Crate pdf_writer

Expand description

A step-by-step PDF writer.

The entry point into the API is the main PdfWriter, which constructs the document into one big internal buffer. The top-level writer has many methods to create specialized writers for specific PDF objects. These all follow the same general pattern: They borrow the main buffer mutably, expose a builder pattern for writing individual fields in a strongly typed fashion and finish up the object when dropped.

There are a few more top-level structs with internal buffers, like the builder for Content streams, but wherever possible buffers are borrowed from parent writers to minimize allocations.

Writers

The writers contained is this crate fall roughly into two categories.

Core writers enable you to write arbitrary PDF objects.

The Obj writer allows to write most fundamental PDF objects (numbers, strings, arrays, dictionaries, …). It is exposed through PdfWriter::indirect to write top-level indirect objects and through Array::push and Dict::insert to compose objects.
Streams are exposed through a separate PdfWriter::stream method since they must be indirect objects.

Specialized writers for things like a page or an image expose the core writer’s capabilities in a strongly typed fashion.

A Page writer, for example, is just a thin wrapper around a Dict and it even derefs to a dictionary in case you need to write a field that is not yet exposed by the typed API.
Similarly, the ImageXObject derefs to a Stream, so that the filter() function can be shared by all kinds of streams. The Stream in turn derefs to a Dict so that you can add arbitrary fields to the stream dictionary.

When you bind a writer to a variable instead of just writing a chained builder pattern, you may need to manually drop it before starting a new object using finish() or drop().

Minimal example

The following example creates a PDF with a single, empty A4 page.

use pdf_writer::{PdfWriter, Rect, Ref};

// Define some indirect reference ids we'll use.
let catalog_id = Ref::new(1);
let page_tree_id = Ref::new(2);
let page_id = Ref::new(3);

// Write a document catalog and a page tree with one A4 page that uses no resources.
let mut writer = PdfWriter::new();
writer.catalog(catalog_id).pages(page_tree_id);
writer.pages(page_tree_id).kids([page_id]).count(1);
writer.page(page_id)
    .parent(page_tree_id)
    .media_box(Rect::new(0.0, 0.0, 595.0, 842.0))
    .resources();

// Finish with cross-reference table and trailer and write to file.
std::fs::write("target/empty.pdf", writer.finish())?;

For more examples, check out the examples folder in the repository.

Note

This crate is rather low-level. It does not allocate or validate indirect reference ids for you and it does not check you write all required fields for an object. Refer to the PDF specification to make sure you create valid PDFs.