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PDF interactive forms (AcroForms) in C#

Sample C# code for using PDFTron SDK with interactive forms (also known as AcroForms). Capabilities include programatically creating new fields and widget annotations, form filling, modifying existing field values, form templating, and flattening form fields. Learn more about our 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.
//---------------------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using pdftron;
using pdftron.Common;
using pdftron.SDF;
using pdftron.PDF;
using pdftron.PDF.Annots;

namespace FormsTestCS
{
	/// <summary>
	///---------------------------------------------------------------------------------------
	/// This sample illustrates basic PDFNet capabilities related to interactive 
	/// forms (also known as AcroForms). 
	///---------------------------------------------------------------------------------------
	/// </summary>
	class Class1
	{
		private static pdftron.PDFNetLoader pdfNetLoader = pdftron.PDFNetLoader.Instance();
		static Class1() {}
		
		static void Main(string[] args)
		{
			PDFNet.Initialize();

			// Relative path to the folder containing test files.
			// string input_path =  "../../../../TestFiles/";
			string output_path = "../../../../TestFiles/Output/";

            // The vector used to store the name and count of all fields.
            // This is used later on to clone the fields
            Dictionary<string, int> field_names = new Dictionary<string, int>();

            //----------------------------------------------------------------------------------
            // Example 1: Programatically create new Form Fields and Widget Annotations.
            //----------------------------------------------------------------------------------
            try
			{
				using (PDFDoc doc = new PDFDoc())
				{
                    // Create a blank new page and add some form fields.
                    Page blank_page = doc.PageCreate();

                    // Text Widget Creation 
                    // Create an empty text widget with black text.
                    TextWidget text1 = TextWidget.Create(doc, new Rect(110, 700, 380, 730));
                    text1.SetText("Basic Text Field");
                    text1.RefreshAppearance();
                    blank_page.AnnotPushBack(text1);
                    // Create a vertical text widget with blue text and a yellow background.
                    TextWidget text2 = TextWidget.Create(doc, new Rect(50, 400, 90, 730));
                    text2.SetRotation(90);
                    // Set the text content.
                    text2.SetText("    ****Lucky Stars!****");
                    // Set the font type, text color, font size, border color and background color.
                    text2.SetFont(Font.Create(doc, Font.StandardType1Font.e_helvetica_oblique));
                    text2.SetFontSize(28);
                    text2.SetTextColor(new ColorPt(0, 0, 1), 3);
                    text2.SetBorderColor(new ColorPt(0, 0, 0), 3);
                    text2.SetBackgroundColor(new ColorPt(1, 1, 0), 3);
                    text2.RefreshAppearance();
                    // Add the annotation to the page.
                    blank_page.AnnotPushBack(text2);
                    // Create two new text widget with Field names employee.name.first and employee.name.last
                    // This logic shows how these widgets can be created using either a field name string or
                    // a Field object
                    TextWidget text3 = TextWidget.Create(doc, new Rect(110, 660, 380, 690), "employee.name.first");
                    text3.SetText("Levi");
                    text3.SetFont(Font.Create(doc, Font.StandardType1Font.e_times_bold));
                    text3.RefreshAppearance();
                    blank_page.AnnotPushBack(text3);
                    Field emp_last_name = doc.FieldCreate("employee.name.last", Field.Type.e_text, "Ackerman");
                    TextWidget text4 = TextWidget.Create(doc, new Rect(110, 620, 380, 650), emp_last_name);
                    text4.SetFont(Font.Create(doc, Font.StandardType1Font.e_times_bold));
                    text4.RefreshAppearance();
                    blank_page.AnnotPushBack(text4);

                    // Signature Widget Creation (unsigned)
                    SignatureWidget signature1 = SignatureWidget.Create(doc, new Rect(110, 560, 260, 610));
                    signature1.RefreshAppearance();
                    blank_page.AnnotPushBack(signature1);

