vfxreview/lib/aspect-overlays.test.ts

import { describe, expect, it } from "vitest";
import {
  ASPECT_PRESETS,
  blankingInsets,
  findAspectPreset,
  isFullFrame,
  letterboxRect,
} from "./aspect-overlays";

describe("letterboxRect", () => {
  it("pillarboxes a 16:9 source in a squarer box", () => {
    const rect = letterboxRect(1000, 1000, 1920, 1080)!;
    expect(rect.width).toBeCloseTo(1000, 6);
    expect(rect.height).toBeCloseTo(562.5, 6);
    expect(rect.top).toBeCloseTo(218.75, 6);
    expect(rect.left).toBeCloseTo(0, 6);
  });

  it("letterboxes a 16:9 source in a wider box", () => {
    const rect = letterboxRect(2000, 500, 1920, 1080)!;
    expect(rect.height).toBeCloseTo(500, 6);
    expect(rect.width).toBeCloseTo(888.888, 2);
    expect(rect.left).toBeCloseTo(555.555, 2);
    expect(rect.top).toBeCloseTo(0, 6);
  });

  it("fills exactly when the box matches the source shape", () => {
    const rect = letterboxRect(1280, 720, 1920, 1080)!;
    expect(rect).toEqual({ left: 0, top: 0, width: 1280, height: 720 });
  });

  it("returns null before metadata gives the video a size", () => {
    expect(letterboxRect(1000, 500, 0, 0)).toBeNull();
    expect(letterboxRect(0, 0, 1920, 1080)).toBeNull();
  });
});

describe("blankingInsets", () => {
  const hd = { left: 0, top: 0, width: 1920, height: 1080 };

  it("blanks top and bottom for a wider delivery ratio", () => {
    const insets = blankingInsets(hd, 2.39);
    // 1920 / 2.39 = 803.35 tall, so 138.32 above and below.
    expect(insets.top).toBeCloseTo(138.3, 1);
    expect(insets.bottom).toBeCloseTo(138.3, 1);
    expect(insets.left).toBe(0);
    expect(insets.right).toBe(0);
  });

  it("blanks left and right for a taller delivery ratio", () => {
    const insets = blankingInsets(hd, 4 / 3);
    // 1080 * 1.333 = 1440 wide, so 240 either side.
    expect(insets.left).toBeCloseTo(240, 4);
    expect(insets.right).toBeCloseTo(240, 4);
    expect(insets.top).toBe(0);
    expect(insets.bottom).toBe(0);
  });

  it("draws nothing when the target matches the source", () => {
    expect(isFullFrame(blankingInsets(hd, 16 / 9))).toBe(true);
  });

  it("suppresses a sub-pixel hairline rather than drawing one", () => {
    // 1.7777... vs a 1.778 label: a real ratio difference, but under half a pixel.
    expect(isFullFrame(blankingInsets(hd, 1.778))).toBe(true);
  });

  it("keeps the blanked area at the requested ratio", () => {
    const insets = blankingInsets(hd, 2.39);
    const visibleHeight = hd.height - insets.top - insets.bottom;
    expect(hd.width / visibleHeight).toBeCloseTo(2.39, 3);
  });

  it("blanks a letterboxed picture rect, not the element box", () => {
    // 16:9 source shown in a tall panel: the picture is 1000x562.5 at y=218.75.
    const rect = letterboxRect(1000, 1000, 1920, 1080)!;
    const insets = blankingInsets(rect, 2.39);
    const visibleHeight = rect.height - insets.top - insets.bottom;
    expect(rect.width / visibleHeight).toBeCloseTo(2.39, 3);
    // Bars stay inside the picture, never spilling into the letterbox.
    expect(insets.top).toBeLessThan(rect.height / 2);
  });

  it("is inert for a zero-size rect", () => {
    expect(isFullFrame(blankingInsets({ left: 0, top: 0, width: 0, height: 0 }, 2.39))).toBe(true);
  });
});

describe("ASPECT_PRESETS", () => {
  it("has unique ids and positive ratios", () => {
    const ids = ASPECT_PRESETS.map((p) => p.id);
    expect(new Set(ids).size).toBe(ids.length);
    for (const p of ASPECT_PRESETS) expect(p.ratio).toBeGreaterThan(0);
  });

  it("runs widest to tallest", () => {
    const ratios = ASPECT_PRESETS.map((p) => p.ratio);
    expect([...ratios].sort((a, b) => b - a)).toEqual(ratios);
  });

  it("looks up by id and ignores unknown ids", () => {
    expect(findAspectPreset("2.39")?.ratio).toBe(2.39);
    expect(findAspectPreset("off")).toBeNull();
    expect(findAspectPreset("nonsense")).toBeNull();
  });
});