Graphite/website/static/js/navbar.js
2022-08-25 21:32:27 -07:00

115 lines
3.7 KiB
JavaScript

const NAV_BUTTON_INITIAL_FONT_SIZE = 32;
const RIPPLE_ANIMATION_MILLISECONDS = 100;
const RIPPLE_WIDTH = 140;
const HANDLE_STRETCH = 0.4;
let ripplesInitialized;
let navButtons;
let rippleSvg;
let ripplePath;
let fullRippleHeight;
let ripples;
let activeRippleIndex;
window.addEventListener("DOMContentLoaded", initializeRipples);
window.addEventListener("resize", () => animate(true));
function initializeRipples() {
ripplesInitialized = true;
navButtons = document.querySelectorAll("header nav a");
rippleSvg = document.querySelector("header .ripple");
ripplePath = rippleSvg.querySelector("path");
fullRippleHeight = Number.parseInt(window.getComputedStyle(rippleSvg).height, 10) - 4;
ripples = Array.from(navButtons).map((button) => ({
element: button,
animationStartTime: 0,
animationEndTime: 0,
goingUp: false,
}));
activeRippleIndex = ripples.findIndex((ripple) => ripple.element.getAttribute("href").replace(/\//g, "") === window.location.pathname.replace(/\//g, ""));
ripples.forEach((ripple) => {
const updateTimings = (goingUp) => {
const start = ripple.animationStartTime;
const now = Date.now();
const stop = ripple.animationStartTime + RIPPLE_ANIMATION_MILLISECONDS;
const elapsed = now - start;
const remaining = stop - now;
ripple.animationStartTime = now < stop ? now - remaining : now;
ripple.animationEndTime = now < stop ? now + elapsed : now + RIPPLE_ANIMATION_MILLISECONDS;
ripple.goingUp = goingUp;
animate(false);
};
ripple.element.addEventListener("pointerenter", () => updateTimings(true));
ripple.element.addEventListener("pointerleave", () => updateTimings(false));
});
ripples[activeRippleIndex] = {
...ripples[activeRippleIndex],
animationStartTime: 1,
animationEndTime: 1 + RIPPLE_ANIMATION_MILLISECONDS,
goingUp: true,
};
setRipples();
}
function animate(forceRefresh) {
if (!ripplesInitialized) return;
const animateThisFrame = ripples.some((ripple) => ripple.animationStartTime && ripple.animationEndTime && Date.now() <= ripple.animationEndTime);
if (animateThisFrame || forceRefresh) {
setRipples();
window.requestAnimationFrame(() => animate(false));
}
}
function setRipples() {
const navButtonFontSize = Number.parseInt(window.getComputedStyle(navButtons[0]).fontSize, 10) || NAV_BUTTON_INITIAL_FONT_SIZE;
const mediaQueryScaleFactor = navButtonFontSize / NAV_BUTTON_INITIAL_FONT_SIZE;
const rippleHeight = fullRippleHeight * (mediaQueryScaleFactor * 0.5 + 0.5);
const rippleSvgRect = rippleSvg.getBoundingClientRect();
const rippleSvgLeft = rippleSvgRect.left;
const rippleSvgWidth = rippleSvgRect.width;
let path = `M 0,${rippleHeight + 3} `;
ripples.forEach((ripple) => {
if (!ripple.animationStartTime || !ripple.animationEndTime) return;
const t = Math.min((Date.now() - ripple.animationStartTime) / (ripple.animationEndTime - ripple.animationStartTime), 1);
const height = rippleHeight * (ripple.goingUp ? ease(t) : 1 - ease(t));
const buttonRect = ripple.element.getBoundingClientRect();
const buttonCenter = buttonRect.width / 2;
const rippleCenter = (RIPPLE_WIDTH / 2) * mediaQueryScaleFactor;
const rippleOffset = rippleCenter - buttonCenter;
const rippleStartX = buttonRect.left - rippleSvgLeft - rippleOffset;
const rippleRadius = (RIPPLE_WIDTH / 2) * mediaQueryScaleFactor;
const handleRadius = rippleRadius * HANDLE_STRETCH;
path += `L ${rippleStartX},${rippleHeight + 3} `;
path += `c ${handleRadius},0 ${rippleRadius - handleRadius},${-height} ${rippleRadius},${-height} `;
path += `s ${rippleRadius - handleRadius},${height} ${rippleRadius},${height} `;
});
path += `l ${rippleSvgWidth},0`;
ripplePath.setAttribute("d", path);
}
function ease(x) {
return 1 - (1 - x) * (1 - x);
}