BezierCurve.js
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var Path = require("../Path");
var vec2 = require("../../core/vector");
var _curve = require("../../core/curve");
var quadraticSubdivide = _curve.quadraticSubdivide;
var cubicSubdivide = _curve.cubicSubdivide;
var quadraticAt = _curve.quadraticAt;
var cubicAt = _curve.cubicAt;
var quadraticDerivativeAt = _curve.quadraticDerivativeAt;
var cubicDerivativeAt = _curve.cubicDerivativeAt;
/**
* 贝塞尔曲线
* @module zrender/shape/BezierCurve
*/
var out = [];
function someVectorAt(shape, t, isTangent) {
var cpx2 = shape.cpx2;
var cpy2 = shape.cpy2;
if (cpx2 === null || cpy2 === null) {
return [(isTangent ? cubicDerivativeAt : cubicAt)(shape.x1, shape.cpx1, shape.cpx2, shape.x2, t), (isTangent ? cubicDerivativeAt : cubicAt)(shape.y1, shape.cpy1, shape.cpy2, shape.y2, t)];
} else {
return [(isTangent ? quadraticDerivativeAt : quadraticAt)(shape.x1, shape.cpx1, shape.x2, t), (isTangent ? quadraticDerivativeAt : quadraticAt)(shape.y1, shape.cpy1, shape.y2, t)];
}
}
var _default = Path.extend({
type: 'bezier-curve',
shape: {
x1: 0,
y1: 0,
x2: 0,
y2: 0,
cpx1: 0,
cpy1: 0,
// cpx2: 0,
// cpy2: 0
// Curve show percent, for animating
percent: 1
},
style: {
stroke: '#000',
fill: null
},
buildPath: function (ctx, shape) {
var x1 = shape.x1;
var y1 = shape.y1;
var x2 = shape.x2;
var y2 = shape.y2;
var cpx1 = shape.cpx1;
var cpy1 = shape.cpy1;
var cpx2 = shape.cpx2;
var cpy2 = shape.cpy2;
var percent = shape.percent;
if (percent === 0) {
return;
}
ctx.moveTo(x1, y1);
if (cpx2 == null || cpy2 == null) {
if (percent < 1) {
quadraticSubdivide(x1, cpx1, x2, percent, out);
cpx1 = out[1];
x2 = out[2];
quadraticSubdivide(y1, cpy1, y2, percent, out);
cpy1 = out[1];
y2 = out[2];
}
ctx.quadraticCurveTo(cpx1, cpy1, x2, y2);
} else {
if (percent < 1) {
cubicSubdivide(x1, cpx1, cpx2, x2, percent, out);
cpx1 = out[1];
cpx2 = out[2];
x2 = out[3];
cubicSubdivide(y1, cpy1, cpy2, y2, percent, out);
cpy1 = out[1];
cpy2 = out[2];
y2 = out[3];
}
ctx.bezierCurveTo(cpx1, cpy1, cpx2, cpy2, x2, y2);
}
},
/**
* Get point at percent
* @param {number} t
* @return {Array.<number>}
*/
pointAt: function (t) {
return someVectorAt(this.shape, t, false);
},
/**
* Get tangent at percent
* @param {number} t
* @return {Array.<number>}
*/
tangentAt: function (t) {
var p = someVectorAt(this.shape, t, true);
return vec2.normalize(p, p);
}
});
module.exports = _default;