viewer: migrate to vue 3, general refactoring and cleanup

Non-exhaustive list of fixes and improvements done at the same time:

- html default background to grey (avoids white flash during init)
- unified links behavior
- added more theme variables
- removed the flex-expand transition (it wasn't working) and replaced it
  with a slide
- fixed LdLoading not centered on the content
- title on removable tags
- fixed an issue with encoded URI from vue-router
- unified Item resource URLs
- removed the iframe for PlainTextViewer (it wasn't working properly)
  and replaced it with a pre
- fixed clear and search buttons tabindex
- fixed the information panel bumping up during the fade animation of
  tag's dropdown
- fixed some focus outlines not appearing correctly
- moved CSS variables to the :root context
- Code cleaning

GitHub: closes #217
GitHub: closes #300
GitHub: closes #297
GitHub: closes #105
GitHub: closes #267
GitHub: closes #275
GitHub: closes #228
GitHub: closes #215
GitHub: closes #112

7 files changed, 317 insertions, 0 deletions

diff --git a/viewer/src/services/ui/ldFullscreen.ts b/viewer/src/services/ui/ldFullscreen.ts
new file mode 100644
index 0000000..80e755d
--- /dev/null
+++ b/viewer/src/services/ui/ldFullscreen.ts
@@ -0,0 +1,41 @@
+/* ldgallery - A static generator which turns a collection of tagged
+--             pictures into a searchable web gallery.
+--
+-- Copyright (C) 2019-2022  Guillaume FOUET
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- 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.  See the
+-- GNU Affero General Public License for more details.
+--
+-- You should have received a copy of the GNU Affero General Public License
+-- along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+import { useUiStore } from '@/store/uiStore';
+import { useEventListener } from '@vueuse/core';
+import { watch } from 'vue';
+
+export const useLdFullscreen = () => {
+  const uiStore = useUiStore();
+
+  useEventListener(document, 'fullscreenchange', onFullscreenChange);
+
+  function onFullscreenChange() {
+    uiStore.toggleFullscreen(isFullscreenActive());
+  }
+
+  function isFullscreenActive(): boolean {
+    return Boolean(document.fullscreenElement);
+  }
+
+  watch(() => uiStore.fullscreen, (fullscreen) => {
+    if (fullscreen && !isFullscreenActive()) document.body.requestFullscreen();
+    else if (isFullscreenActive()) document.exitFullscreen();
+  });
+};
diff --git a/viewer/src/services/ui/ldItemResourceUrl.ts b/viewer/src/services/ui/ldItemResourceUrl.ts
new file mode 100644
index 0000000..7db7ab9
--- /dev/null
+++ b/viewer/src/services/ui/ldItemResourceUrl.ts
@@ -0,0 +1,15 @@
+import { Item } from '@/@types/gallery';
+import { useGalleryStore } from '@/store/galleryStore';
+import { computed } from 'vue';
+import { isDownloadableItem } from '../itemGuards';
+
+export const useItemResource = (item: Item) => {
+  const galleryStore = useGalleryStore();
+  const itemResourceUrl = computed(() => isDownloadableItem(item) ? galleryStore.resourceRoot + item.properties.resource : '');
+  const thumbnailResourceUrl = computed(() => item.thumbnail ? galleryStore.resourceRoot + item.thumbnail.resource : '');
+
+  return {
+    itemResourceUrl,
+    thumbnailResourceUrl,
+  };
+};
diff --git a/viewer/src/services/ui/ldKeepFocus.ts b/viewer/src/services/ui/ldKeepFocus.ts
new file mode 100644
index 0000000..ce9cbc8
--- /dev/null
+++ b/viewer/src/services/ui/ldKeepFocus.ts
@@ -0,0 +1,34 @@
+/* ldgallery - A static generator which turns a collection of tagged
+--             pictures into a searchable web gallery.
+--
+-- Copyright (C) 2019-2022  Guillaume FOUET
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- 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.  See the
+-- GNU Affero General Public License for more details.
+--
+-- You should have received a copy of the GNU Affero General Public License
+-- along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+import { MaybeElementRef, useFocus } from '@vueuse/core';
+import { watch } from 'vue';
+import { useRoute } from 'vue-router';
+
+export const useLdKeepFocus = (element: MaybeElementRef) => {
