113 lines
2.7 KiB
JavaScript
113 lines
2.7 KiB
JavaScript
"use strict";
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const viewport = document.getElementById("viewport");
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const menu = document.getElementById("sidebar");
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const sidebarOverlay = document.getElementById("sidebar-overlay");
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let touchStartPos = null;
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let touchCurPos = null;
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let touchStartTime = 0;
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let menuWidth = 0;
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let menuIsOpen = false;
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let menuIsMoving = false;
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let menuIsAbsolute = false;
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class SlideoutMenu {
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static enable() {
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document.body.addEventListener("touchstart", onTouchStart, {passive: true});
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}
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static toggle(state) {
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menuIsOpen = state;
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viewport.classList.toggle("menu-open", state);
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}
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static isOpen() {
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return menuIsOpen;
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}
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}
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function onTouchStart(e) {
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touchStartPos = touchCurPos = e.touches.item(0);
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if (e.touches.length !== 1) {
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onTouchEnd();
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return;
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}
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const styles = window.getComputedStyle(menu);
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menuWidth = parseFloat(styles.width);
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menuIsAbsolute = styles.position === "absolute";
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if (!menuIsOpen || touchStartPos.screenX > menuWidth) {
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touchStartTime = Date.now();
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document.body.addEventListener("touchmove", onTouchMove, {passive: true});
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document.body.addEventListener("touchend", onTouchEnd, {passive: true});
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}
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}
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function onTouchMove(e) {
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const touch = (touchCurPos = e.touches.item(0));
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let distX = touch.screenX - touchStartPos.screenX;
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const distY = touch.screenY - touchStartPos.screenY;
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if (!menuIsMoving) {
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// tan(45°) is 1. Gestures in 0°-45° (< 1) are considered horizontal, so
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// menu must be open; gestures in 45°-90° (>1) are considered vertical, so
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// chat windows must be scrolled.
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if (Math.abs(distY / distX) >= 1) {
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onTouchEnd();
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return;
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}
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const devicePixelRatio = window.devicePixelRatio || 2;
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if (Math.abs(distX) > devicePixelRatio) {
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viewport.classList.toggle("menu-dragging", true);
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menuIsMoving = true;
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}
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}
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// Do not animate the menu on desktop view
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if (!menuIsAbsolute) {
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return;
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}
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if (menuIsOpen) {
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distX += menuWidth;
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}
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if (distX > menuWidth) {
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distX = menuWidth;
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} else if (distX < 0) {
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distX = 0;
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}
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menu.style.transform = "translate3d(" + distX + "px, 0, 0)";
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sidebarOverlay.style.opacity = distX / menuWidth;
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}
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function onTouchEnd() {
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const diff = touchCurPos.screenX - touchStartPos.screenX;
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const absDiff = Math.abs(diff);
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if (absDiff > menuWidth / 2 || (Date.now() - touchStartTime < 180 && absDiff > 50)) {
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SlideoutMenu.toggle(diff > 0);
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}
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document.body.removeEventListener("touchmove", onTouchMove);
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document.body.removeEventListener("touchend", onTouchEnd);
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viewport.classList.toggle("menu-dragging", false);
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menu.style.transform = null;
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sidebarOverlay.style.opacity = null;
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touchStartPos = null;
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touchCurPos = null;
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touchStartTime = 0;
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menuIsMoving = false;
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}
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module.exports = SlideoutMenu;
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