267 lines
7.5 KiB
TypeScript
267 lines
7.5 KiB
TypeScript
/**
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* 图片尺寸工具
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* 用于获取图片尺寸，生成 QQBot 的 markdown 图片格式
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*
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* QQBot markdown 图片格式: 
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*/
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import { Buffer } from "buffer";
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export interface ImageSize {
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width: number;
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height: number;
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}
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/** 默认图片尺寸（当无法获取时使用） */
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export const DEFAULT_IMAGE_SIZE: ImageSize = { width: 512, height: 512 };
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/**
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* 从 PNG 文件头解析图片尺寸
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* PNG 文件头结构: 前 8 字节是签名，IHDR 块从第 8 字节开始
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* IHDR 块: 长度(4) + 类型(4, "IHDR") + 宽度(4) + 高度(4) + ...
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*/
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function parsePngSize(buffer: Buffer): ImageSize | null {
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// PNG 签名: 89 50 4E 47 0D 0A 1A 0A
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if (buffer.length < 24) return null;
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if (buffer[0] !== 0x89 || buffer[1] !== 0x50 || buffer[2] !== 0x4E || buffer[3] !== 0x47) {
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return null;
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}
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// IHDR 块从第 8 字节开始，宽度在第 16-19 字节，高度在第 20-23 字节
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const width = buffer.readUInt32BE(16);
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const height = buffer.readUInt32BE(20);
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return { width, height };
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}
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/**
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* 从 JPEG 文件解析图片尺寸
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* JPEG 尺寸在 SOF0/SOF2 块中
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*/
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function parseJpegSize(buffer: Buffer): ImageSize | null {
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// JPEG 签名: FF D8 FF
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if (buffer.length < 4) return null;
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if (buffer[0] !== 0xFF || buffer[1] !== 0xD8) {
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return null;
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}
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let offset = 2;
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while (offset < buffer.length - 9) {
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if (buffer[offset] !== 0xFF) {
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offset++;
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continue;
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}
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const marker = buffer[offset + 1];
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// SOF0 (0xC0) 或 SOF2 (0xC2) 包含图片尺寸
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if (marker === 0xC0 || marker === 0xC2) {
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// 格式: FF C0 长度(2) 精度(1) 高度(2) 宽度(2)
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if (offset + 9 <= buffer.length) {
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const height = buffer.readUInt16BE(offset + 5);
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const width = buffer.readUInt16BE(offset + 7);
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return { width, height };
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}
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}
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// 跳过当前块
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if (offset + 3 < buffer.length) {
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const blockLength = buffer.readUInt16BE(offset + 2);
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offset += 2 + blockLength;
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} else {
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break;
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}
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}
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return null;
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}
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/**
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* 从 GIF 文件头解析图片尺寸
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* GIF 文件头: GIF87a 或 GIF89a (6字节) + 宽度(2) + 高度(2)
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*/
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function parseGifSize(buffer: Buffer): ImageSize | null {
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if (buffer.length < 10) return null;
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const signature = buffer.toString("ascii", 0, 6);
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if (signature !== "GIF87a" && signature !== "GIF89a") {
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return null;
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}
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const width = buffer.readUInt16LE(6);
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const height = buffer.readUInt16LE(8);
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return { width, height };
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}
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/**
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* 从 WebP 文件解析图片尺寸
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* WebP 文件头: RIFF(4) + 文件大小(4) + WEBP(4) + VP8/VP8L/VP8X(4) + ...
