Moved re-painting logic to anchor component

src/assets/javascripts/component/anchor/_/index.ts

@@ -0,0 +1,221 @@
+/*
+ * 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 { difference, reverse } from "ramda"
+import {
+  MonoTypeOperatorFunction,
+  Observable,
+  animationFrameScheduler,
+  combineLatest,
+  pipe
+} from "rxjs"
+import {
+  distinctUntilChanged,
+  map,
+  observeOn,
+  scan,
+  shareReplay,
+  switchMap,
+  tap
+} from "rxjs/operators"
+
+import { ViewportOffset, ViewportSize, getElement } from "../../../ui"
+import { Header } from "../../header"
+import {
+  resetAnchor,
+  setAnchorActive,
+  setAnchorBlur
+} from "../element"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Anchor list
+ */
+export interface AnchorList {
+  done: HTMLAnchorElement[][]          /* Done anchors */
+  next: HTMLAnchorElement[][]          /* Next anchors */
+}
+
+/* ----------------------------------------------------------------------------
+ * Function types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch options
+ */
+interface WatchOptions {
+  size$: Observable<ViewportSize>      /* Viewport size observable */
+  offset$: Observable<ViewportOffset>  /* Viewport offset observable */
+  header$: Observable<Header>          /* Header observable */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Create an observable to watch an anchor list
+ *
+ * This is effectively a scroll-spy implementation which will account for the
+ * fixed header and automatically re-calculate anchor offsets when the viewport
+ * is resized. The returned observable will only emit if the anchor list needs
+ * to be re-painted.
+ *
+ * This implementation tracks an anchor element's entire path starting from its
+ * level up to the top-most anchor element, e.g. `[h3, h2, h1]`. Although the
+ * Material theme currently doesn't make use of this information, it enables
+ * the styling of the entire hierarchy through customization.
+ *
+ * @param els - Anchor elements
+ * @param options - Options
+ *
+ * @return Anchor list observable
+ */
+export function watchAnchorList(
+  els: HTMLAnchorElement[], { size$, offset$, header$ }: WatchOptions
+): Observable<AnchorList> {
+  const table = new Map<HTMLAnchorElement, HTMLElement>()
+  for (const el of els) {
+    const target = getElement(decodeURIComponent(el.hash))
+    if (typeof target !== "undefined")
+      table.set(el, target)
+  }
+
+  /* Compute necessary adjustment for header */
+  const adjust$ = header$
+    .pipe(
+      map(header => 18 + header.height)
+    )
+
+  /* Compute partition of done and next anchors */
+  const partition$ = size$.pipe(
+
+    /* Build table to map anchor paths to vertical offsets */
+    map(() => {
+      let path: HTMLAnchorElement[] = []
+      return [...table].reduce((index, [anchor, target]) => {
+        while (path.length) {
+          const last = table.get(path[path.length - 1])!
+          if (last.tagName >= target.tagName) {
+            path.pop()
+          } else {
+            break
+          }
+        }
+        return index.set(
+          reverse(path = [...path, anchor]),
+          target.offsetTop
+        )
+      }, new Map<HTMLAnchorElement[], number>())
+    }),
+
+    /* Re-compute partition when viewport offset changes */
+    switchMap(index => combineLatest(offset$, adjust$)
+      .pipe(
+        scan(([done, next], [{ y }, adjust]) => {
+
+          /* Look forward */
+          while (next.length) {
+            const [, offset] = next[0]
+            if (offset - adjust < y) {
+              done = [...done, next.shift()!]
+            } else {
+              break
+            }
+          }
+
+          /* Look backward */
+          while (done.length) {
+            const [, offset] = done[done.length - 1]
+            if (offset - adjust >= y) {
+              next = [done.pop()!, ...next]
+            } else {
+              break
+            }
+          }
+
+          /* Return partition */
+          return [done, next]
+        }, [[], [...index]]),
+        distinctUntilChanged((a, b) => {
+          return a[0] === b[0]
+              && a[1] === b[1]
+        })
+      )
+    )
+  )
+
+  /* Extract anchor list and return hot observable */
+  return partition$
+    .pipe(
+      map(([done, next]) => ({
+        done: done.map(([path]) => path),
+        next: next.map(([path]) => path)
+      })),
+      shareReplay({ bufferSize: 1, refCount: true })
+    )
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Paint anchor list from source observable
+ *
+ * This operator function will keep track of the anchor list in-between emits
+ * in order to optimize rendering by only re-painting anchor list migrations.
+ * After determining which anchors need to be re-painted, the actual rendering
+ * is deferred to the next animation frame.
+ *
+ * @return Operator function
+ */
+export function paintAnchorList(): MonoTypeOperatorFunction<AnchorList> {
+  return pipe(
+
+    /* Extract anchor list migrations only */
+    scan<AnchorList>((a, b) => {
+      const begin = Math.max(0, Math.min(b.done.length, a.done.length) - 1)
+      const end   = Math.max(b.done.length, a.done.length)
+      return {
+        done: b.done.slice(begin, end + 1),
+        next: difference(b.next, a.next)
+      }
+    }, { done: [], next: [] }),
+
+    /* Defer re-paint to next animation frame */
+    observeOn(animationFrameScheduler),
+    tap(({ done, next }) => {
+
+      /* Look forward */
+      for (const [el] of next)
+        resetAnchor(el)
+
+      /* Look backward */
+      for (const [index, [el]] of done.entries()) {
+        setAnchorBlur(el, true)
+        setAnchorActive(el, index === done.length - 1)
+      }
+    })
+  )
+}

