Modifying AcroForm

Clear Text in Form

This example demonstrates how to clear text from Typewriter form fields in a PDF using Aspose.PDF for Python via .NET. It scans the first page of the PDF, identifies Typewriter forms, removes their content, and saves the updated document. This approach is useful for resetting or sanitizing form fields before redistributing a PDF.

1. Load the input PDF document.
2. Access forms on the first page.
3. Iterate over each form and check if it is a Typewriter form.
4. Use TextFragmentAbsorber to find text fragments in the form.
5. Clear the text of each fragment.
6. Save the modified PDF to the output file.

    import aspose.pdf as ap
    from aspose.pycore import cast, is_assignable

    dataDir = "path/to/your/data/dir/"
    path_infile = dataDir + infile
    path_outfile = dataDir + outfile
    document = ap.Document(path_infile)

    # Get the forms from the first page
    forms = document.pages[1].resources.forms

    for form in forms:
        # Check if the form is of type "Typewriter" and subtype "Form"
        if (form.it == "Typewriter" and form.subtype == "Form"):
            # Create a TextFragmentAbsorber to find text fragments
            absorber = ap.Text.TextFragmentAbsorber()
            absorber.visit(form)

            # Clear the text in each fragment
            for fragment in absorber.text_fragments:
                fragment.Text = ""

    # Save PDF document
    document.save(path_outfile)

Get or Set Field Limit

The FormEditor class set_field_limit(field, limit) method allows you to set a field limit, the maximum number of characters that can be entered into a field.

    import aspose.pdf as ap
    from aspose.pycore import cast, is_assignable

    # The path to the documents directory
    data_dir = "/path/to/your/pdf/files/"
    path_infile = os.path.join(work_dir, infile)
    path_outfile = os.path.join(work_dir, outfile)

    # Create FormEditor instance
    form = ap.facades.FormEditor()

    # Bind PDF document
    form.bind_pdf(path_infile)

    # Set field limit for "First Name"
    form.set_field_limit("First Name", 15)

    # Save PDF document
    form.save(path_outfile)

Similarly, Aspose.PDF has a method that gets the field limit.

    import aspose.pdf as ap
    from aspose.pycore import cast, is_assignable

    # The path to the documents directory
    data_dir = "/path/to/your/pdf/files/"
    path_infile = os.path.join(work_dir, infile)

    document = ap.Document(path_infile)
    if is_assignable(document.form[1], ap.forms.TextBoxField):
        textBoxField = cast(ap.forms.TextBoxField, document.form[1])
        print(f"Limit: {textBoxField.max_len}")

Set Custom Font for the Form Field

Form fields in Adobe PDF files can be configured to use specific default fonts. In the early versions of Aspose.PDF, only the 14 default fonts were supported. Later releases allowed developers to apply any font.

This code updates the appearance of a text box field in a PDF form by setting a custom font, size, and color, and then saves the modified document using Aspose.PDF for Python via .NET.

The following code snippet shows how to set the default font for PDF form fields.

    import aspose.pdf as ap
    from aspose.pycore import cast, is_assignable

    data_dir = "/path/to/your/pdf/files/"
    path_infile = os.path.join(work_dir, infile)
    path_outfile = os.path.join(work_dir, outfile)

    document = ap.Document(path_infile)
    if is_assignable(document.form[1], ap.forms.TextBoxField):
        textBoxField = cast(ap.forms.TextBoxField, document.form[1])
        font = ap.text.FontRepository.find_font("Calibri")
        textBoxField.default_appearance = ap.annotations.DefaultAppearance(font, 10, ap.Color.black.to_rgb())

    document.save(path_outfile)

Remove fields in existing form

This code removes a specific form field (by its name) from a PDF document and saves the updated file using Aspose.PDF for Python via .NET.

1. Load the PDF document.
2. Delete a form field by name.
3. Save the updated PDF.

    import aspose.pdf as ap
    from aspose.pycore import cast, is_assignable

    data_dir = "/path/to/your/pdf/files/"
    path_infile = os.path.join(work_dir, infile)
    path_outfile = os.path.join(work_dir, outfile)

    document = ap.Document(path_infile)
    # Delete a particular field by name
    document.form.delete("First Name")
    # Save PDF document
    document.save(path_outfile)