+  const contentFocus = useFocus(element);
+  const route = useRoute();
+
+  watch(() => route.path, moveFocus);
+
+  function moveFocus() {
+    contentFocus.focused.value = true;
+  }
+  return { moveFocus };
+};
diff --git a/viewer/src/services/ui/ldKeyboard.ts b/viewer/src/services/ui/ldKeyboard.ts
new file mode 100644
index 0000000..8576435
--- /dev/null
+++ b/viewer/src/services/ui/ldKeyboard.ts
@@ -0,0 +1,28 @@
+/* ldgallery - A static generator which turns a collection of tagged
+--             pictures into a searchable web gallery.
+--
+-- Copyright (C) 2019-2022  Guillaume FOUET
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- 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.  See the
+-- GNU Affero General Public License for more details.
+--
+-- You should have received a copy of the GNU Affero General Public License
+-- along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+import { useUiStore } from '@/store/uiStore';
+import { onKeyStroke } from '@vueuse/core';
+
+export const useLdKeyboard = () => {
+  const uiStore = useUiStore();
+
+  // https://developer.mozilla.org/en-US/docs/Web/API/UI_Events/Keyboard_event_key_values
+  onKeyStroke('Escape', () => uiStore.toggleFullscreen(false));
+};
diff --git a/viewer/src/services/ui/ldSaveScroll.ts b/viewer/src/services/ui/ldSaveScroll.ts
new file mode 100644
index 0000000..34e277b
--- /dev/null
+++ b/viewer/src/services/ui/ldSaveScroll.ts
@@ -0,0 +1,37 @@
+/* ldgallery - A static generator which turns a collection of tagged
+--             pictures into a searchable web gallery.
+--
+-- Copyright (C) 2019-2022  Guillaume FOUET
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- 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.  See the
+-- GNU Affero General Public License for more details.
+--
+-- You should have received a copy of the GNU Affero General Public License
+-- along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+import { MaybeElementRef, unrefElement } from '@vueuse/core';
+import { nextTick, watch } from 'vue';
+import { useRoute } from 'vue-router';
+
+type ScrollPosition = Record<string, number>;
+
+export const useLdSaveScroll = (element: MaybeElementRef) => {
+  const scrollPositions: ScrollPosition = {};
+  const route = useRoute();
+
+  watch(() => decodeURIComponent(route.path), (newRoute, oldRoute) => {
+    const el = unrefElement(element);
+    if (!el) return;
+
+    scrollPositions[oldRoute] = el.scrollTop / el.scrollHeight;
+    nextTick(() => (el.scrollTop = scrollPositions[newRoute] * el.scrollHeight));
+  });
+};
diff --git a/viewer/src/services/ui/ldTitle.ts b/viewer/src/services/ui/ldTitle.ts
new file mode 100644
index 0000000..df80140
--- /dev/null
+++ b/viewer/src/services/ui/ldTitle.ts
@@ -0,0 +1,34 @@
+/* ldgallery - A static generator which turns a collection of tagged
+--             pictures into a searchable web gallery.
+--
+-- Copyright (C) 2019-2022  Guillaume FOUET
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- 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.  See the
+-- GNU Affero General Public License for more details.
+--
+-- You should have received a copy of the GNU Affero General Public License
+-- along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+import { useGalleryStore } from '@/store/galleryStore';
+import { useTitle } from '@vueuse/core';
+import { computed } from 'vue';
+
+export const useLdTitle = () => {
+  const galleryStore = useGalleryStore();
+
+  const title = computed(() => {
+    const { currentItem, galleryTitle } = galleryStore;
+    return currentItem?.title
+      ? `${currentItem.title} • ${galleryTitle}`
+      : galleryTitle;
+  });
+  useTitle(title);
+};
diff --git a/viewer/src/services/ui/ldZoom.ts b/viewer/src/services/ui/ldZoom.ts
new file mode 100644
index 0000000..9f77dea
--- /dev/null
+++ b/viewer/src/services/ui/ldZoom.ts
@@ -0,0 +1,128 @@
+/* ldgallery - A static generator which turns a collection of tagged
+--             pictures into a searchable web gallery.
+--
+-- Copyright (C) 2020  Pacien TRAN-GIRARD
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as