react-native-signature-canvas
Version:
A performant, customizable React Native signature canvas with advanced error handling, WebView optimization, and TypeScript support for iOS, Android, and Expo
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JavaScript
export default `
/*!
* Signature Pad v3.0.0-beta.3 | https://github.com/szimek/signature_pad
* (c) 2018 Szymon Nowak | Released under the MIT license
*/
(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
typeof define === 'function' && define.amd ? define(factory) :
(global.SignaturePad = factory());
}(this, (function () { 'use strict';
var Point = (function () {
function Point(x, y, time) {
this.x = x;
this.y = y;
this.time = time || Date.now();
}
Point.prototype.distanceTo = function (start) {
return Math.sqrt(Math.pow(this.x - start.x, 2) + Math.pow(this.y - start.y, 2));
};
Point.prototype.equals = function (other) {
return this.x === other.x && this.y === other.y && this.time === other.time;
};
Point.prototype.velocityFrom = function (start) {
return this.time !== start.time
? this.distanceTo(start) / (this.time - start.time)
: 0;
};
return Point;
}());
var Bezier = (function () {
function Bezier(startPoint, control2, control1, endPoint, startWidth, endWidth) {
this.startPoint = startPoint;
this.control2 = control2;
this.control1 = control1;
this.endPoint = endPoint;
this.startWidth = startWidth;
this.endWidth = endWidth;
}
Bezier.fromPoints = function (points, widths) {
var c2 = this.calculateControlPoints(points[0], points[1], points[2]).c2;
var c3 = this.calculateControlPoints(points[1], points[2], points[3]).c1;
return new Bezier(points[1], c2, c3, points[2], widths.start, widths.end);
};
Bezier.calculateControlPoints = function (s1, s2, s3) {
var dx1 = s1.x - s2.x;
var dy1 = s1.y - s2.y;
var dx2 = s2.x - s3.x;
var dy2 = s2.y - s3.y;
var m1 = { x: (s1.x + s2.x) / 2.0, y: (s1.y + s2.y) / 2.0 };
var m2 = { x: (s2.x + s3.x) / 2.0, y: (s2.y + s3.y) / 2.0 };
var l1 = Math.sqrt(dx1 * dx1 + dy1 * dy1);
var l2 = Math.sqrt(dx2 * dx2 + dy2 * dy2);
var dxm = m1.x - m2.x;
var dym = m1.y - m2.y;
var k = l2 / (l1 + l2);
var cm = { x: m2.x + dxm * k, y: m2.y + dym * k };
var tx = s2.x - cm.x;
var ty = s2.y - cm.y;
return {
c1: new Point(m1.x + tx, m1.y + ty),
c2: new Point(m2.x + tx, m2.y + ty)
};
};
Bezier.prototype.length = function () {
var steps = 10;
var length = 0;
var px;
var py;
for (var i = 0; i <= steps; i += 1) {
var t = i / steps;
var cx = this.point(t, this.startPoint.x, this.control1.x, this.control2.x, this.endPoint.x);
var cy = this.point(t, this.startPoint.y, this.control1.y, this.control2.y, this.endPoint.y);
if (i > 0) {
var xdiff = cx - px;
var ydiff = cy - py;
length += Math.sqrt(xdiff * xdiff + ydiff * ydiff);
}
px = cx;
py = cy;
}
return length;
};
Bezier.prototype.point = function (t, start, c1, c2, end) {
return (start * (1.0 - t) * (1.0 - t) * (1.0 - t))
+ (3.0 * c1 * (1.0 - t) * (1.0 - t) * t)
+ (3.0 * c2 * (1.0 - t) * t * t)
+ (end * t * t * t);
};
return Bezier;
}());
function throttle(fn, wait) {
if (wait === void 0) { wait = 250; }
var previous = 0;
var timeout = null;
var result;
var storedContext;
var storedArgs;
var later = function () {
previous = Date.now();
timeout = null;
result = fn.apply(storedContext, storedArgs);
if (!timeout) {
storedContext = null;
storedArgs = [];
}
};
return function wrapper() {
var args = [];
for (var _i = 0; _i < arguments.length; _i++) {
args[_i] = arguments[_i];
}
var now = Date.now();
var remaining = wait - (now - previous);
storedContext = this;
storedArgs = args;
