PDF分割プログラムです。このプログラムを元にして作った配布用の実行ファイルがあります。コメント欄をご覧ください。

main.rs

use lopdf::{dictionary, Document, Object, ObjectId};
use std::collections::BTreeMap;
use std::env;

fn main() {
    let args: Vec<String> = env::args().collect();
    if args.len() < 2 {
        println!("使い方: pdf_splitter <file.pdf>");
        return;
    }
    let input_path = &args[1];

    if let Err(e) = split_pdf(input_path) {
        eprintln!("エラー: {}", e);
    }
}

fn split_pdf(input_path: &str) -> Result<(), Box<dyn std::error::Error>> {
    let doc = Document::load(input_path)?;
    let pages = doc.get_pages();
    let page_count = pages.len();
    let base_name = input_path.trim_end_matches(".pdf");

    for i in (0..page_count).step_by(10) {
        let mut new_doc = Document::with_version(doc.version.clone());
        let mut copied_objects: BTreeMap<ObjectId, ObjectId> = BTreeMap::new();
        let mut new_page_ids = vec![];

        let start_page = i + 1;
        let end_page = (i + 10).min(page_count);

        for page_num in start_page..=end_page {
            if let Some(&page_id) = pages.get(&(page_num as u32)) {
                copy_object_and_dependencies(page_id, &doc, &mut new_doc, &mut copied_objects)?;
                new_page_ids.push(copied_objects.get(&page_id).cloned().unwrap());
            }
        }

        if new_page_ids.is_empty() {
            continue;
        }

        let pages_id = new_doc.add_object(Object::Dictionary(dictionary! {
            "Type" => "Pages",
            "Kids" => new_page_ids.iter().map(|id| Object::Reference(*id)).collect::<Vec<_>>(),
            "Count" => new_page_ids.len() as i64,
        }));

        let catalog_id = new_doc.add_object(Object::Dictionary(dictionary! {
            "Type" => "Catalog",
            "Pages" => Object::Reference(pages_id),
        }));

        new_doc.trailer.set("Root", Object::Reference(catalog_id));

        let output_path = format!("{}_{}.pdf", base_name, i / 10 + 1);
        new_doc.save(&output_path)?;
        println!("{} を保存しました。", output_path);
    }

    Ok(())
}

fn copy_object_and_dependencies(
    object_id: ObjectId,
    old_doc: &Document,
    new_doc: &mut Document,
    copied_objects: &mut BTreeMap<ObjectId, ObjectId>,
) -> Result<ObjectId, Box<dyn std::error::Error>> {
    if let Some(new_id) = copied_objects.get(&object_id) {
        return Ok(*new_id);
    }

    // Crucially, insert a placeholder ID before recursing to break cycles.
    let new_id = new_doc.new_object_id();
    copied_objects.insert(object_id, new_id);

    let obj = old_doc.get_object(object_id)?.clone();
    let new_obj = deep_copy_object(obj, old_doc, new_doc, copied_objects)?;
    
    // Now, insert the fully processed object at the placeholder ID.
    new_doc.objects.insert(new_id, new_obj);

    Ok(new_id)
}

fn deep_copy_object(
    obj: Object,
    old_doc: &Document,
    new_doc: &mut Document,
    copied_objects: &mut BTreeMap<ObjectId, ObjectId>,
) -> Result<Object, Box<dyn std::error::Error>> {
    let new_obj = match obj {
        Object::Reference(id) => {
            let new_id = copy_object_and_dependencies(id, old_doc, new_doc, copied_objects)?;
            Object::Reference(new_id)
        }
        Object::Array(arr) => {
            let mut new_arr = vec![];
            for item in arr {
                new_arr.push(deep_copy_object(item, old_doc, new_doc, copied_objects)?);
            }
            Object::Array(new_arr)
        }
        Object::Dictionary(mut dict) => {
            for (_, val) in dict.iter_mut() {
                *val = deep_copy_object(val.clone(), old_doc, new_doc, copied_objects)?;
            }
            Object::Dictionary(dict)
        }
        Object::Stream(mut stream) => {
            for (_, val) in stream.dict.iter_mut() {
                *val = deep_copy_object(val.clone(), old_doc, new_doc, copied_objects)?;
            }
            Object::Stream(stream)
        }
        _ => obj.clone(),
    };
    Ok(new_obj)
}

バンドルのための追加のファイルの説明

macOSのアプリケーションバンドル：

% tree pdf_splitter.app
pdf_splitter.app
└── Contents
    ├── Info.plist
    └── MacOS
        ├── pdf_splitter
        └── pdf_splitter_bin

macOS用のInfo.plistファイル：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>CFBundleExecutable</key>
    <string>pdf_splitter</string>
    <key>CFBundleIdentifier</key>
    <string>com.example.pdfsplitter</string>
    <key>CFBundleName</key>
    <string>PDF Splitter</string>
    <key>CFBundlePackageType</key>
    <string>APPL</string>
    <key>CFBundleShortVersionString</key>
    <string>1.0</string>
    <key>CFBundleVersion</key>
    <string>1</string>
    <key>CFBundleDocumentTypes</key>
    <array>
        <dict>
            <key>CFBundleTypeName</key>
            <string>PDF Document</string>
            <key>CFBundleTypeRole</key>
            <string>Editor</string>
            <key>LSHandlerRank</key>
            <string>Owner</string>
            <key>LSItemContentTypes</key>
            <array>
                <string>com.adobe.pdf</string>
                <string>public.pdf</string>
            </array>
        </dict>
    </array>
</dict>
</plist>