mdw@git.distorted.org.uk Git - tgal/blob - static/tgal.js

   1 /* -*-javascript-*-
   2  *
   3  * Interactive features for Trivial Gallery.
   4  *
   5  * (c) 2021 Mark Wooding
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Trivial Gallery.
  11  *
  12  * Trivial Gallery is free software: you can redistribute it and/or modify
  13  * it under the terms of the GNU Affero General Public License as
  14  * published by the Free Software Foundation; either version 3 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * Trivial Gallery is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * Affero General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Affero General Public
  23  * License along with Trivial Gallery.  If not, see
  24  * <https://www.gnu.org/licenses/>.
  25  */
  26
  27 /* Handle keyboard interaction. */
  28 addEventListener("keydown", function (ev) {
  29   var dir;
  30   if (ev.key === " " || ev.key === "ArrowRight") dir = "next";
  31   else if (ev.key === " " || ev.key === "ArrowRight") dir = "next";
  32   else if (ev.key === "Backspace" || ev.key === "ArrowLeft") dir = "prev";
  33   else if (ev.key === "^") dir = "up";
  34   else if (ev.key === "<") dir = "first";
  35   else if (ev.key === ">") dir = "last";
  36   else return;
  37   var elt = document.querySelector("link[rel=" + dir + "]");
  38   if (!elt) return;
  39   location = elt.getAttribute("href");
  40   ev.stopPropagation();
  41 }, true);
  42
  43 /* Scroll the thumbnail strip so that the current image is in the middle. */
  44 (function () {
  45   var obs = null;
  46
  47   var scroll = function(strip) {
  48     var focus = strip.querySelector("figure.focusthumb");
  49     if (focus) {
  50       var stripbox = strip.getBoundingClientRect();
  51       var focusbox = focus.getBoundingClientRect();
  52       strip.scrollLeft +=
  53         (focusbox.x - stripbox.x) -
  54         (stripbox.width - focusbox.width)/2;
  55     }
  56   };
  57
  58   var strips = document.querySelectorAll("div.thumbstrip");
  59   if (window.IntersectionObserver) {
  60     obs = new IntersectionObserver(function (ee) {
  61       ee.forEach(function (e) {
  62         if (e.isIntersecting) {
  63           obs.unobserve(e.target);
  64           scroll(e.target);
  65         }
  66       });
  67     }, {
  68       root: document.querySelector("html")
  69     });
  70     strips.forEach(function (strip) { obs.observe(strip); });
  71   } else {
  72     strips.forEach(scroll);
  73   }
  74 })();
  75
  76 /*----- That's all, folks -------------------------------------------------*/