if (remaining <= 0 || remaining > wait) {
if (timeout) {
clearTimeout(timeout);
timeout = null;
}
previous = now;
result = fn.apply(storedContext, storedArgs);
if (!timeout) {
storedContext = null;
storedArgs = [];
}
}
else if (!timeout) {
timeout = window.setTimeout(later, remaining);
}
return result;
};
}
var SignaturePad = (function () {
function SignaturePad(canvas, options) {
if (options === void 0) options = {};
var _this = this;
this.canvas = canvas;
this.options = options;
this._startingSignature = null;
this._isDrawing = true;
this._history = [];
this._handleMouseDown = function (event) {
if (event.which === 1) {
_this._mouseButtonDown = true;
_this._strokeBegin(event);
}
};
this._handleMouseMove = function (event) {
if (_this._mouseButtonDown) {
_this._strokeMoveUpdate(event);
}
};
this._handleMouseUp = function (event) {
if (event.which === 1 && _this._mouseButtonDown) {
_this._mouseButtonDown = false;
_this._strokeEnd(event);
}
};
this._handleTouchStart = function (event) {
event.preventDefault();
if (event.targetTouches.length === 1) {
var touch = event.changedTouches[0];
_this._strokeBegin(touch);
}
};
this._handleTouchMove = function (event) {
event.preventDefault();
var touch = event.targetTouches[0];
_this._strokeMoveUpdate(touch);
};
this._handleTouchEnd = function (event) {
var wasCanvasTouched = event.target === _this.canvas;
if (wasCanvasTouched) {
event.preventDefault();
var touch = event.changedTouches[0];
_this._strokeEnd(touch);
}
};
this.velocityFilterWeight = options.velocityFilterWeight || 0.7;
this.minWidth = options.minWidth || 0.5;
this.maxWidth = options.maxWidth || 2.5;
this.throttle = "throttle" in options ? options.throttle : 16;
this.minDistance = "minDistance" in options ? options.minDistance : 5;
this._strokeMoveUpdate = this.throttle
? (this._strokeMoveUpdate = throttle(
SignaturePad.prototype._strokeUpdate,
this.throttle
))
: SignaturePad.prototype._strokeUpdate;
this.dotSize = options.dotSize || function dotSize() {return (this.minWidth + this.maxWidth) / 2;};
this.penColor = options.penColor || "black";
this.backgroundColor = options.backgroundColor || "rgba(255,255,255,0)";
this.onBegin = options.onBegin;
this.onEnd = options.onEnd;
this._ctx = canvas.getContext("2d");
this.clear();
this.on();
}
SignaturePad.prototype.clear = function () {
var ctx = this._ctx;
var canvas = this.canvas;
ctx.fillStyle = this.backgroundColor;
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.fillRect(0, 0, canvas.width, canvas.height);
this._data = [];
this._reset();
this._isEmpty = true;
};
SignaturePad.prototype.undo = function () {
const data = this.toData();
if (data && data.length) {
this._history.push(data.pop()); // remove the last stroke
} else if (this._startingSignature) {
return; // they performed undo of background sig
}
this.clear();
if (this._startingSignature) {
this.fromDataURL(this._startingSignature, {}, () => this.fromData(data, true));
} else {
this.fromData(data, true);
}
};
SignaturePad.prototype.redo = function () {
if (!this._history.length) return;
const data = this.toData();
data.push(this._history.pop());
this.clear();
if (this._startingSignature) {
this.fromDataURL(this._startingSignature, {}, () => this.fromData(data, true));
} else {
this.fromData(data, true);
}
};
SignaturePad.prototype.draw = function () {
this._ctx.globalCompositeOperation = "source-over";
this._isDrawing = true;
};
SignaturePad.prototype.erase = function () {
this._ctx.globalCompositeOperation = "destination-out";
this._isDrawing = false;
};
SignaturePad.prototype.fromDataURL = function (dataUrl, options, callback) {
