typewriter

import {Fill, interpolate, useBrand, useFrame, useDesignScale} from "odori";

export type TypewriterProps = {
  text: string;
  label?: string;
  /** Characters revealed per second. */
  charactersPerSecond?: number;
};

/**
 * Typing driven by the frame counter rather than a timer, so scrubbing to a
 * frame shows exactly the characters that frame will render. The caret blinks
 * on a frame cycle for the same reason.
 */
export const Typewriter = ({text, label, charactersPerSecond = 18}: TypewriterProps) => {
  const frame = useFrame();
  const brand = useBrand();
  const scale = useDesignScale();
  const visible = Math.min(text.length, Math.max(0, Math.floor(((frame - 8) / 30) * charactersPerSecond)));
  const typed = text.slice(0, visible);
  const done = visible >= text.length;
  // A 30 frame cycle: on for the first half, off for the second.
  const caretOn = done ? frame % 30 < 15 : true;

  return (
    <Fill
      style={{
        alignItems: "center",
        gap: 26 * scale,
        justifyContent: "center",
        padding: `${120 * scale}px ${140 * scale}px`,
      }}
    >
      {label ? (
        <div
          style={{
            color: brand.colors.muted,
            fontFamily: brand.typography.mono,
            fontSize: 26 * scale,
            opacity: interpolate(frame, [0, 12], [0, 1]),
          }}
        >
          {label}
        </div>
      ) : null}
      <div
        style={{
          alignItems: "center",
          display: "flex",
          fontFamily: brand.typography.mono,
          fontSize: 76 * scale,
          gap: 6 * scale,
          letterSpacing: "-0.02em",
        }}
      >
        <span style={{whiteSpace: "pre"}}>{typed}</span>
        <span
          style={{
            background: brand.colors.accent,
            display: "inline-block",
            height: 76 * scale,
            opacity: caretOn ? 1 : 0,
            width: 10 * scale,
          }}
        />
      </div>
    </Fill>
  );
};

import {defineComponentPreview} from "odori/preview";
import {Typewriter} from "./typewriter";

export default defineComponentPreview({
  title: "Typewriter",
  category: "Typography",
  description: "Deterministic typing with a frame-driven caret.",
  component: Typewriter,
  canvas: {width: 1920, height: 1080, duration: "4s"},
  controls: {
    text: {type: "text", defaultValue: "pnpm odori dev", maxLength: 48},
    label: {type: "text", defaultValue: "one command"},
    charactersPerSecond: {type: "number", defaultValue: 18, min: 4, max: 40},
  },
  examples: [
    {name: "Command", props: {text: "pnpm odori dev", label: "one command"}},
    {name: "Export", props: {text: "pnpm odori export launch", charactersPerSecond: 26}},
  ],
});

import {Scene, Video} from "odori";
import {Typewriter} from "../components/typewriter/typewriter";

<Video>
  <Scene id="typewriter" duration="4s">
    <Typewriter
      text="pnpm odori dev"
      label="one command"
      charactersPerSecond={18}
    />
  </Scene>
</Video>