'''' This code is part of Document Solutions for PDF .NET demos.'' Copyright (c) MESCIUS inc. All rights reserved.''Imports System.IOImports GrapeCity.Documents.PdfImports GrapeCity.Documents.Pdf.AcroFormsImports GrapeCity.Documents.Pdf.Spec
'' This example shows how to load a password protected PDF Form without specifying the password,'' and change the value of a text field and a comb-text field in the form.'' The modified PDF is saved and re-opened with the password so that we can show it in the demo.Public Class NoPassSetFormFields    Public Function CreatePDF(ByVal stream As Stream) As Integer        Using fsSrc = File.OpenRead(Path.Combine("Resources", "PDFs", "FormFields-password-user.pdf"))            '' Set up DecryptionOptions to allow loading password protected PDFs without password:            Dim dopt = New DecryptionOptions() With {.ThrowExceptionIfInvalidPassword = False}            Dim docSrc = New GcPdfDocument()            docSrc.Load(fsSrc, dopt)
            '' Change the value of CheckBoxField.            '            ' Note 1:            ' We cannot access the fields by names, like:            '   doc.AcroForm.Fields["cbf1"];            ' because strings in a password protected PDF are encrypted            ' and cannot be accessed without specifying the password.            ' The only way is to access fields by indices.            Dim cbf = DirectCast(docSrc.AcroForm.Fields(0), CheckBoxField)            cbf.Checked = True
            '' Change the value of RadioButtonField:            Dim rbf = DirectCast(docSrc.AcroForm.Fields(1), RadioButtonField)            Dim values = rbf.GetCheckedAppearanceStreamNames()            rbf.Value = values(0)
            '' Change the value of the TextField, set it to the current date/time:            Dim tf = DirectCast(docSrc.AcroForm.Fields(2), TextField)            ' Note 2:            ' The value of a TextField is specified as a string, but it is not possible            ' to work with strings in a password protected PDF without specifying the password.            ' In such cases it is possible to use a workaround to set it using PdfName,            ' while it is not compliant with the PDF specification,            ' at least Adobe Acrobat supports this scenario:            tf.PdfValue = New PdfName(Util.TimeNow().ToString())
            '' Change the value of a CombTextField to a random string:            Dim ctf = DirectCast(docSrc.AcroForm.Fields(3), CombTextField)            Dim val = Util.LoremIpsum(1, 1, 1, 2, 3)            val = val.Substring(0, Math.Min(val.Length, 10))            ctf.PdfValue = New PdfName(val)
            '' Note 3: appearance streams cannot be generated in a password protected PDF            ' that was loaded without specifying the password, so we set            ' the NeedAppearances entry of the AcroForm, which instructs Acrobat to generate            ' the missing appearance streams:            docSrc.AcroForm.Set(PdfName.Std.NeedAppearances, PdfBool.True)
            '' Demo site specific:            ' We save the modified password protected document to a temp file,            ' and load it again with the password, so that the demo site can show it            ' without asking the user for a password:            Dim fn = Path.GetTempFileName()            docSrc.Save(fn)            Dim doc = New GcPdfDocument()            Using fs = File.OpenRead(fn)                doc.Load(fs, "user")                doc.Save(stream)            End Using            File.Delete(fn)            '' Done:            Return docSrc.Pages.Count        End Using    End FunctionEnd Class