => checkStatus(response) && response.arrayBuffer())
    .then(buffer => {
       console.log(buffer);
       new PNG({ filterType:4 }).parse( buffer, function(error, data) {
         var options = {  colorType: 0 }
         var out = PNG.sync.write(data, options);
         let base64Encoded =  _arrayBufferToBase64(out);
         imageView.image = { src:'data:image/png;base64,' + base64Encoded};
       });
    })
    .catch(err => console.error(err)); // Never forget the final catch!
}

function checkStatus(response) {
  if (!response.ok) {
    throw new Error(`HTTP ${response.status} - ${response.statusText}`);
  }
  return response;
}