position.js

// Copyright (c) 2014 Titanium I.T. LLC. All rights reserved. For license, see "README" or "LICENSE" file.
"use strict";

var ensure = require("../util/ensure.js");
var Value = require("./value.js");
var Pixels = require("./pixels.js");
var Size = require("./size.js");

var X_DIMENSION = "x";
var Y_DIMENSION = "y";

var Me = module.exports = function Position(dimension, value) {
	ensure.signature(arguments, [ String, [Number, Pixels] ]);

	this._dimension = dimension;
	this._value = (typeof value === "number") ? Pixels.create(value) : value;
};
Value.extend(Me);

Me.x = function x(value) {
	return new Me(X_DIMENSION, value);
};

Me.y = function y(value) {
	return new Me(Y_DIMENSION, value);
};

Me.prototype.compatibility = function compatibility() {
	return [ Me, Size ];
};

Me.prototype.plus = Value.safe(function plus(operand) {
	checkAxis(this, operand);
	return new Me(this._dimension, this._value.plus(operand.toPixels()));
});

Me.prototype.minus = Value.safe(function minus(operand) {
	checkAxis(this, operand);
	return new Me(this._dimension, this._value.minus(operand.toPixels()));
});

Me.prototype.midpoint = Value.safe(function midpoint(operand) {
	checkAxis(this, operand);
	return new Me(this._dimension, this._value.average(operand.toPixels()));
});

Me.prototype.diff = Value.safe(function diff(expected) {
	checkAxis(this, expected);

	var actualValue = this._value;
	var expectedValue = expected._value;
	if (actualValue.equals(expectedValue)) return "";

	var direction;
	var comparison = actualValue.compare(expectedValue);
	if (this._dimension === X_DIMENSION) direction = comparison < 0 ? "further left" : "further right";
	else direction = comparison < 0 ? "higher" : "lower";

	return actualValue.diff(expectedValue) + " " + direction;
});

Me.prototype.toString = function toString() {
	ensure.signature(arguments, []);
	return this._value.toString();
};

Me.prototype.toPixels = function toPixels() {
	ensure.signature(arguments, []);
	return this._value;
};

function checkAxis(self, other) {
	if (other instanceof Me) {
		ensure.that(self._dimension === other._dimension, "Can't compare X coordinate to Y coordinate");
	}
}