feat: text & slider animations

2026-06-02 12:18:26 +03:00
4 changed files with 392 additions and 13 deletions
@@ -2,6 +2,26 @@ import type { StorybookConfig } from 'storybook-react-rsbuild';

 /* Dev-only playground. Never shipped — package `files` is ["dist"]. */
 const config: StorybookConfig = {
+  rsbuildFinal: (config) => {
+    config.tools ??= {};
+    // Append our rule without clobbering storybook-react-rsbuild's own
+    // tools.rspack hook (it injects the storybook-config-entry virtual module
+    // in build mode). Mutate in place and return nothing so its config stays.
+    const prev = config.tools.rspack;
+    config.tools.rspack = [
+      ...(Array.isArray(prev) ? prev : prev ? [prev] : []),
+      (rspackConfig) => {
+        rspackConfig.module ??= {};
+        rspackConfig.module.rules ??= [];
+        (rspackConfig.module.rules as unknown[]).push({
+          test: /\.mjs$/,
+          type: 'javascript/auto',
+          resolve: { fullySpecified: false },
+        });
+      },
+    ];
+    return config;
+  },
  stories: ['../src/**/*.mdx', '../src/**/*.stories.@(ts|tsx)'],
  addons: ['@storybook/addon-docs'],
  staticDirs: ['../src/assets'],
@@ -37,9 +37,11 @@ Only `dist/` ships (`files: ["dist"]`), so the playground, stories, and `.storyb

 Fonts are NOT in the core stylesheet. `tokens.css` defines `--font-display/sans/mono` chains that degrade to `system-ui`; the actual faces (Anta `@font-face` + Onest/Geist Mono Google Fonts `@import`) live in `src/styles/fonts.css`, shipped as the optional `modern-sk/fonts.css` export. Consumers either import it, or override the `--font-*` tokens to remap typefaces. Storybook's `preview.tsx` and the dev `global.css` both import `fonts.css` so the playgrounds stay branded.

-### Components (`src/components/ui.tsx`)
+### Components (`src/components/`)

-All components live in one file. Pattern: Radix provides logic/accessibility, every visual comes from CSS. Components are thin wrappers that attach `modern-sk-*` classes and spread props. The `cx()` helper joins class names (no classnames dependency). Components forward refs where they wrap a DOM element. There is no inline styling and no CSS-in-JS — **all appearance is driven by `modern-sk-*` classes resolving against CSS custom properties.**
+`src/components/ui.tsx` is a barrel that re-exports one folder per component (`button/`, `text-field/`, …); `cx`/shared helpers live in `src/components/utils.ts`. Pattern: Radix provides logic/accessibility, every visual comes from CSS. Components are thin wrappers that attach `modern-sk-*` classes and spread props. The `cx()` helper joins class names (no classnames dependency). Components forward refs where they wrap a DOM element. There is no inline styling and no CSS-in-JS — **all appearance is driven by `modern-sk-*` classes resolving against CSS custom properties.**
+
+Exception — text inputs (`text-field/`): `TextField`/`TextArea`/`SearchField` animate letters in/out (osu!-lazer style). Native fields can't animate per-glyph, so the real element renders with transparent text (`modern-sk-field--animated`, caret stays visible) over a mirrored per-character `<span>` overlay that plays the `modern-sk-char-in/out` keyframes; an LCS diff preserves letter identity so only inserted/removed glyphs animate. The overlay still derives all appearance from `modern-sk-*` classes/tokens — the only JS-set styles are the per-letter pin offset and scroll-sync transform. Pass `animated={false}` to opt out and render the plain native field.

 ### Styling system (`src/styles/`)

@@ -47,7 +49,7 @@ All components live in one file. Pattern: Radix provides logic/accessibility, ev
 - `components.css` — the `modern-sk-*` class definitions.
 - Dark/light is driven by `data-theme` on `<html>`, set by `ThemeProvider` (persisted to `localStorage` under key `modern-sk-theme`, default `dark`).

-When adding or changing a component: add the wrapper in `ui.tsx`, define its `modern-sk-*` styles in `components.css`, and pull any new color/spacing value from a token in `tokens.css` rather than hardcoding.
+When adding or changing a component: add the wrapper folder under `src/components/` and re-export it from `ui.tsx`, define its `modern-sk-*` styles in `components.css`, and pull any new color/spacing value from a token in `tokens.css` rather than hardcoding.