var _this = this;
if (options === void 0) options = {};
var image = new Image();
var ratio = options.ratio || window.devicePixelRatio || 1;
var width = options.width || this.canvas.width / ratio;
var height = options.height || this.canvas.height / ratio;
this._reset();
image.src = dataUrl;
image.onload = function () {
_this._ctx.globalCompositeOperation = "source-over";
_this._ctx.drawImage(image, 0, 0, width, height);
_this._ctx.globalCompositeOperation = _this._isDrawing ? "source-over" : "destination-out";
if (callback) {
callback();
}
};
image.onerror = function (error) {
if (callback) {
callback(error);
}
};
this._isEmpty = false;
if (!this._startingSignature) this._startingSignature = dataUrl;
};
SignaturePad.prototype.toDataURL = function (type = "image/png", encoderOptions) {
return type === "image/svg+xml" ? this._toSVG() : this.canvas.toDataURL(type, encoderOptions);
};
SignaturePad.prototype.on = function () {
this.canvas.style.touchAction = 'none';
this.canvas.style.msTouchAction = 'none';
if (window.PointerEvent) {
this._handlePointerEvents();
}
else {
this._handleMouseEvents();
if ('ontouchstart' in window) {
this._handleTouchEvents();
}
}
};
SignaturePad.prototype.off = function () {
this.canvas.style.touchAction = 'auto';
this.canvas.style.msTouchAction = 'auto';
this.canvas.removeEventListener('pointerdown', this._handleMouseDown);
this.canvas.removeEventListener('pointermove', this._handleMouseMove);
document.removeEventListener('pointerup', this._handleMouseUp);
this.canvas.removeEventListener('mousedown', this._handleMouseDown);
this.canvas.removeEventListener('mousemove', this._handleMouseMove);
document.removeEventListener('mouseup', this._handleMouseUp);
this.canvas.removeEventListener('touchstart', this._handleTouchStart);
this.canvas.removeEventListener('touchmove', this._handleTouchMove);
this.canvas.removeEventListener('touchend', this._handleTouchEnd);
};
SignaturePad.prototype.isEmpty = function () {
return this._isEmpty;
};
SignaturePad.prototype.fromData = function (pointGroups, suppressClear = false) {
var _this = this;
if (!suppressClear) this.clear();
if (pointGroups && pointGroups.length > 0) {
this._fromData(
pointGroups,
({ color, curve }) => _this._drawCurve({ color, curve }),
({ color, point, dotSize }) => _this._drawDot({ color, point, dotSize })
);
this._data = pointGroups;
}
};
SignaturePad.prototype.toData = function () {
return this._data;
};
SignaturePad.prototype._strokeBegin = function (event) {
var newPointGroup = {
color: this.penColor,
dotSize: typeof this.dotSize === 'function' ? this.dotSize() : this.dotSize,
minWidth: this.minWidth,
maxWidth: this.maxWidth,
compositeOperation: this._ctx.globalCompositeOperation,
points: [],
};
if (typeof this.onBegin === "function") {
this.onBegin(event);
}
this._data.push(newPointGroup);
this._history = [];
this._reset();
this._strokeUpdate(event);
};
SignaturePad.prototype._strokeUpdate = function (event) {
var x = event.clientX;
var y = event.clientY;
var point = this._createPoint(x, y);
var lastPointGroup = this._data[this._data.length - 1];
var lastPoints = lastPointGroup.points;
var lastPoint = lastPoints.length > 0 && lastPoints[lastPoints.length - 1];
var isLastPointTooClose = lastPoint
? point.distanceTo(lastPoint) <= this.minDistance
: false;
var color = lastPointGroup.color;
if (!lastPoint || !(lastPoint && isLastPointTooClose)) {
var curve = this._addPoint(point);
if (!lastPoint) {
this._drawDot({ color, point });
}
else if (curve) {
this._drawCurve({ color, curve });
}
