452 lines
16 KiB
JavaScript
452 lines
16 KiB
JavaScript
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// darkmode.js: Javascript library for controlling page appearance, toggling between regular white and 'dark mode'
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// Author: Said Achmiz
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// Date: 2020-03-20
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// When: Time-stamp: "2020-03-23 09:36:20 gwern"
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// license: PD
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/* Experimental 'dark mode': Mac OS (Safari) lets users specify via an OS widget 'dark'/'light' to make everything appear */
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/* bright-white or darker (eg for darker at evening to avoid straining eyes & disrupting circadian rhyhms); this then is */
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/* exposed by Safari as a CSS variable which can be selected on. This is also currently supported by Firefox weakly as an */
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/* about:config variable. Hypothetically, iOS in the future might use its camera or the clock to set 'dark mode' */
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/* automatically. https://drafts.csswg.org/mediaqueries-5/#prefers-color-scheme */
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/* https://webkit.org/blog/8718/new-webkit-features-in-safari-12-1/ */
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/* https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme
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/* Because many users do not have access to a browser/OS which explicitly supports dark mode, cannot modify the browser/OS setting without undesired side-effects, wish to opt in only for specific websites, or simply forget that they turned on dark mode & dislike it, we make dark mode controllable by providing a widget at the top of the page. */
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/* For gwern.net, the default white-black */
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/* scheme is 'light', and it can be flipped to a 'dark' scheme fairly easily by inverting it; the main visual problem is */
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/* that blockquotes appear to become much harder to see & image-focus.js doesn't work well without additional tweaks. */
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/* Known bugs: images get inverted on zoom or hover; invert filters are slow, leading to 'janky' slow rendering on scrolling. */
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/****************/
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/* MISC HELPERS */
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/****************/
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/* Given an HTML string, creates an element from that HTML, adds it to
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#ui-elements-container (creating the latter if it does not exist), and
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returns the created element.
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*/
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function addUIElement(element_html) {
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var ui_elements_container = document.querySelector("#ui-elements-container");
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if (!ui_elements_container) {
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ui_elements_container = document.createElement("div");
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ui_elements_container.id = "ui-elements-container";
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document.querySelector("body").appendChild(ui_elements_container);
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}
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ui_elements_container.insertAdjacentHTML("beforeend", element_html);
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return ui_elements_container.lastElementChild;
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}
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if (typeof window.GW == "undefined")
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window.GW = { };
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GW.temp = { };
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if (GW.mediaQueries == null)
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GW.mediaQueries = { };
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GW.mediaQueries.mobileNarrow = matchMedia("(max-width: 520px)");
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GW.mediaQueries.mobileWide = matchMedia("(max-width: 900px)");
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GW.mediaQueries.mobileMax = matchMedia("(max-width: 960px)");
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GW.mediaQueries.hover = matchMedia("only screen and (hover: hover) and (pointer: fine)");
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GW.mediaQueries.systemDarkModeActive = matchMedia("(prefers-color-scheme: dark)");
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GW.modeOptions = [
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[ 'auto', 'Auto', 'Set light or dark mode automatically, according to system-wide setting' ],
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[ 'light', 'Light', 'Light mode at all times' ],
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[ 'dark', 'Dark', 'Dark mode at all times' ]
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];
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GW.modeStyles = `
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:root {
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--GW-blockquote-background-color: #ddd
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}
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body::before,
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body > * {
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filter: invert(90%)
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}
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body::before {
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content: '';
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width: 100vw;
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height: 100%;
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position: fixed;
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left: 0;
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top: 0;
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background-color: #fff;
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z-index: -1
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}
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img,
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video {
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filter: invert(100%);
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}
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#markdownBody, #mode-selector button {
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text-shadow: 0 0 0 #000
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}
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article > :not(#TOC) a:link {
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text-shadow:
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0 0 #777,
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.03em 0 #fff,
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-.03em 0 #fff,
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0 .03em #fff,
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0 -.03em #fff,
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.06em 0 #fff,
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-.06em 0 #fff,
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.09em 0 #fff,
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-.09em 0 #fff,
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.12em 0 #fff,
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-.12em 0 #fff,
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.15em 0 #fff,
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-.15em 0 #fff
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}
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article > :not(#TOC) blockquote a:link {
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text-shadow:
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0 0 #777,
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.03em 0 var(--GW-blockquote-background-color),
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-.03em 0 var(--GW-blockquote-background-color),
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0 .03em var(--GW-blockquote-background-color),
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0 -.03em var(--GW-blockquote-background-color),
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.06em 0 var(--GW-blockquote-background-color),
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-.06em 0 var(--GW-blockquote-background-color),
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.09em 0 var(--GW-blockquote-background-color),
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-.09em 0 var(--GW-blockquote-background-color),
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.12em 0 var(--GW-blockquote-background-color),
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-.12em 0 var(--GW-blockquote-background-color),
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.15em 0 var(--GW-blockquote-background-color),
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-.15em 0 var(--GW-blockquote-background-color)
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}
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#logo img {
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filter: none;
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}
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#mode-selector {
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opacity: 0.6;
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}
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#mode-selector:hover {
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background-color: #fff;
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}
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`;
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/****************/
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/* DEBUG OUTPUT */
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/****************/
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function GWLog (string) {
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if (GW.loggingEnabled || localStorage.getItem("logging-enabled") == "true")
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console.log(string);
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}
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/***********/
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/* HELPERS */
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/***********/
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/* Run the given function immediately if the page is already loaded, or add
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a listener to run it as soon as the page loads.
