Go Requires Chilkat v11.7.0+

Add an Image (Logo) Watermark to a PDF

See more PDF Watermark Examples

Demonstrates an image watermark placed in a corner of every page. The image is a PNG or JPEG given either by path ("image.path") or, as here, as base64 in the JSON itself ("image.base64"), which suits a server that keeps its logo in a database rather than on disk. PNG transparency is kept. Giving only a width keeps the aspect ratio, and the units member says those numbers are inches rather than points. Go

    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 four_pages.pdf

    pdf := chilkat.NewPdf()
    success = pdf.LoadFile("qa_data/pdf/four_pages.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        return
    }

    json := chilkat.NewJsonObject()
    json.UpdateString("type","image")

    //  A small PNG logo, base64 encoded.  Use "image.path" instead to name a PNG or JPEG file:
    //     ignore = json.UpdateString("image.path","logo.png");
    json.UpdateString("image.base64","iVBORw0KGgoAAAANSUhEUgAAAGAAAAAgCAYAAADtwH1UAAAApElEQVR42u3a7QmAIBgAYTdpo/ZphhZti6IBylLrlXoO/G3cIeFHSgAAFDKM08rCy8Jzg6Ug8UJ0JF+EDuSXRGgxX8+jufxlTk0nFuCCiF360aidXICMiDP5uQgCXAxQI782ggAHEu7IP4sgQOcBIMA35ItgBQhQEqBmtbX6xl//hAUI3gcIELwTFiD4LEiA4NNQAYLvA+BGzJ0wvIrwLggA8DgbwPbrr8c7+lkAAAAASUVORK5CYII=")

    //  The size to draw it at.  Give only the width and the height follows the aspect ratio.
    json.UpdateString("units","in")
    json.UpdateNumber("image.width","1.5")

    //  Bottom-right, half an inch in from the page edges.
    json.UpdateString("position.align","bottomRight")
    json.UpdateNumber("position.margin","0.5")
    json.UpdateNumber("opacity","0.85")
    json.UpdateString("id","logo")

    jsonOut := chilkat.NewJsonObject()
    success = pdf.Watermark("add",json,jsonOut)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        return
    }

    fmt.Println("id: ", *jsonOut.StringOf("id"), " pages: ", *jsonOut.StringOf("pages"))

    success = pdf.WriteFile("qa_output/four_pages_logo.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        return
    }

    //  Sample output:

    //  id: logo pages: 1-4

    pdf.DisposePdf()
    json.DisposeJsonObject()
    jsonOut.DisposeJsonObject()