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PDF form fill and form data extraction in Kotlin

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Sample Kotlin code for using PDFTron SDK to programmatically merge forms data with the PDF in order to fill forms, or to extract form field data from the PDF. PDFTron SDK has full support for Forms Data Format (FDF). Learn more about our Kotlin PDF Library and PDF Form Filler SDK.

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//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2019 by PDFTron Systems Inc. All Rights Reserved.
// Consult legal.txt regarding legal and license information.
//---------------------------------------------------------------------------------------
package com.pdftron.android.pdfnetsdksamples.samples

import com.pdftron.android.pdfnetsdksamples.OutputListener
import com.pdftron.android.pdfnetsdksamples.PDFNetSample
import com.pdftron.android.pdfnetsdksamples.R
import com.pdftron.android.pdfnetsdksamples.util.Utils
import com.pdftron.fdf.FDFDoc
import com.pdftron.fdf.FDFField
import com.pdftron.fdf.FDFFieldIterator
import com.pdftron.pdf.FieldIterator
import com.pdftron.pdf.PDFDoc
import com.pdftron.sdf.SDFDoc

class FDFTest : PDFNetSample() {
    override fun run(outputListener: OutputListener?) {
        super.run(outputListener)
        mOutputListener = outputListener
        mFileList.clear()
        printHeader(outputListener!!)

        // Example 1)
        // Iterate over all form fields in the document. Display all field names.
        try {
            val doc = PDFDoc(Utils.getAssetTempFile(INPUT_PATH.toString() + "form1.pdf")!!.getAbsolutePath())
            doc.initSecurityHandler()
            val itr: FieldIterator = doc.getFieldIterator()
            while (itr.hasNext()) {
                val current: com.pdftron.pdf.Field? = itr.next()
                mOutputListener!!.println("Field name: " + current!!.getName())
                mOutputListener!!.println("Field partial name: " + current.getPartialName())
                mOutputListener!!.print("Field type: ")
                val type: Int = current.getType()
                when (type) {
                    com.pdftron.pdf.Field.e_button -> mOutputListener!!.println("Button")
                    com.pdftron.pdf.Field.e_check -> mOutputListener!!.println("Check")
                    com.pdftron.pdf.Field.e_radio -> mOutputListener!!.println("Radio")
                    com.pdftron.pdf.Field.e_text -> mOutputListener!!.println("Text")
                    com.pdftron.pdf.Field.e_choice -> mOutputListener!!.println("Choice")
                    com.pdftron.pdf.Field.e_signature -> mOutputListener!!.println("Signature")
                    com.pdftron.pdf.Field.e_null -> mOutputListener!!.println("Null")
                }
                mOutputListener!!.println("------------------------------")
            }
            doc.close()
            mOutputListener!!.println("Done.")
        } catch (e: java.lang.Exception) {
            mOutputListener!!.printError(e.getStackTrace())
        }

        // Example 2) Import XFDF into FDF, then merge data from FDF into PDF
        try {
            // XFDF to FDF
            // form fields
            mOutputListener!!.println("Import form field data from XFDF to FDF.")
            val fdf_doc1: FDFDoc = FDFDoc.createFromXFDF(Utils.getAssetTempFile(INPUT_PATH.toString() + "form1_data.xfdf")!!.getAbsolutePath())
            fdf_doc1.save(Utils.createExternalFile("form1_data.fdf", mFileList).getAbsolutePath())

            // annotations
            mOutputListener!!.println("Import annotations from XFDF to FDF.")
            val fdf_doc2: FDFDoc = FDFDoc.createFromXFDF(Utils.getAssetTempFile(INPUT_PATH.toString() + "form1_annots.xfdf")!!.getAbsolutePath())
            fdf_doc2.save(Utils.createExternalFile("form1_annots.fdf", mFileList).getAbsolutePath())