                    // CheckBox Widget Creation
                    // Create a check box widget that is not checked.
                    CheckBoxWidget check1 = CheckBoxWidget.Create(doc, new Rect(140, 490, 170, 520));
                    check1.RefreshAppearance();
                    blank_page.AnnotPushBack(check1);
                    // Create a check box widget that is checked.
                    CheckBoxWidget check2 = CheckBoxWidget.Create(doc, new Rect(190, 490, 250, 540), "employee.name.check1");
                    check2.SetBackgroundColor(new ColorPt(1, 1, 1), 3);
                    check2.SetBorderColor(new ColorPt(0, 0, 0), 3);
                    // Check the widget (by default it is unchecked).
                    check2.SetChecked(true);
                    check2.RefreshAppearance();
                    blank_page.AnnotPushBack(check2);

                    // PushButton Widget Creation
                    PushButtonWidget pushbutton1 = PushButtonWidget.Create(doc, new Rect(380, 490, 520, 540));
                    pushbutton1.SetTextColor(new ColorPt(1, 1, 1), 3);
                    pushbutton1.SetFontSize(36);
                    pushbutton1.SetBackgroundColor(new ColorPt(0, 0, 0), 3);
                    // Add a caption for the pushbutton.
                    pushbutton1.SetStaticCaptionText("PushButton");
                    pushbutton1.RefreshAppearance();
                    blank_page.AnnotPushBack(pushbutton1);

                    // ComboBox Widget Creation
                    ComboBoxWidget combo1 = ComboBoxWidget.Create(doc, new Rect(280, 560, 580, 610));
                    // Add options to the combobox widget.
                    combo1.AddOption("Combo Box No.1");
                    combo1.AddOption("Combo Box No.2");
                    combo1.AddOption("Combo Box No.3");
                    // Make one of the options in the combo box selected by default.
                    combo1.SetSelectedOption("Combo Box No.2");
                    combo1.SetTextColor(new ColorPt(1, 0, 0), 3);
                    combo1.SetFontSize(28);
                    combo1.RefreshAppearance();
                    blank_page.AnnotPushBack(combo1);

                    // ListBox Widget Creation
                   ListBoxWidget list1 = ListBoxWidget.Create(doc, new Rect(400, 620, 580, 730));
                    // Add one option to the listbox widget.
                    list1.AddOption("List Box No.1");
                    // Add multiple options to the listbox widget in a batch.
                    string[] list_options = new string[2] {"List Box No.2", "List Box No.3"};
                    list1.AddOptions(list_options);
                    // Select some of the options in list box as default options
                    list1.SetSelectedOptions(list_options);
                    // Enable list box to have multi-select when editing. 
                    list1.GetField().SetFlag(Field.Flag.e_multiselect, true);
                    list1.SetFont(Font.Create(doc, Font.StandardType1Font.e_times_italic));
                    list1.SetTextColor(new ColorPt(1, 0, 0), 3);
                    list1.SetFontSize(28);
                    list1.SetBackgroundColor(new ColorPt(1, 1, 1), 3);
                    list1.RefreshAppearance();
                    blank_page.AnnotPushBack(list1);

                    // RadioButton Widget Creation
                    // Create a radio button group and add three radio buttons in it. 
                    RadioButtonGroup radio_group = RadioButtonGroup.Create(doc, "RadioGroup");
                    RadioButtonWidget radiobutton1 = radio_group.Add(new Rect(140, 410, 190, 460));
                    radiobutton1.SetBackgroundColor(new ColorPt(1, 1, 0), 3);
                    radiobutton1.RefreshAppearance();
                    RadioButtonWidget radiobutton2 = radio_group.Add(new Rect(310, 410, 360, 460));
                    radiobutton2.SetBackgroundColor(new ColorPt(0, 1, 0), 3);
                    radiobutton2.RefreshAppearance();
                    RadioButtonWidget radiobutton3 = radio_group.Add(new Rect(480, 410, 530, 460));
                    // Enable the third radio button. By default the first one is selected
                    radiobutton3.EnableButton();
                    radiobutton3.SetBackgroundColor(new ColorPt(0, 1, 1), 3);
                    radiobutton3.RefreshAppearance();
                    radio_group.AddGroupButtonsToPage(blank_page);

