[0126] 添加任务文档 devel/0126.md

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: da-liii

devel/0126.md

@@ -0,0 +1,53 @@
+# [0126] 优化 smart_font 字体加载性能
+
+## 1 相关文档
+- [dddd.md](dddd.md) - 任务文档模板
+
+## 2 任务相关的代码文件
+- `src/Graphics/Fonts/smart_font.cpp`
+- `src/Graphics/Fonts/smart_font.hpp`
+- `tests/Graphics/Fonts/smart_font_test.cpp`
+
+## 3 如何测试
+
+### 3.1 确定性测试（单元测试）
+```bash
+xmake b smart_font_test
+xmake r smart_font_test
+```
+
+### 3.2 非确定性测试（文档验证）
+```bash
+# 构建并运行字体相关测试，确保所有用例通过
+xmake b smart_font_test && xmake r smart_font_test
+```
+
+## 4 如何提交
+
+提交前执行以下最少步骤：
+
+```bash
+xmake b smart_font_test
+xmake r smart_font_test
+```
+
+## 5 What
+
+通过缓存避免 smart_font 字体加载过程中的重复函数调用，优化性能。
+
+1. 添加 `maybe_initialize_font` 辅助函数，避免对已初始化的子字体重复调用 `initialize_font`
+2. 在构造函数中缓存 `trimmed_tokenize(family, ",")` 结果（`family_tokens`），避免 `resolve(string c)` 和 `is_italic_prime` 中重复分割字符串
+3. 在构造函数中缓存 `logical_font` 结果（`given_font`），避免 `resolve(c, fam, attempt)` 中重复计算
+4. 缓存 `is_italic_prime` 的结果，避免对同一字体的斜体引号判断重复计算
+5. 新增 `test_performance` 和 `test_math_performance` 回归测试
+
+## 6 Why
+
+在字体加载过程中，通过添加日志发现很多函数会被重复调用。例如解析数学模式下 24 个希腊字母时，`initialize_font` 被调用了 21 次，虽然大部分调用的子字体已经初始化过。`trimmed_tokenize(family, ",")` 和 `logical_font` 也在每次 `resolve` 时被重复计算，造成不必要的性能开销。
+
+## 7 How
+
+- `maybe_initialize_font(int nr)`：在调用 `initialize_font` 前检查 `fn[nr]` 是否已初始化，只有未初始化时才执行实际的字体创建逻辑
+- `family_tokens`：在 `smart_font_rep` 构造函数中将 `trimmed_tokenize(family, ",")` 结果保存为成员变量，供 `resolve(string c)` 和 `is_italic_prime` 直接使用
+- `given_font`：在构造函数中将 `logical_font(family, variant, series, rshape)` 结果保存为成员变量，供 `resolve(c, fam, attempt)` 中的 `is_wanted` 调用直接使用
+- `is_italic_prime` 缓存：添加 `italic_prime_cached` 和 `italic_prime_result` 成员变量，首次计算后缓存结果

src/Graphics/Fonts/smart_font.cpp

@@ -34,7 +34,6 @@ bool virtually_defined (string c, string name);
 font smart_font_bis (string f, string v, string s, string sh, double sz,
                      int hdpi, int vdpi);
 
-
 smart_map
 get_smart_map (tree fn) {
   string name= recompose (tuple_as_array (fn), "-");
@@ -626,9 +625,9 @@ smart_font_rep::smart_font_rep (string name, font base_fn, font err_fn,
   fn[SUBFONT_MAIN] = adjust_subfont (base_fn);
   fn[SUBFONT_ERROR]= adjust_subfont (err_fn);
   this->copy_math_pars (base_fn);
-  family_tokens       = trimmed_tokenize (family, ",");
-  given_font          = logical_font (family, variant, series, rshape);
-  italic_prime_cached = false;
+  family_tokens      = trimmed_tokenize (family, ",");
+  given_font         = logical_font (family, variant, series, rshape);
+  italic_prime_cached= false;
   if (shape == "mathitalic" || shape == "mathupright" || shape == "mathshape") {
     if (is_math_family (mfam)) {
       rshape= "right";
@@ -915,9 +914,9 @@ smart_font_rep::resolve (string c, string fam, int attempt) {
   }
   array<string> a= trimmed_tokenize (fam, "=");
   if (N (a) >= 2) {
-    fam                = a[1];
-    array<string> b    = tokenize (a[0], " ");
-    bool          ok   = is_wanted (c, fam, b, given_font);
+    fam             = a[1];
+    array<string> b = tokenize (a[0], " ");
+    bool          ok= is_wanted (c, fam, b, given_font);
     if (!ok) {
       return -1;
     }
@@ -1060,16 +1059,16 @@ bool
 smart_font_rep::is_italic_prime (string c) {
   if (c != "'" && c != "`") return false;
   if (italic_prime_cached) return italic_prime_result;
-  string        s= "<#2B9>";
+  string s= "<#2B9>";
   if (c == "`") s= "<backprime>";
   bool result= true;
   for (int i= 0; i < N (family_tokens); i++)
     if (resolve (s, family_tokens[i], 1) >= 0) {
       result= false;
       break;
     }
-  italic_prime_cached = true;
-  italic_prime_result = result;
+  italic_prime_cached= true;
+  italic_prime_result= result;
   return result;
 }
 

src/Graphics/Fonts/smart_font.hpp

@@ -99,12 +99,12 @@ struct smart_font_rep : font_rep {
   int    math_kind;
   int    italic_nr;
 
-  array<font>    fn;
-  smart_map      sm;
-  array<string>  family_tokens;
-  array<string>  given_font;
-  bool           italic_prime_cached;
-  bool           italic_prime_result;
+  array<font>   fn;
+  smart_map     sm;
+  array<string> family_tokens;
+  array<string> given_font;
+  bool          italic_prime_cached;
+  bool          italic_prime_result;
 
   smart_font_rep (string name, font base_fn, font err_fn, string family,
                   string variant, string series, string shape, double sz,

tests/Graphics/Fonts/smart_font_test.cpp

@@ -177,7 +177,8 @@ TestSmartFont::test_performance () {
 
 void
 TestSmartFont::test_math_performance () {
-  font fn= smart_font ("Latin Modern Math", "rm", "medium", "mathitalic", 10, 600);
+  font fn=
+      smart_font ("Latin Modern Math", "rm", "medium", "mathitalic", 10, 600);
 
   // Trigger math character resolutions
   string math_text= "<alpha><beta><gamma><delta><epsilon><zeta><eta><theta>"