signature_pad/dist/signature_pad.js

/*!
 * Signature Pad v4.0.0 | https://github.com/szimek/signature_pad
 * (c) 2021 Szymon Nowak | Released under the MIT license
 */

class Point {
    constructor(x, y, pressure, time) {
        if (isNaN(x) || isNaN(y)) {
            throw new Error(`Point is invalid: (${x}, ${y})`);
        }
        this.x = +x;
        this.y = +y;
        this.pressure = pressure || 0;
        this.time = time || Date.now();
    }
    distanceTo(start) {
        return Math.sqrt(Math.pow(this.x - start.x, 2) + Math.pow(this.y - start.y, 2));
    }
    equals(other) {
        return (this.x === other.x &&
            this.y === other.y &&
            this.pressure === other.pressure &&
            this.time === other.time);
    }
    velocityFrom(start) {
        return this.time !== start.time
            ? this.distanceTo(start) / (this.time - start.time)
            : 0;
    }
}

class Bezier {
    constructor(startPoint, control2, control1, endPoint, startWidth, endWidth) {
        this.startPoint = startPoint;
        this.control2 = control2;
        this.control1 = control1;
        this.endPoint = endPoint;
        this.startWidth = startWidth;
        this.endWidth = endWidth;
    }
    static fromPoints(points, widths) {
        const c2 = this.calculateControlPoints(points[0], points[1], points[2]).c2;
        const c3 = this.calculateControlPoints(points[1], points[2], points[3]).c1;
        return new Bezier(points[1], c2, c3, points[2], widths.start, widths.end);
    }
    static calculateControlPoints(s1, s2, s3) {
        const dx1 = s1.x - s2.x;
        const dy1 = s1.y - s2.y;
        const dx2 = s2.x - s3.x;
        const dy2 = s2.y - s3.y;
        const m1 = { x: (s1.x + s2.x) / 2.0, y: (s1.y + s2.y) / 2.0 };
        const m2 = { x: (s2.x + s3.x) / 2.0, y: (s2.y + s3.y) / 2.0 };
        const l1 = Math.sqrt(dx1 * dx1 + dy1 * dy1);
        const l2 = Math.sqrt(dx2 * dx2 + dy2 * dy2);
        const dxm = m1.x - m2.x;
        const dym = m1.y - m2.y;
        const k = l2 / (l1 + l2);
        const cm = { x: m2.x + dxm * k, y: m2.y + dym * k };
        const tx = s2.x - cm.x;
        const ty = s2.y - cm.y;
        return {
            c1: new Point(m1.x + tx, m1.y + ty),
            c2: new Point(m2.x + tx, m2.y + ty),
        };
    }
    length() {
        const steps = 10;
        let length = 0;
        let px;
        let py;
        for (let i = 0; i <= steps; i += 1) {
            const t = i / steps;
            const cx = this.point(t, this.startPoint.x, this.control1.x, this.control2.x, this.endPoint.x);
            const cy = this.point(t, this.startPoint.y, this.control1.y, this.control2.y, this.endPoint.y);
            if (i > 0) {
                const xdiff = cx - px;
                const ydiff = cy - py;
                length += Math.sqrt(xdiff * xdiff + ydiff * ydiff);
            }
            px = cx;
            py = cy;
        }
        return length;
    }
    point(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);
    }
}

function throttle(fn, wait = 250) {
    let previous = 0;
    let timeout = null;
    let result;
    let storedContext;
    let storedArgs;
    const later = () => {
        previous = Date.now();
        timeout = null;
        result = fn.apply(storedContext, storedArgs);
        if (!timeout) {
            storedContext = null;
            storedArgs = [];
        }
    };
    return function wrapper(...args) {
        const now = Date.now();
        const 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;
    };
}

class SignaturePad extends EventTarget {
    constructor(canvas, options = {}) {
        super();
        this.canvas = canvas;
        this.options = options;
        this._handleMouseDown = (event) => {
            if (event.buttons === 1) {
                this._drawningStroke = true;
                this._strokeBegin(event);
            }
        };
        this._handleMouseMove = (event) => {
            if (this._drawningStroke) {
                this._strokeMoveUpdate(event);
            }
        };
        this._handleMouseUp = (event) => {
            if (event.buttons === 1 && this._drawningStroke) {
                this._drawningStroke = false;
                this._strokeEnd(event);
            }
        };
        this._handleTouchStart = (event) => {
            event.preventDefault();
            if (event.targetTouches.length === 1) {
                const touch = event.changedTouches[0];
                this._strokeBegin(touch);
            }
        };
