From 6146da5eb71da2942fa3da9dfdd8a5cc5f3734d9 Mon Sep 17 00:00:00 2001
From: Joe <33972521+hnb-ku@users.noreply.github.com>
Date: Wed, 29 Jun 2022 18:01:46 +0800
Subject: [PATCH] DEV: Use `performance.timing` as a baseline for the splash
 (#17275)

* update styles

* remove unused code

* use request time as a baseline
---
 app/assets/javascripts/discourse/app/app.js |  9 ---
 app/views/common/_discourse_splash.html.erb | 74 ++++++++++++++++++---
 public/images/preloader.svg                 | 29 ++++----
 3 files changed, 81 insertions(+), 31 deletions(-)

diff --git a/app/assets/javascripts/discourse/app/app.js b/app/assets/javascripts/discourse/app/app.js
index be305596c42..19da3d28362 100644
--- a/app/assets/javascripts/discourse/app/app.js
+++ b/app/assets/javascripts/discourse/app/app.js
@@ -81,15 +81,6 @@ const Discourse = Application.extend({
         initialize: () => withPluginApi(cb.version, cb.code),
       });
     });
-
-    window.addEventListener(
-      "load",
-      () => {
-        // The app booted. Remove the splash screen
-        document.querySelector("#d-splash")?.remove();
-      },
-      { once: true }
-    );
   },
 
   _registerPluginCode(version, code) {
diff --git a/app/views/common/_discourse_splash.html.erb b/app/views/common/_discourse_splash.html.erb
index 08b92b65f53..25f5a9dcd3e 100644
--- a/app/views/common/_discourse_splash.html.erb
+++ b/app/views/common/_discourse_splash.html.erb
@@ -9,13 +9,14 @@
       display: grid;
       place-items: center;
       backface-visibility: hidden;
+      background: var(--secondary);
       position: absolute;
       left: 0;
       top: 0;
       height: 100%;
       width: 100%;
-      z-index: 1001; /* above the header */
-      background: var(--secondary);
+      z-index: 1001;
+      --animation-state: paused;
     }
 
     #d-splash .preloader-image {
@@ -25,22 +26,26 @@
 
     #d-splash .preloader-text {
       padding-top: 4em;
-          position: absolute;
-          opacity: 0;
-          animation: fade-in 0.5s ease-in-out;
-          animation-delay: 2.5s;
-          animation-fill-mode: forwards;
-          color: var(--primary);
+      position: absolute;
+      opacity: 0;
+      animation: fade-in 0.5s ease-in-out;
+      animation-delay: 1s;
+      animation-fill-mode: forwards;
+      animation-play-state: var(--animation-state);
+      color: var(--primary);
     }
 
     #d-splash .preloader-text:after {
       animation: loading-text 3s infinite;
       content: "";
       position: absolute;
+      top: 4em;
       margin: 0 0.1em;
+      left: 100%;
     }
 
     .rtl #d-splash .preloader-text:after {
+      left: 0;
       right: 100%;
     }
 
@@ -71,7 +76,7 @@
 
   <img
     class="preloader-image"
-    src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' version='1.1' data-ember-extension='1'%3E%3Cstyle%3E /* these need to be injected dynamicly to match theme colors */ :root %7B --primary: %23222222; --secondary: %23ffffff; --tertiary: %23f15c21; --highlight: %23f0ea88; --quaternary: %2365ccff; --success: %23009900; %7D /* these styles need to live here because the SVG has a different scope */ .dots %7B animation-name: loader; animation-timing-function: ease-in-out; animation-duration: 3s; animation-iteration-count: infinite; animation-delay: 1.5s; stroke: %23fff; stroke-width: 0.5px; transform-origin: center; opacity: 0; r: max(1vw, 11px); cy: 50%25; %7D .dots:first-child %7B fill: var(--tertiary); animation-delay: 1.25s; %7D .dots:nth-child(2) %7B fill: var(--tertiary); animation-delay: 1.35s; %7D .dots:nth-child(3) %7B fill: var(--highlight); animation-delay: 1.45s; %7D .dots:nth-child(4) %7B fill: var(--quaternary); animation-delay: 1.55s; %7D .dots:nth-child(5) %7B fill: var(--quaternary); animation-delay: 1.65s; %7D @keyframes loader %7B 0%25 %7B opacity: 0; transform: scale(1); %7D 45%25 %7B opacity: 1; transform: scale(0.7); %7D 65%25 %7B opacity: 1; transform: scale(0.7); %7D 100%25 %7B opacity: 0; transform: scale(1); %7D %7D %3C/style%3E%3Cg class='container'%3E%3Ccircle class='dots' cx='30vw'/%3E%3Ccircle class='dots' cx='40vw'/%3E%3Ccircle class='dots' cx='50vw'/%3E%3Ccircle class='dots' cx='60vw'/%3E%3Ccircle class='dots' cx='70vw'/%3E%3C/g%3E%3C/svg%3E%0A"
+    src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' version='1.1'%0A%3E%3Cstyle%3E /* these need to be injected dynamicly to match theme colors */ :root %7B --primary: %23222222; --secondary: %23ffffff; --tertiary: %23f15c21; --highlight: %23f0ea88; --quaternary: %2365ccff; --success: %23009900; --animation-state: paused; %7D /* these styles need to live here because the SVG has a different scope */ .dots %7B animation-name: loader; animation-timing-function: ease-in-out; animation-duration: 3s; animation-iteration-count: infinite; animation-play-state: var(--animation-state); stroke: %23fff; stroke-width: 0.5px; transform-origin: center; opacity: 0; r: max(1vw, 11px); cy: 50%25; %7D .dots:first-child %7B fill: var(--tertiary); %7D .dots:nth-child(2) %7B fill: var(--tertiary); animation-delay: 0.15s; %7D .dots:nth-child(3) %7B fill: var(--highlight); animation-delay: 0.3s; %7D .dots:nth-child(4) %7B fill: var(--quaternary); animation-delay: 0.45s; %7D .dots:nth-child(5) %7B fill: var(--quaternary); animation-delay: 0.6s; %7D @keyframes loader %7B 0%25 %7B opacity: 0; transform: scale(1); %7D 45%25 %7B opacity: 1; transform: scale(0.7); %7D 65%25 %7B opacity: 1; transform: scale(0.7); %7D 100%25 %7B opacity: 0; transform: scale(1); %7D %7D %3C/style%3E%3Cg class='container'%3E%3Ccircle class='dots' cx='30vw' /%3E%3Ccircle class='dots' cx='40vw' /%3E%3Ccircle class='dots' cx='50vw' /%3E%3Ccircle class='dots' cx='60vw' /%3E%3Ccircle class='dots' cx='70vw' /%3E%3C/g%3E%3C/svg%3E%0A"
     alt="<%=SiteSetting.title%>"
   />
 
