Middle Click Scroll

单击中键激活/关闭滚动。激活后,页面会根据鼠标与初始点的距离和方向持续自动滚动。

As of 2025-09-12. See the latest version.

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         Middle Click Scroll
// @namespace    http://tampermonkey.net/
// @version      3.0
// @description  单击中键激活/关闭滚动。激活后,页面会根据鼠标与初始点的距离和方向持续自动滚动。
// @description:en Click middle mouse button to toggle scroll mode. Once active, the page continuously scrolls based on the mouse's distance and direction from the initial point.
// @author       Xy2002
// @match        *://*/*
// @grant        GM_addStyle
// @license      MIT
// ==/UserScript==

(function() {
    'use strict';

    /** @type {boolean} - 标记滚动模式是否激活 */
    let isScrollModeActive = false;

    /** @type {number} - 激活模式时鼠标的初始Y坐标 */
    let startY = 0;

    /** @type {number} - 当前需要持续滚动的量 */
    let scrollAmount = 0;

    /** @type {number | null} - 用于存储 requestAnimationFrame 的 ID */
    let animationFrameId = null;

    /** @type {number} - 灵敏度/速度因子,可以调整这个值来改变滚动的快慢 */
    const SENSITIVITY_FACTOR = 0.15;

    // --- 创建并注入视觉指示器的样式 ---
    GM_addStyle(`
        #mmb-scroll-indicator {
            position: fixed;
            width: 32px;
            height: 32px;
            background-color: rgba(0, 0, 0, 0.5);
            border: 2px solid white;
            border-radius: 50%;
            z-index: 99999999;
            pointer-events: none; /* 让鼠标事件可以穿透这个元素 */
            display: none; /* 默认隐藏 */
            background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="white"><path d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"/><path d="M7.41 8.59L12 13.17l4.59-4.58L18 10l-6 6-6-6z"/></svg>');
            background-size: 80%;
            background-repeat: no-repeat;
            background-position: center;
        }
    `);

    // --- 创建视觉指示器元素 ---
    const indicator = document.createElement('div');
    indicator.id = 'mmb-scroll-indicator';
    document.body.appendChild(indicator);

    /**
     * 持续滚动的核心函数
     */
    const performScroll = () => {
        if (!isScrollModeActive) {
            if (animationFrameId) {
                cancelAnimationFrame(animationFrameId);
                animationFrameId = null;
            }
            return;
        }
        if (scrollAmount !== 0) {
            window.scrollBy(0, scrollAmount);
        }
        animationFrameId = requestAnimationFrame(performScroll);
    };

    // --- 新增:激活滚动模式的函数 ---
    const activateScrollMode = (e) => {
        isScrollModeActive = true;
        startY = e.clientY;
        document.body.style.cursor = 'all-scroll';

        indicator.style.left = `${e.clientX - 16}px`;
        indicator.style.top = `${e.clientY - 16}px`;
        indicator.style.display = 'block';

        // 启动滚动循环
        performScroll();
    };

    // --- 新增:封装了退出滚动模式的逻辑,方便复用 ---
    const deactivateScrollMode = () => {
        isScrollModeActive = false;
        document.body.style.cursor = 'default';
        indicator.style.display = 'none';
        scrollAmount = 0; // 重置滚动量
        // 循环会在下一次 performScroll 检查时自动停止
    };

    /**
     * 鼠标点击事件处理,用于切换或退出模式
     * @param {MouseEvent} e
     */
    const handleMouseDown = (e) => {
        // e.button === 0 -> 左键
        // e.button === 1 -> 中键
        // e.button === 2 -> 右键

        // 如果是中键点击,则切换滚动模式
        if (e.button === 1) {
            e.preventDefault(); // 阻止中键点击的默认行为 (例如在链接上点击会新建标签页)
            if (isScrollModeActive) {
                deactivateScrollMode();
            } else {
                activateScrollMode(e);
            }
            return; // 处理完毕,直接返回
        }

        // ---【核心修改】---
        // 如果当前是滚动模式,并且点击的是左键或右键,则退出滚动模式
        if (isScrollModeActive && (e.button === 0 || e.button === 2)) {
            e.preventDefault(); // 阻止默认行为,如右键菜单或拖拽选中文本
            deactivateScrollMode();
        }
    };

    /**
     * 鼠标移动事件处理,仅用于更新滚动速度和方向
     * @param {MouseEvent} e
     */
    const handleMouseMove = (e) => {
        if (!isScrollModeActive) return;

        const currentY = e.clientY;
        const deltaY = currentY - startY;

        scrollAmount = deltaY * SENSITIVITY_FACTOR;
    };

    // 绑定事件监听器 (将 handleMiddleClick 重命名为更通用的 handleMouseDown)
    window.addEventListener('mousedown', handleMouseDown, true); // 使用捕获阶段以优先处理
    window.addEventListener('mousemove', handleMouseMove, false);

})();