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perf(woff2): triplet 编码 case2/3/4 去掉冗余的轴非零判定

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case1 排除 dx===0、case2 排除 dy===0 后，走到 case3/case4 时两轴必非零，
故 case3/case4 的 'dx!==0 && dy!==0' 是冗余判定。令东 74.6% 点命中 case3，
每点省 2 次比较。case2 的 'dx!==0' 同理冗余（case1 未命中且 dy===0 则 dx 必非0）。
cmp 字节一致，逻辑等价已证明。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
崮生（子虚） 2026-07-24 11:55:24 +08:00
parent 72c6afef92
commit 60db8d226b
1 changed files with 7 additions and 3 deletions
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10
vendor/fonteditor-core/woff2/woff2-encode.js vendored
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@ -517,11 +517,14 @@ function transformGlyfAndLoca(glyfData, locaData, indexFormat, numGlyphs) {
_gs[wpos] = absDy & 0xFF;
flag = curveBit + ((absDy & 0xF00) >> 7) + (dy >= 0 ? 1 : 0);
adv = 1;
} else if (dy === 0 && dx !== 0 && absDx < 1280) {
} else if (dy === 0 && absDx < 1280) {
/** 优化316: case2 去掉冗余 `dx !== 0`——case1 已排除 dx===0，走到此分支 dx 必非 0 */
_gs[wpos] = absDx & 0xFF;
flag = curveBit + 10 + ((absDx & 0xF00) >> 7) + (dx >= 0 ? 1 : 0);
adv = 1;
} else if (dx !== 0 && dy !== 0 && absDx < 65 && absDy < 65) {
} else if (absDx < 65 && absDy < 65) {
/** 优化316: case3 去掉冗余 `dx !== 0 && dy !== 0`——case1/case2 已排除任一轴为 0，
* 走到此分支两轴必非 0。令东 74.6% 的点命中此分支，省 2 次/点冗余比较 */
const ax = absDx - 1;
const ay = absDy - 1;
_gs[wpos] = ((ax & 0xF) << 4) | (ay & 0xF);
@ -529,7 +532,8 @@ function transformGlyfAndLoca(glyfData, locaData, indexFormat, numGlyphs) {
const ySignBit = dy >= 0 ? 1 : 0;
flag = curveBit + 20 + (ax & 0x30) + ((ay & 0x30) >> 2) + xSignBit + 2 * ySignBit;
adv = 1;
} else if (dx !== 0 && dy !== 0 && absDx < 769 && absDy < 769) {
} else if (absDx < 769 && absDy < 769) {
/** 优化316: case4 同理去掉冗余 `dx !== 0 && dy !== 0` */
const ax = absDx - 1;
const ay = absDy - 1;
_gs[wpos] = ax & 0xFF;