diff options
Diffstat (limited to '')
| -rw-r--r-- | main/survey/js/signature_pad.js | 323 |
1 files changed, 323 insertions, 0 deletions
diff --git a/main/survey/js/signature_pad.js b/main/survey/js/signature_pad.js new file mode 100644 index 0000000..703c579 --- /dev/null +++ b/main/survey/js/signature_pad.js @@ -0,0 +1,323 @@ +var SignaturePad = (function (document) {
+ "use strict";
+
+ var SignaturePad = function (canvas, options) {
+ var self = this,
+ opts = options || {};
+
+ this.velocityFilterWeight = opts.velocityFilterWeight || 0.7;
+ this.minWidth = opts.minWidth || 0.5;
+ this.maxWidth = opts.maxWidth || 2.5;
+ this.dotSize = opts.dotSize || function () {
+ return (this.minWidth + this.maxWidth) / 2;
+ };
+ this.penColor = opts.penColor || "black";
+ this.backgroundColor = opts.backgroundColor || "rgba(0,0,0,0)";
+ this.onEnd = opts.onEnd;
+ this.onBegin = opts.onBegin;
+
+ this._canvas = canvas;
+ this._ctx = canvas.getContext("2d");
+ this.clear();
+
+ this._handleMouseEvents();
+ this._handleTouchEvents();
+ };
+
+ SignaturePad.prototype.clear = function () {
+ var ctx = this._ctx,
+ canvas = this._canvas;
+
+ ctx.fillStyle = this.backgroundColor;
+ ctx.clearRect(0, 0, canvas.width, canvas.height);
+ ctx.fillRect(0, 0, canvas.width, canvas.height);
+ this._reset();
+ };
+
+ SignaturePad.prototype.toDataURL = function (imageType, quality) {
+ var canvas = this._canvas;
+ return canvas.toDataURL.apply(canvas, arguments);
+ };
+
+ SignaturePad.prototype.fromDataURL = function (dataUrl) {
+ var self = this,
+ image = new Image();
+
+ this._reset();
+ image.src = dataUrl;
+ image.onload = function () {
+ self._ctx.drawImage(image, 0, 0, self._canvas.width, self._canvas.height);
+ };
+ this._isEmpty = false;
+ };
+
+ SignaturePad.prototype._strokeUpdate = function (event) {
+ var point = this._createPoint(event);
+ this._addPoint(point);
+ };
+
+ SignaturePad.prototype._strokeBegin = function (event) {
+ this._reset();
+ this._strokeUpdate(event);
+ if (typeof this.onBegin === 'function') {
+ this.onBegin(event);
+ }
+ };
+
+ SignaturePad.prototype._strokeDraw = function (point) {
+ var ctx = this._ctx,
+ dotSize = typeof(this.dotSize) === 'function' ? this.dotSize() : this.dotSize;
+
+ ctx.beginPath();
+ this._drawPoint(point.x, point.y, dotSize);
+ ctx.closePath();
+ ctx.fill();
+ };
+
+ SignaturePad.prototype._strokeEnd = function (event) {
+ var canDrawCurve = this.points.length > 2,
+ point = this.points[0];
+
+ if (!canDrawCurve && point) {
+ this._strokeDraw(point);
+ }
+ if (typeof this.onEnd === 'function') {
+ this.onEnd(event);
+ }
+ };
+
+ SignaturePad.prototype._handleMouseEvents = function () {
+ var self = this;
+ this._mouseButtonDown = false;
+
+ this._canvas.addEventListener("mousedown", function (event) {
+ if (event.which === 1) {
+ self._mouseButtonDown = true;
+ self._strokeBegin(event);
+ }
+ });
+
+ this._canvas.addEventListener("mousemove", function (event) {
+ if (self._mouseButtonDown) {
+ self._strokeUpdate(event);
+ }
+ });
+
+ document.addEventListener("mouseup", function (event) {
+ if (event.which === 1 && self._mouseButtonDown) {
+ self._mouseButtonDown = false;
+ self._strokeEnd(event);
+ }
+ });
+ };
+
+ SignaturePad.prototype._handleTouchEvents = function () {
+ var self = this;
+
+ // Pass touch events to canvas element on mobile IE.
+ this._canvas.style.msTouchAction = 'none';
+
+ this._canvas.addEventListener("touchstart", function (event) {
+ var touch = event.changedTouches[0];
+ self._strokeBegin(touch);
+ });
+
+ this._canvas.addEventListener("touchmove", function (event) {
+ // Prevent scrolling.
+ event.preventDefault();
+
+ var touch = event.changedTouches[0];
+ self._strokeUpdate(touch);
+ });
+
+ document.addEventListener("touchend", function (event) {
+ var wasCanvasTouched = event.target === self._canvas;
+ if (wasCanvasTouched) {
+ self._strokeEnd(event);
+ }
+ });
+ };
+
+ SignaturePad.prototype.isEmpty = function () {
+ return this._isEmpty;
+ };
+
+ SignaturePad.prototype._reset = function () {
+ this.points = [];
+ this._lastVelocity = 0;
+ this._lastWidth = (this.minWidth + this.maxWidth) / 2;
+ this._isEmpty = true;
+ this._ctx.fillStyle = this.penColor;
+ };
+
+ SignaturePad.prototype._createPoint = function (event) {
+ var rect = this._canvas.getBoundingClientRect();
+ return new Point(
+ event.clientX - rect.left,
+ event.clientY - rect.top
+ );
+ };
+
+ SignaturePad.prototype._addPoint = function (point) {
+ var points = this.points,
+ c2, c3,
+ curve, tmp;
+
+ points.push(point);
+
+ if (points.length > 2) {
+ // To reduce the initial lag make it work with 3 points
+ // by copying the first point to the beginning.
