YeonGyu-Kim
0dd9ac43ea
Previously decoded entire image buffer to read headers. Now slices base64 to 32KB prefix before decoding — sufficient for PNG/GIF/WebP/JPEG headers. Dramatically reduces memory allocation for large images.
127 lines
3.3 KiB
TypeScript
127 lines
3.3 KiB
TypeScript
/// <reference types="bun-types" />
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import { describe, expect, it } from "bun:test"
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import { parseImageDimensions } from "./image-dimensions"
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const PNG_1X1_DATA_URL =
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"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg=="
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const GIF_1X1_DATA_URL =
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"data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7"
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function createPngDataUrl(width: number, height: number): string {
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const buf = Buffer.alloc(33)
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buf.set([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a], 0)
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buf.writeUInt32BE(13, 8)
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buf.set([0x49, 0x48, 0x44, 0x52], 12)
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buf.writeUInt32BE(width, 16)
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buf.writeUInt32BE(height, 20)
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return `data:image/png;base64,${buf.toString("base64")}`
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}
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function createGifDataUrl(width: number, height: number): string {
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const buf = Buffer.alloc(10)
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buf.set([0x47, 0x49, 0x46, 0x38, 0x39, 0x61], 0)
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buf.writeUInt16LE(width, 6)
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buf.writeUInt16LE(height, 8)
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return `data:image/gif;base64,${buf.toString("base64")}`
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}
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function createLargePngDataUrl(width: number, height: number, extraBase64Chars: number): string {
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const baseDataUrl = createPngDataUrl(width, height)
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const base64Data = baseDataUrl.slice(baseDataUrl.indexOf(",") + 1)
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const paddedBase64 = `${base64Data}${"A".repeat(extraBase64Chars)}`
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return `data:image/png;base64,${paddedBase64}`
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}
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describe("parseImageDimensions", () => {
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it("parses PNG 1x1 dimensions", () => {
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//#given
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const dataUrl = PNG_1X1_DATA_URL
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//#when
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const result = parseImageDimensions(dataUrl, "image/png")
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//#then
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expect(result).toEqual({ width: 1, height: 1 })
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})
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it("parses PNG dimensions from IHDR", () => {
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//#given
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const dataUrl = createPngDataUrl(3000, 2000)
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//#when
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const result = parseImageDimensions(dataUrl, "image/png")
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//#then
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expect(result).toEqual({ width: 3000, height: 2000 })
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})
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it("parses PNG dimensions from a very large base64 payload", () => {
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//#given
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const dataUrl = createLargePngDataUrl(4096, 2160, 10 * 1024 * 1024)
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//#when
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const result = parseImageDimensions(dataUrl, "image/png")
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//#then
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expect(result).toEqual({ width: 4096, height: 2160 })
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})
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it("parses GIF 1x1 dimensions", () => {
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//#given
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const dataUrl = GIF_1X1_DATA_URL
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//#when
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const result = parseImageDimensions(dataUrl, "image/gif")
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//#then
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expect(result).toEqual({ width: 1, height: 1 })
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})
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it("parses GIF dimensions from logical screen descriptor", () => {
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//#given
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const dataUrl = createGifDataUrl(320, 240)
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//#when
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const result = parseImageDimensions(dataUrl, "image/gif")
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//#then
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expect(result).toEqual({ width: 320, height: 240 })
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})
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it("returns null for empty input", () => {
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//#given
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const dataUrl = ""
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//#when
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const result = parseImageDimensions(dataUrl, "image/png")
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//#then
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expect(result).toBeNull()
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})
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it("returns null for too-short PNG buffer", () => {
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//#given
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const dataUrl = "data:image/png;base64,AAAA"
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//#when
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const result = parseImageDimensions(dataUrl, "image/png")
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//#then
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expect(result).toBeNull()
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})
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it("returns null for unsupported mime type", () => {
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//#given
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const dataUrl = PNG_1X1_DATA_URL
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//#when
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const result = parseImageDimensions(dataUrl, "image/heic")
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//#then
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expect(result).toBeNull()
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})
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})
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