developer_liu
102 lines
2.8 KiB
TypeScript
102 lines
2.8 KiB
TypeScript
import { BadRequestException } from '@nestjs/common';
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import {
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activityPosterResizeTarget,
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activityPosterTemplateTooLarge,
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} from '@dukang/shared-types';
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import sharp from 'sharp';
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const JPEG_QUALITY = 85;
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export type ActivityPosterUploadPrepared = {
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buffer: Buffer;
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mimeType: string;
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width: number;
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height: number;
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originalWidth: number;
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originalHeight: number;
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compressed: boolean;
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};
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function resolveOutputMime(hasAlpha: boolean, inputMime?: string): string {
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if (hasAlpha) return 'image/png';
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if (inputMime === 'image/webp') return 'image/jpeg';
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if (inputMime?.startsWith('image/')) return inputMime;
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return 'image/jpeg';
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}
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async function encodeImage(
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pipeline: sharp.Sharp,
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mimeType: string,
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): Promise<Buffer> {
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if (mimeType === 'image/png') {
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return pipeline.png().toBuffer();
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}
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if (mimeType === 'image/jpeg' || mimeType === 'image/jpg') {
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return pipeline.jpeg({ quality: JPEG_QUALITY }).toBuffer();
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}
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if (mimeType === 'image/webp') {
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return pipeline.webp({ quality: JPEG_QUALITY }).toBuffer();
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}
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return pipeline.jpeg({ quality: JPEG_QUALITY }).toBuffer();
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}
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export async function prepareActivityPosterUpload(input: {
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buffer: Buffer;
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mimeType?: string;
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}): Promise<ActivityPosterUploadPrepared> {
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if (!input.buffer?.length) {
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throw new BadRequestException('活动图文件为空');
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}
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if (input.mimeType && !input.mimeType.startsWith('image/')) {
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throw new BadRequestException('活动图仅支持图片文件');
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}
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const meta = await sharp(input.buffer, { failOn: 'none' }).metadata();
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if (!meta.width || !meta.height) {
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throw new BadRequestException('活动图无法读取尺寸，请换一张图片');
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}
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const originalWidth = meta.width;
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const originalHeight = meta.height;
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const resizeTarget = activityPosterResizeTarget(originalWidth, originalHeight);
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if (!resizeTarget) {
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return {
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buffer: input.buffer,
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mimeType: input.mimeType || 'image/jpeg',
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width: originalWidth,
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height: originalHeight,
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originalWidth,
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originalHeight,
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compressed: false,
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};
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}
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const hasAlpha = meta.hasAlpha === true;
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const outputMime = resolveOutputMime(hasAlpha, input.mimeType);
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const buffer = await encodeImage(
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sharp(input.buffer, { failOn: 'none' }).resize(resizeTarget.width, resizeTarget.height, {
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fit: 'inside',
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withoutEnlargement: true,
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}),
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outputMime,
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);
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const metaOut = await sharp(buffer).metadata();
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const width = metaOut.width ?? resizeTarget.width;
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const height = metaOut.height ?? resizeTarget.height;
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if (activityPosterTemplateTooLarge(width, height)) {
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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');
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}
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return {
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buffer,
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mimeType: outputMime,
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width,
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height,
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originalWidth,
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originalHeight,
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compressed: true,
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};
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}
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