utils.js

var utils = {};

//跨平台计算鼠标位置
utils.captureMouse = function (element) {
	var mouse = {x: 0, y: 0};

	element.addEventListener('mousemove', function(event) {
		var x, y;
		if (event.pageX || event.pageY) {
			x = event.pageX;
			y = event.pageY;
		}
		else {
			x = event.clientX + document.body.scrollLeft +
				document.documentElement.scrollLeft;
			y = event.clientY + document.body.scrollTop +
				document.docuemntElement.scrollTop;
		}
		x -= element.offsetLeft;
		y -= element.offsetTop;

		mouse.x = x;
		mouse.y = y;
	}, false);

	return mouse;
};

//触摸位置
utils.captureTouch = function (element) {
	var touch = {x: null, y: null, isPressed: false};

	element.addEventListener('touchstart', function (event) {
		touch.isPressed = true;
	}, false);

	element.addEventListener('touchend', function (event) {
		touch.isPressed = false;
		touch.x = null;
		touch.y = null;
	}, false);

	element.addEventListener('touchmove', function (event){
		var x, y,
			touch_event = event.touches[0]; //first touch

		if (touch_event.pageX || touch_event.pageY) {
			x = touch_event.pageX;
			y = touch_event.pageY;
		} else {
			x = touch_event.clientX + document.body.scrollLeft +
				document.documentElement.scrollLeft;
			y = touch_event.clientY + document.body.scrollTop +
				document.documentElement.scrollTop;
		}
		x -= element.offsetLeft;
		y -= element.offsetTop;
	}, false);

	return touch;
};

//返回是否在指定矩形内
utils.containsPoint = function (rect, x, y) {
	return !(x < rect.x || x > rect.x + rect.width ||
			 y < rect.y || y > rect.y + rect.height);
};
//碰撞检测(矩形范围)
utils.intersects = function (rectA, rectB) {
	return !(rectA.x + rectA.width < rectB.x ||
				rectB.x + rectB.width < rectA.x ||
				rectA.y + rectA.height < rectB.y ||
				rectB.y + rectB.height < rectA.y);
};

//color2RGB
utils.colorToRGB = function (color, alpha) {
	if (typeof color === "string" && color[0] === "#") {
		color = window.parseInt(color.slice(1), 16);
	}
	alpha = (alpha === undefined ? 1 : alpha);

	var r = color >> 16 & 0xFF,
		g = color >> 8 & 0xFF,
		a = (alpha < 0) ? 0 : ((alpha > 1) ? 1 : alpha);

	if (a === 1){
		return "rgb("+ r +","+ g +","+ b +")";
	} else {
		return "rgba("+ r +","+ g +","+ b +","+ a +")";
	}
};

//parseColor 数字值转十六进制，十六进制转数字值
utils.parseColor = function (color, toNumber) {
	if (toNumber === true) {
		if (typeof color === 'number') {
			return (color | 0);
		}
		if (typeof color === 'string' && color[0] === '#') {
			color = color.slice(1);
		}
		return window.parseInt(color, 16);
	}
	else {
		if (typeof color === 'number') {
			color = '#' + ('000000' + (color | 0).toString(16)).substr(-6);
		}
		return color;
	}
};

utils.randColor = function() {
    var r = Math.floor(Math.random() * 255);
    var g = Math.floor(Math.random() * 255);
    var b = Math.floor(Math.random() * 255);
    return 'rgb('+ r +','+ g +','+ b +')';
};