Leaflet/src/geometry/Transformation.js

/*
 * L.Transformation is an utility class to perform simple point transformations through a 2d-matrix. 
 */

L.Transformation = L.Class.extend({
	initialize: function(/*Number*/ a, /*Number*/ b, /*Number*/ c, /*Number*/ d) {
		this._a = a;
		this._b = b;
		this._c = c;
		this._d = d;
	},

	transform: function(point, scale) {
		return this._transform(point.clone(), scale);
	},
	
	// destructive transform (faster)
	_transform: function(/*Point*/ point, /*Number*/ scale) /*-> Point*/ {	
		scale = scale || 1;
		point.x = scale * (this._a * point.x + this._b); 
		point.y = scale * (this._c * point.y + this._d);
		return point;
	},
	
	untransform: function(/*Point*/ point, /*Number*/ scale) /*-> Point*/ {
		scale = scale || 1;
		return new L.Point(
			(point.x/scale - this._b) / this._a,
			(point.y/scale - this._d) / this._c);
	}
});