feat(layout): detect reflowable vs fixed-layout EPUB, fix pagination overflow

src/book.rs

@@ -187,22 +187,57 @@ pub struct Section {
     pub pages: Vec<usize>,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum BookLayout {
+    Reflowable,
+    FixedLayout,
+}
+
+impl BookLayout {
+    pub fn label(&self) -> &str {
+        match self {
+            BookLayout::Reflowable => "重排",
+            BookLayout::FixedLayout => "固定",
+        }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct Book {
     pub title: String,
     pub author: String,
     pub cover: Option<Vec<u8>>,
+    pub layout: BookLayout,
     pub sections: Vec<Section>,
     pub toc: Vec<TocEntry>,
 }
 
 use std::path::Path;
 
+fn detect_layout(doc: &mut epub::doc::EpubDoc<std::io::BufReader<std::fs::File>>) -> BookLayout {
+    if let Some(vals) = doc.metadata.get("rendition:layout") {
+        if vals.iter().any(|v| v == "pre-paginated") {
+            return BookLayout::FixedLayout;
+        }
+    }
+    if let Ok(opf) = doc.get_resource_str_by_path(&doc.root_file.clone()) {
+        if opf.contains("rendition:layout") && opf.contains("pre-paginated") {
+            return BookLayout::FixedLayout;
+        }
+        if opf.contains("rendition:layout-pre-paginated") {
+            return BookLayout::FixedLayout;
+        }
+    }
+    BookLayout::Reflowable
+}
+
 pub fn load_epub(path: impl AsRef<Path>) -> Result<Book, String> {
     let path = path.as_ref();
     let mut doc = epub::doc::EpubDoc::new(path)
         .map_err(|e| format!("无法打开文件: {}", e))?;
 
+    let layout = detect_layout(&mut doc);
+
     let title = doc.mdata("title").unwrap_or_else(|| "未知标题".to_string());
     let author = doc.mdata("creator").unwrap_or_else(|| "未知作者".to_string());
     let cover = doc.get_cover().ok();
@@ -225,7 +260,7 @@ pub fn load_epub(path: impl AsRef<Path>) -> Result<Book, String> {
     let raw_toc = std::mem::take(&mut doc.toc);
     let toc = build_toc(&raw_toc, &spine);
 
-    Ok(Book { title, author, cover, sections, toc })
+    Ok(Book { title, author, cover, layout, sections, toc })
 }
 
 fn extract_title(html: &str) -> Option<String> {