 ## Consumer contract

@@ -1,24 +1,276 @@
-import { forwardRef, type ComponentPropsWithoutRef, type ReactNode } from 'react';
+import {
+  forwardRef,
+  useCallback,
+  useId,
+  useLayoutEffect,
+  useRef,
+  useState,
+  type ComponentPropsWithoutRef,
+  type ReactNode,
+  type Ref,
+} from 'react';
 import { cx } from '../utils';

-export const TextField = forwardRef<HTMLInputElement, ComponentPropsWithoutRef<'input'>>(
-  ({ className, ...props }, ref) => (
-    <input ref={ref} className={cx('modern-sk-field', className)} {...props} />
+/* ------------------------------------------------------------------ *
+ * Typing animation (osu!-lazer style)
+ *
+ * Native inputs draw their own text, so individual letters can't be
+ * animated. Instead the real field renders transparent (caret stays
+ * visible) and a mirrored per-character <span> overlay sits behind it:
+ * newly typed letters rise + fade in, erased letters fall + fade out.
+ * ------------------------------------------------------------------ */
+
+type FieldElement = HTMLInputElement | HTMLTextAreaElement;
+
+interface CharEntry {
+  id: number;
+  char: string;
+  leaving: boolean;
+  x?: number;
+  y?: number;
+}
+
+/** Longest-common-subsequence match so unchanged letters keep their id
+ *  (and thus don't replay the appear animation on every keystroke). */
+function diffChars(prev: ReadonlyArray<{ id: number; char: string }>, next: string) {
+  const n = prev.length;
+  const m = next.length;
+  const dp: number[][] = Array.from({ length: n + 1 }, () => new Array(m + 1).fill(0));
+  for (let i = n - 1; i >= 0; i--) {
+    for (let j = m - 1; j >= 0; j--) {
+      dp[i][j] =
+        prev[i].char === next[j]
+          ? dp[i + 1][j + 1] + 1
+          : Math.max(dp[i + 1][j], dp[i][j + 1]);
+    }
+  }
+  const reusedId: Array<number | null> = new Array(m).fill(null);
+  const keptPrev = new Array(n).fill(false);
+  let i = 0;
+  let j = 0;
+  while (i < n && j < m) {
+    if (prev[i].char === next[j]) {
+      reusedId[j] = prev[i].id;
+      keptPrev[i] = true;
+      i++;
+      j++;
+    } else if (dp[i + 1][j] >= dp[i][j + 1]) {
+      i++;
+    } else {
+      j++;
+    }
+  }
+  return { reusedId, keptPrev };
+}
+
+function useFieldAnimation(
+  multiline: boolean,
+  externalRef: Ref<FieldElement>,
+  controlledValue: ComponentPropsWithoutRef<'input'>['value'],
+  initial: ComponentPropsWithoutRef<'input'>['defaultValue'],
+) {
+  const innerRef = useRef<FieldElement | null>(null);
+  const overlayRef = useRef<HTMLDivElement | null>(null);
+  const spanRefs = useRef<Map<number, HTMLSpanElement>>(new Map());
+  const present = useRef<Array<{ id: number; char: string }>>([]);
+  const nextId = useRef(0);
+  const idPrefix = useId();
+
+  const [text, setText] = useState(() => String(controlledValue ?? initial ?? ''));
+  const [entries, setEntries] = useState<CharEntry[]>([]);
+
+  const setRef = useCallback(
+    (node: FieldElement | null) => {
+      innerRef.current = node;
+      if (typeof externalRef === 'function') externalRef(node);
+      else if (externalRef) (externalRef as { current: FieldElement | null }).current = node;
+    },
+    [externalRef],
+  );
+
+  const syncScroll = useCallback(() => {
+    const el = innerRef.current;
+    const ov = overlayRef.current;
+    if (el && ov) ov.style.transform = `translate(${-el.scrollLeft}px, ${-el.scrollTop}px)`;
+  }, []);
+
+  // Reconcile the overlay whenever the text changes.
+  useLayoutEffect(() => {
+    const prev = present.current;
+    const { reusedId, keptPrev } = diffChars(prev, text);
+
+    const nextPresent: Array<{ id: number; char: string }> = [];
+    for (let k = 0; k < text.length; k++) {
+      const id = reusedId[k] ?? nextId.current++;
+      nextPresent.push({ id, char: text[k] });
+    }
+
+    // Letters that were removed fall away — pin them where they last sat.
+    const leaving: CharEntry[] = [];
+    for (let k = 0; k < prev.length; k++) {
+      if (keptPrev[k]) continue;
+      const el = spanRefs.current.get(prev[k].id);
+      if (el) {
+        leaving.push({
+          id: prev[k].id,
+          char: prev[k].char,
+          leaving: true,
+          x: el.offsetLeft,
+          y: el.offsetTop,
+        });
+      }
+    }
+
+    present.current = nextPresent;
+    setEntries((current) => [
+      ...nextPresent.map((e) => ({ ...e, leaving: false })),
+      ...current.filter((e) => e.leaving),
+      ...leaving,
+    ]);
+    syncScroll();
+  }, [text, syncScroll]);
+
+  // Stay in sync when used as a controlled component.
+  useLayoutEffect(() => {
+    if (controlledValue !== undefined) setText(String(controlledValue));
+  }, [controlledValue]);
+
+  const handleChange = useCallback((value: string) => setText(value), []);
+
+  const onLeaveEnd = useCallback((id: number) => {
+    spanRefs.current.delete(id);
+    setEntries((current) => current.filter((e) => e.id !== id));
+  }, []);
+
+  const overlay = (
+    <div
+      ref={overlayRef}
+      aria-hidden="true"
+      className={cx('modern-sk-field-overlay', multiline && 'modern-sk-field-overlay--multiline')}
+    >
+      {entries.map((e) =>
+        e.leaving ? (
+          <span
+            key={`${idPrefix}-${e.id}`}
+            className="modern-sk-field-char modern-sk-field-char--leaving"
+            style={{ left: e.x, top: e.y }}
+            onAnimationEnd={() => onLeaveEnd(e.id)}
+          >
+            {e.char}
+          </span>
+        ) : (
+          <span
+            key={`${idPrefix}-${e.id}`}
+            ref={(node) => {
+              if (node) spanRefs.current.set(e.id, node);
+              else spanRefs.current.delete(e.id);
+            }}
+            className="modern-sk-field-char"
+          >
+            {e.char}
+          </span>
        ),
+      )}
+    </div>
+  );
+
+  return { setRef, overlay, handleChange, syncScroll };
+}
+
+type TextFieldProps = ComponentPropsWithoutRef<'input'> & { animated?: boolean };
+type TextAreaProps = ComponentPropsWithoutRef<'textarea'> & { animated?: boolean };
+
+export const TextField = forwardRef<HTMLInputElement, TextFieldProps>(
+  ({ className, style, onChange, onScroll, animated = true, ...props }, ref) => {
+    const { setRef, overlay, handleChange, syncScroll } = useFieldAnimation(
+      false,
+      ref,
+      props.value,
+      props.defaultValue,
+    );
+    if (!animated) {
+      return (
+        <input
+          ref={ref}
+          className={cx('modern-sk-field', className)}
+          style={style}
+          onChange={onChange}
+          onScroll={onScroll}
+          {...props}
+        />
+      );
+    }
+    return (
+      <div className={cx('modern-sk-field-wrap', className)} style={style}>
+        <input
+          ref={setRef}
+          className="modern-sk-field modern-sk-field--animated"
+          onChange={(e) => {
+            handleChange(e.currentTarget.value);
+            onChange?.(e);
+          }}
+          onScroll={(e) => {
+            syncScroll();
+            onScroll?.(e);
+          }}
+          {...props}
+        />
+        {overlay}
+      </div>
+    );
+  },
 );
 TextField.displayName = 'TextField';

