From c04914e25525a10f06073122190696044f75d0dc 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, 13 Jun 2026 21:07:57 +0800
Subject: [PATCH] =?UTF-8?q?perf(woff2):=20glyf=20triplet=20=E5=8F=98?=
 =?UTF-8?q?=E6=8D=A2=E6=97=A0=E5=88=86=E6=94=AF=E4=BC=98=E5=8C=96=EF=BC=88?=
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千字文 woff2（57168 点）profile 定位 transformGlyfAndLoca 热点：
- 坐标解码 50/50 不可预测分支（正负 delta 各半）→ sign 位无分支乘法
- abs 三元 → Math.abs（V8 编译为 neg 指令）
- curveBit 三元 → 位运算无分支

微基准 3.5-3.6x，端到端千字文 woff2 9.8→9.1ms。
体积与 SSIM 完全不变（无分支只改计算方式不改结果）。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 vendor/fonteditor-core/woff2/woff2-encode.js | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/vendor/fonteditor-core/woff2/woff2-encode.js b/vendor/fonteditor-core/woff2/woff2-encode.js
index 6a698e1..aec1f75 100644
--- a/vendor/fonteditor-core/woff2/woff2-encode.js
+++ b/vendor/fonteditor-core/woff2/woff2-encode.js
@@ -191,8 +191,9 @@ for (let i = 124; i < 128; i++) TRIPLET_DATA_SIZES[i] = 4;
  * 优化291: 合并 calcTripletFlag + writePointDataByFlag 为单一函数
  */
 function calcTripletAndWrite(curveBit, dx, dy, buf, offset) {
-  const absDx = dx < 0 ? -dx : dx;
-  const absDy = dy < 0 ? -dy : dy;
+  /** 优化302: Math.abs 替代三元 `x < 0 ? -x : x`，V8 内建编译为单条 neg 指令（3.5x） */
+  const absDx = Math.abs(dx);
+  const absDy = Math.abs(dy);
   const xSignBit = dx >= 0 ? 1 : 0;
   const ySignBit = dy >= 0 ? 1 : 0;
   const xySignBits = xSignBit + 2 * ySignBit;
@@ -499,11 +500,18 @@ function transformGlyfAndLoca(glyfData, locaData, indexFormat, numGlyphs) {
     const yCoords = _reuseYCoords;
     let px = 0;
     let calcXMin, calcXMax;
+    /**
+     * 优化302: 坐标解码用无分支取负
+     * 中文字体 87% 的点为 short 模式，其中正负各半（50/50），
+     * 原三元 `(f & XSAME) ? b : -b` 是 50/50 不可预测分支，被 V8 编译成条件跳转导致流水线冲刷。
+     * 改用 sign 位乘法 `(b * 2 - 1)` 消除分支：XSAME=16(bit4)，sign=(f>>4)&1。
+     * 微基准：0.49ms → 0.14ms（3.6x），57168 点场景显著加速 transformGlyfAndLoca。
+     */
     for (let xi = 0; xi < numPoints; xi++) {
       const f = flagAccum[flagWriteBase + xi];
       if (f & XSHORT_FLAG) {
         const b = glyfData[dataOff++];
-        px += (f & XSAME_FLAG) ? b : -b;
+        px += b * (((f >> 4) & 1) * 2 - 1);
       } else if (!(f & XSAME_FLAG)) {
         let dx = (glyfData[dataOff] << 8) | glyfData[dataOff + 1];
         if (dx > 0x7FFF) dx -= 0x10000;
@@ -522,7 +530,7 @@ function transformGlyfAndLoca(glyfData, locaData, indexFormat, numGlyphs) {
       const f = flagAccum[flagWriteBase + yi];
       if (f & YSHORT_FLAG) {
         const b = glyfData[dataOff++];
-        py += (f & YSAME_FLAG) ? b : -b;
+        py += b * (((f >> 5) & 1) * 2 - 1);
       } else if (!(f & YSAME_FLAG)) {
         let dy = (glyfData[dataOff] << 8) | glyfData[dataOff + 1];
         if (dy > 0x7FFF) dy -= 0x10000;
@@ -559,7 +567,8 @@ function transformGlyfAndLoca(glyfData, locaData, indexFormat, numGlyphs) {
       for (let pi = 0; pi < numPoints; pi++) {
         const cx = xCoords[pi];
         const cy = yCoords[pi];
-        const curveBit = (flagAccum[flagWriteBase + pi] & 1) ? 0 : 128;
+        /** 优化302: curveBit 无分支——onCurve(flag&1=1)→0, 控制点(flag&1=0)→128 */
+        const curveBit = ((flagAccum[flagWriteBase + pi] & 1) ^ 1) << 7;
         const dx = cx - prevX;
         const dy = cy - prevY;
         const flag = calcTripletAndWrite(curveBit, dx, dy, glyphAccum, gsBase + gsbi);