39 lines
1.6 KiB
JavaScript
39 lines
1.6 KiB
JavaScript
'use strict';
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const { nativeImage } = require('electron');
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const PREVIEW_BYTES = 12 * 1024; // >12 KB → needs resizing for inline preview
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const SOFT_CAP_BYTES = 2 * 1024 * 1024; // 2 MB
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const RESIZE_WIDTH = 800; // 大图压到这个宽度，保证 SOFT_CAP_BYTES 不爆
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/**
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* Returns { buf, preview }.
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* - buf: input buffer unchanged.
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* - preview: null if the buffer is < PREVIEW_BYTES (12 KB), otherwise the
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* literal string '[图片]'. The caller (main.js) is responsible for
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* actually resizing when buf.length > SOFT_CAP_BYTES (2 MB); the
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* preview marker is purely a signal that the buffer is non-trivial.
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*/
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function capImage(buf) {
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const b = Buffer.isBuffer(buf) ? buf : Buffer.from(buf || []);
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if (b.length < PREVIEW_BYTES) return { buf: b, preview: null };
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return { buf: b, preview: '[图片]' };
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}
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/**
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* 把图片 buffer 按 SOFT_CAP_BYTES 收纳：超出的图压成 RESIZE_WIDTH 宽。
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* 三处共用：pollClipboard / bringFavoriteIntoHistory。
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*
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* 返回 { buf, preview }，preview 由 capImage 给出（无图/小图 = null），
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* 给数据库的 preview 列用。
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*/
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function normalizeImageForStorage(buf) {
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const cap = capImage(buf);
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// 小图/空图：直接原样入库
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if (!cap.preview) return cap;
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if (cap.buf.length <= SOFT_CAP_BYTES) return cap;
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// 大图：nativeImage 重新编码到 RESIZE_WIDTH 宽，PNG 重编码比原图小一个数量级
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const img = nativeImage.createFromBuffer(cap.buf);
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return { buf: img.resize({ width: RESIZE_WIDTH }).toPNG(), preview: cap.preview };
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}
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module.exports = { capImage, normalizeImageForStorage, PREVIEW_BYTES, SOFT_CAP_BYTES, RESIZE_WIDTH }; |