调整网页字体和行间距倍数

脚本菜单可用于调整网页的字体和行间距倍数

// ==UserScript==
// @name 调整网页字体和行间距倍数
// @author ChatGPT
// @version 6.9
// @description 脚本菜单可用于调整网页的字体和行间距倍数
// @match *://*/*
// @grant GM_registerMenuCommand
// @grant GM_setValue
// @grant GM_getValue
// @run-at document-end
// @namespace https://greasyfork.org/uers/452911
// ==/UserScript==

(function () {
    "use strict";

    var storageKey = window.location.hostname;
    var isEnabled = GM_getValue(storageKey + "_enabled", true);
    var fontMultiplier = GM_getValue(storageKey + "_font_multiplier", 1);
    var lineHeightMultiplier = GM_getValue(storageKey + "_line_height_multiplier", 1);
    var originalSizes = {};

    function storeOriginalSizes() {
        const elements = document.querySelectorAll("*");
        elements.forEach((element) => {
            originalSizes[element] = {
                fontSize: parseFloat(getComputedStyle(element).fontSize),
                lineHeight: parseFloat(getComputedStyle(element).lineHeight),
            };
        });
    }

    function enlargeFontSizeAndLineHeight() {
        const rootFontSize = parseFloat(getComputedStyle(document.documentElement).fontSize);
        const newRootFontSize = rootFontSize * fontMultiplier;

        const rootLineHeight = parseFloat(getComputedStyle(document.documentElement).lineHeight);
        const newRootLineHeight = rootLineHeight * lineHeightMultiplier;

        const elementsToScale = document.querySelectorAll("*");
        elementsToScale.forEach((element) => {
            const originalSize = originalSizes[element];
            if (originalSize) {
                const fontSize = originalSize.fontSize;
                element.style.fontSize = `${(fontSize / rootFontSize) * newRootFontSize}px`;

                const lineHeight = originalSize.lineHeight;
                element.style.lineHeight = `${(lineHeight / rootLineHeight) * newRootLineHeight}px`;
            }
        });

        document.documentElement.style.fontSize = `${newRootFontSize}px`;
        document.documentElement.style.lineHeight = `${newRootLineHeight}px`;
    }

    function checkFontSizeAndLineHeight() {
        if (fontMultiplier !== 1 || lineHeightMultiplier !== 1) {
            enlargeFontSizeAndLineHeight();
        }
    }

    function applyFontSizeAndLineHeightChanges() {
        if (fontMultiplier !== 1 || lineHeightMultiplier !== 1) {
            enlargeFontSizeAndLineHeight();
            const elementsToScale = document.querySelectorAll("*");
            elementsToScale.forEach((element) => {
                const originalSize = originalSizes[element];
                if (originalSize) {
                    const fontSize = originalSize.fontSize;
                    element.style.fontSize = `${fontSize * fontMultiplier}px`;

                    const lineHeight = originalSize.lineHeight;
                    element.style.lineHeight = `${lineHeight * lineHeightMultiplier}px`;
                }
            });
        }
    }

    function observeDOMChanges() {
        const observer = new MutationObserver(() => {
            if (fontMultiplier !== 1 || lineHeightMultiplier !== 1) {
                applyFontSizeAndLineHeightChanges();
            }
        });

        observer.observe(document.body, {
            childList: true,
            subtree: true
        });
    }

    function updateMenu() {
        GM_registerMenuCommand(isEnabled ? "禁用字体放大" : "启用字体放大", function () {
            isEnabled = !isEnabled;
            GM_setValue(storageKey + "_enabled", isEnabled);
            if (isEnabled && (fontMultiplier !== 1 || lineHeightMultiplier !== 1)) {
                window.addEventListener("resize", checkFontSizeAndLineHeight);

                // 重新存储原始字体和行间距大小，确保立即生效
                storeOriginalSizes();
                applyFontSizeAndLineHeightChanges();
                observeDOMChanges();
            } else {
                document.documentElement.style.fontSize = "";
                document.documentElement.style.lineHeight = "";
                const elementsToReset = document.querySelectorAll("*");
                elementsToReset.forEach((element) => {
                    element.style.fontSize = "";
                    element.style.lineHeight = "";
                });
                window.removeEventListener("resize", checkFontSizeAndLineHeight);
            }
            // 更新菜单项
            updateMenu();
        });
    }

    GM_registerMenuCommand("调整字体大小", function () {
        var newFontMultiplier = prompt(
            "请输入字体大小倍数",
            fontMultiplier.toString()
        );
        if (newFontMultiplier !== null) {
            fontMultiplier = parseFloat(newFontMultiplier);
            GM_setValue(storageKey + "_font_multiplier", fontMultiplier);
            if (fontMultiplier !== 1 || lineHeightMultiplier !== 1) {
                applyFontSizeAndLineHeightChanges();
            }
        }
    });

    GM_registerMenuCommand("调整行间距", function () {
        var newLineHeightMultiplier = prompt(
            "请输入行间距倍数",
            lineHeightMultiplier.toString()
        );
        if (newLineHeightMultiplier !== null) {
            lineHeightMultiplier = parseFloat(newLineHeightMultiplier);
            GM_setValue(storageKey + "_line_height_multiplier", lineHeightMultiplier);
            if (fontMultiplier !== 1 || lineHeightMultiplier !== 1) {
                applyFontSizeAndLineHeightChanges();
            }
        }
    });

    // 自动应用字体和行间距放大功能
    if (isEnabled && (fontMultiplier !== 1 || lineHeightMultiplier !== 1)) {
        storeOriginalSizes();  // 存储原始尺寸
        applyFontSizeAndLineHeightChanges();  // 应用字体和行间距放大
        observeDOMChanges();  // 监控DOM变化
        window.addEventListener("resize", checkFontSizeAndLineHeight);  // 监听窗口大小变化
    }

    // 初始化菜单
    updateMenu();

})();