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Home » Newsletter » June 2008

By Santhanam L.

On a PDF forms document displayed on a viewer application, we can enter text in more than one line or in multiple paragraph by pressing the Enter key at the end of each line or paragraph.

As programmers, we need to specify the character equivalent of pressing the Enter key in Java code while specifing values for text form fields.

Java uses "\n" and "\r" to signify newline and carriage return characters. The interpretation of these characters varies across platforms. What about PDF Forms?

With a text form field, a "\r" (carriage return) character can be used to separate two lines. (Two consecutive carriage returns can be used to separate two lines with an empty line.)

PDFOne Java also allows the use of "\n" (newline) character but it will be replaced with a "\r" character.

Apprehending that some programmers (particularly those with a "C/C++" background) might use both end-of-line characters to indicate a single line break, PDFOne Java will first replace all instances of "\r\n" and "\n\r" with a single "\r" and then attempt to replace any standalone instances of "\n" with "\r".

Please remember this order of replacement when you specify multi-line strings to text fields. Why is this important?

It is important because "\n\r" or "\r\n" means only one new line while "\r\r" or "\n\n" means two new lines.

A sample class displayed below illustrates several scenarios for end-of-line characters in string values specified for text fields. (To ensure the multiple lines are displayed on viewer applications, PdfFormTextField.setMultiline(boolean multiline) has been set to true.)

import java.awt.Color;
import java.io.File;
import java.io.IOException;

import com.gnostice.pdfone.PDFOne;
import com.gnostice.pdfone.PdfDocument;
import com.gnostice.pdfone.PdfException;
import com.gnostice.pdfone.PdfFormField;
import com.gnostice.pdfone.PdfFormTextField;
import com.gnostice.pdfone.PdfPage;
import com.gnostice.pdfone.PdfRect;
import com.gnostice.pdfone.PdfWriter;
import com.gnostice.pdfone.encodings.PdfEncodings;
import com.gnostice.pdfone.fonts.PdfFont;

public class June2008
{
    static {
        PDFOne.activate("T95VZE:W8HBPVA:74VQ8QV:LO4V8",
                "9B1HRZAP:X5853ERNE:5EREMEGRQ:TX1R10");
    }    
    public static void main(String[] args) 
      throws IOException, PdfException
    {

        PdfDocument doc1 = new PdfDocument();
        PdfFont fontHelvetica = 
            PdfFont.create("Helvetica", 
                           10, 
                           PdfEncodings.CP1252);
        
        // Create a PDF page
        PdfPage page = new PdfPage();
        
        // Create several text form fields with
        // different values 
        PdfFormTextField tf1 = 
            new PdfFormTextField(
                         new PdfRect(100, 100, 150, 50),
                         "tf_name", 
                         PdfFormField.FLAG_REQUIRED, 
                         Color.BLACK, 
                         Color.YELLOW);
        tf1.setBorderColor(Color.BLACK);
        tf1.setFont(fontHelvetica);
        tf1.setMultiline(true);
        tf1.setValue(
            "45, Sankey Road," +
            "Lower Palace Orchards," +
            "Bangalore, India.");
        
        PdfFormTextField tf2 = (PdfFormTextField) tf1.clone();
        tf2.setRect(new PdfRect(100, 200, 150, 50));
        tf2.setName("tf_name2");
        tf2.setValue(
            "45, Sankey Road,\r" +
            "Lower Palace Orchards,\r" +
            "Bangalore, India.");
        
        PdfFormTextField tf3 = (PdfFormTextField) tf1.clone();
        tf3.setRect(new PdfRect(100, 300, 150, 50));
        tf3.setName("tf_name3");
        tf3.setValue(
            "45, Sankey Road,\n" +
            "Lower Palace Orchards,\n" +
            "Bangalore, India.");
        
        PdfFormTextField tf4 = (PdfFormTextField) tf1.clone();
        tf4.setRect(new PdfRect(100, 400, 150, 50));
        tf4.setName("tf_name4");
        tf4.setValue(
            "45, Sankey Road,\n\r" +
            "Lower Palace Orchards,\r\n" +
            "Bangalore, India.");
        
        PdfFormTextField tf5 = (PdfFormTextField) tf1.clone();
        tf5.setRect(new PdfRect(100, 500, 150, 50));
        tf5.setName("tf_name5");
        tf5.setValue(
            "45, Sankey Road,\r\r" +
            "Lower Palace Orchards,\r\r" +
            "Bangalore, India.");
        
        PdfFormTextField tf6 = (PdfFormTextField) tf1.clone();
        tf6.setRect(new PdfRect(100, 600, 150, 50));
        tf6.setName("tf_name6");
        tf6.setValue(
            "45, Sankey Road,\n\n" +
            "Lower Palace Orchards,\n\n" +
            "Bangalore, India.");
        
        // Write form field values near the 
        // the form fields
        page.writeText("45, Sankey Road," +    
                       "Lower Palace Orchards," +
                       "Bangalore, India.",
                       100, 85);
        page.writeText("45, Sankey Road,\\r" +    
                       "Lower Palace Orchards,\\r" +
                       "Bangalore, India.",
                       100, 185);
        page.writeText("45, Sankey Road,\\n" +    
                       "Lower Palace Orchards,\\n" +
                       "Bangalore, India.",
                       100, 285);
        page.writeText("45, Sankey Road,\\n\\r" +    
                       "Lower Palace Orchards,\\r\\n" +
                       "Bangalore, India.",
                       100, 385);
        page.writeText("45, Sankey Road,\\r\\r" +    
                       "Lower Palace Orchards,\\r\\r" +
                       "Bangalore, India.",
                       100, 485);
        page.writeText("45, Sankey Road,\\n\\n" +    
                       "Lower Palace Orchards,\\n\\n" +
                       "Bangalore, India.",
                       100, 585);
        
        // Add the form fields to the page
        page.addFormField(tf1);
        page.addFormField(tf2);
        page.addFormField(tf3);
        page.addFormField(tf4);
        page.addFormField(tf5); 
        page.addFormField(tf6);
            
        doc1.add(page);
        doc1.setOpenAfterSave(true);
        doc1.save("PdfFormTextField_example.pdf");
        doc1.close();      
    }
}

The output PDF document looks like this.

Note how "\r", "\n", "\r\n", and "\n\r" all behave like a single "\r". And, see how "\r\r" and "\n\n" in the last two fields has the same effect.