C++ 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. C++

#include <CkPdf.h>
#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    bool success = false;

    //  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

    CkPdf pdf;
    success = pdf.LoadFile("qa_data/pdf/watersense_accomplishments.pdf");
    if (success == false) {
        std::cout << pdf.lastErrorText() << "\r\n";
        return;
    }

    CkJsonObject json;
    CkJsonObject jsonOut;
    success = pdf.Optimize("audit",json,jsonOut);
    if (success == false) {
        std::cout << pdf.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "fileSize: " << jsonOut.IntOf("fileSize") << "\r\n";
    std::cout << "removeUnreferenced would save: " << jsonOut.IntOf("estimatedSavings.removeUnreferenced") << "\r\n";

    //  Optimize with the defaults and see how many objects were actually dropped.
    success = pdf.Optimize("optimize",json,jsonOut);
    if (success == false) {
        std::cout << pdf.lastErrorText() << "\r\n";
        return;
    }

    success = pdf.WriteFile("qa_output/watersense_optimized.pdf");
    if (success == false) {
        std::cout << pdf.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "objects removed: " << jsonOut.IntOf("actions.removeUnreferenced.count") << "\r\n";
    std::cout << "bytes saved:     " << jsonOut.IntOf("actions.removeUnreferenced.bytesSaved") << "\r\n";

    //  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.
    std::cout << "pages after: " << pdf.get_NumPages() << "\r\n";
    }