                    // Custom push button annotation creation
                    PushButtonWidget custom_pushbutton1 = PushButtonWidget.Create(doc, new Rect(260, 320, 360, 360));
                    // Set the annotation appearance.
                    custom_pushbutton1.SetAppearance(CreateCustomButtonAppearance(doc, false), Annot.AnnotationState.e_normal);
                    // Create 'SubmitForm' action. The action will be linked to the button.
                    FileSpec url = FileSpec.CreateURL(doc, "http://www.pdftron.com");
                    pdftron.PDF.Action button_action = pdftron.PDF.Action.CreateSubmitForm(url);
                    // Associate the above action with 'Down' event in annotations action dictionary.
                    Obj annot_action = custom_pushbutton1.GetSDFObj().PutDict("AA");
                    annot_action.Put("D", button_action.GetSDFObj());
                    blank_page.AnnotPushBack(custom_pushbutton1);

                    // Add the page as the last page in the document.
                    doc.PagePushBack(blank_page);

                    // If you are not satisfied with the look of default auto-generated appearance 
                    // streams you can delete "AP" entry from the Widget annotation and set 
                    // "NeedAppearances" flag in AcroForm dictionary:
                    //    doc.GetAcroForm().PutBool("NeedAppearances", true);
                    // This will force the viewer application to auto-generate new appearance streams 
                    // every time the document is opened.
                    //
                    // Alternatively you can generate custom annotation appearance using ElementWriter 
                    // and then set the "AP" entry in the widget dictionary to the new appearance
                    // stream.
                    //
                    // Yet another option is to pre-populate field entries with dummy text. When 
                    // you edit the field values using PDFNet the new field appearances will match 
                    // the old ones.
                    doc.RefreshFieldAppearances();				

					doc.Save(output_path + "forms_test1.pdf", 0);

					Console.WriteLine("Done.");
				}
			}
			catch (PDFNetException e)
			{
				Console.WriteLine(e.Message);
			}

			//----------------------------------------------------------------------------------
			// Example 2: 
			// Fill-in forms / Modify values of existing fields.
			// Traverse all form fields in the document (and print out their names). 
			// Search for specific fields in the document.
			//----------------------------------------------------------------------------------
			try  
			{
				using (PDFDoc doc = new PDFDoc(output_path + "forms_test1.pdf"))
				{
					doc.InitSecurityHandler();

					FieldIterator itr;
					for(itr=doc.GetFieldIterator(); itr.HasNext(); itr.Next()) 
					{
						Field field = itr.Current();
                        string cur_field_name = field.GetName();
                        // Add one to the count for this field name for later processing
                        field_names[cur_field_name] = (field_names.ContainsKey(cur_field_name) ? field_names[cur_field_name] + 1 : 1);

                        Console.WriteLine("Field name: {0}", field.GetName());
						Console.WriteLine("Field partial name: {0}", field.GetPartialName());
                        string str_val = field.GetValueAsString();

						Console.Write("Field type: ");
						Field.Type type = field.GetType();
						switch(type)
						{
						case Field.Type.e_button: 
							Console.WriteLine("Button");
							break;
						case Field.Type.e_radio: 
							Console.WriteLine("Radio button: Value = " + str_val);
							break;
						case Field.Type.e_check: 
							field.SetValue(true);
							Console.WriteLine("Check box: Value = " + str_val);
							break;
						case Field.Type.e_text:
							{
								Console.WriteLine("Text"); 

								// Edit all variable text in the document
								String old_value = "none";
								if (field.GetValue() != null)
									old_value = field.GetValue().GetAsPDFText();

								field.SetValue("This is a new value. The old one was: " + old_value);
							}
							break;
						case Field.Type.e_choice:
							Console.WriteLine("Choice"); 
							break;
						case Field.Type.e_signature:
							Console.WriteLine("Signature"); 
							break;
						}

						Console.WriteLine("------------------------------");
					}

					// Search for a specific field
					Field fld = doc.GetField("employee.name.first");
					if (fld != null) 
					{
						Console.WriteLine("Field search for {0} was successful", fld.GetName());
					}
					else 
					{
						Console.WriteLine("Field search failed.");
					}

					// Regenerate field appearances.
					doc.RefreshFieldAppearances();
					doc.Save(output_path + "forms_test_edit.pdf", 0);
					Console.WriteLine("Done.");
				}
			}
			catch (PDFNetException e)
			{
				Console.WriteLine(e.Message);
			}

			//----------------------------------------------------------------------------------
			// Sample: Form templating
			// Replicate pages and form data within a document. Then rename field names to make 
			// them unique.
			//----------------------------------------------------------------------------------
			try  
			{
				// Sample: Copying the page with forms within the same document
				using (PDFDoc doc = new PDFDoc(output_path + "forms_test1.pdf"))
				{
					doc.InitSecurityHandler();