@@ -90,5 +95,56 @@
       }
     </style>
   </noscript>
+
+  <script>
+    const connectStart = performance?.timing?.connectStart || 0;
+
+    const SPLASH_DELAY = connectStart ? 2000 : 0;
+    const POLLING_INTERVAL = 50;
+
+    const targetTime = connectStart + SPLASH_DELAY;
+    const splashWrapper = document.querySelector("#d-splash");
+    const image = splashWrapper?.querySelector(".preloader-image");
+
+    let splashInterval;
+    let windowLoaded;
+
+    const swapSplash = () => {
+      splashWrapper?.style.setProperty("--animation-state", "running");
+
+      image.src = image.src.replace(
+        "--animation-state: paused;",
+        "--animation-state: running;"
+      );
+
+      clearSplashInterval();
+    };
+
+    const clearSplashInterval = () => {
+      clearInterval(splashInterval);
+      splashInterval = null;
+    };
+
+    (() => {
+      splashInterval = setInterval(() => {
+        if (windowLoaded) {
+          clearSplashInterval();
+        }
+
+        if (Date.now() > targetTime) {
+          swapSplash();
+        }
+      }, POLLING_INTERVAL);
+    })();
+
+    window.addEventListener(
+      "load",
+      () => {
+        windowLoaded = true;
+        splashWrapper?.remove();
+      },
+      { once: true }
+    );
+  </script>
 </section>
 <%- end %>
diff --git a/public/images/preloader.svg b/public/images/preloader.svg
index b4101b4d679..b2319c1b2fb 100644
--- a/public/images/preloader.svg
+++ b/public/images/preloader.svg
@@ -1,6 +1,9 @@
-<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" data-ember-extension="1">
+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  xmlns:xlink="http://www.w3.org/1999/xlink"
+  version="1.1"
+>
   <style>
-
     /* these need to be injected dynamicly to match theme colors */
     :root {
       --primary: #222222;
@@ -9,6 +12,7 @@
       --highlight: #f0ea88;
       --quaternary: #65ccff;
       --success: #009900;
+      --animation-state: paused;
     }
 
     /* these styles need to live here because the SVG has a different scope */
@@ -17,7 +21,7 @@
       animation-timing-function: ease-in-out;
       animation-duration: 3s;
       animation-iteration-count: infinite;
-      animation-delay: 1.5s;
+      animation-play-state: var(--animation-state);
       stroke: #fff;
       stroke-width: 0.5px;
       transform-origin: center;
@@ -28,27 +32,26 @@
 
     .dots:first-child {
       fill: var(--tertiary);
-      animation-delay: 1.25s;
     }
 
     .dots:nth-child(2) {
       fill: var(--tertiary);
-      animation-delay: 1.35s;
+      animation-delay: 0.15s;
     }
 
     .dots:nth-child(3) {
       fill: var(--highlight);
-      animation-delay: 1.45s;
+      animation-delay: 0.3s;
     }
 
     .dots:nth-child(4) {
       fill: var(--quaternary);
-      animation-delay: 1.55s;
+      animation-delay: 0.45s;
     }
 
     .dots:nth-child(5) {
       fill: var(--quaternary);
-      animation-delay: 1.65s;
+      animation-delay: 0.6s;
     }
 
     @keyframes loader {
@@ -72,10 +75,10 @@
   </style>
 
   <g class="container">
-    <circle class="dots" cx="30vw"/>
-    <circle class="dots" cx="40vw"/>
-    <circle class="dots" cx="50vw"/>
-    <circle class="dots" cx="60vw"/>
-    <circle class="dots" cx="70vw"/>
+    <circle class="dots" cx="30vw" />
+    <circle class="dots" cx="40vw" />
+    <circle class="dots" cx="50vw" />
+    <circle class="dots" cx="60vw" />
+    <circle class="dots" cx="70vw" />
   </g>
 </svg>