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Diffstat (limited to 'src/hbmenu.js')
| -rw-r--r-- | src/hbmenu.js | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/src/hbmenu.js b/src/hbmenu.js new file mode 100644 index 0000000..48218cd --- /dev/null +++ b/src/hbmenu.js @@ -0,0 +1,259 @@ +/* +** Originally: Copyright © 2018 Warren Young +** +** This program is free software; you can redistribute it and/or +** modify it under the terms of the Simplified BSD License (also +** known as the "2-Clause License" or "FreeBSD License".) +** +** This program is distributed in the hope that it will be useful, +** but without any warranty; without even the implied warranty of +** merchantability or fitness for a particular purpose. +** +** Contact: wyoung on the Fossil forum, https://fossil-scm.org/forum/ +** Modified by others. +** +******************************************************************************* +** +** This file contains the JS code used to implement the expanding hamburger +** menu on various skins. +** +** This was original the "js.txt" file for the default skin. It was subsequently +** moved into src/hbmenu.js so that it could be more easily reused by other skins +** using the "builtin_request_js" TH1 command. +** +** Operation: +** +** This script expects the HTML to contain two elements: +** +** <a id="hbbtn"> <--- The hamburger menu button +** <nav id="hbdrop"> <--- Container for the hamburger menu +** +** Bindings are made on hbbtn so that when it is clicked, the following +** happens: +** +** 1. An XHR is made to /sitemap?popup to fetch the HTML for the +** popup menu. +** +** 2. The HTML for the popup is inserted into hddrop. +** +** 3. The hddrop container is made visible. +** +** CSS rules are also needed to cause the hddrop to be initially invisible, +** and to correctly style and position the hddrop container. +*/ +(function() { + var hbButton = document.getElementById("hbbtn"); + if (!hbButton) return; // no hamburger button + if (!document.addEventListener) return; // Incompatible browser + var panel = document.getElementById("hbdrop"); + if (!panel) return; // site admin might've nuked it + if (!panel.style) return; // shouldn't happen, but be sure + var panelBorder = panel.style.border; + var panelInitialized = false; // reset if browser window is resized + var panelResetBorderTimerID = 0; // used to cancel post-animation tasks + + // Disable animation if this browser doesn't support CSS transitions. + // + // We need this ugly calling form for old browsers that don't allow + // panel.style.hasOwnProperty('transition'); catering to old browsers + // is the whole point here. + var animate = panel.style.transition !== null && (typeof(panel.style.transition) == "string"); + + // The duration of the animation can be overridden from the default skin + // header.txt by setting the "data-anim-ms" attribute of the panel. + var animMS = panel.getAttribute("data-anim-ms"); + if (animMS) { // not null or empty string, parse it + animMS = parseInt(animMS); + if (isNaN(animMS) || animMS == 0) + animate = false; // disable animation if non-numeric or zero + else if (animMS < 0) + animMS = 400; // set default animation duration if negative + } + else // attribute is null or empty string, use default + animMS = 400; + + // Calculate panel height despite its being hidden at call time. + // Based on https://stackoverflow.com/a/29047447/142454 + var panelHeight; // computed on first panel display + function calculatePanelHeight() { + + // Clear the max-height CSS property in case the panel size is recalculated + // after the browser window was resized. + panel.style.maxHeight = ''; + + // Get initial panel styles so we can restore them below. + var es = window.getComputedStyle(panel), + edis = es.display, + epos = es.position, + evis = es.visibility; + + // Restyle the panel so we can measure its height while invisible. + panel.style.visibility = 'hidden'; + panel.style.position = 'absolute'; + panel.style.display = 'block'; + panelHeight = panel.offsetHeight + 'px'; + + // Revert styles now that job is done. + panel.style.display = edis; + panel.style.position = epos; + panel.style.visibility = evis; + } + + // Show the panel by changing the panel height, which kicks off the + // slide-open/closed transition set up in the XHR onload handler. + // + // Schedule the change for a near-future time in case this is the + // first call, where the div was initially invisible. If we were + // to change the panel's visibility and height at the same time + // instead, that would prevent the browser from seeing the height + // change as a state transition, so it'd skip the CSS transition: + // + // https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Transitions/Using_CSS_transitions#JavaScript_examples + function