Unicode C Requires Chilkat v11.7.0+

Remove a PDF's Old Revisions

See more PDF Optimization Examples

Demonstrates dropOldRevisions. A PDF that has been edited and saved several times carries every earlier revision: the superseded objects are still in the file, reachable through the older cross-reference sections. The audit reports them as "oldRevisions", and dropping them is often the single largest saving in a real document. Dropping them requires a full rewrite, which is why it invalidates existing digital signatures. Unicode C

#include <C_CkPdfW.h>
#include <C_CkJsonObjectW.h>
#include <C_CkFileAccessW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkPdfW pdf;
    HCkJsonObjectW json;
    HCkJsonObjectW jsonOut;
    HCkFileAccessW fac;

    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 grand_canyon_hiking_guide.pdf

    pdf = CkPdfW_Create();
    success = CkPdfW_LoadFile(pdf,L"qa_data/pdf/grand_canyon_hiking_guide.pdf");
    if (success == FALSE) {
        wprintf(L"%s\n",CkPdfW_lastErrorText(pdf));
        CkPdfW_Dispose(pdf);
        return;
    }

    //  How much of this file is superseded revisions?
    json = CkJsonObjectW_Create();
    jsonOut = CkJsonObjectW_Create();
    success = CkPdfW_Optimize(pdf,L"audit",json,jsonOut);
    if (success == FALSE) {
        wprintf(L"%s\n",CkPdfW_lastErrorText(pdf));
        CkPdfW_Dispose(pdf);
        CkJsonObjectW_Dispose(json);
        CkJsonObjectW_Dispose(jsonOut);
        return;
    }

    wprintf(L"fileSize:     %d\n",CkJsonObjectW_IntOf(jsonOut,L"fileSize"));
    wprintf(L"oldRevisions: %d\n",CkJsonObjectW_IntOf(jsonOut,L"usage.oldRevisions.bytes"));

    //  Drop them, and nothing else, so that the saving is attributable.
    CkJsonObjectW_UpdateBool(json,L"compressUncompressed",FALSE);
    CkJsonObjectW_UpdateBool(json,L"recompressFlate",FALSE);
    CkJsonObjectW_UpdateBool(json,L"replaceLegacyFilters",FALSE);
    CkJsonObjectW_UpdateBool(json,L"imagePredictors",FALSE);
    CkJsonObjectW_UpdateBool(json,L"dedupeStreams",FALSE);
    CkJsonObjectW_UpdateBool(json,L"dedupeObjects",FALSE);
    CkJsonObjectW_UpdateBool(json,L"removeUnreferenced",FALSE);
    CkJsonObjectW_UpdateBool(json,L"removeUnusedResources",FALSE);
    CkJsonObjectW_UpdateBool(json,L"removeUnusedLayers",FALSE);
    CkJsonObjectW_UpdateBool(json,L"coalesceContent",FALSE);
    CkJsonObjectW_UpdateBool(json,L"tidyContent",FALSE);
    CkJsonObjectW_UpdateBool(json,L"subsetFonts",FALSE);
    CkJsonObjectW_UpdateBool(json,L"dropOldRevisions",TRUE);

    success = CkPdfW_Optimize(pdf,L"optimize",json,jsonOut);
    if (success == FALSE) {
        wprintf(L"%s\n",CkPdfW_lastErrorText(pdf));
        CkPdfW_Dispose(pdf);
        CkJsonObjectW_Dispose(json);
        CkJsonObjectW_Dispose(jsonOut);
        return;
    }

    success = CkPdfW_WriteFile(pdf,L"qa_output/grand_canyon_one_revision.pdf");
    if (success == FALSE) {
        wprintf(L"%s\n",CkPdfW_lastErrorText(pdf));
        CkPdfW_Dispose(pdf);
        CkJsonObjectW_Dispose(json);
        CkJsonObjectW_Dispose(jsonOut);
        return;
    }

    //  The saving is an estimate: what the old revisions occupied is known exactly, but the writer
    //  decides the final layout.  Measure the written file for the real number.
    fac = CkFileAccessW_Create();
    wprintf(L"bytesSaved (reported): %d\n",CkJsonObjectW_IntOf(jsonOut,L"bytesSaved"));
    wprintf(L"written file:          %d\n",CkFileAccessW_FileSize(fac,L"qa_output/grand_canyon_one_revision.pdf"));


    CkPdfW_Dispose(pdf);
    CkJsonObjectW_Dispose(json);
    CkJsonObjectW_Dispose(jsonOut);
    CkFileAccessW_Dispose(fac);

    }