lastPoints.push({
time: point.time,
x: point.x,
y: point.y
});
}
};
SignaturePad.prototype._strokeEnd = function (event) {
this._strokeUpdate(event);
if (typeof this.onEnd === 'function') {
this.onEnd(event);
}
};
SignaturePad.prototype._handlePointerEvents = function () {
this._mouseButtonDown = false;
this.canvas.addEventListener('pointerdown', this._handleMouseDown);
this.canvas.addEventListener('pointermove', this._handleMouseMove);
document.addEventListener('pointerup', this._handleMouseUp);
};
SignaturePad.prototype._handleMouseEvents = function () {
this._mouseButtonDown = false;
this.canvas.addEventListener('mousedown', this._handleMouseDown);
this.canvas.addEventListener('mousemove', this._handleMouseMove);
document.addEventListener('mouseup', this._handleMouseUp);
};
SignaturePad.prototype._handleTouchEvents = function () {
this.canvas.addEventListener('touchstart', this._handleTouchStart);
this.canvas.addEventListener('touchmove', this._handleTouchMove);
this.canvas.addEventListener('touchend', this._handleTouchEnd);
};
SignaturePad.prototype._reset = function () {
this._lastPoints = [];
this._lastVelocity = 0;
this._lastWidth = typeof this.dotSize === 'function' ? this.dotSize() : this.dotSize;
this._ctx.fillStyle = this.penColor;
};
SignaturePad.prototype._createPoint = function (x, y) {
var rect = this.canvas.getBoundingClientRect();
if (<%orientation%>) {
return new Point(y - rect.top, rect.left+rect.width-x, new Date().getTime());
} else {
return new Point(x - rect.left, y - rect.top, new Date().getTime());
}
};
SignaturePad.prototype._addPoint = function (point, minWidth = this.minWidth, maxWidth = this.maxWidth) {
var _lastPoints = this._lastPoints;
_lastPoints.push(point);
if (_lastPoints.length > 2) {
if (_lastPoints.length === 3) {
_lastPoints.unshift(_lastPoints[0]);
}
var widths = this._calculateCurveWidths(_lastPoints[1], _lastPoints[2], minWidth, maxWidth);
var curve = Bezier.fromPoints(_lastPoints, widths);
_lastPoints.shift();
return curve;
}
return null;
};
SignaturePad.prototype._calculateCurveWidths = function (startPoint, endPoint, minWidth = this.minWidth, maxWidth = this.maxWidth) {
var velocity = this.velocityFilterWeight * endPoint.velocityFrom(startPoint) +
(1 - this.velocityFilterWeight) * this._lastVelocity;
var newWidth = this._strokeWidth(velocity, minWidth, maxWidth);
var widths = {
end: newWidth,
start: this._lastWidth
};
this._lastVelocity = velocity;
this._lastWidth = newWidth;
return widths;
};
SignaturePad.prototype._strokeWidth = function (velocity, minWidth = this.minWidth, maxWidth = this.maxWidth) {
return Math.max(maxWidth / (velocity + 1), minWidth);
};
SignaturePad.prototype._drawCurveSegment = function (x, y, width) {
var ctx = this._ctx;
ctx.moveTo(x, y);
ctx.arc(x, y, width, 0, 2 * Math.PI, false);
this._isEmpty = false;
};
SignaturePad.prototype._drawCurve = function (_a) {
var color = _a.color, curve = _a.curve;
var ctx = this._ctx;
var widthDelta = curve.endWidth - curve.startWidth;
var drawSteps = Math.floor(curve.length()) * 2;
ctx.beginPath();
ctx.fillStyle = color;
for (var i = 0; i < drawSteps; i += 1) {
var t = i / drawSteps;
var tt = t * t;
var ttt = tt * t;
var u = 1 - t;
var uu = u * u;
var uuu = uu * u;
var x = uuu * curve.startPoint.x;
x += 3 * uu * t * curve.control1.x;
x += 3 * u * tt * curve.control2.x;
x += ttt * curve.endPoint.x;
var y = uuu * curve.startPoint.y;
y += 3 * uu * t * curve.control1.y;
y += 3 * u * tt * curve.control2.y;
y += ttt * curve.endPoint.y;
var width = curve.startWidth + ttt * widthDelta;
this._drawCurveSegment(x, y, width);
