mirror of
https://seed.radicle.dev/rad:z4V1sjrXqjvFdnCUbxPFqd5p4DtH5.git
synced 2026-11-12 10:00:35 +08:00
Rūdolfs Ošiņš
cd8a32a5e7
macOS saves Retina screenshots at 144 DPI and we rendered them at twice the size they had on screen. We now scale PNGs with a 2x or 3x density down; everything else, including 300 DPI print exports, stays 1:1.
113 lines
3.3 KiB
TypeScript
113 lines
3.3 KiB
TypeScript
import { describe, expect, test } from "vitest";
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import { basename, embedPreviewKind, retinaWidth } from "@app/lib/embeds";
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describe("basename", () => {
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test.each([
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["/home/alice/cat.png", "cat.png"],
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["C:\\Users\\alice\\cat.png", "cat.png"],
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["cat.png", "cat.png"],
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])("of %j is %j", (path, expected) => {
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expect(basename(path)).toBe(expected);
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});
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});
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test.each([
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["image/png", "image"],
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["application/pdf", "document"],
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["video/mp4", "video"],
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["audio/ogg", "audio"],
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["text/plain", undefined],
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[null, undefined],
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])("a %j embed previews as %j", (mimeType, expected) => {
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expect(embedPreviewKind(mimeType)).toBe(expected);
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});
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function u32(n: number): number[] {
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return [(n >>> 24) & 0xff, (n >>> 16) & 0xff, (n >>> 8) & 0xff, n & 0xff];
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}
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function bytesOf(text: string): number[] {
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return Array.from(text, c => c.charCodeAt(0));
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}
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function chunk(type: string, data: number[]): number[] {
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return [...u32(data.length), ...bytesOf(type), ...data, 0, 0, 0, 0];
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}
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const signature = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
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function ihdr(width: number): number[] {
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return chunk("IHDR", [...u32(width), ...u32(100), 8, 6, 0, 0, 0]);
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}
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function png(width: number, ...chunks: number[][]): Uint8Array {
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return new Uint8Array([
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...signature,
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...ihdr(width),
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...chunks.flat(),
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...chunk("IEND", []),
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]);
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}
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function pHYs(x: number, y: number = x, unit: number = 1): number[] {
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return chunk("pHYs", [...u32(x), ...u32(y), unit]);
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}
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const retina = 5669;
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describe("retinaWidth", () => {
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test("halves a 144 DPI PNG", () => {
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expect(retinaWidth(png(3680, pHYs(retina)))).toBe(1840);
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});
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test("divides a 216 DPI PNG by three", () => {
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expect(retinaWidth(png(3000, pHYs(8504)))).toBe(1000);
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});
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test("finds pHYs after other chunks", () => {
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const text = chunk("tEXt", bytesOf("a\0b"));
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expect(retinaWidth(png(3680, text, pHYs(retina)))).toBe(1840);
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});
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test("reads bytes at an offset in a larger buffer", () => {
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const bytes = png(3680, pHYs(retina));
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const buffer = new Uint8Array(bytes.length + 3);
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buffer.set(bytes, 3);
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expect(retinaWidth(buffer.subarray(3))).toBe(1840);
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});
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test.each([
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["72 DPI", png(3680, pHYs(2835))],
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["300 DPI", png(3680, pHYs(11811))],
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["a density of zero", png(3680, pHYs(0))],
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["the maximum density", png(3680, pHYs(0xffffffff))],
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["no pHYs chunk", png(3680)],
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["an unknown unit", png(3680, pHYs(retina, retina, 0))],
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["non-square pixels", png(3680, pHYs(retina, 2835))],
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["pHYs after IDAT", png(3680, chunk("IDAT", [0]), pHYs(retina))],
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[
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"a pHYs chunk of the wrong length",
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png(3680, chunk("pHYs", [...u32(retina), ...u32(retina), 1, 0])),
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],
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["a truncated pHYs chunk", png(3680, pHYs(retina)).subarray(0, 45)],
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[
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"no IHDR chunk first",
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new Uint8Array([...signature, ...pHYs(retina), ...ihdr(3680)]),
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],
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["a truncated IHDR chunk", png(3680, pHYs(retina)).subarray(0, 18)],
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])("ignores a PNG with %s", (_, bytes) => {
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expect(retinaWidth(bytes)).toBeUndefined();
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});
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test.each([
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["empty", new Uint8Array()],
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[
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"a JPEG",
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new Uint8Array([0xff, 0xd8, 0xff, 0xe0, ...new Array(30).fill(0)]),
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],
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])("ignores %s input", (_, bytes) => {
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expect(retinaWidth(bytes)).toBeUndefined();
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});
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});
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