MediaWiki:Common.js

/* 这里的任何JavaScript将为所有用户在每次页面载入时加载。 */
function get_attribute(node, attr, default_value) {
	return node.getAttribute(attr) || default_value;
}
//封装方法，压缩之后减少文件大小
function get_by_tagname(name) {
	return document.getElementsByTagName(name);
}
//获取配置参数
function get_config_option() {
	var scripts = get_by_tagname("script"),
		script_len = scripts.length,
		script = scripts[script_len - 1]; //当前加载的script
	return {
		l: script_len, //长度，用于生成id用
		z: get_attribute(script, "zIndex", -1), //z-index
		o: get_attribute(script, "opacity", 0.5), //opacity
		c: get_attribute(script, "color", "0,255,0"), //color
		n: get_attribute(script, "count", 99) //count
	};
}
//设置canvas的高宽
function set_canvas_size() {
	canvas_width = the_canvas.width = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth,
		canvas_height = the_canvas.height = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
}
//绘制过程
function draw_canvas() {
	context.clearRect(0, 0, canvas_width, canvas_height);
	//随机的线条和当前位置联合数组
	var all_array = [current_point].concat(random_lines);
	var e, i, d, x_dist, y_dist, dist; //临时节点
	//遍历处理每一个点
	random_lines.forEach(function(r) {
		r.x += r.xa,
			r.y += r.ya, //移动
			r.xa *= r.x > canvas_width || r.x < 0 ? -1 : 1,
			r.ya *= r.y > canvas_height || r.y < 0 ? -1 : 1, //碰到边界，反向反弹
			context.fillRect(r.x - 0.5, r.y - 0.5, 1, 1); //绘制一个宽高为1的点
		for (i = 0; i < all_array.length; i++) {
			e = all_array[i];
			//不是当前点
			if (r !== e && null !== e.x && null !== e.y) {
				x_dist = r.x - e.x, //x轴距离 l
					y_dist = r.y - e.y, //y轴距离 n
					dist = x_dist * x_dist + y_dist * y_dist; //总距离, m
				dist < e.max && (e === current_point && dist >= e.max / 2 && (r.x -= 0.03 * x_dist, r.y -= 0.03 * y_dist), //靠近的时候加速
					d = (e.max - dist) / e.max,
					context.beginPath(),
					context.lineWidth = d / 2,
					context.strokeStyle = "rgba(" + config.c + "," + (d + 0.2) + ")",
					context.moveTo(r.x, r.y),
					context.lineTo(e.x, e.y),
					context.stroke());
			}
		}
		all_array.splice(all_array.indexOf(r), 1);
	}), frame_func(draw_canvas);
}
//创建画布，并添加到body中
var the_canvas = document.createElement("canvas"), //画布
	config = get_config_option(), //配置
	canvas_id = "c_n" + config.l, //canvas id
	context = the_canvas.getContext("2d"),
	canvas_width, canvas_height,
	frame_func = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function(func) {
		window.setTimeout(func, 1000 / 45);
	},
	random = Math.random,
	current_point = {
		x: null, //当前鼠标x
		y: null, //当前鼠标y
		max: 20000
	};
the_canvas.id = canvas_id;
the_canvas.style.cssText = "position:fixed;top:0;left:0;z-index:" + config.z + ";opacity:" + config.o;
get_by_tagname("body")[0].appendChild(the_canvas);
//初始化画布大小
set_canvas_size(), window.onresize = set_canvas_size;
//当时鼠标位置存储，离开的时候，释放当前位置信息
window.onmousemove = function(e) {
	e = e || window.event, current_point.x = e.clientX, current_point.y = e.clientY;
}, window.onmouseout = function() {
	current_point.x = null, current_point.y = null;
};
//随机生成config.n条线位置信息
for (var random_lines = [], i = 0; config.n > i; i++) {
	var x = random() * canvas_width, //随机位置
		y = random() * canvas_height,
		xa = 2 * random() - 1, //随机运动方向
		ya = 2 * random() - 1;
	random_lines.push({
		x: x,
		y: y,
		xa: xa,
		ya: ya,
		max: 6000 //沾附距离
	});
}
//0.1秒后绘制
setTimeout(function() {
	draw_canvas();
}, 100);