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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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Step 2: Add the code:

//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2018 by PDFTron Systems Inc. All Rights Reserved.
// Consult legal.txt regarding legal and license information.
//---------------------------------------------------------------------------------------

#include <PDF/PDFNet.h>
#include <PDF/PDFDoc.h>
#include <PDF/Annot.h>
#include <PDF/Field.h>
#include <PDF/ElementBuilder.h>
#include <PDF/ElementWriter.h>

#include <iostream>

using namespace std;
using namespace pdftron;
using namespace SDF;
using namespace PDF;


//---------------------------------------------------------------------------------------
// This sample illustrates basic PDFNet capabilities related to interactive 
// forms (also known as AcroForms). 
//---------------------------------------------------------------------------------------

void RenameAllFields(PDFDoc& doc, const UString& name)
{
	char tmp[32];
	FieldIterator itr = doc.GetFieldIterator(name);
	for (int counter=0; itr.HasNext();
		itr=doc.GetFieldIterator(name), ++counter)
	{
		Field f = itr.Current();
		sprintf(tmp, "%d", counter);
		f.Rename(name + tmp);		
	}
}

enum CheckStyle {
	e_check,
	e_circle,
	e_cross,
	e_diamond,
	e_square,
	e_star
}; 

// Note: The visual appearance of check-marks and radio-buttons in PDF documents is 
// not limited to CheckStyle-s. It is possible to create a visual appearance using 
// arbitrary glyph, text, raster image, or path object. Although most PDF producers 
// limit the options to the above 'standard' styles, using PDFNet you can generate 
// arbitrary appearances.
Obj CreateCheckmarkAppearance(PDFDoc& doc, CheckStyle style) 
{
	// Create a checkmark appearance stream ------------------------------------
	ElementBuilder build;
	ElementWriter writer;
	writer.Begin(doc);
	writer.WriteElement(build.CreateTextBegin());

	char symbol;
	switch (style) {
		case e_circle: symbol = '\154'; break;
		case e_diamond: symbol = '\165'; break;
		case e_cross: symbol = '\65'; break;
		case e_square: symbol = '\156'; break;
		case e_star: symbol = '\110'; break;
			// ...
			// See section D.4 "ZapfDingbats Set and Encoding" in PDF Reference Manual 
			// (http://www.pdftron.com/downloads/PDFReference16.pdf) for the complete 
			// graphical map for ZapfDingbats font. Please note that all character codes
			// are represented using the 'octal' notation.
		default:  // e_check
			symbol = '\64';
	}

	Element checkmark = build.CreateTextRun(&symbol, 1, Font::Create(doc, PDF::Font::e_zapf_dingbats), 1);
	writer.WriteElement(checkmark);
	writer.WriteElement(build.CreateTextEnd());

	Obj stm = writer.End();
	stm.PutRect("BBox", -0.2, -0.2, 1, 1); // Clip
	stm.PutName("Subtype", "Form");
	return stm;
}

Obj CreateButtonAppearance(PDFDoc& doc, bool button_down) 
{
	// Create a button appearance stream ------------------------------------
	ElementBuilder build;
	ElementWriter writer;
	writer.Begin(doc); 

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

	// Draw 'Submit' text
	writer.WriteElement(build.CreateTextBegin()); 
	{
		const char* text = "Submit";
		element = build.CreateTextRun(text, UInt32(strlen(text)), Font::Create(doc, PDF::Font::e_helvetica_bold), 12);
		element.GetGState().SetFillColor(ColorPt(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(build.CreateTextEnd());

	Obj stm = writer.End(); 

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

int main(int argc, char *argv[])
{
	int ret = 0;
	PDFNet::Initialize();

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

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

		// Create new fields.
		Field emp_first_name = doc.FieldCreate("employee.name.first", Field::e_text, "John", "");
		Field emp_last_name = doc.FieldCreate("employee.name.last", Field::e_text, "Doe", "");
		Field emp_last_check1 = doc.FieldCreate("employee.name.check1", Field::e_check, "Yes", "");

		Field submit = doc.FieldCreate("submit", Field::e_button);

		// Create page annotations for the above fields.

		// Create text annotations
		Annots::Widget annot1 = Annots::Widget::Create(doc, Rect(50, 550, 350, 600), emp_first_name);
		Annots::Widget annot2 = Annots::Widget::Create(doc, Rect(50, 450, 350, 500), emp_last_name);

		// Create a check-box annotation
		Annots::Widget annot3 = Annots::Widget::Create(doc, Rect(64, 356, 120, 410), emp_last_check1);
		// Set the annotation appearance for the "Yes" state...
		// NOTE: if we call RefreshFieldAppearances after this the appearance will be discarded
		annot3.SetAppearance(CreateCheckmarkAppearance(doc, e_check), Annot::e_normal, "Yes");
		
		// Create button annotation
		Annots::Widget annot4 = Annots::Widget::Create(doc, Rect(64, 284, 163, 320), submit);
		// Set the annotation appearances for the down and up state...
		annot4.SetAppearance(CreateButtonAppearance(doc, false), Annot::e_normal);
		annot4.SetAppearance(CreateButtonAppearance(doc, true), Annot::e_down);
		