-export const TextArea = forwardRef<HTMLTextAreaElement, ComponentPropsWithoutRef<'textarea'>>(
-  ({ className, ...props }, ref) => (
-    <textarea ref={ref} className={cx('modern-sk-field', className)} {...props} />
-  ),
+export const TextArea = forwardRef<HTMLTextAreaElement, TextAreaProps>(
+  ({ className, style, onChange, onScroll, animated = true, ...props }, ref) => {
+    const { setRef, overlay, handleChange, syncScroll } = useFieldAnimation(
+      true,
+      ref,
+      props.value,
+      props.defaultValue,
+    );
+    if (!animated) {
+      return (
+        <textarea
+          ref={ref}
+          className={cx('modern-sk-field', className)}
+          style={style}
+          onChange={onChange}
+          onScroll={onScroll}
+          {...props}
+        />
+      );
+    }
+    return (
+      <div
+        className={cx('modern-sk-field-wrap', 'modern-sk-field-wrap--multiline', className)}
+        style={style}
+      >
+        <textarea
+          ref={setRef}
+          className="modern-sk-field modern-sk-field--animated"
+          onChange={(e) => {
+            handleChange(e.currentTarget.value);
+            onChange?.(e);
+          }}
+          onScroll={(e) => {
+            syncScroll();
+            onScroll?.(e);
+          }}
+          {...props}
+        />
+        {overlay}
+      </div>
+    );
+  },
 );
 TextArea.displayName = 'TextArea';

 export const SearchField = ({
  icon,
  ...props
-}: ComponentPropsWithoutRef<'input'> & { icon: ReactNode }) => (
+}: TextFieldProps & { icon: ReactNode }) => (
  <div className="modern-sk-search">
    <span className="ph">{icon}</span>
    <TextField {...props} />
@@ -224,6 +224,94 @@ textarea.modern-sk-field {
  padding-left: 34px;
 }

