toot medias: extract color from blurhash

src/platform/blurhash.ts

@@ -0,0 +1,164 @@
+/*
+Blurhash toolkit.
+
+base83 decoder/encoder is copied from
+https://github.com/woltapp/blurhash/blob/master/TypeScript/src/base83.ts,
+which is MIT Licensed: https://github.com/woltapp/blurhash?tab=MIT-1-ov-file#readme
+*/
+const digitCharacters = [
+  "0",
+  "1",
+  "2",
+  "3",
+  "4",
+  "5",
+  "6",
+  "7",
+  "8",
+  "9",
+  "A",
+  "B",
+  "C",
+  "D",
+  "E",
+  "F",
+  "G",
+  "H",
+  "I",
+  "J",
+  "K",
+  "L",
+  "M",
+  "N",
+  "O",
+  "P",
+  "Q",
+  "R",
+  "S",
+  "T",
+  "U",
+  "V",
+  "W",
+  "X",
+  "Y",
+  "Z",
+  "a",
+  "b",
+  "c",
+  "d",
+  "e",
+  "f",
+  "g",
+  "h",
+  "i",
+  "j",
+  "k",
+  "l",
+  "m",
+  "n",
+  "o",
+  "p",
+  "q",
+  "r",
+  "s",
+  "t",
+  "u",
+  "v",
+  "w",
+  "x",
+  "y",
+  "z",
+  "#",
+  "$",
+  "%",
+  "*",
+  "+",
+  ",",
+  "-",
+  ".",
+  ":",
+  ";",
+  "=",
+  "?",
+  "@",
+  "[",
+  "]",
+  "^",
+  "_",
+  "{",
+  "|",
+  "}",
+  "~",
+];
+
+function decode83(str: string) {
+  let value = 0;
+  for (let i = 0; i < str.length; i++) {
+    const c = str[i];
+    const digit = digitCharacters.indexOf(c);
+    value = value * 83 + digit;
+  }
+  return value;
+}
+
+function encode83(n: number, length: number): string {
+  var result = "";
+  for (let i = 1; i <= length; i++) {
+    let digit = (Math.floor(n) / Math.pow(83, length - i)) % 83;
+    result += digitCharacters[Math.floor(digit)];
+  }
+  return result;
+}
+
+/* toColorHex() is modified from
+https://www.xaymar.com/articles/2020/12/08/fastest-uint8array-to-hex-string-conversion-in-javascript/,
+licensed BSD-3. */
+
+// Pre-Init
+const LUT_HEX_4b = [
+  "0",
+  "1",
+  "2",
+  "3",
+  "4",
+  "5",
+  "6",
+  "7",
+  "8",
+  "9",
+  "A",
+  "B",
+  "C",
+  "D",
+  "E",
+  "F",
+];
+const LUT_HEX_8b = new Array(0x100);
+for (let n = 0; n < 0x100; n++) {
+  LUT_HEX_8b[n] = `${LUT_HEX_4b[(n >>> 4) & 0xf]}${LUT_HEX_4b[n & 0xf]}`;
+}
+// End Pre-Init
+function toColorHex(buffer: Uint8ClampedArray): `#${string}` {
+  let out = "#";
+  for (let idx = 0, edx = buffer.length; idx < edx; idx++) {
+    out += LUT_HEX_8b[buffer[idx]];
+  }
+  return out as `#${string}`;
+}
+
+export function averageColor(blurhash: string) {
+  const v = decode83(blurhash.substring(2, 6)); // 24-bit RGB
+
+  return [v >> 16, (v >> 8) & 255, v & 255] as const;
+}
+
+export function averageColorHex(blurhash: string) : `#${string}` {
+  const [r, g, b] = averageColor(blurhash);
+
+  const buf = new Uint8ClampedArray(3);
+  buf[0] = r;
+  buf[1] = g;
+  buf[2] = b;
+
+  return toColorHex(buf);
+}

src/timelines/MediaAttachmentGrid.tsx

@@ -20,6 +20,7 @@ import {
 } from "@solid-primitives/resize-observer";
 import { useStore } from "@nanostores/solid";
 import { $settings } from "../settings/stores";
+import { averageColorHex } from "../platform/blurhash";
 
 type ElementSize = { width: number; height: number };
 