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*/
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function doWhenPageLoaded(f) {
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if (document.readyState == "complete")
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f();
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else
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window.addEventListener("load", f);
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}
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/* Adds an event listener to a button (or other clickable element), attaching
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it to both "click" and "keyup" events (for use with keyboard navigation).
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Optionally also attaches the listener to the 'mousedown' event, making the
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element activate on mouse down instead of mouse up.
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*/
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Element.prototype.addActivateEvent = function(func, includeMouseDown) {
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let ael = this.activateEventListener = (event) => { if (event.button === 0 || event.key === ' ') func(event) };
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if (includeMouseDown) this.addEventListener("mousedown", ael);
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this.addEventListener("click", ael);
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this.addEventListener("keyup", ael);
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}
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/* Adds a scroll event listener to the page.
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*/
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function addScrollListener(fn, name) {
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let wrapper = (event) => {
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requestAnimationFrame(() => {
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fn(event);
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document.addEventListener("scroll", wrapper, { once: true, passive: true });
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});
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}
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document.addEventListener("scroll", wrapper, { once: true, passive: true });
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// Retain a reference to the scroll listener, if a name is provided.
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if (typeof name != "undefined")
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GW[name] = wrapper;
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}
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/************************/
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/* ACTIVE MEDIA QUERIES */
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/************************/
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/* This function provides two slightly different versions of its functionality,
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depending on how many arguments it gets.
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If one function is given (in addition to the media query and its name), it
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is called whenever the media query changes (in either direction).
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If two functions are given (in addition to the media query and its name),
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then the first function is called whenever the media query starts matching,
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and the second function is called whenever the media query stops matching.
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If you want to call a function for a change in one direction only, pass an
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empty closure (NOT null!) as one of the function arguments.
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There is also an optional fifth argument. This should be a function to be
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called when the active media query is canceled.
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*/
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function doWhenMatchMedia(mediaQuery, name, ifMatchesOrAlwaysDo, otherwiseDo = null, whenCanceledDo = null) {
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if (typeof GW.mediaQueryResponders == "undefined")
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GW.mediaQueryResponders = { };
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let mediaQueryResponder = (event, canceling = false) => {
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if (canceling) {
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GWLog(`Canceling media query “${name}â€`);
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if (whenCanceledDo != null)
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whenCanceledDo(mediaQuery);
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} else {
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let matches = (typeof event == "undefined") ? mediaQuery.matches : event.matches;
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GWLog(`Media query “${name}†triggered (matches: ${matches ? "YES" : "NO"})`);
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if (otherwiseDo == null || matches) ifMatchesOrAlwaysDo(mediaQuery);
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else otherwiseDo(mediaQuery);
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}
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};
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mediaQueryResponder();
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mediaQuery.addListener(mediaQueryResponder);
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GW.mediaQueryResponders[name] = mediaQueryResponder;
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}
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/* Deactivates and discards an active media query, after calling the function
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that was passed as the whenCanceledDo parameter when the media query was
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added.
