form_checkbox:一个在PDF上添加CheckBox的例子（来自itextpdf的ex系列）

有人需要就贴了出来了，这个系列的100多个demo去年已经翻译完毕，一直想不出有什么必要放出来，搁置半年了。

using System;
using iTextSharp.text;
using iTextSharp.text.pdf;
using System.IO;
public class form_checkbox
{
    
    
    [STAThread]
    public static void  Main(string[] args)
    {
        Document document = new Document(PageSize.A4, 50, 50, 50, 50);
        try
        {
            // creation of the different writers
            PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(@"e:\java\form_checkbox.Pdf", FileMode.Create));
            
            document.Open();
            PdfContentByte cb = writer.DirectContent;
            cb.MoveTo(0, 0);
            PdfFormField field = PdfFormField.CreateCheckBox(writer);
            PdfAppearance tpOff = cb.CreateAppearance(20, 20);
            PdfAppearance tpOn = cb.CreateAppearance(20, 20);
            tpOff.Rectangle(1, 1, 18, 18);
            tpOff.Stroke();
            
            tpOn.SetRGBColorFill(255, 128, 128);
            tpOn.Rectangle(1, 1, 18, 18);
            tpOn.FillStroke();
            tpOn.MoveTo(1, 1);
            tpOn.LineTo(19, 19);
            tpOn.MoveTo(1, 19);
            tpOn.LineTo(19, 1);
            tpOn.Stroke();
            
            field.SetWidget(new Rectangle(100, 700, 120, 720), PdfAnnotation.HIGHLIGHT_INVERT);
            field.FieldName=("Urgent");
            field.ValueAsName=("Off");
            field.AppearanceState=("Off");
            field.SetAppearance(PdfAnnotation.APPEARANCE_NORMAL, "Off", tpOff);
            field.SetAppearance(PdfAnnotation.APPEARANCE_NORMAL, "On", tpOn);
            writer.AddAnnotation(field);
            document.Close();
            System.Console.Out.WriteLine("FIM.");
        }
        catch (System.Exception de)
        {
            System.Console.Error.WriteLine(de.Message);
        }
    }
}