diff --git a/src/image-size/index.ts b/src/image-size/index.ts new file mode 100644 index 00000000..717a7df2 --- /dev/null +++ b/src/image-size/index.ts @@ -0,0 +1,412 @@ +import * as fs from 'fs'; +import { ReadStream } from 'fs'; + +export interface ImageSize { + width: number; + height: number; +} + +export enum ImageType { + JPEG = 'jpeg', + PNG = 'png', + BMP = 'bmp', + GIF = 'gif', + WEBP = 'webp', + UNKNOWN = 'unknown', +} + +interface ImageParser { + readonly type: ImageType; + canParse(buffer: Buffer): boolean; + parseSize(stream: ReadStream): Promise; +} + +// 魔术匹配 +function matchMagic(buffer: Buffer, magic: number[], offset = 0): boolean { + if (buffer.length < offset + magic.length) return false; + + for (let i = 0; i < magic.length; i++) { + if (buffer[offset + i] !== magic[i]) return false; + } + return true; +} + +// PNG解析器 +class PngParser implements ImageParser { + readonly type = ImageType.PNG; + // PNG 魔术头:89 50 4E 47 0D 0A 1A 0A + private readonly PNG_SIGNATURE = [0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A]; + + canParse(buffer: Buffer): boolean { + return matchMagic(buffer, this.PNG_SIGNATURE); + } + + async parseSize(stream: ReadStream): Promise { + return new Promise((resolve, reject) => { + stream.once('error', reject); + stream.once('readable', () => { + const buf = stream.read(24) as Buffer; + if (!buf || buf.length < 24) return resolve(undefined); + if (this.canParse(buf)) { + const width = buf.readUInt32BE(16); + const height = buf.readUInt32BE(20); + resolve({ width, height }); + } else { + resolve(undefined); + } + }); + }); + } +} + +// JPEG解析器 +class JpegParser implements ImageParser { + readonly type = ImageType.JPEG; + // JPEG 魔术头:FF D8 + private readonly JPEG_SIGNATURE = [0xFF, 0xD8]; + + // JPEG标记常量 + private readonly SOF_MARKERS = { + SOF0: 0xC0, // 基线DCT + SOF1: 0xC1, // 扩展顺序DCT + SOF2: 0xC2, // 渐进式DCT + SOF3: 0xC3, // 无损 + } as const; + + // 非SOF标记 + private readonly NON_SOF_MARKERS: number[] = [ + 0xC4, // DHT + 0xC8, // JPEG扩展 + 0xCC, // DAC + ] as const; + + canParse(buffer: Buffer): boolean { + return matchMagic(buffer, this.JPEG_SIGNATURE); + } + + isSOFMarker(marker: number): boolean { + return ( + marker === this.SOF_MARKERS.SOF0 || + marker === this.SOF_MARKERS.SOF1 || + marker === this.SOF_MARKERS.SOF2 || + marker === this.SOF_MARKERS.SOF3 + ); + } + + isNonSOFMarker(marker: number): boolean { + return this.NON_SOF_MARKERS.includes(marker); + } + + async parseSize(stream: ReadStream): Promise { + return new Promise((resolve, reject) => { + const BUFFER_SIZE = 1024; // 读取块大小,可以根据需要调整 + let buffer = Buffer.alloc(0); + let offset = 0; + let found = false; + + // 处理错误 + stream.on('error', (err) => { + stream.destroy(); + reject(err); + }); + + // 处理数据块 + stream.on('data', (chunk: Buffer | string) => { + // 追加新数据到缓冲区 + const chunkBuffer = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk); + buffer = Buffer.concat([buffer.subarray(offset), chunkBuffer]); + offset = 0; + + // 保持缓冲区在合理大小内,只保留最后的部分用于跨块匹配 + const bufferSize = buffer.length; + const MIN_REQUIRED_BYTES = 10; // SOF段最低字节数 + + // 从JPEG头部后开始扫描 + while (offset < bufferSize - MIN_REQUIRED_BYTES) { + // 寻找FF标记 + if (buffer[offset] === 0xFF && buffer[offset + 1]! >= 0xC0 && buffer[offset + 1]! <= 0xCF) { + const marker = buffer[offset + 1]; + if (!marker) break; + // 跳过非SOF标记 + if (this.isNonSOFMarker(marker)) { + offset += 2; + continue; + } + + // 处理SOF标记 (包含尺寸信息) + if (this.isSOFMarker(marker)) { + // 确保缓冲区中有足够数据读取尺寸 + if (offset + 9 < bufferSize) { + // 解析尺寸: FF XX YY YY PP HH HH WW WW ... + // XX = 标记, YY YY = 段长度, PP = 精度, HH HH = 高, WW WW = 宽 + const height = buffer.readUInt16BE(offset + 5); + const width = buffer.readUInt16BE(offset + 7); + + found = true; + stream.destroy(); + resolve({ width, height }); + return; + } else { + // 如果缓冲区内数据不够,保留当前位置等待更多数据 + break; + } + } + } + + offset++; + } + + // 缓冲区管理: 如果处理了许多数据但没找到标记, + // 保留最后N字节用于跨块匹配,丢弃之前的数据 + if (offset > BUFFER_SIZE) { + const KEEP_BYTES = 20; // 保留足够数据以处理跨块边界的情况 + if (offset > KEEP_BYTES) { + buffer = buffer.slice(offset - KEEP_BYTES); + offset = KEEP_BYTES; + } + } + }); + + // 处理流结束 + stream.on('end', () => { + if (!found) { + resolve(undefined); + } + }); + }); + } +} + +// BMP解析器 +class BmpParser implements ImageParser { + readonly type = ImageType.BMP; + // BMP 魔术头:42 4D (BM) + private readonly BMP_SIGNATURE = [0x42, 0x4D]; + + canParse(buffer: Buffer): boolean { + return matchMagic(buffer, this.BMP_SIGNATURE); + } + + async parseSize(stream: ReadStream): Promise { + return new Promise((resolve, reject) => { + stream.once('error', reject); + stream.once('readable', () => { + const buf = stream.read(26) as Buffer; + if (!buf || buf.length < 26) return resolve(undefined); + if (this.canParse(buf)) { + const width = buf.readUInt32LE(18); + const height = buf.readUInt32LE(22); + resolve({ width, height }); + } else { + resolve(undefined); + } + }); + }); + } +} + +// GIF解析器 +class GifParser implements ImageParser { + readonly type = ImageType.GIF; + // GIF87a 魔术头:47 49 46 38 37 61 + private readonly GIF87A_SIGNATURE = [0x47, 0x49, 0x46, 0x38, 0x37, 0x61]; + // GIF89a 魔术头:47 49 46 38 39 61 + private readonly GIF89A_SIGNATURE = [0x47, 0x49, 0x46, 0x38, 0x39, 0x61]; + + canParse(buffer: Buffer): boolean { + return ( + matchMagic(buffer, this.GIF87A_SIGNATURE) || + matchMagic(buffer, this.GIF89A_SIGNATURE) + ); + } + + async parseSize(stream: ReadStream): Promise { + return new Promise((resolve, reject) => { + stream.once('error', reject); + stream.once('readable', () => { + const buf = stream.read(10) as Buffer; + if (!buf || buf.length < 10) return resolve(undefined); + if (this.canParse(buf)) { + const width = buf.readUInt16LE(6); + const height = buf.readUInt16LE(8); + resolve({ width, height }); + } else { + resolve(undefined); + } + }); + }); + } +} + +// WEBP解析器 - 完整支持VP8, VP8L, VP8X格式 +class WebpParser implements ImageParser { + readonly type = ImageType.WEBP; + // WEBP RIFF 头:52 49 46 46 (RIFF) + private readonly RIFF_SIGNATURE = [0x52, 0x49, 0x46, 0x46]; + // WEBP 魔术头:57 45 42 50 (WEBP) + private readonly WEBP_SIGNATURE = [0x57, 0x45, 0x42, 0x50]; + + // WEBP 块头 + private readonly CHUNK_VP8 = [0x56, 0x50, 0x38, 0x20]; // "VP8 " + private readonly CHUNK_VP8L = [0x56, 0x50, 0x38, 0x4C]; // "VP8L" + private readonly CHUNK_VP8X = [0x56, 0x50, 0x38, 0x58]; // "VP8X" + + canParse(buffer: Buffer): boolean { + return ( + buffer.length >= 12 && + matchMagic(buffer, this.RIFF_SIGNATURE, 0) && + matchMagic(buffer, this.WEBP_SIGNATURE, 8) + ); + } + + isChunkType(buffer: Buffer, offset: number, chunkType: number[]): boolean { + return buffer.length >= offset + 4 && matchMagic(buffer, chunkType, offset); + } + + async parseSize(stream: ReadStream): Promise { + return