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*/
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function cancelDoWhenMatchMedia(name) {
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GW.mediaQueryResponders[name](null, true);
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for ([ key, mediaQuery ] of Object.entries(GW.mediaQueries))
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mediaQuery.removeListener(GW.mediaQueryResponders[name]);
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GW.mediaQueryResponders[name] = null;
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}
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/******************/
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/* MODE SELECTION */
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/******************/
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function injectModeSelector() {
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GWLog("injectModeSelector");
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// Get saved mode setting (or default).
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let currentMode = localStorage.getItem("selected-mode") || 'auto';
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// Inject the mode selector widget and activate buttons.
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let modeSelector = addUIElement(
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"<div id='mode-selector'>" +
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String.prototype.concat.apply("", GW.modeOptions.map(modeOption => {
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let [ name, label, desc ] = modeOption;
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let selected = (name == currentMode ? ' selected' : '');
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let disabled = (name == currentMode ? ' disabled' : '');
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return `<button type='button' class='select-mode-${name}${selected}'${disabled} tabindex='-1' data-name='${name}' title='${desc}'>${label}</button>`})) +
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"</div>");
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modeSelector.querySelectorAll("button").forEach(button => {
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button.addActivateEvent(GW.modeSelectButtonClicked = (event) => {
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GWLog("GW.modeSelectButtonClicked");
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// Determine which setting was chosen (i.e., which button was clicked).
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let selectedMode = event.target.dataset.name;
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// Save the new setting.
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if (selectedMode == "auto") localStorage.removeItem("selected-mode");
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else localStorage.setItem("selected-mode", selectedMode);
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// Actually change the mode.
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setMode(selectedMode);
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});
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});
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document.querySelector("head").insertAdjacentHTML("beforeend", `<style id='mode-selector-styles'>
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#mode-selector {
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position: absolute;
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right: 3px;
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top: 4px;
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display: flex;
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background-color: #fff;
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padding: 0.125em 0.25em;
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border: 3px solid transparent;
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opacity: 0.3;
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transition:
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opacity 2s ease;
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}
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#mode-selector.hidden {
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opacity: 0;
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}
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#mode-selector:hover {
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transition: none;
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opacity: 1.0;
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border: 3px double #aaa;
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}
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#mode-selector button {
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-moz-appearance: none;
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appearance: none;
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border: none;
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background-color: transparent;
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padding: 0.5em;
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margin: 0;
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line-height: 1;
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font-family: Lucida Sans Unicode, Source Sans Pro, Helvetica, Trebuchet MS, sans-serif;
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font-size: 0.75rem;
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text-align: center;
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color: #777;
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position: relative;
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}
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#mode-selector button:hover,
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#mode-selector button.selected {
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box-shadow:
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0 2px 0 6px #fff inset,
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0 1px 0 6px currentColor inset;
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}
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#mode-selector button:not(:disabled):hover {
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color: #000;
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cursor: pointer;
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}
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#mode-selector button:not(:disabled):active {
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transform: translateY(2px);
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box-shadow:
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0 0px 0 6px #fff inset,
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0 -1px 0 6px currentColor inset;
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}
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#mode-selector button.active:not(:hover)::after {
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content: "";
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position: absolute;
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bottom: 0.25em;
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left: 0;
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right: 0;
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border-bottom: 1px dotted currentColor;
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width: calc(100% - 12px);
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margin: auto;
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}
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</style>`);
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document.querySelector("head").insertAdjacentHTML("beforeend", `<style id='mode-styles'></style>`);
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setMode(currentMode);
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// We pre-query the relevant elements, so we don’t have to run queryAll on
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// every firing of the scroll listener.
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GW.scrollState = {
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"lastScrollTop": window.pageYOffset || document.documentElement.scrollTop,
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"unbrokenDownScrollDistance": 0,
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"unbrokenUpScrollDistance": 0,
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"modeSelector": document.querySelectorAll("#mode-selector"),
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};
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addScrollListener(updateModeSelectorVisibility, "updateModeSelectorVisibilityScrollListener");
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GW.scrollState.modeSelector[0].addEventListener("mouseover", () => { showModeSelector(); });
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doWhenMatchMedia(GW.mediaQueries.systemDarkModeActive, "updateModeSelectorStateForSystemDarkMode", () => { updateModeSelectorState(); });
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}
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/* Show/hide the mode selector in response to scrolling.
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Called by the ‘updateModeSelectorVisibilityScrollListener’ scroll listener.
