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perf(gpos): subsetGPOS 全模块 origToNew(Map)→gidLookup(Int32Array)
套用 gsub 侧已验证的 Int32Array gidLookup 模式到 GPOS： - subsetGPOS 入口构建 gidLookup（动态容量 maxOrigGid+1，fill -1） - remapGid 的 Map.get（7处）+ subtableCoverageHits 的 Map.has 改数组索引 - 涉及函数签名全部 origToNew:Map → gidLookup:GidLookup A/B 11 字体字节全 IDENTICAL；基准测试 SSIM 全通过。 性能 best-of N=2000： - 思源千字文中段 min -2.6% - 思源标点 min -2.5% - 千字文96 min -1.2% - FiraCode 持平（GSUB 已用 gidLookup，GPOS 增量小） 关键：gidLookup[越界] 返回 undefined（非 -1），GPOS coverage 常引用 大于子集 maxGid 的 gid，remapGid 须 origGid < length 保护（否则 undefined < 0 = false 误判有效，同 gsub type234 undefined bug）。 容量必须动态，65536 固定容量 fill 在小 GPOS 用例倒贴（篆体 +12.5%）。 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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崮生（子虚）
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ae41a99e95
commit
0cfd9851df
@ -123,6 +123,17 @@ export function subsetGPOS(
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const dv = new DataView(gposBytes.buffer, gposBytes.byteOffset, gposBytes.byteLength);
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const r = new Reader(dv);
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/**
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* 优化335：原gid → 新gid 的 Int32Array 查找表（下标=原gid，值=新gid，-1=不在子集），
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* 替代全模块的 origToNew.get/has（Map 查询 ~9ns vs 数组索引 ~1ns）。
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* coverage/ClassDef/PairPos 序列化每字形都查，CJK 标点字体调用密集。
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* 容量按 subsetGids 的最大原 gid 分配（远小于 65536，避免大数组 fill 抵消收益——
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* GPOS coverage 常引用大于子集 maxGid 的 gid，remapGid 内做越界判定返回 -1）。 */
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let maxOrigGid = 0;
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for (const g of origToNew.keys()) if (g > maxOrigGid) maxOrigGid = g;
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const gidLookup: GidLookup = new Int32Array(maxOrigGid + 1).fill(-1);
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for (const [g, n] of origToNew) gidLookup[g] = n;
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/** ---- GPOS Header ---- */
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const major = dv.getUint16(0, false);
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const minor = dv.getUint16(2, false);
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@ -185,7 +196,7 @@ export function subsetGPOS(
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const hits: boolean[] = [];
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if (lk.supported) {
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for (let j = 0; j < lk.subtableAbsOffs.length; j++) {
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hits.push(subtableCoverageHits(r, lk.subtableAbsOffs[j], origToNew));
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hits.push(subtableCoverageHits(r, lk.subtableAbsOffs[j], gidLookup));
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}
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}
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subtableHits.push(hits);
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@ -315,7 +326,7 @@ export function subsetGPOS(
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for (let j = 0; j < lk.subtableAbsOffs.length; j++) {
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subtableAbsPositions[j] = w.length;
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r.clearError();
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const ok = serializeSubtable(w, r, lk.subtableAbsOffs[j], lk.effectiveType, origToNew, hits[j]);
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const ok = serializeSubtable(w, r, lk.subtableAbsOffs[j], lk.effectiveType, gidLookup, hits[j]);
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/** 越界读取（异常表）也降级为保留原始 GPOS 字节（调用方安全降级） */
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if (!ok || r.errorFlag) return null;
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w.writeInt16At(subtableSlotsStart + j * 2, subtableAbsPositions[j] - lookupStart);
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@ -359,7 +370,7 @@ function serializeSubtable(
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r: Reader,
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subAbs: number,
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type: number,
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origToNew: Map<number, number>,
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gidLookup: GidLookup,
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/** 预扫描结果：该 subtable coverage 是否含任意子集字形。false 时 coverage 必空，直接写空 subtable 跳过全量解析 */
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coverageHit: boolean,
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): boolean {
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@ -370,15 +381,22 @@ function serializeSubtable(
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writeEmptyPosSubtable(w, type);
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return true;
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}
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if (type === LT_SINGLE_POS) return serializeSinglePos(w, r, subAbs, origToNew);
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if (type === LT_PAIR_POS) return serializePairPos(w, r, subAbs, origToNew);
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if (type === LT_SINGLE_POS) return serializeSinglePos(w, r, subAbs, gidLookup);
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if (type === LT_PAIR_POS) return serializePairPos(w, r, subAbs, gidLookup);
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return false;
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}
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/** 重映射原 gid；不在子集中返回 -1 */
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function remapGid(origGid: number, origToNew: Map<number, number>): number {
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const ng = origToNew.get(origGid);
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return ng === undefined ? -1 : ng;
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/** 原gid → 新gid 数组查找表（下标=原gid，值=新gid，-1=不在子集）。数组索引比 Map.get 快数倍，
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* GPOS coverage/ClassDef/PairPos 序列化热路径每字形都查，CJK 标点字体调用密集。 */
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type GidLookup = Int32Array;
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/** 重映射原 gid；不在子集中返回 -1。
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* 优化335：gidLookup（Int32Array 索引，~1ns）替代 origToNew.get（Map.get ~9ns），
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* 语义等价：gidLookup[g] >= 0 ⟺ origToNew.has(g) 且值相同。对越界 gid（g >= length，GPOS coverage
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* 常引用大于子集 maxGid 的 gid）显式返回 -1——gidLookup[越界] 返回 undefined，`undefined < 0` 为 false