            // FDF to PDF
            // form fields
            mOutputListener!!.println("Merge form field data from FDF.")
            val doc = PDFDoc(Utils.getAssetTempFile(INPUT_PATH.toString() + "form1.pdf")!!.getAbsolutePath())
            doc.initSecurityHandler()
            doc.fdfMerge(fdf_doc1)

            // Refreshing missing appearances is not required here, but is recommended to make them
            // visible in PDF viewers with incomplete annotation viewing support. (such as Chrome)
            doc.refreshAnnotAppearances()
            doc.save(Utils.createExternalFile("form1_filled.pdf", mFileList).getAbsolutePath(), SDFDoc.SaveMode.LINEARIZED, null)

            // annotations
            mOutputListener!!.println("Merge annotations from FDF.")
            doc.fdfMerge(fdf_doc2)
            // Refreshing missing appearances is not required here, but is recommended to make them
            // visible in PDF viewers with incomplete annotation viewing support. (such as Chrome)
            doc.refreshAnnotAppearances()
            doc.save(Utils.createExternalFile("form1_filled_with_annots.pdf", mFileList).getAbsolutePath(), SDFDoc.SaveMode.LINEARIZED, null)
            doc.close()
            mOutputListener!!.println("Done.")
        } catch (e: java.lang.Exception) {
            mOutputListener!!.printError(e.getStackTrace())
        }

        // Example 3) Extract data from PDF to FDF, then export FDF as XFDF
        try {
            // PDF to FDF
            val in_doc = PDFDoc(Utils.createExternalFile("form1_filled_with_annots.pdf", mFileList).getAbsolutePath())
            in_doc.initSecurityHandler()

            // form fields only
            mOutputListener!!.println("Extract form fields data to FDF.")
            val doc_fields: FDFDoc = in_doc.fdfExtract(PDFDoc.e_forms_only)
            doc_fields.setPDFFileName(Utils.createExternalFile("form1_filled_with_annots.pdf", mFileList).getAbsolutePath())
            doc_fields.save(Utils.createExternalFile("form1_filled_data.fdf", mFileList).getAbsolutePath())

            // annotations only
            mOutputListener!!.println("Extract annotations to FDF.")
            val doc_annots: FDFDoc = in_doc.fdfExtract(PDFDoc.e_annots_only)
            doc_annots.setPDFFileName(Utils.createExternalFile("form1_filled_with_annots.pdf", mFileList).getAbsolutePath())
            doc_annots.save(Utils.createExternalFile("form1_filled_annot.fdf", mFileList).getAbsolutePath())

            // both form fields and annotations
            mOutputListener!!.println("Extract both form fields and annotations to FDF.")
            val doc_both: FDFDoc = in_doc.fdfExtract(PDFDoc.e_both)
            doc_both.setPDFFileName(Utils.createExternalFile("form1_filled_with_annots.pdf", mFileList).getAbsolutePath())
            doc_both.save(Utils.createExternalFile("form1_filled_both.fdf", mFileList).getAbsolutePath())

            // FDF to XFDF
            // form fields
            mOutputListener!!.println("Export form field data from FDF to XFDF.")
            doc_fields.saveAsXFDF(Utils.createExternalFile("form1_filled_data.xfdf", mFileList).getAbsolutePath())

            // annotations
            mOutputListener!!.println("Export annotations from FDF to XFDF.")
            doc_annots.saveAsXFDF(Utils.createExternalFile("form1_filled_annot.xfdf", mFileList).getAbsolutePath())

            // both form fields and annotations
            mOutputListener!!.println("Export both form fields and annotations from FDF to XFDF.")
            doc_both.saveAsXFDF(Utils.createExternalFile("form1_filled_both.xfdf", mFileList).getAbsolutePath())
            in_doc.close()
            mOutputListener!!.println("Done.")
        } catch (e: java.lang.Exception) {
            mOutputListener!!.printError(e.getStackTrace())
        }

