/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.pdfbox.examples.signature;

import java.io.IOException;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDResources;
import org.apache.pdfbox.pdmodel.common.PDRectangle;
import org.apache.pdfbox.pdmodel.font.PDFont;
import org.apache.pdfbox.pdmodel.font.PDType1Font;
import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotationWidget;
import org.apache.pdfbox.pdmodel.interactive.form.PDAcroForm;
import org.apache.pdfbox.pdmodel.interactive.form.PDSignatureField;

/**
 * An example of creating an AcroForm and an empty signature field from scratch.
 * 
 * An actual signature can be added by clicking on it in Adobe Reader.
 * 
 */
public final class CreateEmptySignatureForm
{
    private CreateEmptySignatureForm()
    {
    }
    
    public static void main(String[] args) throws IOException
    {
        // Create a new document with an empty page.
        try (PDDocument document = new PDDocument())
        {
            PDPage page = new PDPage(PDRectangle.A4);
            document.addPage(page);

            // Adobe Acrobat uses Helvetica as a default font and
            // stores that under the name '/Helv' in the resources dictionary
            PDFont font = PDType1Font.HELVETICA;
            PDResources resources = new PDResources();
            resources.put(COSName.getPDFName("Helv"), font);

            // Add a new AcroForm and add that to the document
            PDAcroForm acroForm = new PDAcroForm(document);
            document.getDocumentCatalog().setAcroForm(acroForm);

            // Add and set the resources and default appearance at the form level
            acroForm.setDefaultResources(resources);

            // Acrobat sets the font size on the form level to be
            // auto sized as default. This is done by setting the font size to '0'
            String defaultAppearanceString = "/Helv 0 Tf 0 g";
            acroForm.setDefaultAppearance(defaultAppearanceString);
            // --- end of general AcroForm stuff ---

            // Create empty signature field, it will get the name "Signature1"
            PDSignatureField signatureField = new PDSignatureField(acroForm);
            PDAnnotationWidget widget = signatureField.getWidgets().get(0);
            PDRectangle rect = new PDRectangle(50, 650, 200, 50);
            widget.setRectangle(rect);
            widget.setPage(page);
            page.getAnnotations().add(widget);

            acroForm.getFields().add(signatureField);

            document.save("target/EmptySignatureForm.pdf");
        }
    }
}