Introduction
Universal Windows Store
application project provides a good way to share code and develop Windows Phone
and Windows Store version of the application at the same time. In case of our
library it’s even more fun because API remains the same and you can use the
same PDF .NET library for both projects.
PDF files can contain forms
consisting of fields where the information can be stored for later use and
processing. If you’d like to read more about PDF forms and fields, official PDF
specification is an invaluable resource. This topic is also covered in our pdf
cookbook “Apitron PDF Kit in action” (available for free by the following link), see
sections 3.7 “Interactive Forms” and
section 4.4 “Content Element And
Controls”. There are examples on how to create, edit or read data stored in
PDF forms, written in C# with detailed explanation.
A good example demonstrating how
to work with PDF forms is a questionnaire app gathering some data from the user
and storing it in PDF document as a form. So we decided to go through and
prepared sample universal app using our Apitron PDF Kit library that generates,
saves and loads product questionnaire data.
Solution overview
To keep this sample as simple as
possible we used single XAML page representing form layout and providing the data
bound view for questionnaire data.
Data Model
Data model is represented by base
class called ProductQuestionnaireForm and
by its specific implementation ApitronProductQuestionnaireForm.
See the diagram below.
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Pic. 1 Class digram, Apitron questionnaire sample
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Page controls are bound to properties of ApitronProductQuestionnaireForm instance,
so we don’t have to write any code to handle form updates if user changes their
content.
Windows Phone App
The view is represented by XAML
app page, see picture below showing desktop and phone versions. They are almost
identical and use same markup except some minor changes needed to fit content
on the phone screen.
 |
Pic. 2 Questionnaire App, Windows Phone version
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Windows Store App
Form
layout for Windows Store app is shown here, below is a screenshot from Visual
Studio XAML designer.
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Pic. 3 Questionnaire app, Windows Store version
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Workflow
Using this app the user can fill
the questionnaire form provided, in our case it’s a test form collecting
opinions about Apitron products. After that, he can save entered data to local
app storage as PDF form or load an existing form from it.
For simplicity, data is being
saved as file “form.pdf” located in local
app folder, which can be opened by using the following “known” folder: ApplicationData.Current.LocalFolder.
Output
Generated questionnaire pdf form
is shown on the image below. Both applications generate identical PDF files.
 |
Pic. 4 Generated questionnaire pdf form
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This file can be found by the following path:
C:\Users\[user name]\AppData\Local\Packages\[deployed
package guid]\LocalState\form.pdf
Same form but opened in design
mode is shown below. You can see field names assigned to each widget annotation
present on page. Widget annotations are special kind of controls used to define
visual representation of form fields data. In our case all controls created for
this PDF form are made read-only, however it’s possible to make form data
editable after generation if needed.
 |
Pic. 5 Generated questionnaire pdf form opened in design mode
|
The code
Complete app sample can be found
in Apitron PDF Kit download package available on our website, check out this link.
Here we’d like to highlight PDF specific code that is
responsible for form generation. It can be found in ProductQuestionnaireForm class and is provided below.
PDF Form generation and saving
/// <summary>
/// Creates FlowDocument that represents PDF form.
