code-diff-wipe

1import { loadFont } from "@remotion/google-fonts/JetBrainsMono";
2import {
3  interpolate,
4  spring,
5  useCurrentFrame,
6  useVideoConfig,
7} from "remotion";
8import { stageScale } from "@/remotion/lib/ai-composer-utils";
9import { CODE_THEMES, CodeLine, tokenizeCode } from "@/remotion/lib/code-syntax";
10import { EASING } from "@/remotion/lib/motion-tokens";
11 
12const { fontFamily } = loadFont("normal", {
13  weights: ["400", "500", "700"],
14  subsets: ["latin"],
15});
16 
17/** Reference stage the window is laid out against, then uniformly scaled. */
18const REF_WIDTH = 1280;
19const REF_HEIGHT = 720;
20 
21const WINDOW_WIDTH = 940;
22const HEADER_HEIGHT = 46;
23const BODY_PADDING = 22;
24const ROW_HEIGHT = 34;
25const FONT_SIZE = 20;
26const GUTTER_WIDTH = 46;
27const CODE_INSET = 18;
28 
29export type CodeDiffWipeProps = {
30  /** Source before the patch. */
31  before?: string;
32  /** Source after the patch. */
33  after?: string;
34  /** Filename on the window header. */
35  title?: string;
36  /** Seconds the patch front takes to travel the file. */
37  wipeSeconds?: number;
38  accentColor?: string;
39  /** Overrides the page background behind the window. */
40  backgroundColor?: string;
41  theme?: "dark" | "light";
42  /** Animation speed multiplier. */
43  speed?: number;
44};
45 
46const DEFAULT_BEFORE = `export function render(scene) {
47  const frames = scene.frames;
48  return frames.map(draw);
49}`;
50 
51const DEFAULT_AFTER = `export function render(scene, options) {
52  const frames = scene.frames;
53  const scale = options.scale ?? 1;
54  return frames.map((frame) => draw(frame, scale));
55}`;
56 
57type DiffKind = "context" | "remove" | "add";
58 
59type DiffRow = {
60  kind: DiffKind;
61  text: string;
62};
63 
64/**
65 * Line-level LCS diff. Snippets in a video are a handful of lines, so the
66 * quadratic table is free and the result is the one a reader expects.
67 */
68function diffLines(before: string[], after: string[]): DiffRow[] {
69  const table: number[][] = Array.from({ length: before.length + 1 }, () =>
70    new Array(after.length + 1).fill(0),
71  );
72 
73  for (let i = before.length - 1; i >= 0; i -= 1) {
74    for (let j = after.length - 1; j >= 0; j -= 1) {
75      table[i][j] =
76        before[i] === after[j]
77          ? table[i + 1][j + 1] + 1
78          : Math.max(table[i + 1][j], table[i][j + 1]);
79    }
80  }
81 
82  const rows: DiffRow[] = [];
83  let i = 0;
84  let j = 0;
85 
86  while (i < before.length && j < after.length) {
87    if (before[i] === after[j]) {
88      rows.push({ kind: "context", text: before[i] });
89      i += 1;
90      j += 1;
91// … truncated