v4.0.15上传图片自动压缩

2026-09-03 16:04:10 +08:00
parent b60b16a84f
commit c26ebdde1b
9 changed files with 308 additions and 13 deletions
@@ -0,0 +1,101 @@
+import { BadRequestException } from '@nestjs/common';
+import {
+  activityPosterResizeTarget,
+  activityPosterTemplateTooLarge,
+} from '@dukang/shared-types';
+import sharp from 'sharp';
+
+const JPEG_QUALITY = 85;
+
+export type ActivityPosterUploadPrepared = {
+  buffer: Buffer;
+  mimeType: string;
+  width: number;
+  height: number;
+  originalWidth: number;
+  originalHeight: number;
+  compressed: boolean;
+};
+
+function resolveOutputMime(hasAlpha: boolean, inputMime?: string): string {
+  if (hasAlpha) return 'image/png';
+  if (inputMime === 'image/webp') return 'image/jpeg';
+  if (inputMime?.startsWith('image/')) return inputMime;
+  return 'image/jpeg';
+}
+
+async function encodeImage(
+  pipeline: sharp.Sharp,
+  mimeType: string,
+): Promise<Buffer> {
+  if (mimeType === 'image/png') {
+    return pipeline.png().toBuffer();
+  }
+  if (mimeType === 'image/jpeg' || mimeType === 'image/jpg') {
+    return pipeline.jpeg({ quality: JPEG_QUALITY }).toBuffer();
+  }
+  if (mimeType === 'image/webp') {
+    return pipeline.webp({ quality: JPEG_QUALITY }).toBuffer();
+  }
+  return pipeline.jpeg({ quality: JPEG_QUALITY }).toBuffer();
+}
+
+export async function prepareActivityPosterUpload(input: {
+  buffer: Buffer;
+  mimeType?: string;
+}): Promise<ActivityPosterUploadPrepared> {
+  if (!input.buffer?.length) {
+    throw new BadRequestException('活动图文件为空');
+  }
+  if (input.mimeType && !input.mimeType.startsWith('image/')) {
+    throw new BadRequestException('活动图仅支持图片文件');
+  }
+
+  const meta = await sharp(input.buffer, { failOn: 'none' }).metadata();
+  if (!meta.width || !meta.height) {
+    throw new BadRequestException('活动图无法读取尺寸，请换一张图片');
+  }
+
+  const originalWidth = meta.width;
+  const originalHeight = meta.height;
+  const resizeTarget = activityPosterResizeTarget(originalWidth, originalHeight);
+
+  if (!resizeTarget) {
+    return {
+      buffer: input.buffer,
+      mimeType: input.mimeType || 'image/jpeg',
+      width: originalWidth,
+      height: originalHeight,
+      originalWidth,
+      originalHeight,
+      compressed: false,
+    };
+  }
+
+  const hasAlpha = meta.hasAlpha === true;
+  const outputMime = resolveOutputMime(hasAlpha, input.mimeType);
+  const buffer = await encodeImage(
+    sharp(input.buffer, { failOn: 'none' }).resize(resizeTarget.width, resizeTarget.height, {
+      fit: 'inside',
+      withoutEnlargement: true,
+    }),
+    outputMime,
+  );
+  const metaOut = await sharp(buffer).metadata();
+  const width = metaOut.width ?? resizeTarget.width;
+  const height = metaOut.height ?? resizeTarget.height;
+
+  if (activityPosterTemplateTooLarge(width, height)) {
+    throw new BadRequestException('活动图压缩后仍超出尺寸限制，请换一张较小的图片');
+  }
+
+  return {
+    buffer,
+    mimeType: outputMime,
+    width,
+    height,
+    originalWidth,
+    originalHeight,
+    compressed: true,
+  };
+}