Release Font Tools v0.1.0

tests/core/sfnt.test.ts

@@ -0,0 +1,67 @@
+import { describe, expect, it } from "vitest";
+import { decodeEmbedding, inspectDirectory } from "../../src/core/sfnt";
+
+describe("SFNT directory validation", () => {
+  it("inventories bounded TrueType tables", () => {
+    const report = inspectDirectory(sfnt(["head", "cmap", "OS/2"]));
+    expect(report.container).toBe("truetype");
+    expect(report.tables.map((table) => table.tag)).toEqual([
+      "head",
+      "cmap",
+      "OS/2",
+    ]);
+    expect(report.tables[2]?.description).toContain("embedding");
+  });
+
+  it("rejects unsupported and out-of-bounds containers before library parsing", () => {
+    expect(() => inspectDirectory(signature("wOF2"))).toThrow(/WOFF2/u);
+    const invalid = sfnt(["head"]),
+      view = new DataView(invalid);
+    view.setUint32(12 + 8, invalid.byteLength - 2, false);
+    view.setUint32(12 + 12, 12, false);
+    expect(() => inspectDirectory(invalid)).toThrow(/file boundary/u);
+  });
+});
+
+describe("embedding flags", () => {
+  it("decodes and enforces subsetting restrictions", () => {
+    expect(decodeEmbedding(0).subsetAllowed).toBe(true);
+    expect(decodeEmbedding(0x0002).level).toBe("restricted");
+    expect(decodeEmbedding(0x0100)).toMatchObject({
+      noSubsetting: true,
+      subsetAllowed: false,
+    });
+    expect(decodeEmbedding(0x0208)).toMatchObject({
+      level: "editable",
+      bitmapOnly: true,
+      subsetAllowed: false,
+    });
+  });
+});
+
+function signature(value: string) {
+  const bytes = new Uint8Array(4);
+  [...value].forEach(
+    (character, index) => (bytes[index] = character.charCodeAt(0)),
+  );
+  return bytes.buffer;
+}
+
+function sfnt(tags: string[]) {
+  const directoryBytes = 12 + tags.length * 16,
+    tableBytes = 12,
+    buffer = new ArrayBuffer(directoryBytes + tags.length * tableBytes),
+    view = new DataView(buffer);
+  view.setUint32(0, 0x0001_0000, false);
+  view.setUint16(4, tags.length, false);
+  tags.forEach((tag, index) => {
+    const base = 12 + index * 16;
+    [...tag].forEach((character, offset) =>
+      view.setUint8(base + offset, character.charCodeAt(0)),
+    );
+    view.setUint32(base + 4, index + 1, false);
+    view.setUint32(base + 8, directoryBytes + index * tableBytes, false);
+    view.setUint32(base + 12, tableBytes, false);
+  });
+  return buffer;
+}