        this._handleTouchMove = (event) => {
            event.preventDefault();
            const touch = event.targetTouches[0];
            this._strokeMoveUpdate(touch);
        };
        this._handleTouchEnd = (event) => {
            const wasCanvasTouched = event.target === this.canvas;
            if (wasCanvasTouched) {
                event.preventDefault();
                const touch = event.changedTouches[0];
                this._strokeEnd(touch);
            }
        };
        this._handlePointerStart = (event) => {
            this._drawningStroke = true;
            event.preventDefault();
            this._strokeBegin(event);
        };
        this._handlePointerMove = (event) => {
            if (this._drawningStroke) {
                event.preventDefault();
                this._strokeMoveUpdate(event);
            }
        };
        this._handlePointerEnd = (event) => {
            this._drawningStroke = false;
            const wasCanvasTouched = event.target === this.canvas;
            if (wasCanvasTouched) {
                event.preventDefault();
                this._strokeEnd(event);
            }
        };
        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.dotSize = options.dotSize || 0;
        this.penColor = options.penColor || 'black';
        this.backgroundColor = options.backgroundColor || 'rgba(0,0,0,0)';
        this._strokeMoveUpdate = this.throttle
            ? throttle(SignaturePad.prototype._strokeUpdate, this.throttle)
            : SignaturePad.prototype._strokeUpdate;
        this._ctx = canvas.getContext('2d');
        this.clear();
        this.on();
    }
    clear() {
        const { _ctx: ctx, canvas } = this;
        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;
    }
    fromDataURL(dataUrl, options = {}) {
        return new Promise((resolve, reject) => {
            const image = new Image();
            const ratio = options.ratio || window.devicePixelRatio || 1;
            const width = options.width || this.canvas.width / ratio;
            const height = options.height || this.canvas.height / ratio;
            const xOffset = options.xOffset || 0;
            const yOffset = options.yOffset || 0;
            this._reset();
            image.onload = () => {
                this._ctx.drawImage(image, xOffset, yOffset, width, height);
                resolve();
            };
            image.onerror = (error) => {
                reject(error);
            };
            image.crossOrigin = 'anonymous';
            image.src = dataUrl;
            this._isEmpty = false;
        });
    }
    toDataURL(type = 'image/png', encoderOptions) {
        switch (type) {
            case 'image/svg+xml':
                return this._toSVG();
            default:
                return this.canvas.toDataURL(type, encoderOptions);
        }
    }
    on() {
        this.canvas.style.touchAction = 'none';
        this.canvas.style.msTouchAction = 'none';
        if (window.PointerEvent) {
            this._handlePointerEvents();
        }
        else {
            this._handleMouseEvents();
            if ('ontouchstart' in window) {
                this._handleTouchEvents();
            }
        }
    }
    off() {
        this.canvas.style.touchAction = 'auto';
        this.canvas.style.msTouchAction = 'auto';
        this.canvas.removeEventListener('pointerdown', this._handlePointerStart);
        this.canvas.removeEventListener('pointermove', this._handlePointerMove);
        document.removeEventListener('pointerup', this._handlePointerEnd);
        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);
    }
    isEmpty() {
        return this._isEmpty;
    }
    fromData(pointGroups, { clear = true } = {}) {
        if (clear) {
            this.clear();
        }
        this._fromData(pointGroups, this._drawCurve.bind(this), this._drawDot.bind(this));
        this._data = clear ? pointGroups : this._data.concat(pointGroups);
    }
    toData() {
        return this._data;
    }
    _strokeBegin(event) {
        this.dispatchEvent(new CustomEvent('beginStroke', { detail: event }));
        const newPointGroup = {
            dotSize: this.dotSize,
            minWidth: this.minWidth,
            maxWidth: this.maxWidth,
            penColor: this.penColor,
            points: [],
        };
        this._data.push(newPointGroup);
        this._reset();
        this._strokeUpdate(event);
    }
    _strokeUpdate(event) {
        if (this._data.length === 0) {
            this._strokeBegin(event);
            return;