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* 会被误判为有效（[[gsub-serialize-type234-no-hotspot]] 同类 undefined bug）。 */
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function remapGid(origGid: number, gidLookup: GidLookup): number {
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return origGid < gidLookup.length ? gidLookup[origGid] : -1;
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}
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/**
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@ -386,7 +404,7 @@ function remapGid(origGid: number, origToNew: Map<number, number>): number {
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* 用于 lookup 折叠预扫描——subtable 头的 coverageOff 在偏移 +2（SinglePos/PairPos format 一致）。
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* 读 coverage 逐 gid 查 origToNew，命中即返回 true，避免 readCoverageGids 的全量展开 + 数组分配。
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*/
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function subtableCoverageHits(r: Reader, subAbs: number, origToNew: Map<number, number>): boolean {
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function subtableCoverageHits(r: Reader, subAbs: number, gidLookup: GidLookup): boolean {
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const dv = r.dv;
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const len = dv.byteLength;
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const coverageOff = r.u16(subAbs + 2);
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@ -398,7 +416,7 @@ function subtableCoverageHits(r: Reader, subAbs: number, origToNew: Map<number,
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const base = covAbs + 4;
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if (base + count * 2 > len) return false;
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for (let i = 0; i < count; i++) {
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if (origToNew.has(dv.getUint16(base + i * 2, false))) return true;
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if (gidLookup[dv.getUint16(base + i * 2, false)] >= 0) return true;
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}
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return false;
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}
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@ -411,7 +429,7 @@ function subtableCoverageHits(r: Reader, subAbs: number, origToNew: Map<number,
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const end = dv.getUint16(p + 2, false);
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/** range 内逐 gid 查子集；range 通常很短（CJK 标点压缩覆盖分散），逐个可接受且命中即退出 */
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for (let g = start; g <= end; g++) {
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if (origToNew.has(g)) return true;
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if (gidLookup[g] >= 0) return true;
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}
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p += 6;
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}
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@ -583,7 +601,7 @@ function emitClassDefFromClassMap(w: Writer, classMap: Map<number, number>): boo
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function readClassDefMap(
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r: Reader,
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classDefAbs: number,
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origToNew: Map<number, number>,
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gidLookup: GidLookup,
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): Map<number, number> | null {
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const out = new Map<number, number>();
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const dv = r.dv;
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@ -592,7 +610,7 @@ function readClassDefMap(
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const startGlyph = dv.getUint16(classDefAbs + 2, false);
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const glyphCount = dv.getUint16(classDefAbs + 4, false);
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for (let i = 0; i < glyphCount; i++) {
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const ng = remapGid(startGlyph + i, origToNew);
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const ng = remapGid(startGlyph + i, gidLookup);
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if (ng < 0) continue;
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out.set(ng, dv.getUint16(classDefAbs + 6 + i * 2, false));
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}
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@ -604,7 +622,7 @@ function readClassDefMap(
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const end = dv.getUint16(recOff + 2, false);
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const cls = dv.getUint16(recOff + 4, false);
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for (let g = start; g <= end; g++) {
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const ng = remapGid(g, origToNew);
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const ng = remapGid(g, gidLookup);
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if (ng >= 0) out.set(ng, cls);
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}
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}
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@ -623,7 +641,7 @@ function serializeSinglePos(
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w: Writer,
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r: Reader,
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subAbs: number,
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origToNew: Map<number, number>,
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gidLookup: GidLookup,
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): boolean {
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const fmt = r.u16(subAbs);
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const coverageOff = r.u16(subAbs + 2);
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@ -637,7 +655,7 @@ function serializeSinglePos(
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const sz = vrCount(valueFormat);
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const kept: Array<{ newGid: number; valueAbs: number }> = [];
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for (let idx = 0; idx < origGids.length; idx++) {
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const ng = remapGid(origGids[idx], origToNew);
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const ng = remapGid(origGids[idx], gidLookup);
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if (ng < 0) continue;
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if (fmt === 1) {
