presto_gestures.user.js

// ==UserScript==
// @name        Presto Gestures
// @namespace   https://x.com/cxx
// @version     0.1.2
// @description Opera-like mouse gestures with middle mouse button instead of right
// @match       *://*/*
// @grant       GM_openInTab
// @grant       window.close
// ==/UserScript==

(function() {
    "use strict";

    const BTN_LEFT_MASK = 1;
    const BTN_RIGHT_MASK = 2;
    const BTN_MIDDLE_MASK = 4;
    const BTN_BACK_MASK = 8;
    const BTN_FORWARD_MASK = 16;

    let gestureButtons = BTN_MIDDLE_MASK;
    let threshold = 50;
    let gestures = [
        { gesture: "L",  action: () => history.back() },
        { gesture: "R",  action: () => history.forward() },
        { gesture: "UL", action: goToParentDirectory },
        { gesture: "UD", action: () => location.reload() },
        { gesture: "U",  action: () => stop() },
        { gesture: "D",  action: () => GM_openInTab("about:newtab", false) },
        { gesture: "DU", action: () => GM_openInTab(location.toString()) },
        { gesture: "DR", action: () => close() }
    ];

    function goToParentDirectory() {
        const url = new URL(location.toString());
        url.pathname = url.pathname.replace(/[^/]*\/?$/, "");
        url.search = "";
        url.hash = "";
        location.assign(url.toString());
    }

    function initGesture(x, y) {
        start = { x: x, y: y };
        strokes = "";
    }

    function updateGesture(x, y) {
        let direction;
        const dx = x - start.x;
        const dy = y - start.y;

        if (Math.abs(dx) > Math.abs(dy))
            direction = (dx < 0) ? "L" : "R";
        else
            direction = (dy < 0) ? "U" : "D";

        if (strokes.endsWith(direction))
            start = { x: x, y: y };
        else if (Math.abs(dx) > threshold || Math.abs(dy) > threshold) {
            start = { x: x, y: y };
            strokes += direction;
        }
    }

    function endGesture() {
        const found = gestures.find((item) => item.gesture == strokes);
        if (found)
            found.action();
        start = null;
        strokes = "";
    }

    let start = null;
    let strokes = "";

    addEventListener("mousedown", (event) => {
        if (event.buttons == gestureButtons)
            initGesture(event.clientX, event.clientY);
    });

    addEventListener("mousemove", (event) => {
        if (start)
            updateGesture(event.clientX, event.clientY);
    });

    addEventListener("mouseup", (event) => {
        if (strokes.length > 0) {
            event.preventDefault();
            event.stopPropagation();
        }
    }, true);

    addEventListener("auxclick", (event) => {
        if (strokes.length > 0) {
            event.preventDefault();
            event.stopPropagation();
        }
        endGesture();
    }, true);
})();