        }
        this.dispatchEvent(new CustomEvent('beforeUpdateStroke', { detail: event }));
        const x = event.clientX;
        const y = event.clientY;
        const pressure = event.pressure !== undefined
            ? event.pressure
            : event.force !== undefined
                ? event.force
                : 0;
        const point = this._createPoint(x, y, pressure);
        const lastPointGroup = this._data[this._data.length - 1];
        const lastPoints = lastPointGroup.points;
        const lastPoint = lastPoints.length > 0 && lastPoints[lastPoints.length - 1];
        const isLastPointTooClose = lastPoint
            ? point.distanceTo(lastPoint) <= this.minDistance
            : false;
        const { penColor, dotSize, minWidth, maxWidth } = lastPointGroup;
        if (!lastPoint || !(lastPoint && isLastPointTooClose)) {
            const curve = this._addPoint(point);
            if (!lastPoint) {
                this._drawDot(point, {
                    penColor,
                    dotSize,
                    minWidth,
                    maxWidth,
                });
            }
            else if (curve) {
                this._drawCurve(curve, {
                    penColor,
                    dotSize,
                    minWidth,
                    maxWidth,
                });
            }
            lastPoints.push({
                time: point.time,
                x: point.x,
                y: point.y,
                pressure: point.pressure,
            });
        }
        this.dispatchEvent(new CustomEvent('afterUpdateStroke', { detail: event }));
    }
    _strokeEnd(event) {
        this._strokeUpdate(event);
        this.dispatchEvent(new CustomEvent('endStroke', { detail: event }));
    }
    _handlePointerEvents() {
        this._drawningStroke = false;
        this.canvas.addEventListener('pointerdown', this._handlePointerStart);
        this.canvas.addEventListener('pointermove', this._handlePointerMove);
        document.addEventListener('pointerup', this._handlePointerEnd);
    }
    _handleMouseEvents() {
        this._drawningStroke = false;
        this.canvas.addEventListener('mousedown', this._handleMouseDown);
        this.canvas.addEventListener('mousemove', this._handleMouseMove);
        document.addEventListener('mouseup', this._handleMouseUp);
    }
    _handleTouchEvents() {
        this.canvas.addEventListener('touchstart', this._handleTouchStart);
        this.canvas.addEventListener('touchmove', this._handleTouchMove);
        this.canvas.addEventListener('touchend', this._handleTouchEnd);
    }
    _reset() {
        this._lastPoints = [];
        this._lastVelocity = 0;
        this._lastWidth = (this.minWidth + this.maxWidth) / 2;
        this._ctx.fillStyle = this.penColor;
    }
    _createPoint(x, y, pressure) {
        const rect = this.canvas.getBoundingClientRect();
        return new Point(x - rect.left, y - rect.top, pressure, new Date().getTime());
    }
    _addPoint(point) {
        const { _lastPoints } = this;
        _lastPoints.push(point);
        if (_lastPoints.length > 2) {
            if (_lastPoints.length === 3) {
                _lastPoints.unshift(_lastPoints[0]);
            }
            const widths = this._calculateCurveWidths(_lastPoints[1], _lastPoints[2]);
            const curve = Bezier.fromPoints(_lastPoints, widths);
            _lastPoints.shift();
            return curve;
        }
        return null;
    }
    _calculateCurveWidths(startPoint, endPoint) {
        const velocity = this.velocityFilterWeight * endPoint.velocityFrom(startPoint) +
            (1 - this.velocityFilterWeight) * this._lastVelocity;
        const newWidth = this._strokeWidth(velocity);
        const widths = {
            end: newWidth,
            start: this._lastWidth,
        };
        this._lastVelocity = velocity;
        this._lastWidth = newWidth;
        return widths;
    }
    _strokeWidth(velocity) {
        return Math.max(this.maxWidth / (velocity + 1), this.minWidth);
    }
    _drawCurveSegment(x, y, width) {
        const ctx = this._ctx;
        ctx.moveTo(x, y);
        ctx.arc(x, y, width, 0, 2 * Math.PI, false);
        this._isEmpty = false;
    }
    _drawCurve(curve, options) {
        const ctx = this._ctx;
        const widthDelta = curve.endWidth - curve.startWidth;
        const drawSteps = Math.ceil(curve.length()) * 2;
        ctx.beginPath();
        ctx.fillStyle = options.penColor;
        for (let i = 0; i < drawSteps; i += 1) {
