改进标题渲染：按层级差异化显示（字号/加粗/间距/对齐）

src/book.rs

@@ -65,10 +65,11 @@ pub fn strip_html(input: &str) -> String {
         // Emit text before the tag
         if tag_start > pos {
             let text = decode_entities(&input[pos..tag_start]);
-            if heading_level.is_some() {
+            if let Some(level) = heading_level {
-                out.push_str("\x01");
+                out.push('\x01');
+                out.push(char::from_digit(level, 10).unwrap_or('1'));
                 out.push_str(&text);
-                out.push_str("\x02");
+                out.push('\x02');
             } else {
                 out.push_str(&text);
             }
@@ -182,7 +183,7 @@ pub struct TocEntry {
 #[derive(Debug, Clone)]
 pub struct ContentBlock {
     pub text: String,
-    pub is_heading: bool,
+    pub heading_level: u8, // 0 = body, 1-6 = h1-h6
 }
 
 #[derive(Debug, Clone)]

src/reader.rs

@@ -10,22 +10,54 @@ fn parse_blocks(raw_text: &str) -> Vec<ContentBlock> {
         if trimmed.is_empty() {
             continue;
         }
-        let is_heading = trimmed.contains('\x01');
+        let mut heading_level = 0u8;
-        let text = trimmed.replace('\x01', "").replace('\x02', "");
+        let mut text = trimmed.to_string();
+        if text.contains('\x01') {
+            if let Some(pos) = text.find('\x01') {
+                let rest = &text[pos + 1..];
+                heading_level = rest
+                    .chars()
+                    .next()
+                    .and_then(|c| c.to_digit(10))
+                    .unwrap_or(1) as u8;
+                text.drain(pos..pos + 2);
+            }
+            text = text.replace('\x02', "");
+        }
         let text = text.trim().to_string();
         if !text.is_empty() {
-            blocks.push(ContentBlock { text, is_heading });
+            blocks.push(ContentBlock { text, heading_level });
         }
     }
     if blocks.is_empty() {
         blocks.push(ContentBlock {
             text: String::new(),
-            is_heading: false,
+            heading_level: 0,
         });
     }
     blocks
 }
 
+fn heading_font_size(base_size: f32, level: u8) -> f32 {
+    match level {
+        1 => base_size * 1.6,
+        2 => base_size * 1.35,
+        3 => base_size * 1.15,
+        4 => base_size * 1.05,
+        _ => base_size,
+    }
+}
+
+fn heading_top_spacing(para_spacing: f32, level: u8) -> f32 {
+    match level {
+        1 => para_spacing * 3.5,
+        2 => para_spacing * 3.0,
+        3 => para_spacing * 2.5,
+        4 => para_spacing * 2.0,
+        _ => 0.0,
+    }
+}
+
 fn measure_block_height(
     ctx: &egui::Context,
     text: &str,
@@ -104,13 +136,19 @@ pub fn recalculate_pages(
         let mut current_height: f32 = 0.0;
 
         for (i, block) in section.blocks.iter().enumerate() {
-            let display_text = if block.is_heading || indent_str.is_empty() {
+            let block_font_size = if block.heading_level > 0 {
+                heading_font_size(font_size, block.heading_level)
+            } else {
+                font_size
+            };
+
+            let display_text = if block.heading_level > 0 || indent_str.is_empty() {
                 block.text.clone()
             } else {
                 format!("{}{}", indent_str, block.text)
             };
 
-            let block_height = measure_block_height(ctx, &display_text, font_size, available_width);
+            let block_height = measure_block_height(ctx, &display_text, block_font_size, available_width);
 
             let spacing = if i > page_start_block && i > 0 {
                 para_spacing
@@ -414,7 +452,7 @@ egui::ComboBox::from_id_salt("bg_type_selector")
                                  }
 
                                   let block = &section.blocks[i];
-                                 let display_text = if block.is_heading || indent_str.is_empty() {
+                                  let display_text = if block.heading_level > 0 || indent_str.is_empty() {
                                       block.text.clone()
                                   } else {
                                       format!("{}{}", indent_str, block.text)
@@ -424,13 +462,31 @@ egui::ComboBox::from_id_salt("bg_type_selector")
                                       continue;
                                   }
 
+                                   if block.heading_level > 0 && i > block_start {
+                                       ui.add_space(heading_top_spacing(para_spacing, block.heading_level));
+                                   }
+
+                                   let block_font_size = if block.heading_level > 0 {
+                                       heading_font_size(style.font_size, block.heading_level)
+                                   } else {
+                                       style.font_size
+                                   };
+
                                    let mut rt = egui::RichText::new(&display_text)
-                                     .size(style.font_size)
+                                       .size(block_font_size)
                                        .color(colors.text);
-                                 if block.is_heading {
+                                   if block.heading_level >= 1 && block.heading_level <= 4 {
                                        rt = rt.strong();
                                    }
-                                 ui.add(egui::Label::new(rt).wrap());
+
+                                   let label = egui::Label::new(rt).wrap();
+                                   if block.heading_level == 1 {
+                                       ui.centered_and_justified(|ui| {
+                                           ui.add(label);
+                                       });
+                                   } else {
+                                       ui.add(label);
+                                   }
                              }
                          },
                      );
@@ -544,7 +600,7 @@ mod tests {
         let blocks = parse_blocks("Hello World");
         assert_eq!(blocks.len(), 1);
         assert_eq!(blocks[0].text, "Hello World");
-        assert!(!blocks[0].is_heading);
+        assert_eq!(blocks[0].heading_level, 0);
     }
 
     #[test]
@@ -558,14 +614,28 @@ mod tests {
 
     #[test]
     fn test_parse_blocks_heading() {
-        let blocks = parse_blocks("\x01标题\x02\n\n正文内容");
+        let blocks = parse_blocks("\x011标题\x02\n\n正文内容");
         assert_eq!(blocks.len(), 2);
-        assert!(blocks[0].is_heading);
+        assert_eq!(blocks[0].heading_level, 1);
         assert_eq!(blocks[0].text, "标题");
-        assert!(!blocks[1].is_heading);
+        assert_eq!(blocks[1].heading_level, 0);
         assert_eq!(blocks[1].text, "正文内容");
     }
 
+    #[test]
+    fn test_parse_blocks_heading_levels() {
+        let blocks = parse_blocks("\x011一级\x02\n\n\x012二级\x02\n\n\x013三级\x02\n\n正文");
+        assert_eq!(blocks.len(), 4);
+        assert_eq!(blocks[0].heading_level, 1);
+        assert_eq!(blocks[0].text, "一级");
+        assert_eq!(blocks[1].heading_level, 2);
+        assert_eq!(blocks[1].text, "二级");
+        assert_eq!(blocks[2].heading_level, 3);
+        assert_eq!(blocks[2].text, "三级");
+        assert_eq!(blocks[3].heading_level, 0);
+        assert_eq!(blocks[3].text, "正文");
+    }
+
     #[test]
     fn test_parse_blocks_extra_newlines() {
         let blocks = parse_blocks("段一\n\n\n\n段二");