lopdf 0.40.0

A Rust library for PDF document manipulation.
Documentation 
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use lopdf::{Document, SaveOptions};

#[cfg(feature = "async")]
use tokio::runtime::Builder;

#[cfg(not(feature = "async"))]
fn load_document(path: &str) -> Result<Document, lopdf::Error> {
    Document::load(path)
}

#[cfg(feature = "async")]
fn load_document(path: &str) -> Result<Document, lopdf::Error> {
    Builder::new_current_thread()
        .enable_all()
        .build()
        .unwrap()
        .block_on(async move {
            Document::load(path).await
        })
}

fn main() {
    println!("Debugging object stream compression in detail...\n");
    
    // Load the user's PDF
    let pdf_path = "/Users/nicolasdao/Downloads/pdfs/RFQ - SDS WebApp.docx.pdf";
    println!("Loading PDF: {}", pdf_path);
    
    let mut doc = match load_document(pdf_path) {
        Ok(d) => d,
        Err(e) => {
            eprintln!("Failed to load PDF: {}", e);
            return;
        }
    };
    
    println!("Loaded {} objects", doc.objects.len());
    
    // Count how many objects can be compressed
    let mut compressible_count = 0;
    for (id, obj) in &doc.objects {
        if id.1 == 0 && lopdf::ObjectStream::can_be_compressed(*id, obj, &doc) {
            compressible_count += 1;
        }
    }
    println!("Compressible objects: {}", compressible_count);
    
    // Save with object streams
    println!("\nSaving with object streams (compression level 6)...");
    let options = SaveOptions {
        use_object_streams: true,
        use_xref_streams: true,  // MUST use xref streams with object streams!
        object_stream_config: lopdf::ObjectStreamConfig {
            max_objects_per_stream: 100,
            compression_level: 6,
        },
        ..Default::default()
    };
    
    let mut buffer = Vec::new();
    doc.save_with_options(&mut buffer, options).unwrap();
    
    println!("Saved {} bytes", buffer.len());
    
    // Write to file for inspection
    std::fs::write("debug_compression.pdf", &buffer).unwrap();
    
    // Load back and check
    println!("\nLoading back and checking object streams...");
    let loaded = Document::load_mem(&buffer).unwrap();
    
    let mut obj_stream_count = 0;
    let mut obj_stream_with_filter = 0;
    
    for (id, obj) in &loaded.objects {
        if let lopdf::Object::Stream(stream) = obj {
            if let Ok(type_obj) = stream.dict.get(b"Type") {
                if let Ok(type_name) = type_obj.as_name() {
                    if type_name == b"ObjStm" {
                        obj_stream_count += 1;
                        let has_filter = stream.dict.get(b"Filter").is_ok();
                        if has_filter {
                            obj_stream_with_filter += 1;
                        }
                        
                        println!("\nObject Stream {} 0 R:", id.0);
                        println!("  Has Filter: {}", has_filter);
                        if let Ok(n) = stream.dict.get(b"N").and_then(|o| o.as_i64()) {
                            println!("  Contains {} objects", n);
                        }
                        if let Ok(first) = stream.dict.get(b"First").and_then(|o| o.as_i64()) {
                            println!("  First offset: {}", first);
                        }
                        println!("  Content size: {} bytes", stream.content.len());
                        
                        // Check if content looks compressed
                        let looks_compressed = stream.content.iter().take(20).any(|&b| b > 127);
                        println!("  Content looks compressed: {}", looks_compressed);
                    }
                }
            }
        }
    }
    
    println!("\nSummary:");
    println!("  Total object streams: {}", obj_stream_count);
    println!("  Object streams with Filter: {}", obj_stream_with_filter);
    
    if obj_stream_with_filter < obj_stream_count {
        println!("\nWARNING: {} object streams are missing Filter!", obj_stream_count - obj_stream_with_filter);
    }
}