META-INF.resources.EffectsHelper.js Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of com.liferay.frontend.image.editor.capability.effects

Liferay Frontend Image Editor Capability Effects

There is a newer version: 4.0.5

Show newest version

/**
 * At least two points are needed to interpolate something.
 * @class Lagrange polynomial interpolation.
 * The computed interpolation polynomial will be reffered to as L(x).
 * @example
 * var l = new Lagrange(0, 0, 1, 1);
 * var index = l.addPoint(0.5, 0.8);
 * console.log(l.valueOf(0.1));
 *
 * l.changePoint(index, 0.5, 0.1);
 * console.log(l.valueOf(0.1));
 *
 * https://gist.github.com/maccesch/995144
 */
var Lagrange = function(x1, y1, x2, y2) {
this.xs = [x1, x2];
this.ys = [y1, y2];
this.ws = [];
this._updateWeights();
};

/**
 * Adds a new point to the polynomial. L(x) = y
 * @return {Number} The index of the added point. Used for changing the point. See changePoint.
 */
Lagrange.prototype.addPoint = function(x, y) {
this.xs.push(x);
this.ys.push(y);
this._updateWeights();
return this.xs.length-1;
};

/**
 * Changes a previously added point.
 */
Lagrange.prototype.changePoint = function(index, x, y) {
this.xs[index] = x;
this.ys[index] = y;
this._updateWeights();
};

/**
 * Recalculate barycentric weights.
 */
Lagrange.prototype._updateWeights = function() {
var k = this.xs.length;
var w;

for (var j = 0; j < k; ++j) {
	w = 1;
	for (var i = 0; i < k; ++i) {
	  if (i != j) {
		w *= this.xs[j] - this.xs[i];
	  }
	}
	this.ws[j] = 1/w;
}
};

/**
 * Calculate L(x)
 */
Lagrange.prototype.valueOf = function(x) {
var a = 0;
var b = 0;
var c = 0;

for (var j = 0; j < this.xs.length; ++j) {
	if (x != this.xs[j]) {
	  a = this.ws[j] / (x - this.xs[j]);
	  b += a * this.ys[j];
	  c += a;
	} else {
	  return this.ys[j];
	}
}

return b / c;
};

Lagrange.prototype.addMultiPoints = function(arr) {
for(var i = 0, n = arr.length; i < n; i++) {
	if (i !== 0 && i !== 1) {
	  this.addPoint(arr[i][1], arr[i][2]);
	}
}
};