1 | const pi = Math.PI, tau = 2 * pi, epsilon = 1e-6, tauEpsilon = tau - epsilon;
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2 | function Path() {
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3 | this._x0 = this._y0 =
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4 | this._x1 = this._y1 = null;
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5 | this._ = "";
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6 | }
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7 | function path() {
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8 | return new Path();
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9 | }
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10 | Path.prototype = path.prototype = {
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11 | constructor: Path,
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12 | moveTo: function(x, y) {
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13 | this._ += "M" + (this._x0 = this._x1 = +x) + "," + (this._y0 = this._y1 = +y);
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14 | },
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15 | closePath: function() {
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16 | if (this._x1 !== null) {
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17 | this._x1 = this._x0, this._y1 = this._y0;
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18 | this._ += "Z";
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19 | }
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20 | },
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21 | lineTo: function(x, y) {
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22 | this._ += "L" + (this._x1 = +x) + "," + (this._y1 = +y);
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23 | },
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24 | quadraticCurveTo: function(x1, y1, x, y) {
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25 | this._ += "Q" + +x1 + "," + +y1 + "," + (this._x1 = +x) + "," + (this._y1 = +y);
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26 | },
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27 | bezierCurveTo: function(x1, y1, x2, y2, x, y) {
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28 | this._ += "C" + +x1 + "," + +y1 + "," + +x2 + "," + +y2 + "," + (this._x1 = +x) + "," + (this._y1 = +y);
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29 | },
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30 | arcTo: function(x1, y1, x2, y2, r) {
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31 | x1 = +x1, y1 = +y1, x2 = +x2, y2 = +y2, r = +r;
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32 | var x0 = this._x1, y0 = this._y1, x21 = x2 - x1, y21 = y2 - y1, x01 = x0 - x1, y01 = y0 - y1, l01_2 = x01 * x01 + y01 * y01;
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33 | if (r < 0)
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34 | throw new Error("negative radius: " + r);
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35 | if (this._x1 === null) {
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36 | this._ += "M" + (this._x1 = x1) + "," + (this._y1 = y1);
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37 | } else if (!(l01_2 > epsilon))
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38 | ;
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39 | else if (!(Math.abs(y01 * x21 - y21 * x01) > epsilon) || !r) {
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40 | this._ += "L" + (this._x1 = x1) + "," + (this._y1 = y1);
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41 | } else {
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42 | var x20 = x2 - x0, y20 = y2 - y0, l21_2 = x21 * x21 + y21 * y21, l20_2 = x20 * x20 + y20 * y20, l21 = Math.sqrt(l21_2), l01 = Math.sqrt(l01_2), l = r * Math.tan((pi - Math.acos((l21_2 + l01_2 - l20_2) / (2 * l21 * l01))) / 2), t01 = l / l01, t21 = l / l21;
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43 | if (Math.abs(t01 - 1) > epsilon) {
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44 | this._ += "L" + (x1 + t01 * x01) + "," + (y1 + t01 * y01);
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45 | }
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46 | this._ += "A" + r + "," + r + ",0,0," + +(y01 * x20 > x01 * y20) + "," + (this._x1 = x1 + t21 * x21) + "," + (this._y1 = y1 + t21 * y21);
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47 | }
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48 | },
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49 | arc: function(x, y, r, a0, a1, ccw) {
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50 | x = +x, y = +y, r = +r, ccw = !!ccw;
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51 | var dx = r * Math.cos(a0), dy = r * Math.sin(a0), x0 = x + dx, y0 = y + dy, cw = 1 ^ ccw, da = ccw ? a0 - a1 : a1 - a0;
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52 | if (r < 0)
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53 | throw new Error("negative radius: " + r);
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54 | if (this._x1 === null) {
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55 | this._ += "M" + x0 + "," + y0;
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56 | } else if (Math.abs(this._x1 - x0) > epsilon || Math.abs(this._y1 - y0) > epsilon) {
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57 | this._ += "L" + x0 + "," + y0;
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58 | }
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59 | if (!r)
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60 | return;
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61 | if (da < 0)
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62 | da = da % tau + tau;
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63 | if (da > tauEpsilon) {
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64 | this._ += "A" + r + "," + r + ",0,1," + cw + "," + (x - dx) + "," + (y - dy) + "A" + r + "," + r + ",0,1," + cw + "," + (this._x1 = x0) + "," + (this._y1 = y0);
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65 | } else if (da > epsilon) {
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66 | this._ += "A" + r + "," + r + ",0," + +(da >= pi) + "," + cw + "," + (this._x1 = x + r * Math.cos(a1)) + "," + (this._y1 = y + r * Math.sin(a1));
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67 | }
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68 | },
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69 | rect: function(x, y, w, h) {
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70 | this._ += "M" + (this._x0 = this._x1 = +x) + "," + (this._y0 = this._y1 = +y) + "h" + +w + "v" + +h + "h" + -w + "Z";
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71 | },
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72 | toString: function() {
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73 | return this._;
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74 | }
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75 | };
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76 | function constant(x) {
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77 | return function constant2() {
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78 | return x;
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79 | };
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80 | }
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81 | export {
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82 | constant as c,
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83 | path as p
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84 | };
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