cat-shark
215 lines
7.8 KiB
TypeScript
215 lines
7.8 KiB
TypeScript
import sharp from 'sharp';
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import * as fs from 'fs';
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import * as path from 'path';
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import { PlatformCoverRequirements, CoverAdaptResult } from './types';
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import {Log} from '../log/main';
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/**
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* 各平台封面要求
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*/
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const PLATFORM_REQUIREMENTS: Record<string, PlatformCoverRequirements> = {
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douyin: {
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width: 1080,
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height: 1920,
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ratio: '9:16',
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maxSize: 5000, // 5MB
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format: 'jpg'
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},
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kuaishou: {
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width: 1080,
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height: 1440,
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ratio: '3:4',
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maxSize: 3000,
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format: 'jpg'
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},
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shipin: {
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width: 1280,
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height: 720,
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ratio: '16:9',
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maxSize: 2000,
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format: 'jpg'
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},
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xiaohongshu: {
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width: 1080,
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height: 1440,
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ratio: '3:4',
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maxSize: 5000, // 5MB
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format: 'jpg'
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}
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};
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export class CoverAdapter {
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/**
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* 智能适配封面到平台要求
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*/
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static async adaptCover(params: {
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coverPath: string;
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platform: string;
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outputDir: string;
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}): Promise<CoverAdaptResult> {
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const { coverPath, platform, outputDir } = params;
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const requirements = PLATFORM_REQUIREMENTS[platform];
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if (!requirements) {
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throw new Error(`不支持的平台: ${platform}`);
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}
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// 检查输入文件是否存在
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if (!fs.existsSync(coverPath)) {
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throw new Error(`封面文件不存在: ${coverPath}`);
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}
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const adjustments: string[] = [];
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try {
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// 1. 读取原始图片信息
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const image = sharp(coverPath);
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const metadata = await image.metadata();
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if (!metadata.width || !metadata.height) {
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throw new Error('无法读取图片尺寸信息');
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}
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const originalSize = {
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width: metadata.width,
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height: metadata.height
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};
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Log.info(`原始封面尺寸: ${originalSize.width}x${originalSize.height}`, { platform });
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// 2. 计算目标尺寸和裁剪策略
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const targetRatio = requirements.width / requirements.height;
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const currentRatio = originalSize.width / originalSize.height;
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let processedImage = sharp(coverPath);
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// 3. 处理宽高比不匹配的情况
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// 视频号和抖音都使用contain（保留完整内容），其他平台使用cover（裁剪）
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const usePadding = platform === 'shipin' || platform === 'douyin'; // 视频号和抖音使用填充而不是裁剪
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if (Math.abs(currentRatio - targetRatio) > 0.01) {
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adjustments.push(`调整宽高比从${currentRatio.toFixed(2)}到${targetRatio.toFixed(2)}`);
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if (!usePadding) {
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// 其他平台：裁剪策略
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if (currentRatio > targetRatio) {
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// 原图更宽，需要裁剪左右
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const newWidth = Math.round(originalSize.height * targetRatio);
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const left = Math.round((originalSize.width - newWidth) / 2);
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processedImage = processedImage.extract({
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left: left,
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top: 0,
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width: newWidth,
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height: originalSize.height
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});
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adjustments.push(`裁剪宽度: ${originalSize.width} -> ${newWidth} (居中裁剪)`);
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} else {
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// 原图更高，需要裁剪上下
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const newHeight = Math.round(originalSize.width / targetRatio);
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const top = Math.round((originalSize.height - newHeight) / 2);
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processedImage = processedImage.extract({
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left: 0,
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top: top,
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width: originalSize.width,
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height: newHeight
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});
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adjustments.push(`裁剪高度: ${originalSize.height} -> ${newHeight} (居中裁剪)`);
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}
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} else {
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// 视频号和抖音：使用填充（添加黑边保留完整内容）
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adjustments.push(`使用等比例缩放+黑边填充（保留完整图片）`);
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}
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}
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// 4. 调整到目标分辨率
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processedImage = processedImage.resize(requirements.width, requirements.height, {
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fit: usePadding ? 'contain' : 'cover', // 抖音和视频号使用contain保留完整内容，其他使用cover裁剪
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position: 'center',
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background: { r: 0, g: 0, b: 0, alpha: 1 } // 黑色背景
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});
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if (usePadding) {
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adjustments.push(`等比例缩放至: ${requirements.width}x${requirements.height} (添加黑边)`);
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} else {
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adjustments.push(`缩放至: ${requirements.width}x${requirements.height}`);
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}
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// 5. 转换格式并调整质量
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let pipeline: sharp.Sharp;
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if (requirements.format === 'jpg') {
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pipeline = processedImage.jpeg({ quality: 90 });
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adjustments.push('转换为JPEG格式（质量90%）');
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} else if (requirements.format === 'png') {
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pipeline = processedImage.png({ compressionLevel: 9 });
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adjustments.push('转换为PNG格式');
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} else {
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pipeline = processedImage.webp({ quality: 90 });
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adjustments.push('转换为WebP格式（质量90%）');
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}
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// 6. 创建输出目录（如果不存在）
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if (!fs.existsSync(outputDir)) {
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fs.mkdirSync(outputDir, { recursive: true });
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}
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// 7. 保存处理后的图片
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const timestamp = Date.now();
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const adaptedPath = path.join(outputDir, `cover_${platform}_${timestamp}.${requirements.format}`);
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await pipeline.toFile(adaptedPath);
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// 8. 检查文件大小，如果超过限制则降低质量
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let fileSize = fs.statSync(adaptedPath).size / 1024; // KB
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if (fileSize > requirements.maxSize) {
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adjustments.push(`文件过大(${fileSize.toFixed(0)}KB)，压缩至${requirements.maxSize}KB以内`);
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let quality = 80;
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while (fileSize > requirements.maxSize && quality > 50) {
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quality -= 10;
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await sharp(coverPath)
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.resize(requirements.width, requirements.height, {
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fit: usePadding ? 'contain' : 'cover',
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position: 'center',
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background: { r: 0, g: 0, b: 0, alpha: 1 }
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})
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.jpeg({ quality })
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.toFile(adaptedPath);
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fileSize = fs.statSync(adaptedPath).size / 1024;
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}
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adjustments.push(`最终质量: ${quality}%，文件大小: ${fileSize.toFixed(0)}KB`);
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}
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Log.info(`封面适配完成: ${adaptedPath}`, { platform, adjustments });
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return {
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success: true,
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adaptedPath,
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originalSize,
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adaptedSize: {
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width: requirements.width,
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height: requirements.height
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},
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adjustments
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};
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} catch (error) {
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Log.error(`封面适配失败`, { platform, error });
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throw error;
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}
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}
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/**
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* 获取平台预设要求
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*/
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static getPlatformRequirements(platform: string): PlatformCoverRequirements | null {
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return PLATFORM_REQUIREMENTS[platform] || null;
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}
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}
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