wiki-grav/plugins/form/templates/forms/fields/signature/signature.html.twig
2022-04-24 14:32:58 +02:00

105 lines
4.0 KiB
Twig

{% extends "forms/field.html.twig" %}
{% block prepend %}
<div id="signature-pad" class="signature-pad">
<div class="signature-pad--body">
<canvas></canvas>
</div>
<div class="signature-pad--footer">
<div class="description">Sign above</div>
<div class="signature-pad--actions">
<div>
<button type="button" class="btn btn-primary-border" data-action="clear">Clear Signature</button>
</div>
</div>
</div>
</div>
<script src="{{ url('plugin://form/assets/signature_pad.js') }}"></script>
<script>
var wrapper = document.getElementById("signature-pad");
var clearButton = wrapper.querySelector("[data-action=clear]");
var canvas = wrapper.querySelector("canvas");
var signaturePad = new SignaturePad(canvas, {
// It's Necessary to use an opaque color when saving image as JPEG;
// this option can be omitted if only saving as PNG or SVG
backgroundColor: 'rgb(255, 255, 255)',
onEnd: function() {
var input = document.querySelector('[name="data[{{ field.name }}]"]');
input.value = this.toDataURL();
}
});
// Adjust canvas coordinate space taking into account pixel ratio,
// to make it look crisp on mobile devices.
// This also causes canvas to be cleared.
function resizeCanvas() {
// When zoomed out to less than 100%, for some very strange reason,
// some browsers report devicePixelRatio as less than 1
// and only part of the canvas is cleared then.
var ratio = Math.max(window.devicePixelRatio || 1, 1);
// This part causes the canvas to be cleared
canvas.width = canvas.offsetWidth * ratio;
canvas.height = canvas.offsetHeight * ratio;
canvas.getContext("2d").scale(ratio, ratio);
// This library does not listen for canvas changes, so after the canvas is automatically
// cleared by the browser, SignaturePad#isEmpty might still return false, even though the
// canvas looks empty, because the internal data of this library wasn't cleared. To make sure
// that the state of this library is consistent with visual state of the canvas, you
// have to clear it manually.
signaturePad.clear();
}
// On mobile devices it might make more sense to listen to orientation change,
// rather than window resize events.
window.onresize = resizeCanvas;
resizeCanvas();
function download(dataURL, filename) {
var blob = dataURLToBlob(dataURL);
var url = window.URL.createObjectURL(blob);
var a = document.createElement("a");
a.style = "display: none";
a.href = url;
a.download = filename;
document.body.appendChild(a);
a.click();
window.URL.revokeObjectURL(url);
}
// One could simply use Canvas#toBlob method instead, but it's just to show
// that it can be done using result of SignaturePad#toDataURL.
function dataURLToBlob(dataURL) {
// Code taken from https://github.com/ebidel/filer.js
var parts = dataURL.split(';base64,');
var contentType = parts[0].split(":")[1];
var raw = window.atob(parts[1]);
var rawLength = raw.length;
var uInt8Array = new Uint8Array(rawLength);
for (var i = 0; i < rawLength; ++i) {
uInt8Array[i] = raw.charCodeAt(i);
}
return new Blob([uInt8Array], { type: contentType });
}
clearButton.addEventListener("click", function (event) {
signaturePad.clear();
});
</script>
{% endblock prepend %}
{% block input_attributes %}
type="hidden"
{{ parent() }}
{% endblock %}