Java 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. Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.JsonObject;
import com.chilkatsoft.chilkat2.Pdf;

public class ChilkatExample {

    public static void main(String[] args) {
        // 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

        Pdf pdf = new Pdf();
        try {
            pdf.loadFile("qa_data/pdf/watersense_accomplishments.pdf");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        JsonObject json = new JsonObject();
        JsonObject jsonOut = new JsonObject();
        try {
            pdf.optimize("audit", json, jsonOut);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("fileSize: " + jsonOut.intOf("fileSize"));
        System.out.println("removeUnreferenced would save: " + jsonOut.intOf("estimatedSavings.removeUnreferenced"));

        // Optimize with the defaults and see how many objects were actually dropped.
        try {
            pdf.optimize("optimize", json, jsonOut);

            pdf.writeFile("qa_output/watersense_optimized.pdf");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("objects removed: " + jsonOut.intOf("actions.removeUnreferenced.count"));
        System.out.println("bytes saved:     " + jsonOut.intOf("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.
        System.out.println("pages after: " + pdf.getNumPages());
    }
}