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*/
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function parseWebpSize(buffer: Buffer): ImageSize | null {
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if (buffer.length < 30) return null;
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// 检查 RIFF 和 WEBP 签名
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const riff = buffer.toString("ascii", 0, 4);
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const webp = buffer.toString("ascii", 8, 12);
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if (riff !== "RIFF" || webp !== "WEBP") {
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return null;
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}
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const chunkType = buffer.toString("ascii", 12, 16);
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// VP8 (有损压缩)
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if (chunkType === "VP8 ") {
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// VP8 帧头从第 23 字节开始，检查签名 9D 01 2A
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if (buffer.length >= 30 && buffer[23] === 0x9D && buffer[24] === 0x01 && buffer[25] === 0x2A) {
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const width = buffer.readUInt16LE(26) & 0x3FFF;
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const height = buffer.readUInt16LE(28) & 0x3FFF;
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return { width, height };
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}
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}
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// VP8L (无损压缩)
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if (chunkType === "VP8L") {
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// VP8L 签名: 0x2F
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if (buffer.length >= 25 && buffer[20] === 0x2F) {
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const bits = buffer.readUInt32LE(21);
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const width = (bits & 0x3FFF) + 1;
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const height = ((bits >> 14) & 0x3FFF) + 1;
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return { width, height };
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}
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}
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// VP8X (扩展格式)
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if (chunkType === "VP8X") {
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if (buffer.length >= 30) {
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// 宽度和高度在第 24-26 和 27-29 字节（24位小端）
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const width = (buffer[24] | (buffer[25] << 8) | (buffer[26] << 16)) + 1;
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const height = (buffer[27] | (buffer[28] << 8) | (buffer[29] << 16)) + 1;
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return { width, height };
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}
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}
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return null;
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}
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/**
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* 从图片数据 Buffer 解析尺寸
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*/
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export function parseImageSize(buffer: Buffer): ImageSize | null {
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// 尝试各种格式
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return parsePngSize(buffer)
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?? parseJpegSize(buffer)
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?? parseGifSize(buffer)
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?? parseWebpSize(buffer);
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}
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/**
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* 从公网 URL 获取图片尺寸
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* 只下载前 64KB 数据，足够解析大部分图片格式的头部
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*/
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export async function getImageSizeFromUrl(url: string, timeoutMs = 5000): Promise<ImageSize | null> {
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try {
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const controller = new AbortController();
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const timeoutId = setTimeout(() => controller.abort(), timeoutMs);
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// 使用 Range 请求只获取前 64KB
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const response = await fetch(url, {
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signal: controller.signal,
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headers: {
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"Range": "bytes=0-65535",
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"User-Agent": "QQBot-Image-Size-Detector/1.0",
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},
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});
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clearTimeout(timeoutId);
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if (!response.ok && response.status !== 206) {
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console.log(`[image-size] Failed to fetch ${url}: ${response.status}`);
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return null;
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}
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const arrayBuffer = await response.arrayBuffer();
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const buffer = Buffer.from(arrayBuffer);
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const size = parseImageSize(buffer);
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if (size) {
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console.log(`[image-size] Got size from URL: ${size.width}x${size.height} - ${url.slice(0, 60)}...`);
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}
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return size;
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} catch (err) {
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console.log(`[image-size] Error fetching ${url.slice(0, 60)}...: ${err}`);
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return null;
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}
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}
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/**
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* 从 Base64 Data URL 获取图片尺寸
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*/
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export function getImageSizeFromDataUrl(dataUrl: string): ImageSize | null {
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try {
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// 格式: data:image/png;base64,xxxxx
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const matches = dataUrl.match(/^data:image\/[^;]+;base64,(.+)$/);
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if (!matches) {
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return null;
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}
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const base64Data = matches[1];
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const buffer = Buffer.from(base64Data, "base64");
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const size = parseImageSize(buffer);
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if (size) {
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console.log(`[image-size] Got size from Base64: ${size.width}x${size.height}`);
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}
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return size;
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} catch (err) {
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console.log(`[image-size] Error parsing Base64: ${err}`);
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return null;
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}
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}
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/**
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* 获取图片尺寸（自动判断来源）
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* @param source - 图片 URL 或 Base64 Data URL
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* @returns 图片尺寸，失败返回 null
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*/
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export async function getImageSize(source: string): Promise<ImageSize | null> {
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if (source.startsWith("data:")) {
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return getImageSizeFromDataUrl(source);
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}
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if (source.startsWith("http://") || source.startsWith("https://")) {
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return getImageSizeFromUrl(source);
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}
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return null;
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}
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/**
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* 生成 QQBot markdown 图片格式
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* 格式: 
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*
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* @param url - 图片 URL
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* @param size - 图片尺寸，如果为 null 则使用默认尺寸
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* @returns QQBot markdown 图片字符串
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*/
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export function formatQQBotMarkdownImage(url: string, size: ImageSize | null): string {
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const { width, height } = size ?? DEFAULT_IMAGE_SIZE;
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return ``;
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}
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/**
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* 检查 markdown 图片是否已经包含 QQBot 格式的尺寸信息
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* 格式: 
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*/
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export function hasQQBotImageSize(markdownImage: string): boolean {
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return /!\[#\d+px\s+#\d+px\]/.test(markdownImage);
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}
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/**
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* 从已有的 QQBot 格式 markdown 图片中提取尺寸
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* 格式: 
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*/
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export function extractQQBotImageSize(markdownImage: string): ImageSize | null {
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const match = markdownImage.match(/!\[#(\d+)px\s+#(\d+)px\]/);
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if (match) {
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return { width: parseInt(match[1], 10), height: parseInt(match[2], 10) };
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}
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return null;
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}
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