62 lines
1.6 KiB
JavaScript
62 lines
1.6 KiB
JavaScript
export function point(that, x, y) {
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that._context.bezierCurveTo(
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that._x1 + that._k * (that._x2 - that._x0),
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that._y1 + that._k * (that._y2 - that._y0),
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that._x2 + that._k * (that._x1 - x),
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that._y2 + that._k * (that._y1 - y),
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that._x2,
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that._y2
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);
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}
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export function Cardinal(context, tension) {
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this._context = context;
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this._k = (1 - tension) / 6;
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}
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Cardinal.prototype = {
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areaStart: function() {
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this._line = 0;
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},
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areaEnd: function() {
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this._line = NaN;
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},
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lineStart: function() {
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this._x0 = this._x1 = this._x2 =
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this._y0 = this._y1 = this._y2 = NaN;
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this._point = 0;
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},
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lineEnd: function() {
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switch (this._point) {
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case 2: this._context.lineTo(this._x2, this._y2); break;
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case 3: point(this, this._x1, this._y1); break;
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}
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if (this._line || (this._line !== 0 && this._point === 1)) this._context.closePath();
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this._line = 1 - this._line;
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},
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point: function(x, y) {
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x = +x, y = +y;
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switch (this._point) {
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case 0: this._point = 1; this._line ? this._context.lineTo(x, y) : this._context.moveTo(x, y); break;
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case 1: this._point = 2; this._x1 = x, this._y1 = y; break;
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case 2: this._point = 3; // falls through
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default: point(this, x, y); break;
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}
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this._x0 = this._x1, this._x1 = this._x2, this._x2 = x;
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this._y0 = this._y1, this._y1 = this._y2, this._y2 = y;
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}
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};
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export default (function custom(tension) {
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function cardinal(context) {
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return new Cardinal(context, tension);
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}
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cardinal.tension = function(tension) {
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return custom(+tension);
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};
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return cardinal;
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})(0);
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