131 lines
4.2 KiB
JavaScript
131 lines
4.2 KiB
JavaScript
/**
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* reveal-header
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* A filter that adds header text and logo.
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*
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* MIT License
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* Copyright (c) 2023 Shafayet Khan Shafee.
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*/
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function header() {
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// add the header structure as the firstChild of div.reveal-header
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function add_header() {
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let header = document.querySelector("div.reveal-header");
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let reveal = document.querySelector(".reveal");
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reveal.insertBefore(header, reveal.firstChild);
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logo_img = document.querySelector('.header-logo img');
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if (logo_img.getAttribute('src') == null) {
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if (logo_img?.getAttribute('data-src') != null) {
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logo_img.src = logo_img?.getAttribute('data-src') || "";
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logo_img.removeAttribute('data-src');
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};
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};
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};
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// add the class inverse-header for slide with has-dark-background class
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// otherwise remove it.
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function add_class(has_dark, header_paras) {
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header_paras.forEach(el => {
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el.classList.remove('inverse-header');
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if(has_dark) {
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el.classList.add('inverse-header');
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};
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});
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};
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// dynamically changing the header
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function change_header(dheader, cheader, ctext) {
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// dhead => dynamic header
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// chead => constant header
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// ctext => contstant header_text inner html
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if (dheader !== null) {
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cheader.innerHTML = dheader.innerHTML;
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} else {
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cheader.innerHTML = ctext;
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};
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};
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function hide_from_title_slide(element) {
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Reveal.on( 'slidechanged' , event => {
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if (event.currentSlide.matches('#title-slide')) {
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element.style.visibility = 'hidden';
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} else {
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element.style.visibility = 'visible';
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}
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});
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};
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if (Reveal.isReady()) {
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add_header();
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if (document.querySelector('div.reveal.has-logo') != null) {
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var slide_number = document.querySelector('div.slide-number');
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var header = document.querySelector("div.reveal-header");
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header.appendChild(slide_number);
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};
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// Get the default header text element and innner HTML (i.e. literal text)
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var header_text = document.querySelector("div.header-text p");
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const header_inner_html = header_text.innerHTML;
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var header_paras = document.querySelectorAll("div.reveal-header p");
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var dark = Reveal.getCurrentSlide().classList.contains('has-dark-background');
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add_class(dark, header_paras);
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Reveal.on( 'slidechanged', event => {
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var has_dark = event.currentSlide.classList.contains('has-dark-background');
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add_class(has_dark, header_paras);
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});
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// make the visibility of slide specific header text defined in slide body none
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document.querySelectorAll('div.header').forEach(el => {
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el.style.display = 'none';
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});
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// change the header if currently loaded slide has the header div defined
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// which won't be captured by slidechanged event unless we change slides.
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let dynamic_header = Reveal.getCurrentSlide().querySelector('div.header p');
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change_header(dynamic_header, header_text, header_inner_html);
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Reveal.on( 'slidechanged', event => {
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let dyn_header = event.currentSlide.querySelector('div.header p');
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change_header(dyn_header, header_text, header_inner_html);
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});
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/************** header text in title slide if title or ***********************/
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/************* subtitle is used as header text ***********************/
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var title_text = document.querySelector('.reveal-header .title-text p');
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if (title_text != null) {
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title_text.style.visibility = 'hidden';
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hide_from_title_slide(title_text);
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};
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/*************** hide header text and logo on title slide ********************/
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var hide_header_text = document.querySelector('.header-text').getAttribute('data-hide-from-titleslide');
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var hide_header_logo = document.querySelector('.header-logo').getAttribute('data-hide-from-titleslide');
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if (hide_header_text == 'true') {
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header_text.style.visibility = 'hidden';
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hide_from_title_slide(header_text);
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}
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if (hide_header_logo == 'true') {
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logo_img.style.visibility = 'hidden';
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hide_from_title_slide(logo_img);
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}
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};
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};
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window.addEventListener("load", (event) => {
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header();
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});
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