}
ctx.closePath();
ctx.fill();
};
SignaturePad.prototype._drawDot = function (_a) {
var color = _a.color, point = _a.point;
var ctx = this._ctx;
var width = _a.dotSize ? _a.dotSize : typeof this.dotSize === "function" ? this.dotSize() : this.dotSize;
ctx.beginPath();
this._drawCurveSegment(point.x, point.y, width);
ctx.closePath();
ctx.fillStyle = color;
ctx.fill();
};
SignaturePad.prototype._fromData = function (pointGroups, drawCurve, drawDot) {
for (var i = 0; i < pointGroups.length; i++) {
var group = pointGroups[i];
var color = group.color, points = group.points;
var minWidth = group.minWidth, maxWidth = group.maxWidth, dotSize = group.dotSize;
var compositeOperation = group.compositeOperation;
this._reset();
this._lastWidth = dotSize;
if (points.length > 1) {
for (var j = 0; j < points.length; j++) {
var point = new Point(points[j].x, points[j].y, points[j].time);
this._ctx.globalCompositeOperation = compositeOperation;
var curve = this._addPoint(point, minWidth, maxWidth);
if (curve) drawCurve({ color, curve });
};
} else drawDot({ color, point: points[0], dotSize });
};
this._ctx.globalCompositeOperation = this._isDrawing ? "source-over" : "destination-out";
};
SignaturePad.prototype._toSVG = function () {
var _this = this;
var pointGroups = this._data;
var ratio = Math.max(window.devicePixelRatio || 1, 1);
var minX = 0;
var minY = 0;
var maxX = this.canvas.width / ratio;
var maxY = this.canvas.height / ratio;
var svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
svg.setAttribute('width', this.canvas.width.toString());
svg.setAttribute('height', this.canvas.height.toString());
this._fromData(pointGroups, function (_a) {
var color = _a.color, curve = _a.curve;
var path = document.createElement("path");
if (!isNaN(curve.control1.x) && !isNaN(curve.control1.y) && !isNaN(curve.control2.x) && !isNaN(curve.control2.y)) {
var attr = "M " + curve.startPoint.x.toFixed(3) + "," + curve.startPoint.y.toFixed(3) + " " + ("C " + curve.control1.x.toFixed(3) + "," + curve.control1.y.toFixed(3) + " ") + (curve.control2.x.toFixed(3) + "," + curve.control2.y.toFixed(3) + " ") + (curve.endPoint.x.toFixed(3) + "," + curve.endPoint.y.toFixed(3));
path.setAttribute("d", attr);
path.setAttribute("stroke-width", (curve.endWidth * 2.25).toFixed(3));
path.setAttribute("stroke", color);
path.setAttribute("fill", "none");
path.setAttribute("stroke-linecap", "round");
svg.appendChild(path);
}
},
function (_a) {
var color = _a.color,point = _a.point;
var circle = document.createElement("circle");
var dotSize = _a.dotSize ? _a.dotSize : typeof _this.dotSize === "function" ? _this.dotSize() : _this.dotSize;
circle.setAttribute("r", dotSize.toString());
circle.setAttribute("cx", point.x.toString());
circle.setAttribute("cy", point.y.toString());
circle.setAttribute("fill", color);
svg.appendChild(circle);
}
);
var prefix = 'data:image/svg+xml;base64,';
var header = '<svg' +
' xmlns="http://www.w3.org/2000/svg"' +
' xmlns:xlink="http://www.w3.org/1999/xlink"' +
(" viewBox=\\"" + minX + " " + minY + " " + maxX + " " + maxY + "\\"") +
(" width=\\"" + maxX + "\\"") +
(" height=\\"" + maxY + "\\"") +
'>';
var body = svg.innerHTML;
if (body === undefined) {
var dummy = document.createElement('dummy');
var nodes = svg.childNodes;
dummy.innerHTML = '';
for (var i = 0; i < nodes.length; i += 1) {
dummy.appendChild(nodes[i].cloneNode(true));
}
body = dummy.innerHTML;
}
var footer = '</svg>';
var data = header + body + footer;
return prefix + btoa(data);
};
return SignaturePad;
}());
return SignaturePad;
})));
`;