我的鼠标手势

一个简单的鼠标手势脚本
当前为 2014-11-21 提交的版本，查看最新版本。
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// ==UserScript==
// @name               My Mouse Gestures
// @name:zh-CN         我的鼠标手势
// @name:zh-TW         我的滑鼠手勢
// @description        A simple mouse gesture script
// @description:zh-CN  一个简单的鼠标手势脚本
// @description:zh-TW  一個簡單的滑鼠手勢腳本
// @version            0.1.2
// @include            *
// @run-at             document-start
// @grant              GM_openInTab
// @noframes
// @namespace          https://greasyfork.org/users/4968
// ==/UserScript==


// --- Settings ---
var SENSITIVITY = 3; // 1 ~ 5
var TOLERANCE = 3; // 1 ~ 5
var funcs = {
	'DR': function() {
		window.top.close();
	},
	'U': function() {
		window.scrollTo(0, 0);
	},
	'D': function() {
		window.scrollTo(0, 1073741824);
	},
	'L': function() {
		window.history.back();
	},
	'R': function() {
		window.history.forward();
	},
	'RU': function() {
		GM_openInTab('about:newtab', false);
	},
	'UD': function() {
		window.location.reload();
	}
};
// ----------------

var s = 1 << ((7 - SENSITIVITY) << 1);
var t1 = Math.tan(0.15708 * TOLERANCE), t2 = 1 / t1;

var x, y, path;
var canvas, g;

function createCanvas() {
	canvas = document.createElement('canvas');
	canvas.style.position = 'fixed';
	canvas.style.zIndex = 255;
	canvas.style.top = 0;
	canvas.style.left = 0;
	document.body.appendChild(canvas);
	canvas.width = document.body.clientWidth;
	canvas.height = document.body.clientHeight;
	g = canvas.getContext('2d');
	g.lineWidth = 3;
	g.moveTo(x, y);
}

function tracer(e) {
	var cx = e.clientX,
		cy = e.clientY,
		deltaX = cx - x,
		deltaY = cy - y,
		slope = Math.abs(deltaY / deltaX),
		distance = deltaX * deltaX + deltaY * deltaY,
		direction = '';
	if (distance > s) {
		if (slope > t1) {
			if (deltaY > 0) {
				direction = 'D';
			} else {
				direction = 'U';
			}
		} else if (slope <= t2) {
			if (deltaX > 0) {
				direction = 'R';
			} else {
				direction = 'L';
			}
		}
		if (path.slice(-1) != direction) {
			path += direction;
		}
		x = cx;
		y = cy;
		g.lineTo(x, y);
		g.stroke();
	}
}

window.addEventListener('mousedown', function(e) {
	if (e.which == 3) {
		x = e.clientX;
		y = e.clientY;
		path = '';
		createCanvas();
		canvas.addEventListener('mousemove', tracer, false);
	}
}, false);

window.addEventListener('contextmenu', function(e) {
	if (path != '') {
		e.preventDefault();
		if (funcs.hasOwnProperty(path)) {
			funcs[path]();
		}
	}
}, false);

window.addEventListener('mouseup', function(e) {
	canvas.removeEventListener('mousemove', tracer, false);
	if (e.which == 3) {
		canvas.remove();
	}
}, false);