misskey/packages/client/src/pages/admin/_header_.vue

<template>
<div ref="el" class="fdidabkc" :style="{ background: bg }" @click="onClick">
	<template v-if="metadata">
		<div class="titleContainer" @click="showTabsPopup">
			<i v-if="metadata.icon" class="icon" :class="metadata.icon"></i>

			<div class="title">
				<div class="title">{{ metadata.title }}</div>
			</div>
		</div>
		<div class="tabs">
			<button v-for="tab in tabs" :ref="(el) => tabRefs[tab.key] = el" v-tooltip="tab.title" class="tab _button" :class="{ active: tab.key != null && tab.key === props.tab }" @mousedown="(ev) => onTabMousedown(tab, ev)" @click="(ev) => onTabClick(tab, ev)">
				<i v-if="tab.icon" class="icon" :class="tab.icon"></i>
				<span v-if="!tab.iconOnly" class="title">{{ tab.title }}</span>
			</button>
			<div ref="tabHighlightEl" class="highlight"></div>
		</div>
	</template>
	<div class="buttons right">
		<template v-if="actions">
			<template v-for="action in actions">
				<MkButton v-if="action.asFullButton" class="fullButton" primary @click.stop="action.handler"><i :class="action.icon" style="margin-right: 6px;"></i>{{ action.text }}</MkButton>
				<button v-else v-tooltip="action.text" class="_button button" :class="{ highlighted: action.highlighted }" @click.stop="action.handler" @touchstart="preventDrag"><i :class="action.icon"></i></button>
			</template>
		</template>
	</div>
</div>
</template>

<script lang="ts" setup>
import { computed, onMounted, onUnmounted, ref, inject, watch } from 'vue';
import tinycolor from 'tinycolor2';
import { popupMenu } from '@/os';
import { url } from '@/config';
import { scrollToTop } from '@/scripts/scroll';
import MkButton from '@/components/ui/button.vue';
import { i18n } from '@/i18n';
import { globalEvents } from '@/events';
import { injectPageMetadata } from '@/scripts/page-metadata';

type Tab = {
	key?: string | null;
	title: string;
	icon?: string;
	iconOnly?: boolean;
	onClick?: (ev: MouseEvent) => void;
};

const props = defineProps<{
	tabs?: Tab[];
	tab?: string;
	actions?: {
		text: string;
		icon: string;
		asFullButton?: boolean;
		handler: (ev: MouseEvent) => void;
	}[];
	thin?: boolean;
}>();

const emit = defineEmits<{
	(ev: 'update:tab', key: string);
}>();

const metadata = injectPageMetadata();

const el = ref<HTMLElement>(null);
const tabRefs = {};
const tabHighlightEl = $ref<HTMLElement | null>(null);
const bg = ref(null);
const height = ref(0);
const hasTabs = computed(() => {
	return props.tabs && props.tabs.length > 0;
});

const showTabsPopup = (ev: MouseEvent) => {
	if (!hasTabs.value) return;
	if (!narrow.value) return;
	ev.preventDefault();
	ev.stopPropagation();
	const menu = props.tabs.map(tab => ({
		text: tab.title,
		icon: tab.icon,
		active: tab.key != null && tab.key === props.tab,
		action: (ev) => {
			onTabClick(tab, ev);
		},
	}));
	popupMenu(menu, ev.currentTarget ?? ev.target);
};

const preventDrag = (ev: TouchEvent) => {
	ev.stopPropagation();
};

const onClick = () => {
	scrollToTop(el.value, { behavior: 'smooth' });
};

function onTabMousedown(tab: Tab, ev: MouseEvent): void {
	// ユーザビリティの観点からmousedown時にはonClickは呼ばない
	if (tab.key) {
		emit('update:tab', tab.key);
	}
}

function onTabClick(tab: Tab, ev: MouseEvent): void {
	if (tab.onClick) {
		ev.preventDefault();
		ev.stopPropagation();
		tab.onClick(ev);
	}
	if (tab.key) {
		emit('update:tab', tab.key);
	}
}