            const t = i / drawSteps;
            const tt = t * t;
            const ttt = tt * t;
            const u = 1 - t;
            const uu = u * u;
            const uuu = uu * u;
            let x = uuu * curve.startPoint.x;
            x += 3 * uu * t * curve.control1.x;
            x += 3 * u * tt * curve.control2.x;
            x += ttt * curve.endPoint.x;
            let y = uuu * curve.startPoint.y;
            y += 3 * uu * t * curve.control1.y;
            y += 3 * u * tt * curve.control2.y;
            y += ttt * curve.endPoint.y;
            const width = Math.min(curve.startWidth + ttt * widthDelta, options.maxWidth);
            this._drawCurveSegment(x, y, width);
        }
        ctx.closePath();
        ctx.fill();
    }
    _drawDot(point, options) {
        const ctx = this._ctx;
        const width = options.dotSize > 0
            ? options.dotSize
            : (options.minWidth + options.maxWidth) / 2;
        ctx.beginPath();
        this._drawCurveSegment(point.x, point.y, width);
        ctx.closePath();
        ctx.fillStyle = options.penColor;
        ctx.fill();
    }
    _fromData(pointGroups, drawCurve, drawDot) {
        for (const group of pointGroups) {
            const { penColor, dotSize, minWidth, maxWidth, points } = group;
            if (points.length > 1) {
                for (let j = 0; j < points.length; j += 1) {
                    const basicPoint = points[j];
                    const point = new Point(basicPoint.x, basicPoint.y, basicPoint.pressure, basicPoint.time);
                    this.penColor = penColor;
                    if (j === 0) {
                        this._reset();
                    }
                    const curve = this._addPoint(point);
                    if (curve) {
                        drawCurve(curve, {
                            penColor,
                            dotSize,
                            minWidth,
                            maxWidth,
                        });
                    }
                }
            }
            else {
                this._reset();
                drawDot(points[0], {
                    penColor,
                    dotSize,
                    minWidth,
                    maxWidth,
                });
            }
        }
    }
    _toSVG() {
        const pointGroups = this._data;
        const ratio = Math.max(window.devicePixelRatio || 1, 1);
        const minX = 0;
        const minY = 0;
        const maxX = this.canvas.width / ratio;
        const maxY = this.canvas.height / ratio;
        const 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, (curve, { penColor }) => {
            const path = document.createElement('path');
            if (!isNaN(curve.control1.x) &&
                !isNaN(curve.control1.y) &&
                !isNaN(curve.control2.x) &&
                !isNaN(curve.control2.y)) {
                const 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', penColor);
                path.setAttribute('fill', 'none');
                path.setAttribute('stroke-linecap', 'round');
                svg.appendChild(path);
            }
        }, (point, { penColor, dotSize, minWidth, maxWidth }) => {
            const circle = document.createElement('circle');
            const size = dotSize > 0 ? dotSize : (minWidth + maxWidth) / 2;
            circle.setAttribute('r', size.toString());
            circle.setAttribute('cx', point.x.toString());
            circle.setAttribute('cy', point.y.toString());
            circle.setAttribute('fill', penColor);
            svg.appendChild(circle);
        });
        const prefix = 'data:image/svg+xml;base64,';
        const header = '<svg' +
            ' xmlns="http://www.w3.org/2000/svg"' +
            ' xmlns:xlink="http://www.w3.org/1999/xlink"' +
            ` viewBox="${minX} ${minY} ${this.canvas.width} ${this.canvas.height}"` +
            ` width="${maxX}"` +
            ` height="${maxY}"` +
            '>';
        let body = svg.innerHTML;
        if (body === undefined) {
            const dummy = document.createElement('dummy');
            const nodes = svg.childNodes;
            dummy.innerHTML = '';
            for (let i = 0; i < nodes.length; i += 1) {
                dummy.appendChild(nodes[i].cloneNode(true));
            }
            body = dummy.innerHTML;
        }
        const footer = '</svg>';
        const data = header + body + footer;
        return prefix + btoa(data);
    }
}

export { SignaturePad as default };
//# sourceMappingURL=signature_pad.js.map