Rust Requires Chilkat v11.7.0+

Remove PDF Objects Nothing Refers To

See more PDF Optimization Examples

Demonstrates removeUnreferenced. When a page, an image or a whole section is replaced in an editor, the objects it used often stay in the file with nothing pointing at them any more. They are not old revisions -- they are in the current revision, simply unreachable -- so only a reachability walk from the document catalog finds them. In a publication assembled over several editing passes this is frequently the largest single saving. Rust

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// The PDF used in this example is available at watersense_accomplishments.pdf

let pdf = chilkat::Pdf::new();
if pdf.load_file("qa_data/pdf/watersense_accomplishments.pdf").is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

let json = chilkat::JsonObject::new();
let json_out = chilkat::JsonObject::new();
if pdf.optimize("audit", &json, &json_out).is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

println!("fileSize: {}", json_out.int_of("fileSize"));
println!("removeUnreferenced would save: {}", json_out.int_of("estimatedSavings.removeUnreferenced"));

// Optimize with the defaults and see how many objects were actually dropped.
if pdf.optimize("optimize", &json, &json_out).is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

if pdf.write_file("qa_output/watersense_optimized.pdf").is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

println!("objects removed: {}", json_out.int_of("actions.removeUnreferenced.count"));
println!("bytes saved:     {}", json_out.int_of("actions.removeUnreferenced.bytesSaved"));

// Nothing a page needs is ever removed: the walk starts at the document catalog and follows every
// reference, including the ones in annotations, the structure tree, named destinations and the
// optional-content configuration.
println!("pages after: {}", pdf.num_pages());