const calcBg = () => {
	const rawBg = metadata?.bg || 'var(--bg)';
	const tinyBg = tinycolor(rawBg.startsWith('var(') ? getComputedStyle(document.documentElement).getPropertyValue(rawBg.slice(4, -1)) : rawBg);
	tinyBg.setAlpha(0.85);
	bg.value = tinyBg.toRgbString();
};

onMounted(() => {
	calcBg();
	globalEvents.on('themeChanged', calcBg);

	watch(() => props.tab, () => {
		const tabEl = tabRefs[props.tab];
		if (tabEl && tabHighlightEl) {
			// offsetWidth や offsetLeft は少数を丸めてしまうため getBoundingClientRect を使う必要がある
			// https://developer.mozilla.org/ja/docs/Web/API/HTMLElement/offsetWidth#%E5%80%A4
			const parentRect = tabEl.parentElement.getBoundingClientRect();
			const rect = tabEl.getBoundingClientRect();
			tabHighlightEl.style.width = rect.width + 'px';
			tabHighlightEl.style.left = (rect.left - parentRect.left) + 'px';
		}
	}, {
		immediate: true,
	});
});

onUnmounted(() => {
	globalEvents.off('themeChanged', calcBg);
});
</script>

<style lang="scss" scoped>
.fdidabkc {
	--height: 60px;
	display: flex;
	position: sticky;
	top: var(--stickyTop, 0);
	z-index: 1000;
	width: 100%;
	-webkit-backdrop-filter: var(--blur, blur(15px));
	backdrop-filter: var(--blur, blur(15px));

	> .buttons {
		--margin: 8px;
		display: flex;
    align-items: center;
		height: var(--height);
		margin: 0 var(--margin);

		&.right {
			margin-left: auto;
		}

		&:empty {
			width: var(--height);
		}

		> .button {
			display: flex;
			align-items: center;
			justify-content: center;
			height: calc(var(--height) - (var(--margin) * 2));
			width: calc(var(--height) - (var(--margin) * 2));
			box-sizing: border-box;
			position: relative;
			border-radius: 5px;

			&:hover {
				background: rgba(0, 0, 0, 0.05);
			}

			&.highlighted {
				color: var(--accent);
			}
		}

		> .fullButton {
			& + .fullButton {
				margin-left: 12px;
			}
		}
	}

	> .titleContainer {
		display: flex;
		align-items: center;
		max-width: 400px;
		overflow: auto;
		white-space: nowrap;
		text-align: left;
		font-weight: bold;
		flex-shrink: 0;
		margin-left: 24px;

		> .avatar {
			$size: 32px;
			display: inline-block;
			width: $size;
			height: $size;
			vertical-align: bottom;
			margin: 0 8px;
			pointer-events: none;
		}

		> .icon {
			margin-right: 8px;
			width: 16px;
			text-align: center;
		}

		> .title {
			min-width: 0;
			overflow: hidden;
			text-overflow: ellipsis;
			white-space: nowrap;
			line-height: 1.1;

			> .subtitle {
				opacity: 0.6;
				font-size: 0.8em;
				font-weight: normal;
				white-space: nowrap;
				overflow: hidden;
				text-overflow: ellipsis;

				&.activeTab {
					text-align: center;

					> .chevron {
						display: inline-block;
						margin-left: 6px;
					}
				}
			}
		}
	}

	> .tabs {
		position: relative;
		margin-left: 16px;
		font-size: 0.8em;
		overflow: auto;
		white-space: nowrap;

		> .tab {
			display: inline-block;
			position: relative;
			padding: 0 10px;
			height: 100%;
			font-weight: normal;
			opacity: 0.7;

			&:hover {
				opacity: 1;
			}

			&.active {
				opacity: 1;
			}

			> .icon + .title {
				margin-left: 8px;
			}
		}

		> .highlight {
			position: absolute;
			bottom: 0;
			height: 3px;
			background: var(--accent);
			border-radius: 999px;
			transition: all 0.2s ease;
			pointer-events: none;
		}
	}
}
</style>