		// Create 'SubmitForm' action. The action will be linked to the button.
		FileSpec url = FileSpec::CreateURL(doc, "http://www.pdftron.com");
		Action button_action = Action::CreateSubmitForm(url);

		// Associate the above action with 'Down' event in annotations action dictionary.
		Obj annot_action = annot4.GetSDFObj().PutDict("AA");
		annot_action.Put("D", button_action.GetSDFObj());

		blank_page.AnnotPushBack(annot1);  // Add annotations to the page
		blank_page.AnnotPushBack(annot2);
		blank_page.AnnotPushBack(annot3);
		blank_page.AnnotPushBack(annot4);

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

		// 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.GetAcroForm().PutBool("NeedAppearances", true);
		// NOTE: RefreshFieldAppearances will replace previously generated appearance streams
		doc.RefreshFieldAppearances();

		doc.Save((output_path + "forms_test1.pdf").c_str(), 0, 0);
		cout << "Done." << endl;
	}
	catch(Common::Exception& e)
	{
		cout << e << endl;
		ret = 1;
	}
	catch(...)
	{
		cout << "Unknown Exception" << endl;
		ret = 1;
	}

	//----------------------------------------------------------------------------------
	// 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  
	{
		PDFDoc doc((output_path + "forms_test1.pdf").c_str());
		doc.InitSecurityHandler();

		FieldIterator itr = doc.GetFieldIterator();
		for(; itr.HasNext(); itr.Next()) 
		{
			cout << "Field name: " << itr.Current().GetName() << endl;
			cout << "Field partial name: " << itr.Current().GetPartialName() << endl;

			cout << "Field type: ";
			Field::Type type = itr.Current().GetType();
			UString str_val = itr.Current().GetValueAsString();

			switch(type)
			{
			case Field::e_button: 
				cout << "Button" << endl; 
				break;
			case Field::e_radio: 
				cout << "Radio button: Value = " << str_val << endl; 
				break;
			case Field::e_check: 
				itr.Current().SetValue(true);
				cout << "Check box: Value = " << str_val << endl; 
				break;
			case Field::e_text: 
				{
					cout << "Text" << endl;
					// Edit all variable text in the document
					itr.Current().SetValue(UString("This is a new value. The old one was: ") + str_val);
				}
				break;
			case Field::e_choice: cout << "Choice" << endl; break;
			case Field::e_signature: cout << "Signature" << endl; break;
			}

			cout << "------------------------------" << endl;
		}

		// Search for a specific field
		Field f = doc.GetField("employee.name.first");
		if (f) 
		{
			cout << "Field search for " << f.GetName() << " was successful" << endl;
		}
		else 
		{
			cout << "Field search failed" << endl;
		}

		// Regenerate field appearances.
		doc.RefreshFieldAppearances();
		doc.Save((output_path + "forms_test_edit.pdf").c_str(), 0, NULL);
		cout << "Done." << endl;
	}
	catch(Common::Exception& e)
	{
		cout << e << endl;
		ret = 1;
	}
	catch(...)
	{
		cout << "Unknown Exception" << endl;
		ret = 1;
	}

	//----------------------------------------------------------------------------------
	// 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
		PDFDoc doc((output_path + "forms_test1.pdf").c_str());
		doc.InitSecurityHandler();

		Page src_page = doc.GetPage(1);
		doc.PagePushBack(src_page);  // Append several copies of the first 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. 
		RenameAllFields(doc, "employee.name.first");
		RenameAllFields(doc, "employee.name.last");
		RenameAllFields(doc, "employee.name.check1");
		RenameAllFields(doc, "submit");

		doc.Save((output_path + "forms_test1_cloned.pdf").c_str(), 0, 0);
		cout << "Done." << endl;
	}
	catch(Common::Exception& e)
	{
		cout << e << endl;
		ret = 1;
	}
	catch(...)
	{
		cout << "Unknown Exception" << endl;
		ret = 1;
	}

	//----------------------------------------------------------------------------------
	// 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  
	{
		PDFDoc doc((output_path + "forms_test1.pdf").c_str());
		doc.InitSecurityHandler();

		// Traverse all pages
		if (true) {
			doc.FlattenAnnotations();
		}
		else // Manual flattening
		{			
			
			for (PageIterator pitr = doc.GetPageIterator(); 
				pitr.HasNext(); pitr.Next())  
			{
				Page page = pitr.Current();
				Obj annots = page.GetAnnots();
				if (annots)
				{	// Look for all widget annotations (in reverse order)
					for (int i = int(annots.Size())-1; i>=0; --i)
					{
						if (!strcmp(annots.GetAt(i).Get("Subtype").Value().GetName(), "Widget"))
						{
							Field field(annots.GetAt(i));
							field.Flatten(page);

							// Another way of making a read only field is by modifying 
							// field's e_read_only flag: 
							//    field.SetFlag(Field::e_read_only, true);
						}
					}
				}
			}
		}

		doc.Save((output_path + "forms_test1_flattened.pdf").c_str(), 0, 0);
		cout << "Done." << endl;
	}
	catch(Common::Exception& e)
	{
		cout << e << endl;
		ret = 1;
	}
	catch(...)
	{
		cout << "Unknown Exception" << endl;
		ret = 1;
	}

	PDFNet::Terminate();
	return ret;
}