Adds progress notification bar (#526)

assets/components/ScrollProgress.vue

@@ -0,0 +1,103 @@
+<template>
+  <div class="scroll-progress">
+    <svg width="100" height="100" viewBox="0 0 100 100">
+      <circle r="44" cx="50" cy="50" :style="{ '--progress': scrollProgress }" />
+    </svg>
+    <div class="percent columns is-vcentered is-centered">
+      <span class="column is-narrow is-paddingless is-size-2">
+        {{ Math.ceil(scrollProgress * 100) }}
+      </span>
+      <span class="column is-narrow is-paddingless">
+        %
+      </span>
+    </div>
+  </div>
+</template>
+
+<script>
+import { mapState } from "vuex";
+import throttle from "lodash.throttle";
+
+export default {
+  name: "ScrollProgress",
+  data() {
+    return {
+      scrollProgress: 0,
+      animation: { cancel: () => {} },
+      parentElement: document,
+    };
+  },
+  created() {
+    this.onScrollThrottled = throttle(this.onScroll, 150);
+  },
+  mounted() {
+    this.attachEvents();
+    this.$once("hook:beforeDestroy", this.detachEvents);
+  },
+  watch: {
+    activeContainers() {
+      this.detachEvents();
+      this.attachEvents();
+    },
+  },
+  computed: {
+    ...mapState(["activeContainers"]),
+  },
+  methods: {
+    attachEvents() {
+      this.parentElement = this.$el.closest("[data-scrolling]") || document;
+      this.parentElement.addEventListener("scroll", this.onScrollThrottled);
+    },
+    detachEvents() {
+      this.parentElement.removeEventListener("scroll", this.onScrollThrottled);
+    },
+    onScroll() {
+      const p = this.parentElement == document ? document.documentElement : this.parentElement;
+      this.scrollProgress = p.scrollTop / (p.scrollHeight - p.clientHeight);
+      this.animation.cancel();
+      this.animation = this.$el.animate(
+        { opacity: [1, 0] },
+        {
+          duration: 500,
+          delay: 2000,
+          fill: "both",
+          easing: "ease-out",
+        }
+      );
+    },
+  },
+};
+</script>
+<style scoped lang="scss">
+.scroll-progress {
+  display: inline-block;
+  position: relative;
+  circle {
+    fill: #000;
+    fill-opacity: 0.6;
+    transition: stroke-dashoffset 0.35s ease-out;
+    transform: rotate(-90deg);
+    transform-origin: 50% 50%;
+    stroke: #00d1b2;
+    stroke-dashoffset: calc(276.32 - var(--progress) * 276.32);
+    stroke-dasharray: 276.32 276.32;
+    stroke-width: 3;
+    will-change: stroke-dashoffset;
+    html.has-light-theme & {
+      fill-opacity: 0.1;
+    }
+  }
+
+  .percent {
+    position: absolute;
+    left: 0;
+    top: 0;
+    right: 0;
+    bottom: 0;
+
+    html.has-light-theme & {
+      color: #333;
+    }
+  }
+}
+</style>