Added container component implementation

src/assets/javascripts/component/container/index.ts

@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2016-2019 Martin Donath <martin.donath@squidfunk.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+import { reduce } from "ramda"
+import { Observable, combineLatest } from "rxjs"
+import { distinctUntilChanged, map, shareReplay } from "rxjs/operators"
+
+import { ViewportOffset, ViewportSize } from "../../ui"
+import { toArray } from "../../utilities"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Container state
+ */
+export interface ContainerState {
+  offset: number                       /* Container top offset */
+  height: number                       /* Container height */
+  active: boolean                      /* Scrolled past top */
+}
+
+/* ----------------------------------------------------------------------------
+ * Function types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Options
+ */
+interface Options {
+  size$: Observable<ViewportSize>      /* Viewport size observable */
+  offset$: Observable<ViewportOffset>  /* Viewport offset observable */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Create an observable for the container component
+ *
+ * The container represents the main content area including the sidebars (table
+ * of contents and navigation), as well as the actual page content.
+ *
+ * @param container - Container element
+ * @param header - Header element
+ * @param options - Options
+ *
+ * @return Container state observable
+ */
+export function fromContainer(
+  container: HTMLElement, header: HTMLElement, options: Options
+): Observable<ContainerState> {
+
+  /* Adjust top offset if header is fixed */
+  const adjust = getComputedStyle(header)
+    .getPropertyValue("position") === "fixed"
+      ? header.offsetHeight
+      : 0
+
+  /* Compute the container's top offset */
+  const offset$ = options.size$.pipe(
+    map(() => reduce((offset, child) => {
+      return Math.max(offset, child.offsetTop)
+    }, 0, toArray(container.children)) - adjust),
+    distinctUntilChanged(),
+    shareReplay({ bufferSize: 1, refCount: true })
+  )
+
+  /* Compute the container's available height */
+  const height$ = combineLatest(options.offset$, options.size$, offset$).pipe(
+    map(([{ y }, { height }, offset]) => {
+      const bottom = container.offsetTop + container.offsetHeight
+      return height - adjust
+        - Math.max(0, offset - y)
+        - Math.max(0, height + y - bottom)
+    }),
+    distinctUntilChanged()
+  )
+
+  /* Compute whether the viewport offset is past the container's top */
+  const active$ = combineLatest(options.offset$, offset$).pipe(
+    map(([{ y }, threshold]) => y >= threshold),
+    distinctUntilChanged()
+  )
+
+  /* Combine into a single hot observable */
+  return combineLatest(offset$, height$, active$).pipe(
+    map(([offset, height, active]) => ({ offset, height, active })),
+    shareReplay({ bufferSize: 1, refCount: true })
+  )
+}

src/assets/javascripts/ui/location/index.ts

@@ -21,12 +21,7 @@
  */
 
 import { Observable, fromEvent } from "rxjs"
-import {
-  filter,
-  map,
-  shareReplay,
-  startWith
-} from "rxjs/operators"
+import { filter, map, shareReplay, startWith } from "rxjs/operators"
 
 /* ----------------------------------------------------------------------------
  * Data