scroll-button (Draggable & Auto-Fade)
As of
// ==UserScript==
// @name scroll-button
// @namespace https://github.com/livinginpurple
// @version 20251217.06
// @description scroll-button (Draggable & Auto-Fade)
// @license WTFPL
// @author livinginpurple
// @include *
// @run-at document-end
// @grant none
// ==/UserScript==
(() => {
'use strict';
const init = () => {
const btnId = 'gamma-scroll-btn';
if (document.getElementById(btnId)) return;
// --- 1. 設定與記憶 ---
const STORAGE_KEY = 'gamma-scroll-pos';
let savedPos = null;
try {
savedPos = JSON.parse(localStorage.getItem(STORAGE_KEY));
} catch (e) {}
// SVG 圖示
const icons = {
up: `<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" fill="white" viewBox="0 0 16 16"><path fill-rule="evenodd" d="M8 12a.5.5 0 0 0 .5-.5V5.707l2.146 2.147a.5.5 0 0 0 .708-.708l-3-3a.5.5 0 0 0-.708 0l-3 3a.5.5 0 1 0 .708.708L7.5 5.707V11.5a.5.5 0 0 0 .5.5z"/></svg>`,
down: `<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" fill="white" viewBox="0 0 16 16"><path fill-rule="evenodd" d="M8 4a.5.5 0 0 1 .5.5v5.793l2.146-2.147a.5.5 0 0 1 .708.708l-3 3a.5.5 0 0 1-.708 0l-3-3a.5.5 0 1 1 .708-.708L7.5 10.293V4.5A.5.5 0 0 1 8 4z"/></svg>`
};
const btn = document.createElement('button');
btn.id = btnId;
btn.type = 'button';
btn.setAttribute('aria-label', 'Scroll navigation');
// --- 2. 樣式定義 ---
// 判斷初始位置：如果有存檔用存檔的位置，否則預設右下角
const initialStyles = savedPos
? { left: savedPos.x + 'px', top: savedPos.y + 'px' }
: { right: '20px', bottom: '20px' };
Object.assign(btn.style, {
position: 'fixed',
...initialStyles,
width: '40px',
height: '40px',
borderRadius: '50%',
backgroundColor: '#0d6efd',
border: 'none',
boxShadow: '0 0.2rem 0.5rem rgba(0,0,0,0.3)',
zIndex: '10000',
cursor: 'grab',
display: 'flex',
justifyContent: 'center',
alignItems: 'center',
// 注意：不對 left/top 設 transition，避免拖曳時遲滯
transition: 'opacity 0.5s ease-in-out, transform 0.1s, background-color 0.2s',
touchAction: 'none', // 關鍵：防止拖曳時觸發網頁捲動
padding: '0',
opacity: '0.3'
});
// 互動視覺效果
btn.onmouseenter = () => { btn.style.transform = 'scale(1.1)'; };
btn.onmouseleave = () => { btn.style.transform = 'scale(1)'; };
document.body.appendChild(btn);
// --- 3. 狀態與透明度控制 ---
const State = { TOP: 'top', SCROLLED: 'scrolled' };
let idleTimer = null;
const activeHandler = () => {
btn.style.opacity = '1';
if (idleTimer) clearTimeout(idleTimer);
idleTimer = setTimeout(() => {
btn.style.opacity = '0.3';
}, 2000);
};
const updateButtonState = () => {
activeHandler();
const scrollTop = window.scrollY || document.documentElement.scrollTop;
const isAtTop = scrollTop < 50;
const nextState = isAtTop ? State.TOP : State.SCROLLED;
if (btn.dataset.state === nextState) return;
if (isAtTop) {
btn.innerHTML = icons.down;
btn.dataset.state = State.TOP;
} else {
btn.innerHTML = icons.up;
btn.dataset.state = State.SCROLLED;
}
};
// --- 4. 拖曳邏輯核心 (Drag Core) ---
let isDragging = false;
let hasMoved = false;
let startX, startY, initialRect;
// 處理開始 (Mouse & Touch)
const onDragStart = (e) => {
const clientX = e.type.includes('touch') ? e.touches[0].clientX : e.clientX;
const clientY = e.type.includes('touch') ? e.touches[0].clientY : e.clientY;
isDragging = true;
hasMoved = false;
startX = clientX;
startY = clientY;
initialRect = btn.getBoundingClientRect(); // 取得當前絕對位置
// 確保切換為絕對定位模式 (避免從 right/bottom 切換時跳動)
btn.style.right = 'auto';
btn.style.bottom = 'auto';
btn.style.left = initialRect.left + 'px';
btn.style.top = initialRect.top + 'px';
btn.style.cursor = 'grabbing';
btn.style.backgroundColor = '#0b5ed7'; // 按下變深色
activeHandler();
};
// 處理移動
const onDragMove = (e) => {
if (!isDragging) return;
const clientX = e.type.includes('touch') ? e.touches[0].clientX : e.clientX;
const clientY = e.type.includes('touch') ? e.touches[0].clientY : e.clientY;
const deltaX = clientX - startX;
const deltaY = clientY - startY;
// 判定是否真的在拖曳 (超過 5px)
if (Math.abs(deltaX) > 5 || Math.abs(deltaY) > 5) {
hasMoved = true;
}
// 計算新位置並限制在視窗內
let newX = initialRect.left + deltaX;
let newY = initialRect.top + deltaY;
const maxX = window.innerWidth - 40; // 40 is btn width
const maxY = window.innerHeight - 40;
newX = Math.max(0, Math.min(newX, maxX));
newY = Math.max(0, Math.min(newY, maxY));
btn.style.left = newX + 'px';
btn.style.top = newY + 'px';
};
// 處理結束
const onDragEnd = () => {
if (!isDragging) return;
isDragging = false;
btn.style.cursor = 'grab';
btn.style.backgroundColor = '#0d6efd';
if (hasMoved) {
// 儲存位置
localStorage.setItem(STORAGE_KEY, JSON.stringify({
x: parseFloat(btn.style.left),
y: parseFloat(btn.style.top)
}));
}
activeHandler();
};
// 綁定事件 (支援 PC 與 Mobile)
btn.addEventListener('mousedown', onDragStart);
window.addEventListener('mousemove', onDragMove);
window.addEventListener('mouseup', onDragEnd);
btn.addEventListener('touchstart', onDragStart, { passive: false });
window.addEventListener('touchmove', onDragMove, { passive: false });
window.addEventListener('touchend', onDragEnd);
// --- 5. 點擊捲動邏輯 ---
btn.addEventListener('click', (e) => {
// 如果剛才發生了拖曳位移，則不執行捲動
if (hasMoved) {
e.preventDefault();
e.stopImmediatePropagation();
return;
}
e.preventDefault();
activeHandler();
if (btn.dataset.state === State.TOP) {
window.scrollTo({ top: document.body.scrollHeight, behavior: 'smooth' });
} else {
window.scrollTo({ top: 0, behavior: 'smooth' });
}
});
window.addEventListener('scroll', updateButtonState, { passive: true });
// 初始化狀態
updateButtonState();
};
if (document.readyState === 'loading') {
document.addEventListener('DOMContentLoaded', init);
} else {
init();
}
})();