/// </summary>
private FlowDocument CreatePDFDocument()
{
FlowDocument document = new FlowDocument(){Margin = new Apitron.PDF.Kit.Styles.Thickness(10)};
// add
form fields and set text values based on form data
document.Fields.Add(new TextField("SelectedProduct",
SelectedProduct){IsReadOnly = true});
document.Fields.Add(new TextField("UsagePeriod",
UsagePeriod) { IsReadOnly = true });
document.Fields.Add(new TextField("SatisfactionLevel", SatisfactionLevel) { IsReadOnly = true });
document.Fields.Add(new TextField("UserCompanyName",
UserCompanyName) { IsReadOnly = true });
document.Fields.Add(new TextField("Feedback",
Feedback) { IsReadOnly = true, IsMultiline = true});
//
register styles defining controls appearance
document.StyleManager.RegisterStyle(".formHeader",new Apitron.PDF.Kit.Styles.Style()
{Display
= Display.Block,
Font = new Font(StandardFonts.HelveticaBold,
20)});
document.StyleManager.RegisterStyle("TextBlock, TextBox", new Apitron.PDF.Kit.Styles.Style()
{
Font = new Font(StandardFonts.Helvetica,
14)});
document.StyleManager.RegisterStyle("TextBlock + TextBox", new Apitron.PDF.Kit.Styles.Style()
{
BorderColor = RgbColors.Black, Border = new Border(1), Height = 20, Background = RgbColors.LightGray});
document.StyleManager.RegisterStyle("Br", new Apitron.PDF.Kit.Styles.Style() { Height = 10});
// add
document content elements
document.Add(new TextBlock("Product questionnaire
form"){Class = "formHeader"});
document.Add(new TextBlock("Generated on " + DateTime.Now.ToString("dd/MM/yyyy
HH:mm")));
document.Add(new Hr(){Height = 2, Margin = new Thickness(0,5,0,5)});
document.Add(new TextBlock("Selected
product:"));
document.Add(new TextBox("SelectedProduct"));
document.Add(new Br());
document.Add(new TextBlock("Usage period:"));
document.Add(new TextBox("UsagePeriod"));
document.Add(new Br());
document.Add(new TextBlock("SatisfactionLevel:"));
document.Add(new TextBox("SatisfactionLevel"));
document.Add(new Br());
document.Add(new TextBlock("User company
name:"));
document.Add(new TextBox("UserCompanyName"));
document.Add(new Br());
document.Add(new TextBlock("Feedback:"));
document.Add(new TextBox("Feedback"){Height = 100});
return document;
}
/// <summary>
/// Saves current form data to local storage.
/// </summary>
public async Task<bool> SaveToLocalStorage(string fileName)
{
try
{
FlowDocument pdfDocument = CreatePDFDocument();
StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync(fileName,CreationCollisionOption.ReplaceExisting);
using (Stream outputStream = await file.OpenStreamForWriteAsync())
{
pdfDocument.Write(outputStream, new ResourceManager(), new PageBoundary(Boundaries.A4));
}
}
catch (Exception e)
{
Debug.WriteLine(e.Message);
return false;
}
return true;
}
Loading stored PDF form data
/// <summary>
/// Load form data from PDF file using given filename.
/// </summary>
public static async Task<ProductQuestionnaireForm> LoadFromLocalStorage(string fileName)
{
try
{
StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync(fileName);
using (Stream inputStream = await file.OpenStreamForReadAsync())
{
// use
fixed document for reading form data
FixedDocument pdfDocument = new FixedDocument(inputStream);
//
create and initialize form object instance
ProductQuestionnaireForm form = new ApitronProductQuestionnaireForm();
form.SelectedProduct = ((TextField)pdfDocument.AcroForm["SelectedProduct"]).Text;
form.UsagePeriod = ((TextField)pdfDocument.AcroForm["UsagePeriod"]).Text;
form.SatisfactionLevel = ((TextField)pdfDocument.AcroForm["SatisfactionLevel"]).Text;
form.UserCompanyName = ((TextField)pdfDocument.AcroForm["UserCompanyName"]).Text;
form.Feedback = ((TextField)pdfDocument.AcroForm["Feedback"]).Text;
return form;
}
}
catch (Exception e)
{
Debug.WriteLine(e.Message);
}
return null;
}
Conclusion
This
approach can be used to create PDF forms in Windows Forms, WPF, Xamarin
(Android and iOS), console, web or cloud applications. As you can see from
samples above it takes less than 30 lines
of code to produce a basic form having all necessary content set.
But Apitron
PDF Kit library is not limited to just PDF forms, it provides full support for
PDF features defined in official specification and can be used to create apps
targeting all of the modern mobile, desktop or web platforms. Free evaluation is available for all our
products.
We’d be
happy to get any feedback from you, feel free to contact our support with any
questions you may have.
Downloadable version of this article can be found by the following link [PDF].
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