src/assets/javascripts/component/anchor/element/index.ts

@@ -0,0 +1,63 @@
+/*
+ * 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.
+ */
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Set anchor blur
+ *
+ * @param el - Anchor element
+ * @param value - Whether the anchor is blurred
+ */
+export function setAnchorBlur(
+  el: HTMLElement, value: boolean
+): void {
+  el.setAttribute("data-md-state", value ? "blur" : "")
+}
+
+/**
+ * Set anchor active
+ *
+ * @param el - Anchor element
+ * @param value - Whether the anchor is active
+ */
+export function setAnchorActive(
+  el: HTMLElement, value: boolean
+): void {
+  el.classList.toggle("md-nav__link--active", value)
+}
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Reset anchor
+ *
+ * @param el - Anchor element
+ */
+export function resetAnchor(
+  el: HTMLElement
+): void {
+  el.removeAttribute("data-md-state")
+  el.classList.remove("md-nav__link--active")
+}

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

@@ -20,158 +20,5 @@
  * IN THE SOFTWARE.
  */
 
-import { reduce, reverse } from "ramda"
+export * from "./_"
-import { Observable, combineLatest } from "rxjs"
+export * from "./element"
-import { distinctUntilChanged, map, scan, shareReplay } from "rxjs/operators"
-
-import { ViewportOffset, getElement } from "../../ui"
-import { Header } from "../header"
-
-/* ----------------------------------------------------------------------------
- * Types
- * ------------------------------------------------------------------------- */
-
-/**
- * Anchors
- */
-export interface Anchors {
-  done: HTMLAnchorElement[][]          /* Done anchors */
-  next: HTMLAnchorElement[][]          /* Next anchors */
-}
-
-/* ----------------------------------------------------------------------------
- * Function types
- * ------------------------------------------------------------------------- */
-
-/**
- * Watch options
- */
-interface WatchOptions {
-  offset$: Observable<ViewportOffset>  /* Viewport offset observable */
-  header$: Observable<Header>          /* Header observable */
-}
-
-/* ----------------------------------------------------------------------------
- * Functions
- * ------------------------------------------------------------------------- */
-
-/**
- * Set anchor blur
- *
- * @param el - Anchor element
- * @param blur - Anchor blur
- */
-export function setAnchorBlur(
-  el: HTMLAnchorElement, blur: boolean
-): void {
-  el.setAttribute("data-md-state", blur ? "blur" : "")
-}
-
-/**
- * Set anchor active
- *
- * @param el - Anchor element
- * @param active - Whether the anchor is active
- */
-export function setAnchorActive(
-  el: HTMLAnchorElement, active: boolean
-): void {
-  el.classList.toggle("md-nav__link--active", active)
-}
-
-/**
- * Reset anchor
- *
- * @param el - Anchor element
- */
-export function resetAnchor(el: HTMLAnchorElement) {
-  el.removeAttribute("data-md-state")
-  el.classList.remove("md-nav__link--active")
-}
-
-/* ------------------------------------------------------------------------- */
-
-/**
- * Create an observable to monitor all anchors in respect to viewport offset
- *
- * @param els - Anchor elements
- * @param options - Options
- *
- * @return Anchors observable
- */
-export function watchAnchors(
-  els: HTMLAnchorElement[], { offset$, header$ }: WatchOptions
-): Observable<Anchors> {
-
-  /* Build index to map anchors to their targets */
-  const index = new Map<HTMLAnchorElement, HTMLElement>()
-  for (const el of els) {
-    const target = getElement(decodeURIComponent(el.hash))
-    if (typeof target !== "undefined")
-      index.set(el, target)
-  }
-
-  /* Build table to map anchor paths to vertical offsets */
-  const table = new Map<HTMLAnchorElement[], number>()
-  reduce((path: HTMLAnchorElement[], [anchor, target]) => {
-    while (path.length) {
-      const last = index.get(path[path.length - 1])!
-      if (last.tagName >= target.tagName)
-        path.pop()
-      else
-        break
-    }
-    table.set(reverse(path = [...path, anchor]), target.offsetTop)
-    return path
-  }, [], [...index])
-
-  /* Compute necessary adjustment for header */
-  const adjust$ = header$
-    .pipe(
-      map(header => 18 + header.height)
-    )
-
-  /* Compute partition of done and next anchors */
-  const partition$ = combineLatest(offset$, adjust$)
-    .pipe(
-      scan(([done, next], [{ y }, adjust]) => {
-
-        /* Look forward */
-        while (next.length) {
-          const [, offset] = next[0]
-          if (offset - adjust < y) {
-            done = [...done, next.shift()!]
-          } else {
-            break
-          }
-        }
-
-        /* Look backward */
-        while (done.length) {
-          const [, offset] = done[done.length - 1]
-          if (offset - adjust >= y) {
-            next = [done.pop()!, ...next]
-          } else {
-            break
-          }
-        }
-
-        /* Return partition */
-        return [done, next]
-      }, [[], [...table]]),
-      distinctUntilChanged((a, b) => {
-        return a[0] === b[0]
-            && a[1] === b[1]
-      })
-    )
-
-  /* Extract anchors and return hot observable */
-  return partition$
-    .pipe(
-      map(([done, next]) => ({
-        done: done.map(([anchors]) => anchors),
-        next: next.map(([anchors]) => anchors)
-      })),
-      shareReplay({ bufferSize: 1, refCount: true })
-    )
-}

