/// /// class DocumentPrinter { WIDTH = 384; thresholdInput = document.getElementById('filter_threshold'); bluetoothMACInput = document.getElementById('bt_mac'); container = document.getElementById('container'); printButton = document.getElementById('print_button'); threshold = 0.6; imagePreview = document.getElementById('image_preview'); monoMethod = imageDataColorToMonoSquare; constructor() { this.thresholdInput.onchange = event => { this.threshold = this.thresholdInput.value; } this.printButton.addEventListener('click', event => { html2canvas(this.container).then(canvas => { notice('Printing, please wait.'); let context = canvas.getContext('2d'); let imagedata = context.getImageData(0, 0, this.WIDTH, canvas.height); let mono_imagedata = this.monoMethod(imagedata, this.threshold); context.putImageData(mono_imagedata, 0, 0); this.imagePreview.appendChild(canvas); let pbm_data = imageDataMonoToPBM(mono_imagedata); let xhr = new XMLHttpRequest(); xhr.open('POST', '/~print?address=' + this.bluetoothMACInput.value); xhr.setRequestHeader('Content-Type', 'application-octet-stream'); xhr.onload = () => { notice(xhr.responseText); } xhr.send(pbm_data); }) }); } } var document_printer = new DocumentPrinter();