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54 lines
1.3 KiB
54 lines
1.3 KiB
1 year ago
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function Step(context, t) {
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this._context = context;
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this._t = t;
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}
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Step.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._x = this._y = NaN;
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this._point = 0;
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},
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lineEnd: function() {
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if (0 < this._t && this._t < 1 && this._point === 2) this._context.lineTo(this._x, this._y);
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if (this._line || (this._line !== 0 && this._point === 1)) this._context.closePath();
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if (this._line >= 0) this._t = 1 - this._t, 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; // proceed
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default: {
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if (this._t <= 0) {
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this._context.lineTo(this._x, y);
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this._context.lineTo(x, y);
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} else {
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var x1 = this._x * (1 - this._t) + x * this._t;
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this._context.lineTo(x1, this._y);
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this._context.lineTo(x1, y);
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}
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break;
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}
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}
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this._x = x, this._y = y;
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}
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};
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export default function(context) {
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return new Step(context, 0.5);
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}
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export function stepBefore(context) {
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return new Step(context, 0);
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}
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export function stepAfter(context) {
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return new Step(context, 1);
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}
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