pdfrum-edit

The crate that writes (ISO 32000-1 §7.5.8). A save either rewrites the whole file or appends a new body, cross-reference section and trailer to the bytes already there. Page import and reordering, N-up imposition, font subsetting, image embedding and re-encryption live here.

use std::sync::Arc;
use pdfrum_edit::{EditDoc, SaveOptions, save};
use pdfrum_parser::{LoadOptions, load};

let bytes = std::fs::read(concat!(env!("CARGO_MANIFEST_DIR"), "/tests/files/hello.pdf"))?;
let doc = load(Arc::from(bytes), &LoadOptions::default())?;
let mut out = Vec::new();
save(&EditDoc::new(&doc), &SaveOptions::default(), &mut out)?;
assert!(out.starts_with(b"%PDF"));
# Ok::<(), Box<dyn std::error::Error>>(())

An untouched page is copied as stored; a touched one is regenerated, and regeneration is lossy. This is the single fact to know before editing. The content of a page you did not modify is written back byte for byte, so a save is not a re-encode of the document. A page whose graph you did change has its content stream rebuilt from that graph, and the rebuild does not preserve everything the original said: colour comes back as rg/RG, and shadings, text clipping modes and Type 3 glyph runs are dropped. Edit the pages you mean to change and nothing else.

[SaveMode] chooses between the two file shapes. An incremental save appends and leaves the original bytes intact, which is what keeps an existing digital signature verifiable and what a reader expects of a form fill; a full save rewrites and can drop what nothing references any more. An unencrypted save is byte-reproducible under [IdSource::Fixed]. An encrypted one draws its file key and AES vectors from the operating system: reproducible ciphertext is reproducible secrets, which is not what a seed is for.

Part of pdfrum. #![forbid(unsafe_code)].

MIT OR Apache-2.0