quixote/src/descriptors/relative_position.js

CSS unit and integration testing

// 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 Descriptor = require("./descriptor.js");
var PositionDescriptor = require("./position_descriptor.js");
var Value = require("../values/value.js");
var Size = require("../values/size.js");

var X_DIMENSION = "x";
var Y_DIMENSION = "y";
var PLUS = 1;
var MINUS = -1;

var Me = module.exports = function RelativePosition(dimension, direction, relativeTo, relativeAmount) {
	ensure.signature(arguments, [ String, Number, Descriptor, [Number, Descriptor, Value] ]);

	this.should = this.createShould();

	if (dimension === X_DIMENSION) PositionDescriptor.x(this);
	else if (dimension === Y_DIMENSION) PositionDescriptor.y(this);
	else ensure.unreachable("Unknown dimension: " + dimension);

	this._dimension = dimension;
	this._direction = direction;
	this._relativeTo = relativeTo;

	if (typeof relativeAmount === "number") {
		if (relativeAmount < 0) this._direction *= -1;
		this._amount = Size.create(Math.abs(relativeAmount));
	}
	else {
		this._amount = relativeAmount;
	}
};
PositionDescriptor.extend(Me);

Me.right = createFn(X_DIMENSION, PLUS);
Me.down = createFn(Y_DIMENSION, PLUS);
Me.left = createFn(X_DIMENSION, MINUS);
Me.up = createFn(Y_DIMENSION, MINUS);

function createFn(dimension, direction) {
	return function create(relativeTo, relativeAmount) {
		return new Me(dimension, direction, relativeTo, relativeAmount);
	};
}

Me.prototype.value = function value() {
	ensure.signature(arguments, []);

	var baseValue = this._relativeTo.value();
	var relativeValue = this._amount.value();

	if (this._direction === PLUS) return baseValue.plus(relativeValue);
	else return baseValue.minus(relativeValue);
};

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

	var base = this._relativeTo.toString();
	if (this._amount.equals(Size.create(0))) return base;

	var relation = this._amount.toString();
	if (this._dimension === X_DIMENSION) relation += (this._direction === PLUS) ? " to right of " : " to left of ";
	else relation += (this._direction === PLUS) ? " below " : " above ";

	return relation + base;
};