Visual FoxPro 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. Visual FoxPro

LOCAL lnSuccess
LOCAL loPdf
LOCAL loJson
LOCAL loJsonOut

lnSuccess = 0

*  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

loPdf = CreateObject('Chilkat.Pdf')
lnSuccess = loPdf.LoadFile("qa_data/pdf/watersense_accomplishments.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    CANCEL
ENDIF

loJson = CreateObject('Chilkat.JsonObject')
loJsonOut = CreateObject('Chilkat.JsonObject')
lnSuccess = loPdf.Optimize("audit",loJson,loJsonOut)
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loJsonOut
    CANCEL
ENDIF

? "fileSize: " + STR(loJsonOut.IntOf("fileSize"))
? "removeUnreferenced would save: " + STR(loJsonOut.IntOf("estimatedSavings.removeUnreferenced"))

*  Optimize with the defaults and see how many objects were actually dropped.
lnSuccess = loPdf.Optimize("optimize",loJson,loJsonOut)
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loJsonOut
    CANCEL
ENDIF

lnSuccess = loPdf.WriteFile("qa_output/watersense_optimized.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loJsonOut
    CANCEL
ENDIF

? "objects removed: " + STR(loJsonOut.IntOf("actions.removeUnreferenced.count"))
? "bytes saved:     " + STR(loJsonOut.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.
? "pages after: " + STR(loPdf.NumPages)

RELEASE loPdf
RELEASE loJson
RELEASE loJsonOut