1 | const pi = Math.PI,
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2 | tau = 2 * pi,
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3 | epsilon = 1e-6,
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4 | tauEpsilon = tau - epsilon;
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5 |
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6 | function append(strings) {
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7 | this._ += strings[0];
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8 | for (let i = 1, n = strings.length; i < n; ++i) {
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9 | this._ += arguments[i] + strings[i];
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10 | }
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11 | }
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12 |
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13 | function appendRound(digits) {
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14 | let d = Math.floor(digits);
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15 | if (!(d >= 0)) throw new Error(`invalid digits: ${digits}`);
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16 | if (d > 15) return append;
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17 | const k = 10 ** d;
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18 | return function(strings) {
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19 | this._ += strings[0];
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20 | for (let i = 1, n = strings.length; i < n; ++i) {
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21 | this._ += Math.round(arguments[i] * k) / k + strings[i];
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22 | }
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23 | };
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24 | }
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25 |
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26 | export class Path {
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27 | constructor(digits) {
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28 | this._x0 = this._y0 =
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29 | this._x1 = this._y1 = null;
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30 | this._ = "";
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31 | this._append = digits == null ? append : appendRound(digits);
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32 | }
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33 | moveTo(x, y) {
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34 | this._append`M${this._x0 = this._x1 = +x},${this._y0 = this._y1 = +y}`;
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35 | }
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36 | closePath() {
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37 | if (this._x1 !== null) {
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38 | this._x1 = this._x0, this._y1 = this._y0;
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39 | this._append`Z`;
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40 | }
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41 | }
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42 | lineTo(x, y) {
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43 | this._append`L${this._x1 = +x},${this._y1 = +y}`;
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44 | }
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45 | quadraticCurveTo(x1, y1, x, y) {
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46 | this._append`Q${+x1},${+y1},${this._x1 = +x},${this._y1 = +y}`;
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47 | }
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48 | bezierCurveTo(x1, y1, x2, y2, x, y) {
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49 | this._append`C${+x1},${+y1},${+x2},${+y2},${this._x1 = +x},${this._y1 = +y}`;
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50 | }
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51 | arcTo(x1, y1, x2, y2, r) {
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52 | x1 = +x1, y1 = +y1, x2 = +x2, y2 = +y2, r = +r;
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53 |
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54 |
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55 | if (r < 0) throw new Error(`negative radius: ${r}`);
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56 |
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57 | let x0 = this._x1,
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58 | y0 = this._y1,
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59 | x21 = x2 - x1,
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60 | y21 = y2 - y1,
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61 | x01 = x0 - x1,
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62 | y01 = y0 - y1,
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63 | l01_2 = x01 * x01 + y01 * y01;
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64 |
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65 |
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66 | if (this._x1 === null) {
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67 | this._append`M${this._x1 = x1},${this._y1 = y1}`;
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68 | }
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69 |
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70 |
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71 | else if (!(l01_2 > epsilon));
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72 |
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73 |
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74 |
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75 |
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76 | else if (!(Math.abs(y01 * x21 - y21 * x01) > epsilon) || !r) {
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77 | this._append`L${this._x1 = x1},${this._y1 = y1}`;
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78 | }
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79 |
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80 |
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81 | else {
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82 | let x20 = x2 - x0,
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83 | y20 = y2 - y0,
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84 | l21_2 = x21 * x21 + y21 * y21,
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85 | l20_2 = x20 * x20 + y20 * y20,
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86 | l21 = Math.sqrt(l21_2),
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87 | l01 = Math.sqrt(l01_2),
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88 | l = r * Math.tan((pi - Math.acos((l21_2 + l01_2 - l20_2) / (2 * l21 * l01))) / 2),
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89 | t01 = l / l01,
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90 | t21 = l / l21;
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91 |
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92 |
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93 | if (Math.abs(t01 - 1) > epsilon) {
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94 | this._append`L${x1 + t01 * x01},${y1 + t01 * y01}`;
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95 | }
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96 |
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97 | this._append`A${r},${r},0,0,${+(y01 * x20 > x01 * y20)},${this._x1 = x1 + t21 * x21},${this._y1 = y1 + t21 * y21}`;
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98 | }
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99 | }
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100 | arc(x, y, r, a0, a1, ccw) {
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101 | x = +x, y = +y, r = +r, ccw = !!ccw;
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102 |
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103 |
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104 | if (r < 0) throw new Error(`negative radius: ${r}`);
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105 |
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106 | let dx = r * Math.cos(a0),
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107 | dy = r * Math.sin(a0),
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108 | x0 = x + dx,
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109 | y0 = y + dy,
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110 | cw = 1 ^ ccw,
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111 | da = ccw ? a0 - a1 : a1 - a0;
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112 |
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113 |
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114 | if (this._x1 === null) {
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115 | this._append`M${x0},${y0}`;
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116 | }
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117 |
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118 |
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119 | else if (Math.abs(this._x1 - x0) > epsilon || Math.abs(this._y1 - y0) > epsilon) {
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120 | this._append`L${x0},${y0}`;
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121 | }
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122 |
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123 |
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124 | if (!r) return;
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125 |
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126 |
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127 | if (da < 0) da = da % tau + tau;
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128 |
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129 |
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130 | if (da > tauEpsilon) {
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131 | this._append`A${r},${r},0,1,${cw},${x - dx},${y - dy}A${r},${r},0,1,${cw},${this._x1 = x0},${this._y1 = y0}`;
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132 | }
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133 |
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134 |
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135 | else if (da > epsilon) {
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136 | this._append`A${r},${r},0,${+(da >= pi)},${cw},${this._x1 = x + r * Math.cos(a1)},${this._y1 = y + r * Math.sin(a1)}`;
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137 | }
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138 | }
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139 | rect(x, y, w, h) {
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140 | this._append`M${this._x0 = this._x1 = +x},${this._y0 = this._y1 = +y}h${w = +w}v${+h}h${-w}Z`;
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141 | }
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142 | toString() {
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143 | return this._;
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144 | }
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145 | }
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146 |
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147 | export function path() {
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148 | return new Path;
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149 | }
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150 |
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151 |
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152 | path.prototype = Path.prototype;
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153 |
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154 | export function pathRound(digits = 3) {
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155 | return new Path(+digits);
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156 | }
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