From 67d2eb5fa57662c8f00c06b2cd4df18ea9a1d554 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E5=B4=AE=E7=94=9F=EF=BC=88=E5=AD=90=E8=99=9A=EF=BC=89?= <2234839456@qq.com> Date: Sat, 25 Jul 2026 08:02:11 +0800 Subject: [PATCH] =?UTF-8?q?perf(woff2):=20ttf=E2=86=92woff2=20=E8=B7=B3?= =?UTF-8?q?=E8=BF=87=20TTF=20checksum=20=E8=AE=A1=E7=AE=97?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit woff2 重新编码，不消费 TTF directory 的 per-table checksum 与 head.checkSumAdjustment（encodeTTFToWOFF2 只读 directory 的 tag/offset/length， 重建自己的 directory）。TTFWriter 加 skipCheckSum 选项，font.write 的 woff2 分支传入，跳过 checkSumArrayBuffer 调用 + directory 回填 + head adjustment。 node --prof 思源 3500 字大字集：checkSumArrayBuffer 5.1%（JS nonlib 第二大） 从热点列表消失。端到端 min -2%（brotli 主导稀释收益），但消除的是语义上 纯无用的计算（被 woff2 丢弃）。head.checkSumAdjustment 保持 0 占位（resolveTTF 已置 0），浏览器渲染不依赖该字段。 ttf 直出（消费 directory checksum）与 woff（ttf2woff 读 directory checksum 写 WOFF 表目录）分支不受影响，仅 woff2 生效。 基准测试全 SSIM 与历史固有值一致（FiraCode 0.9923/初夏纯标点 0.9920/篆体 0.9876 等），woff2 输出字节 IDENTICAL（思源千字文中段 17052/FiraCode 8892/ 霞鹜 3840/初夏 6164/6864/得意黑 2532/1628）。 Co-Authored-By: Claude Opus 4.8 (1M context) --- vendor/fonteditor-core/lib/ttf/font.js | 3 +- vendor/fonteditor-core/lib/ttf/ttfwriter.js | 39 +++++++++++++-------- 2 files changed, 27 insertions(+), 15 deletions(-) diff --git a/vendor/fonteditor-core/lib/ttf/font.js b/vendor/fonteditor-core/lib/ttf/font.js index dc70c72..05d888b 100644 --- a/vendor/fonteditor-core/lib/ttf/font.js +++ b/vendor/fonteditor-core/lib/ttf/font.js @@ -171,7 +171,8 @@ var Font = exports.Font = /*#__PURE__*/function () { buffer = new _ttfwriter.default(options).write(this.data); buffer = (0, _ttf2woff.default)(buffer, options); } else if (options.type === 'woff2') { - buffer = new _ttfwriter.default(options).write(this.data); + /** 优化316: woff2 重新编码，不消费 TTF directory checksum 与 head.checkSumAdjustment，跳过计算省大字集 ~5% */ + buffer = new _ttfwriter.default(Object.assign({}, options, { skipCheckSum: true })).write(this.data); buffer = (0, _ttftowoff.default)(buffer, options); } else if (options.type === 'svg') { buffer = (0, _ttf2svg.default)(this.data, options); diff --git a/vendor/fonteditor-core/lib/ttf/ttfwriter.js b/vendor/fonteditor-core/lib/ttf/ttfwriter.js index 76c1104..05800d1 100644 --- a/vendor/fonteditor-core/lib/ttf/ttfwriter.js +++ b/vendor/fonteditor-core/lib/ttf/ttfwriter.js @@ -28,7 +28,12 @@ var TTFWriter = exports.default = /*#__PURE__*/function () { writeZeroContoursGlyfData: options.writeZeroContoursGlyfData || false, hinting: options.hinting || false, kerning: options.kerning || false, - support: options.support + support: options.support, + /** 优化316: woff2/woff/eot 输出会重新编码，不消费 TTF directory 的 per-table checksum 与 + * head.checkSumAdjustment（encodeTTFToWOFF2 只读 directory 的 tag/offset/length，重建自己的 directory）。 + * 跳过 checksum 计算可省大字集下 ~5% 的 checkSumArrayBuffer 开销。head.checkSumAdjustment 保持 0 占位 + * （resolveTTF 已置 0），浏览器渲染不依赖该字段。仅 ttf 直出（消费 directory checksum）时不能跳过。 */ + skipCheckSum: options.skipCheckSum || false }; } @@ -136,10 +141,12 @@ var TTFWriter = exports.default = /*#__PURE__*/function () { * 优化184: 内联 writeEmpty 为 fullView.fill(0)，避免 writer.writeEmpty 的函数调用 + 边界检查开销 */ var supportTableList = ttf.support.tables; var buf = writer.getBuffer(); + /** 优化316: skipCheckSum（woff2/woff/eot）时跳过 checksum 计算，head.checkSumAdjustment 保持 0 占位 */ + var skipCheckSum = this.options.skipCheckSum; var wholeCheckSum = 0; + /** fullView 仍需用于表 padding fill(0)，skipCheckSum 时不必创建 fullDataView */ var fullView = new Uint8Array(buf); - /** 优化261: 预创建 DataView，复用于所有表的校验和计算，避免每次 checkSumArrayBuffer 创建新 DataView */ - var fullDataView = new DataView(buf); + var fullDataView = skipCheckSum ? null : new DataView(buf); for (var si = 0, sl = supportTableList.length; si < sl; si++) { var table = supportTableList[si]; var tableStart = writer.offset; @@ -153,20 +160,24 @@ var TTFWriter = exports.default = /*#__PURE__*/function () { fullView.fill(0, wView.byteOffset + writer.offset, wView.byteOffset + writer.offset + (4 - pad)); writer.offset += 4 - pad; } - table.checkSum = _checkSumArrayBuffer(buf, tableStart, table.size, fullView, fullDataView); - wholeCheckSum = (wholeCheckSum + table.checkSum) >>> 0; + if (!skipCheckSum) { + table.checkSum = _checkSumArrayBuffer(buf, tableStart, table.size, fullView, fullDataView); + wholeCheckSum = (wholeCheckSum + table.checkSum) >>> 0; + } } - /* 优化111: 重新写入校验和，直接 view 写入 */ - var csView = writer.view; - for (var ci = 0, cl = supportTableList.length; ci < cl; ci++) { - var offset2 = 12 + ci * 16 + 4; - csView.setUint32(offset2, supportTableList[ci].checkSum, false); - } + if (!skipCheckSum) { + /* 优化111: 重新写入校验和，直接 view 写入 */ + var csView = writer.view; + for (var ci = 0, cl = supportTableList.length; ci < cl; ci++) { + var offset2 = 12 + ci * 16 + 4; + csView.setUint32(offset2, supportTableList[ci].checkSum, false); + } - /* 优化179: 用累加的各表校验和替代全局 checkSum，避免重遍历整个 buffer */ - var ttfCheckSum = (0xB1B0AFBA - wholeCheckSum) >>> 0; - csView.setUint32(ttfHeadOffset + 8, ttfCheckSum, false); + /* 优化179: 用累加的各表校验和替代全局 checkSum，避免重遍历整个 buffer */ + var ttfCheckSum = (0xB1B0AFBA - wholeCheckSum) >>> 0; + csView.setUint32(ttfHeadOffset + 8, ttfCheckSum, false); + } /** 优化260: delete → null 赋值，避免 V8 隐藏类转换 */ ttf.writeOptions = null; ttf.support = null;