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/** format1 所有 glyph 共用 subAbs + 6 处的 ValueRecord */
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@ -681,17 +699,17 @@ function serializePairPos(
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w: Writer,
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r: Reader,
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subAbs: number,
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origToNew: Map<number, number>,
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gidLookup: GidLookup,
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): boolean {
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const fmt = r.u16(subAbs);
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const coverageOff = r.u16(subAbs + 2);
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const valueFormat1 = r.u16(subAbs + 4);
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const valueFormat2 = r.u16(subAbs + 6);
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if (fmt === 1) {
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return serializePairPosFormat1(w, r, subAbs, coverageOff, valueFormat1, valueFormat2, origToNew);
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return serializePairPosFormat1(w, r, subAbs, coverageOff, valueFormat1, valueFormat2, gidLookup);
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}
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if (fmt === 2) {
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return serializePairPosFormat2(w, r, subAbs, coverageOff, valueFormat1, valueFormat2, origToNew);
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return serializePairPosFormat2(w, r, subAbs, coverageOff, valueFormat1, valueFormat2, gidLookup);
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}
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return false;
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}
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@ -707,7 +725,7 @@ function serializePairPosFormat1(
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coverageOff: number,
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valueFormat1: number,
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valueFormat2: number,
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origToNew: Map<number, number>,
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gidLookup: GidLookup,
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): boolean {
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const firstGids = readCoverageGids(r, subAbs + coverageOff);
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if (!firstGids) return false;
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@ -719,7 +737,7 @@ function serializePairPosFormat1(
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/** 重建每个保留 firstGlyph 的 PairSet */
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const rebuilt: Array<{ newFirstGid: number; pairSetBytes: Uint8Array }> = [];
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for (let idx = 0; idx < pairSetCount; idx++) {
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const newFirstGid = remapGid(firstGids[idx], origToNew);
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const newFirstGid = remapGid(firstGids[idx], gidLookup);
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if (newFirstGid < 0) continue;
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const pairSetOff = subAbs + dv.getUint16(subAbs + 10 + idx * 2, false);
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const pairValueCount = dv.getUint16(pairSetOff, false);
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@ -727,7 +745,7 @@ function serializePairPosFormat1(
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const keptSeconds: Array<{ newSecondGid: number; recAbs: number }> = [];
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for (let p = 0; p < pairValueCount; p++) {
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const recAbs = pairSetOff + 2 + p * (2 + vr1 * 2 + vr2 * 2);
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const newSecondGid = remapGid(dv.getUint16(recAbs, false), origToNew);
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const newSecondGid = remapGid(dv.getUint16(recAbs, false), gidLookup);
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if (newSecondGid < 0) continue;
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keptSeconds.push({ newSecondGid, recAbs });
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}
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@ -785,15 +803,15 @@ function serializePairPosFormat2(
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coverageOff: number,
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valueFormat1: number,
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valueFormat2: number,
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origToNew: Map<number, number>,
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gidLookup: GidLookup,
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): boolean {
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const classDef1Off = r.u16(subAbs + 8);
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const classDef2Off = r.u16(subAbs + 10);
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const class2Count = r.u16(subAbs + 14);
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/** 解析原始 classDef → 新gid -> 原class（classDef 未出现的 gid 默认 class 0） */
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const gidToClass1 = readClassDefMap(r, subAbs + classDef1Off, origToNew);
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const gidToClass2 = readClassDefMap(r, subAbs + classDef2Off, origToNew);
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const gidToClass1 = readClassDefMap(r, subAbs + classDef1Off, gidLookup);
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const gidToClass2 = readClassDefMap(r, subAbs + classDef2Off, gidLookup);
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if (!gidToClass1 || !gidToClass2) return false;
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/** 收集实际命中的 class（class 0 永远保留） */
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@ -827,7 +845,7 @@ function serializePairPosFormat2(
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if (!covGids) return false;
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const newCovGids: number[] = [];
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for (const g of covGids) {
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const ng = remapGid(g, origToNew);
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const ng = remapGid(g, gidLookup);
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if (ng >= 0) newCovGids.push(ng);
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}
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newCovGids.sort((a, b) => a - b);
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