new Promise((resolve, reject) => { + // 需要读取足够的字节来检测所有三种格式 + const MAX_HEADER_SIZE = 32; + let totalBytes = 0; + let buffer = Buffer.alloc(0); + + stream.on('error', reject); + + stream.on('data', (chunk: Buffer | string) => { + const chunkBuffer = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk); + buffer = Buffer.concat([buffer, chunkBuffer]); + totalBytes += chunk.length; + + // 检查是否有足够的字节进行格式检测 + if (totalBytes >= MAX_HEADER_SIZE) { + stream.destroy(); + + // 检查基本的WEBP签名 + if (!this.canParse(buffer)) { + return resolve(undefined); + } + + // 检查chunk头部,位于字节12-15 + if (this.isChunkType(buffer, 12, this.CHUNK_VP8)) { + // VP8格式 - 标准WebP + // 宽度和高度在帧头中 + const width = buffer.readUInt16LE(26) & 0x3FFF; + const height = buffer.readUInt16LE(28) & 0x3FFF; + return resolve({ width, height }); + + } else if (this.isChunkType(buffer, 12, this.CHUNK_VP8L)) { + // VP8L格式 - 无损WebP + // 1字节标记后是14位宽度和14位高度 + const bits = buffer.readUInt32LE(21); + const width = 1 + (bits & 0x3FFF); + const height = 1 + ((bits >> 14) & 0x3FFF); + return resolve({ width, height }); + + } else if (this.isChunkType(buffer, 12, this.CHUNK_VP8X)) { + // VP8X格式 - 扩展WebP + // 24位宽度和高度(减去1) + if (!buffer[24] || !buffer[25] || !buffer[26] || !buffer[27] || !buffer[28] || !buffer[29]) { + return resolve(undefined); + } + const width = 1 + ((buffer[24] | (buffer[25] << 8) | (buffer[26] << 16)) & 0xFFFFFF); + const height = 1 + ((buffer[27] | (buffer[28] << 8) | (buffer[29] << 16)) & 0xFFFFFF); + return resolve({ width, height }); + } else { + // 未知的WebP子格式 + return resolve(undefined); + } + } + }); + + stream.on('end', () => { + // 如果没有读到足够的字节 + if (totalBytes < MAX_HEADER_SIZE) { + resolve(undefined); + } + }); + }); + } +} + +const parsers: ReadonlyArray = [ + new PngParser(), + new JpegParser(), + new BmpParser(), + new GifParser(), + new WebpParser(), +]; + +export async function detectImageType(filePath: string): Promise { + return new Promise((resolve, reject) => { + const stream = fs.createReadStream(filePath, { + highWaterMark: 64, // 优化读取buffer大小 + start: 0, + end: 63 + }); + + let buffer: Buffer | null = null; + + stream.once('error', (err) => { + stream.destroy(); + reject(err); + }); + + stream.once('readable', () => { + buffer = stream.read(64) as Buffer; + stream.destroy(); + + if (!buffer) { + return resolve(ImageType.UNKNOWN); + } + + for (const parser of parsers) { + if (parser.canParse(buffer)) { + return resolve(parser.type); + } + } + + resolve(ImageType.UNKNOWN); + }); + + stream.once('end', () => { + if (!buffer) { + resolve(ImageType.UNKNOWN); + } + }); + }); +} + +export async function imageSizeFromFile(filePath: string): Promise { + try { + // 先检测类型 + const type = await detectImageType(filePath); + const parser = parsers.find(p => p.type === type); + if (!parser) return undefined; + + // 用流式方式解析尺寸 + const stream = fs.createReadStream(filePath); + try { + return await parser.parseSize(stream); + } catch (err) { + console.error(`解析图片尺寸出错: ${err}`); + return undefined; + } finally { + if (!stream.destroyed) { + stream.destroy(); + } + } + } catch (err) { + console.error(`检测图片类型出错: ${err}`); + return undefined; + } +} + +export async function imageSizeFallBack( + filePath: string, + fallback: ImageSize = { + width: 1024, + height: 1024, + } +): Promise { + return await imageSizeFromFile(filePath) ?? fallback; +} \ No newline at end of file