@@ -120,7 +121,9 @@ const MediaAttachmentGrid: Component<{
     // we may need better tool to manage the performance impact
     // before using this. See #37.
     // TODO: use fast average color to extract accent color
-    const accentColor = item.meta?.colors?.accent;
+    const accentColor =
+      item.meta?.colors?.accent ??
+      (item.blurhash ? averageColorHex(item.blurhash) : undefined);
 
     return Object.assign(
       {

src/timelines/RegularToot.tsx

@@ -6,6 +6,7 @@ import {
   Show,
   createRenderEffect,
   createEffect,
+  createMemo,
 } from "solid-js";
 import tootStyle from "./toot.module.css";
 import { formatRelative } from "date-fns";
@@ -29,13 +30,13 @@ import { Divider } from "@suid/material";
 import cardStyle from "../material/cards.module.css";
 import Button from "../material/Button.js";
 import MediaAttachmentGrid from "./MediaAttachmentGrid.js";
-import { FastAverageColor } from "fast-average-color";
 import Color from "colorjs.io";
 import { useDateFnLocale } from "../platform/i18n";
 import { canShare, share } from "../platform/share";
 import { makeAcctText, useDefaultSession } from "../masto/clients";
 import TootContent from "./toot-components/TootContent";
 import BoostIcon from "./toot-components/BoostIcon";
+import { averageColorHex } from "../platform/blurhash";
 
 type TootActionGroupProps<T extends mastodon.v1.Status> = {
   onRetoot?: (value: T) => void;
@@ -205,31 +206,44 @@ export function TootPreviewCard(props: {
     }
   });
 
-  const onImgLoad = (event: Event & { currentTarget: HTMLImageElement }) => {
-    // TODO: better extraction algorithm
-    // I'd like to use a pattern panel and match one in the panel from the extracted color
-    const fac = new FastAverageColor();
-    const result = fac.getColor(event.currentTarget);
-    if (result.error) {
-      console.error(result.error);
-      fac.destroy();
+  const imgAverageColor = createMemo(() => {
+    if (!props.src.image) return;
+    return new Color(averageColorHex(props.src.blurhash));
+  });
+
+  const prefersWhiteText = createMemo(() => {
+    const oc = imgAverageColor();
+    if (!oc) return;
+    const colorWhite = new Color("white");
+
+    return colorWhite.luminance / oc.luminance > 3.5;
+  });
+
+  const focusSurfaceColor = createMemo(() => {
+    const oc = imgAverageColor();
+    if (!oc) return;
+    if (prefersWhiteText()) {
+      return new Color(oc).darken(0.2);
+    } else {
+      return new Color(oc).lighten(0.2);
+    }
+  });
+
+  const textColorName = createMemo(() => {
+    const useWhiteText = prefersWhiteText();
+    if (typeof useWhiteText === "undefined") {
       return;
     }
-    root.style.setProperty("--tutu-color-surface", result.hex);
-    const focusSurface = result.isDark
-      ? new Color(result.hex).darken(0.2)
-      : new Color(result.hex).lighten(0.2);
-    root.style.setProperty("--tutu-color-surface-d", focusSurface.toString());
-    const textColor = result.isDark ? "white" : "black";
-    const secondaryTextColor = new Color(textColor);
-    secondaryTextColor.alpha = 0.75;
-    root.style.setProperty("--tutu-color-on-surface", textColor);
-    root.style.setProperty(
-      "--tutu-color-secondary-text-on-surface",
-      secondaryTextColor.toString(),
-    );
-    fac.destroy();
-  };
+    return useWhiteText ? "white" : "black";
+  });
+
+  const secondaryTextColor = createMemo(() => {
+    const tcn = textColorName();
+    if (!tcn) return;
+    const tc = new Color(tcn);
+    tc.alpha = 0.75;
+    return tc;
+  });
 
   return (
     <a
@@ -238,12 +252,18 @@ export function TootPreviewCard(props: {
       href={props.src.url}
       target="_blank"
       referrerPolicy="unsafe-url"
+      style={{
+        "--tutu-color-surface": imgAverageColor()?.toString(),
+        "--tutu-color-surface-d": focusSurfaceColor()?.toString(),
+        "--tutu-color-on-surface": textColorName(),
+        "--tutu-color-secondary-text-on-surface":
+          secondaryTextColor()?.toString(),
+      }}
     >
       <Show when={props.src.image}>
         <img
           crossOrigin="anonymous"
           src={props.src.image!}
-          onLoad={onImgLoad}
           width={props.src.width || undefined}
           height={props.src.height || undefined}
           loading="lazy"

src/timelines/TootList.tsx

@@ -183,6 +183,7 @@ const TootList: Component<{
   return (
     <ErrorBoundary
       fallback={(err, reset) => {
+        console.error(err);
         return <p>Oops: {String(err)}</p>;
       }}
     >

src/timelines/toot.module.css

@@ -135,6 +135,7 @@
   position: relative;
 
   >img {
+    background-color: #eeeeee;
     max-width: 100%;
     height: auto;
   }
@@ -260,11 +261,8 @@
 
     &:hover,
     &:focus-visible {
-      /* TODO: the goal is to use the media's accent color as the outline */
-      /* but our infra is not prepared for this. The average color thing is slow */
-      /* and we need further managing to control its performance impact. */
       outline: 8px solid var(--media-color-accent, var(--tutu-color-surface-d));
-      border-color: transparent;
+      border: none;
     }
   }
 }