Form Exporter

In this article, we will show you how to use the FormFlattener plugin, which can flatten form fields in PDF files.

Prerequisites

You will need the following:

  • Visual Studio 2019 or later
  • Aspose.PDF for .NET 21.1 or later
  • A sample PDF file that contains some form fields

You can download the Aspose.PDF for .NET library from the official website or install them using the NuGet Package Manager in Visual Studio.

Steps

The basic steps to flatten form fields in PDF files using the FormFlattener plugin are:

  1. Create an object of the FormFlattener class
  2. Create an object of the FormFlattenAllFieldsOptions or FormFlattenSelectedFieldsOptions class, depending on whether you want to flatten all or some fields
  3. Add the input and output data sources to the options object
  4. Run the Process method of the FormFlattener object

Let’s see how to implement these steps in C# code.

Step 1: Create an object of the FormFlattener class

The FormFlattener class is the main class that provides the functionality of flattening form fields in PDF files. To use it, you need to create an instance of it using the default constructor:

// Create an instance of the FormFlattener plugin
var plugin = new FormFlattener();

Step 2: Create an object of the FormFlattenAllFieldsOptions or FormFlattenSelectedFieldsOptions class, depending on whether you want to flatten all or some fields

The FormFlattenAllFieldsOptions and FormFlattenSelectedFieldsOptions classes are helper classes that allow you to specify various options and parameters for the flattening process. The FormFlattenAllFieldsOptions class flattens all the form fields in the PDF file, while the FormFlattenSelectedFieldsOptions class flattens only the form fields that match a given predicate. To use these classes, you need to create an instance of the appropriate class using the default constructor or passing a predicate as a parameter. For example, to flatten all the form fields in the PDF file, you can use the following code:

// Create options for flattening all fields
var options = new FormFlattenAllFieldsOptions();

To flatten only the form fields whose lower-left x-coordinate is greater than 300, you can use the following code:

// Create options for flattening selected fields
var options = new FormFlattenSelectedFieldsOptions((field) => field.Rect.LLX > 300);

Step 3: Add the input and output data sources to the options object

The input and output data sources are the PDF files that you want to flatten and save. They can be either file paths or streams. To add them to the options object, you need to use the Inputs and Outputs properties of the options class. These properties are collections of data sources that you can add using the Add method. For example, to flatten a PDF file named sample.pdf in the current folder and save it as sample-flat.pdf in the same folder, you can use the following code:

// Add input and output data sources to the options
options.Inputs.Add(new FileDataSource("sample.pdf"));
options.Outputs.Add(new FileDataSource("sample-flat.pdf"));

Step 4: Run the Process method of the FormFlattener object

The final step is to run the Process method of the FormFlattener object, passing the options object as a parameter. This method will perform the flattening process and return a ResultContainer object, which contains the results of the process, such as the status, the messages, the output data sources, etc. You can access the results using the properties and methods of the ResultContainer class. For example, to get the first result from the result collection and print it to the console, you can use the following code:

// Process the options and get the result container
var resultContainer = plugin.Process(options);

// Get the first result from the result container
var result = resultContainer.ResultCollection[0];

// Print the result
Console.WriteLine(result);

The result will contain information such as output file paths.

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