Question 1

How to merge PDF files with lopdf?

Accepted Answer

Use the provided merge example in the README, which involves iterating over documents, renumbering objects, and combining pages and objects into a single Document. This preserves bookmarks but requires careful handling of object IDs and dictionaries, making it more complex than a simple one-liner.

Question 2

Does lopdf support PDF/A or other PDF standards?

Accepted Answer

lopdf focuses on core PDF specification compliance (1.7 and 2.0) but does not explicitly mention PDF/A or other specialized standards. Developers must manually ensure generated documents meet such requirements, which may involve additional validation and tweaking.

Question 3

lopdf vs pdf-rs: which should I use for Rust PDF manipulation?

Accepted Answer

lopdf offers more low-level control and modern features like object streams for size reduction, while pdf-rs is often simpler for basic read/write operations. Choose lopdf if you need fine-grained manipulation and compression, but opt for pdf-rs for straightforward tasks without deep PDF spec knowledge.

Question 4

How to replace text in a PDF using lopdf?

Accepted Answer

Use the replace_text or replace_partial_text methods on a loaded Document, as shown in the example. Note that this requires enabling the nom_parser feature and works on specific pages, but text replacement may be limited by PDF encoding and layout constraints.

Question 5

What's the performance impact of object streams in lopdf?

Accepted Answer

Object streams reduce file size by 11-61% with minimal save-time overhead, as noted in the README's benchmarks. However, they require PDF 1.5+ compatibility and can increase parsing complexity for some PDF readers, though lopdf handles reading them automatically.

Question 6

Can lopdf handle encrypted PDFs with custom passwords?

Accepted Answer

Only partially: it automatically decrypts empty-password PDFs, but for custom passwords, you must use the authenticate_password method. The README indicates this support is limited, and some encryption algorithms may not be fully implemented.

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