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*/
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function updateModeSelectorVisibility(event) {
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GWLog("updateModeSelectorVisibility");
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let newScrollTop = window.pageYOffset || document.documentElement.scrollTop;
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GW.scrollState.unbrokenDownScrollDistance = (newScrollTop > GW.scrollState.lastScrollTop) ?
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(GW.scrollState.unbrokenDownScrollDistance + newScrollTop - GW.scrollState.lastScrollTop) :
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0;
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GW.scrollState.unbrokenUpScrollDistance = (newScrollTop < GW.scrollState.lastScrollTop) ?
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(GW.scrollState.unbrokenUpScrollDistance + GW.scrollState.lastScrollTop - newScrollTop) :
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0;
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GW.scrollState.lastScrollTop = newScrollTop;
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// Hide mode selector when scrolling a full page down.
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if (GW.scrollState.unbrokenDownScrollDistance > window.innerHeight) {
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hideModeSelector();
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}
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// On desktop, show mode selector when scrolling to top of page,
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// or a full page up.
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// On mobile, show mode selector on ANY scroll up.
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if (GW.mediaQueries.mobileNarrow.matches) {
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if (GW.scrollState.unbrokenUpScrollDistance > 0 || GW.scrollState.lastScrollTop <= 0)
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showModeSelector();
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} else if ( GW.scrollState.unbrokenUpScrollDistance > window.innerHeight
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|| GW.scrollState.lastScrollTop == 0) {
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showModeSelector();
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}
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}
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function hideModeSelector() {
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GWLog("hideModeSelector");
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GW.scrollState.modeSelector[0].classList.add("hidden");
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}
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function showModeSelector() {
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GWLog("showModeSelector");
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GW.scrollState.modeSelector[0].classList.remove("hidden");
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}
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/* Update the states of the mode selector buttons.
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*/
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|||
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function updateModeSelectorState() {
|
|||
|
// Get saved mode setting (or default).
|
|||
|
let currentMode = localStorage.getItem("selected-mode") || 'auto';
|
|||
|
|
|||
|
// Clear current buttons state.
|
|||
|
let modeSelector = document.querySelector("#mode-selector");
|
|||
|
modeSelector.childNodes.forEach(button => {
|
|||
|
button.classList.remove("active", "selected");
|
|||
|
button.disabled = false;
|
|||
|
});
|
|||
|
|
|||
|
// Set the correct button to be selected.
|
|||
|
modeSelector.querySelectorAll(`.select-mode-${currentMode}`).forEach(button => {
|
|||
|
button.classList.add("selected");
|
|||
|
button.disabled = true;
|
|||
|
});
|
|||
|
|
|||
|
// Ensure the right button (light or dark) has the “currently activeâ€
|
|||
|
// indicator, if the current mode is ‘auto’.
|
|||
|
if (currentMode == "auto") {
|
|||
|
if (GW.mediaQueries.systemDarkModeActive.matches)
|
|||
|
modeSelector.querySelector(".select-mode-dark").classList.add("active");
|
|||
|
else
|
|||
|
modeSelector.querySelector(".select-mode-light").classList.add("active");
|
|||
|
}
|
|||
|
}
|
|||
|
|
|||
|
/* Set specified color mode (auto, light, dark).
|
|||
|
*/
|
|||
|
function setMode(modeOption) {
|
|||
|
GWLog("setMode");
|
|||
|
|
|||
|
// Inject the appropriate styles.
|
|||
|
let modeStyles = document.querySelector("#mode-styles");
|
|||
|
if (modeOption == 'auto') {
|
|||
|
modeStyles.innerHTML = `@media (prefers-color-scheme:dark) {${GW.modeStyles}}`;
|
|||
|
} else if (modeOption == 'dark') {
|
|||
|
modeStyles.innerHTML = GW.modeStyles;
|
|||
|
} else {
|
|||
|
modeStyles.innerHTML = "";
|
|||
|
}
|
|||
|
|
|||
|
// Update selector state.
|
|||
|
updateModeSelectorState();
|
|||
|
}
|
|||
|
|
|||
|
/******************/
|
|||
|
/* INITIALIZATION */
|
|||
|
/******************/
|
|||
|
|
|||
|
doWhenPageLoaded(() => {
|
|||
|
injectModeSelector();
|
|||
|
});
|