        // Example 4) Merge/Extract XFDF into/from PDF
        try {
            // Merge XFDF from string
            val in_doc = PDFDoc(Utils.getAssetTempFile(INPUT_PATH.toString() + "numbered.pdf")!!.getAbsolutePath())
            in_doc.initSecurityHandler()
            mOutputListener!!.println("Merge XFDF string into PDF.")
            val str = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?><xfdf xmlns=\"http://ns.adobe.com/xfdf\" xml:space=\"preserve\"><square subject=\"Rectangle\" page=\"0\" name=\"cf4d2e58-e9c5-2a58-5b4d-9b4b1a330e45\" title=\"user\" creationdate=\"D:20120827112326-07'00'\" date=\"D:20120827112326-07'00'\" rect=\"227.7814207650273,597.6174863387978,437.07103825136608,705.0491803278688\" color=\"#000000\" interior-color=\"#FFFF00\" flags=\"print\" width=\"1\"><popup flags=\"print,nozoom,norotate\" open=\"no\" page=\"0\" rect=\"0,792,0,792\" /></square></xfdf>"
            val fdoc: FDFDoc = FDFDoc.createFromXFDF(str)
            in_doc.fdfMerge(fdoc)
            in_doc.save(Utils.createExternalFile("numbered_modified.pdf", mFileList).getAbsolutePath(), SDFDoc.SaveMode.LINEARIZED, null)
            mOutputListener!!.println("Merge complete.")

            // Extract XFDF as string
            mOutputListener!!.println("Extract XFDF as a string.")
            val fdoc_new: FDFDoc = in_doc.fdfExtract(PDFDoc.e_both)
            val XFDF_str: String = fdoc_new.saveAsXFDF()
            mOutputListener!!.println("Extracted XFDF: ")
            mOutputListener!!.println(XFDF_str)
            in_doc.close()
            mOutputListener!!.println("Extract complete.")
        } catch (e: java.lang.Exception) {
            mOutputListener!!.printError(e.getStackTrace())
        }

        // Example 5) Read FDF files directly
        try {
            val doc = FDFDoc(Utils.createExternalFile("form1_filled_data.fdf", mFileList).getAbsolutePath())
            val itr: FDFFieldIterator = doc.getFieldIterator()
            while (itr.hasNext()) {
                val current: FDFField? = itr.next()
                mOutputListener!!.println("Field name: " + current!!.getName())
                mOutputListener!!.println("Field partial name: " + current.getPartialName())
                mOutputListener!!.println("------------------------------")
            }
            doc.close()
            mOutputListener!!.println("Done.")
        } catch (e: java.lang.Exception) {
            mOutputListener!!.printError(e.getStackTrace())
        }

        // Example 6) Direct generation of FDF.
        try {
            val doc = FDFDoc()
            // Create new fields (i.e. key/value pairs).
            doc.fieldCreate("Company", com.pdftron.pdf.Field.e_text, "PDFTron Systems")
            doc.fieldCreate("First Name", com.pdftron.pdf.Field.e_text, "John")
            doc.fieldCreate("Last Name", com.pdftron.pdf.Field.e_text, "Doe")
            // ...

            // doc.setPdfFileName("mydoc.pdf");
            doc.save(Utils.createExternalFile("sample_output.fdf", mFileList).getAbsolutePath())
            doc.close()
            mOutputListener!!.println("Done. Results saved in sample_output.fdf")
        } catch (e: java.lang.Exception) {
            mOutputListener!!.printError(e.getStackTrace())
        }
        for (file in mFileList) {
            addToFileList(file)
        }
        printFooter(outputListener)
    }

    companion object {
        private var mOutputListener: OutputListener? = null
        private val mFileList: java.util.ArrayList<String> = java.util.ArrayList<String>()
    }

    init {
        setTitle(R.string.sample_fdf_title)
        setDescription(R.string.sample_fdf_description)
    }
}