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53 lines
1.3 KiB
53 lines
1.3 KiB
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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