showPanel() { + // Cancel the timer to remove the panel border after the closing animation, + // otherwise double-clicking the hamburger button with the panel opened will + // remove the borders from the (closed and immediately reopened) panel. + if (panelResetBorderTimerID) { + clearTimeout(panelResetBorderTimerID); + panelResetBorderTimerID = 0; + } + if (animate) { + if (!panelInitialized) { + panelInitialized = true; + // Set up a CSS transition to animate the panel open and + // closed. Only needs to be done once per page load. + // Based on https://stackoverflow.com/a/29047447/142454 + calculatePanelHeight(); + panel.style.transition = 'max-height ' + animMS + + 'ms ease-in-out'; + panel.style.overflowY = 'hidden'; + panel.style.maxHeight = '0'; + } + setTimeout(function() { + panel.style.maxHeight = panelHeight; + panel.style.border = panelBorder; + }, 40); // 25ms is insufficient with Firefox 62 + } + panel.style.display = 'block'; + document.addEventListener('keydown',panelKeydown,/* useCapture == */true); + document.addEventListener('click',panelClick,false); + } + + var panelKeydown = function(event) { + var key = event.which || event.keyCode; + if (key == 27) { + event.stopPropagation(); // ignore other keydown handlers + panelToggle(true); + } + }; + + var panelClick = function(event) { + if (!panel.contains(event.target)) { + // Call event.preventDefault() to have clicks outside the opened panel + // just close the panel, and swallow clicks on links or form elements. + //event.preventDefault(); + panelToggle(true); + } + }; + + // Return true if the panel is showing. + function panelShowing() { + if (animate) { + return panel.style.maxHeight == panelHeight; + } + else { + return panel.style.display == 'block'; + } + } + + // Check if the specified HTML element has any child elements. Note that plain + // text nodes, comments, and any spaces (presentational or not) are ignored. + function hasChildren(element) { + var childElement = element.firstChild; + while (childElement) { + if (childElement.nodeType == 1) // Node.ELEMENT_NODE == 1 + return true; + childElement = childElement.nextSibling; + } + return false; + } + + // Reset the state of the panel to uninitialized if the browser window is + // resized, so the dimensions are recalculated the next time it's opened. + window.addEventListener('resize',function(event) { + panelInitialized = false; + },false); + + // Click handler for the hamburger button. + hbButton.addEventListener('click',function(event) { + // Break the event handler chain, or the handler for document → click + // (about to be installed) may already be triggered by the current event. + event.stopPropagation(); + event.preventDefault(); // prevent browser from acting on <a> click + panelToggle(false); + },false); + + function panelToggle(suppressAnimation) { + if (panelShowing()) { + document.removeEventListener('keydown',panelKeydown,/* useCapture == */true); + document.removeEventListener('click',panelClick,false); + // Transition back to hidden state. + if (animate) { + if (suppressAnimation) { + var transition = panel.style.transition; + panel.style.transition = ''; + panel.style.maxHeight = '0'; + panel.style.border = 'none'; + setTimeout(function() { + // Make sure CSS transition won't take effect now, so restore it + // asynchronously. Outer variable 'transition' still valid here. + panel.style.transition = transition; + }, 40); // 25ms is insufficient with Firefox 62 + } + else { + panel.style.maxHeight = '0'; + panelResetBorderTimerID = setTimeout(function() { + // Browsers show a 1px high border line when maxHeight == 0, + // our "hidden" state, so hide the borders in that state, too. + panel.style.border = 'none'; + panelResetBorderTimerID = 0; // clear ID of completed timer + }, animMS); + } + } + else { + panel.style.display = 'none'; + } + } + else { + if (!hasChildren(panel)) { + // Only get the sitemap once per page load: it isn't likely to + // change on us. + var xhr = new XMLHttpRequest(); + xhr.onload = function() { + var doc = xhr.responseXML; + if (doc) { + var sm = doc.querySelector("ul#sitemap"); + if (sm && xhr.status == 200) { + // Got sitemap. Insert it into the drop-down panel. + panel.innerHTML = sm.outerHTML; + // Display the panel + showPanel(); + } + } + // else, can't parse response as HTML or XML + } + // The extra "popup" query parameter is a single to the server that the + // header and footer boiler-plate can be omitted. The boiler-plate is + // ignored if it is included. The popup query parameter is just an + // optimization. + var url = hbButton.href + (hbButton.href.includes("?")?"&popup":"?popup") + xhr.open("GET", url); + xhr.responseType = "document"; + xhr.send(); + } + else { + showPanel(); // just show what we built above + } + } + } +})(); |