+/* ---------- TYPING ANIMATION (osu!-lazer style char in/out) ---------- */
+/* The real field renders transparent over a mirrored per-letter overlay. */
+.modern-sk-field-wrap {
+  position: relative;
+  width: 100%;
+}
+.modern-sk-search .modern-sk-field-wrap {
+  width: 100%;
+}
+.modern-sk-field--animated {
+  color: transparent;
+  caret-color: var(--fg-1);
+}
+.modern-sk-field--animated::placeholder {
+  color: var(--fg-3);
+}
+
+.modern-sk-field-overlay {
+  position: absolute;
+  inset: 0;
+  overflow: hidden;
+  pointer-events: none;
+  /* transparent border mirrors the field's 1px border so content aligns */
+  border: 1px solid transparent;
+  padding: var(--field-pad-y) var(--field-pad-x);
+  font-family: var(--font-sans);
+  font-size: 14px;
+  line-height: normal;
+  color: var(--fg-1);
+  white-space: pre;
+  text-align: left;
+  will-change: transform;
+}
+.modern-sk-field-overlay--multiline {
+  white-space: pre-wrap;
+  overflow-wrap: break-word;
+  line-height: 1.5;
+}
+.modern-sk-search .modern-sk-field-overlay {
+  padding-left: 34px;
+}
+
+.modern-sk-field-char {
+  /* inline (not inline-block) so the overlay wraps exactly like the field;
+     inherit white-space so multiline (pre-wrap) wraps while input (pre) won't.
+     'pre' on the span itself would suppress wrapping at its boundaries. */
+  position: relative;
+  white-space: inherit;
+  animation: modern-sk-char-in var(--dur-base) var(--ease-snap) both;
+}
+.modern-sk-field-char--leaving {
+  display: inline-block;
+  position: absolute;
+  white-space: pre;
+  animation: modern-sk-char-out var(--dur-base) var(--ease-out) forwards;
+}
+
+/* inline elements ignore transform, so the rise uses top instead */
+@keyframes modern-sk-char-in {
+  from {
+    opacity: 0;
+    top: -0.32em;
+  }
+  to {
+    opacity: 1;
+    top: 0;
+  }
+}
+@keyframes modern-sk-char-out {
+  from {
+    opacity: 1;
+    transform: translateY(0);
+  }
+  to {
+    opacity: 0;
+    transform: translateY(0.7em) scale(0.9);
+  }
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .modern-sk-field-char {
+    animation: none;
+  }
+  .modern-sk-field-char--leaving {
+    animation: modern-sk-char-out 1ms linear forwards;
+  }
+}
+
 /* ---------- SELECT (Radix Select, styled as the glossy key) ---------- */
 .modern-sk-select {
  font-family: var(--font-sans);
@@ -538,6 +626,11 @@ textarea.modern-sk-field {
  border-radius: 3px;
  background: linear-gradient(90deg, var(--lime-deep), var(--lime));
  box-shadow: 0 0 10px rgba(190, 242, 100, 0.4);
+  /* Radix positions the range via left/right offsets (not width); ease those
+     so the fill glides between discrete steps while dragging. */
+  transition:
+    left 0.12s ease-out,
+    right 0.12s ease-out;
 }
 .modern-sk-slider__thumb {
  display: block;
@@ -551,6 +644,18 @@ textarea.modern-sk-field {
  cursor: pointer;
  outline: none;
 }
+/* Radix sets the step position (left) on a WRAPPER span around the thumb, not on
+   the thumb element itself — so the transition must live on that wrapper. The
+   wrapper is the slider's direct child span that isn't the track. */
+.modern-sk-slider > span:not(.modern-sk-slider__track) {
+  transition: left 0.12s ease-out;
+}
+@media (prefers-reduced-motion: reduce) {
+  .modern-sk-slider > span:not(.modern-sk-slider__track),
+  .modern-sk-slider__range {
+    transition: none;
+  }
+}
 .modern-sk-slider--knob-square .modern-sk-slider__thumb {
  --ms-thumb-w: 14px;
 }