					Page src_page = doc.GetPage(1);
					doc.PagePushBack(src_page);  // Append several copies of the second page
					doc.PagePushBack(src_page);	 // Note that forms are successfully copied
					doc.PagePushBack(src_page);
                    doc.PagePushBack(src_page);

                    // Now we rename fields in order to make every field unique.
                    // You can use this technique for dynamic template filling where you have a 'master'
                    // form page that should be replicated, but with unique field names on every page. 
                    foreach (KeyValuePair<string, int> cur_field in field_names)
                    {
                        RenameAllFields(doc, cur_field.Key, cur_field.Value);
                    }

                    doc.Save(output_path + "forms_test1_cloned.pdf", 0);
					Console.WriteLine("Done.");
				}
			}
			catch (PDFNetException e)
			{
				Console.WriteLine(e.Message);
			}

			//----------------------------------------------------------------------------------
			// Sample: 
			// Flatten all form fields in a document.
			// Note that this sample is intended to show that it is possible to flatten
			// individual fields. PDFNet provides a utility function PDFDoc.FlattenAnnotations()
			// that will automatically flatten all fields.
			//----------------------------------------------------------------------------------
			try  
			{
				using (PDFDoc doc = new PDFDoc(output_path + "forms_test1.pdf"))
				{
					doc.InitSecurityHandler();

					bool auto = true;
					if (auto)
					{
						doc.FlattenAnnotations();
					}
					else  // Manual flattening 
					{
						// Traverse all pages
						PageIterator pitr = doc.GetPageIterator();
						for (; pitr.HasNext(); pitr.Next())
						{
							Page page = pitr.Current();
                            for (int i = page.GetNumAnnots() - 1; i >= 0; --i)
                            {
                                Annot annot = page.GetAnnot(i);
                                if (annot.GetType() == Annot.Type.e_Widget)
                                {
                                    annot.Flatten(page);
                                }
                            }
						}
					}

					doc.Save(output_path + "forms_test1_flattened.pdf", 0);
					Console.WriteLine("Done.");
				}
			}
			catch (PDFNetException e)
			{
				Console.WriteLine(e.Message);
			}
		}

        // field_nums has to be greater than 0.
        static void RenameAllFields(PDFDoc doc, String name, int field_nums = 1)
		{
			Field fld = doc.GetField(name);
			for (int counter = 1; fld != null; ++counter)
			{
                string field_new_name = name;
                int update_count = System.Convert.ToInt32(Math.Ceiling(counter / (double)field_nums));
                fld.Rename(name + "-" + update_count.ToString());
                fld = doc.GetField(name);
            }
		}

		static Obj CreateCustomButtonAppearance(PDFDoc doc, bool button_down) 
		{
			// Create a button appearance stream ------------------------------------
			using (ElementBuilder builder = new ElementBuilder())
			using (ElementWriter writer = new ElementWriter())
			{
				writer.Begin(doc); 

				// Draw background
				Element element = builder.CreateRect(0, 0, 101, 37);
				element.SetPathFill(true);
				element.SetPathStroke(false);
				element.GetGState().SetFillColorSpace(ColorSpace.CreateDeviceGray());
				element.GetGState().SetFillColor(new ColorPt(0.75, 0.0, 0.0));
				writer.WriteElement(element); 

				// Draw 'Submit' text
				writer.WriteElement(builder.CreateTextBegin()); 
		
				element = builder.CreateTextRun("Submit", Font.Create(doc, Font.StandardType1Font.e_helvetica_bold), 12);
				element.GetGState().SetFillColor(new ColorPt(0, 0, 0));

				if (button_down) 
					element.SetTextMatrix(1, 0, 0, 1, 33, 10);
				else 
					element.SetTextMatrix(1, 0, 0, 1, 30, 13);
				writer.WriteElement(element);
				writer.WriteElement(builder.CreateTextEnd());

				Obj stm = writer.End();

				// Set the bounding box
				stm.PutRect("BBox", 0, 0, 101, 37);
				stm.PutName("Subtype", "Form");
				return stm;
			}
		}
	}
}
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