+ if (points.length === 3) points.unshift(points[0]);
+
+ tmp = this._calculateCurveControlPoints(points[0], points[1], points[2]);
+ c2 = tmp.c2;
+ tmp = this._calculateCurveControlPoints(points[1], points[2], points[3]);
+ c3 = tmp.c1;
+ curve = new Bezier(points[1], c2, c3, points[2]);
+ this._addCurve(curve);
+
+ // Remove the first element from the list,
+ // so that we always have no more than 4 points in points array.
+ points.shift();
+ }
+ };
+
+ SignaturePad.prototype._calculateCurveControlPoints = function (s1, s2, s3) {
+ var dx1 = s1.x - s2.x, dy1 = s1.y - s2.y,
+ dx2 = s2.x - s3.x, dy2 = s2.y - s3.y,
+
+ m1 = {x: (s1.x + s2.x) / 2.0, y: (s1.y + s2.y) / 2.0},
+ m2 = {x: (s2.x + s3.x) / 2.0, y: (s2.y + s3.y) / 2.0},
+
+ l1 = Math.sqrt(dx1*dx1 + dy1*dy1),
+ l2 = Math.sqrt(dx2*dx2 + dy2*dy2),
+
+ dxm = (m1.x - m2.x),
+ dym = (m1.y - m2.y),
+
+ k = l2 / (l1 + l2),
+ cm = {x: m2.x + dxm*k, y: m2.y + dym*k},
+
+ tx = s2.x - cm.x,
+ ty = s2.y - cm.y;
+
+ return {
+ c1: new Point(m1.x + tx, m1.y + ty),
+ c2: new Point(m2.x + tx, m2.y + ty)
+ };
+ };
+
+ SignaturePad.prototype._addCurve = function (curve) {
+ var startPoint = curve.startPoint,
+ endPoint = curve.endPoint,
+ velocity, newWidth;
+
+ velocity = endPoint.velocityFrom(startPoint);
+ velocity = this.velocityFilterWeight * velocity
+ + (1 - this.velocityFilterWeight) * this._lastVelocity;
+
+ newWidth = this._strokeWidth(velocity);
+ this._drawCurve(curve, this._lastWidth, newWidth);
+
+ this._lastVelocity = velocity;
+ this._lastWidth = newWidth;
+ };
+
+ SignaturePad.prototype._drawPoint = function (x, y, size) {
+ var ctx = this._ctx;
+
+ ctx.moveTo(x, y);
+ ctx.arc(x, y, size, 0, 2 * Math.PI, false);
+ this._isEmpty = false;
+ };
+
+ SignaturePad.prototype._drawCurve = function (curve, startWidth, endWidth) {
+ var ctx = this._ctx,
+ widthDelta = endWidth - startWidth,
+ drawSteps, width, i, t, tt, ttt, u, uu, uuu, x, y;
+
+ drawSteps = Math.floor(curve.length());
+ ctx.beginPath();
+ for (i = 0; i < drawSteps; i++) {
+ // Calculate the Bezier (x, y) coordinate for this step.
+ t = i / drawSteps;
+ tt = t * t;
+ ttt = tt * t;
+ u = 1 - t;
+ uu = u * u;
+ uuu = uu * u;
+
+ x = uuu * curve.startPoint.x;
+ x += 3 * uu * t * curve.control1.x;
+ x += 3 * u * tt * curve.control2.x;
+ x += ttt * curve.endPoint.x;
+
+ y = uuu * curve.startPoint.y;
+ y += 3 * uu * t * curve.control1.y;
+ y += 3 * u * tt * curve.control2.y;
+ y += ttt * curve.endPoint.y;
+
+ width = startWidth + ttt * widthDelta;
+ this._drawPoint(x, y, width);
+ }
+ ctx.closePath();
+ ctx.fill();
+ };
+
+ SignaturePad.prototype._strokeWidth = function (velocity) {
+ return Math.max(this.maxWidth / (velocity + 1), this.minWidth);
+ };
+
+
+ var Point = function (x, y, time) {
+ this.x = x;
+ this.y = y;
+ this.time = time || new Date().getTime();
+ };
+
+ Point.prototype.velocityFrom = function (start) {
+ return (this.time !== start.time) ? this.distanceTo(start) / (this.time - start.time) : 1;
+ };
+
+ Point.prototype.distanceTo = function (start) {
+ return Math.sqrt(Math.pow(this.x - start.x, 2) + Math.pow(this.y - start.y, 2));
+ };
+
+ var Bezier = function (startPoint, control1, control2, endPoint) {
+ this.startPoint = startPoint;
+ this.control1 = control1;
+ this.control2 = control2;
+ this.endPoint = endPoint;
+ };
+
+ // Returns approximated length.
+ Bezier.prototype.length = function () {
+ var steps = 10,
+ length = 0,
+ i, t, cx, cy, px, py, xdiff, ydiff;
+
+ for (i = 0; i <= steps; i++) {
+ t = i / steps;
+ cx = this._point(t, this.startPoint.x, this.control1.x, this.control2.x, this.endPoint.x);
+ cy = this._point(t, this.startPoint.y, this.control1.y, this.control2.y, this.endPoint.y);
+ if (i > 0) {
+ xdiff = cx - px;
+ 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 SignaturePad;
+})(document);
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