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

@@ -37,7 +37,7 @@ import { toArray } from "../../utilities"
  * @param selector - Query selector
  * @param node - Node of reference
  *
- * @return HTML element
+ * @return Element
  */
 export function getElement<T extends HTMLElement>(
   selector: string, node: ParentNode = document
@@ -53,7 +53,7 @@ export function getElement<T extends HTMLElement>(
  * @param selector - Query selector
  * @param node - Node of reference
  *
- * @return HTML elements
+ * @return Elements
  */
 export function getElements<T extends HTMLElement>(
   selector: string, node: ParentNode = document
@@ -72,7 +72,7 @@ export function getElements<T extends HTMLElement>(
  *
  * @param node - Node of reference
  *
- * @return HTML element observable
+ * @return Operator function
  */
 export function withElement<T extends HTMLElement>(
   node: ParentNode = document
@@ -90,7 +90,7 @@ export function withElement<T extends HTMLElement>(
  *
  * @param node - Node of reference
  *
- * @return HTML elements observable
+ * @return Operator function
  */
 export function withElements<T extends HTMLElement>(
   node: ParentNode = document

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

@@ -37,7 +37,7 @@ const hash$ = fromEvent<HashChangeEvent>(window, "hashchange")
  * ------------------------------------------------------------------------- */
 
 /**
- * Create an observable to monitor the location hash
+ * Create an observable to watch the location hash
  *
  * @return Location hash observable
  */

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

@@ -28,7 +28,7 @@ import { shareReplay, startWith } from "rxjs/operators"
  * ------------------------------------------------------------------------- */
 
 /**
- * Create an observable from a media query
+ * Create an observable to watch a media query
  *
  * @param query - Media query
  *

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

@@ -88,7 +88,7 @@ export function getViewportSize(): ViewportSize {
 /* ------------------------------------------------------------------------- */
 
 /**
- * Create an observable to monitor the viewport offset
+ * Create an observable to watch the viewport offset
  *
  * @return Viewport offset observable
  */
@@ -102,7 +102,7 @@ export function watchViewportOffset(): Observable<ViewportOffset> {
 }
 
 /**
- * Create an observable to monitor the viewport size
+ * Create an observable to watch the viewport size
  *
  * @return Viewport size observable
  */

src/assets/javascripts/utilities/index.ts

@@ -28,13 +28,13 @@ import { switchMap } from "rxjs/operators"
  * ------------------------------------------------------------------------- */
 
 /**
- * Convert a HTML collection to an array
+ * Convert a collection to an array
  *
- * @template T - HTML element type
+ * @template T - Element type
  *
- * @param collection - HTML collection
+ * @param collection - Collection or node list
  *
- * @return Array of HTML elements
+ * @return Array of elements
  */
 export function toArray<
   T extends HTMLElement