SetFormFieldsNeedAppearances Method (GdPicturePDF)

In This Topic

Sets the value of NeedAppearances flag related to interactive form fields in the currently loaded PDF document.

Sometimes fields may contain values that are not know until the document is viewed. This flag specifies whether to construct appearance streams and appearance dictionaries for form fields in the loaded document to properly render the document when viewing.

Syntax

Visual Basic
C#
Delphi
JScript
Managed Extensions for C++
C++/CLI

'Declaration
 
Public Function SetFormFieldsNeedAppearances( _
   ByVal NeedAppearances As Boolean _
) As GdPictureStatus

public GdPictureStatus SetFormFieldsNeedAppearances( 
   bool NeedAppearances
)

public function SetFormFieldsNeedAppearances( 
    NeedAppearances: Boolean
): GdPictureStatus;

public function SetFormFieldsNeedAppearances( 
   NeedAppearances : boolean
) : GdPictureStatus;

public: GdPictureStatus SetFormFieldsNeedAppearances( 
   bool NeedAppearances
)

public:
GdPictureStatus SetFormFieldsNeedAppearances( 
   bool NeedAppearances
)

Parameters

NeedAppearances: Set this parameter to true, if you want to enable the NeedAppearances flag, otherwise set it to false to disable it. Setting this flag to true can improve rendering of incorrectly constructed form fields appearances for proper document viewing.

Return Value

A member of the GdPictureStatus enumeration. If the method has been successfully followed, then the return value is GdPictureStatus.OK.

We strongly recommend always checking this status first.

Remarks

This method is only allowed for use with non-encrypted documents.

Just to inform you, that this flag is only related to interactive form fields, if any are present in the currently loaded PDF document. Please use the GetFormFieldsNeedAppearances method to find out if form fields appearances need to be constructed before viewing.

Example

How to force form fields appearance reconstruction during the rendering process.

VB.NET
C#

Dim caption As String = "Example: SetFormFieldsNeedAppearances"
Dim gdpicturePDF As GdPicturePDF = New GdPicturePDF()
Dim gdpictureImaging As GdPictureImaging = New GdPictureImaging()
If gdpicturePDF.LoadFromFile("test.pdf", False) = GdPictureStatus.OK Then
    Dim formsCount As Integer = gdpicturePDF.GetFormFieldsCount()
    If gdpicturePDF.GetStat() = GdPictureStatus.OK Then
        If formsCount > 0 Then
            If (gdpicturePDF.GetFormFieldsNeedAppearances() = False) AndAlso
               (gdpicturePDF.GetStat() = GdPictureStatus.OK) Then
                'Forcing the toolkit to construct form fields appearances for proper rendering.
                gdpicturePDF.SetFormFieldsNeedAppearances(True)
            End If
        End If
        If gdpicturePDF.GetStat() = GdPictureStatus.OK Then
            Dim count As Integer = gdpicturePDF.GetPageCount()
            If gdpicturePDF.GetStat() = GdPictureStatus.OK Then
                Dim message As String = ""
                Dim image_index As Integer = 0
                Dim filename As String = "image_page0.png"
                For i As Integer = 1 To count
                    If gdpicturePDF.SelectPage(i) = GdPictureStatus.OK Then
                        image_index = gdpicturePDF.RenderPageToGdPictureImage(200, True)
                        If gdpicturePDF.GetStat() = GdPictureStatus.OK Then
                            filename = filename.Replace((i - 1).ToString(), i.ToString())
                            If gdpictureImaging.SaveAsPNG(image_index, filename) = GdPictureStatus.OK Then
                                message = message + "The image of the page nr." + i.ToString() + " has been successfully saved." + vbCrLf
                            Else
                                message = message + "The SaveAsPNG() method has failed for the page nr." + i.ToString() + " with the status: " + gdpicturePDF.GetStat().ToString() + vbCrLf
                            End If
            
                            gdpictureImaging.ReleaseGdPictureImage(image_index)
                        Else
                            message = message + "The RenderPageToGdPictureImage() method has failed for the page nr." + i.ToString() + " with the status: " + gdpicturePDF.GetStat().ToString() + vbCrLf
                        End If
                    Else
                        message = message + "The SelectPage() method has failed for the page nr." + i.ToString() + " with the status: " + gdpicturePDF.GetStat().ToString() + vbCrLf
                    End If
                Next
                MessageBox.Show(message, caption)
            Else
                MessageBox.Show("The GetPageCount() method has failed with the status: " + gdpicturePDF.GetStat().ToString(), caption)
            End If
        Else
            MessageBox.Show("The handling of form fields appearance flag has failed with the status: " + gdpicturePDF.GetStat().ToString(), caption)
        End If
    Else
        MessageBox.Show("The GetFormFieldsCount() method has failed with the status: " + gdpicturePDF.GetStat().ToString(), caption)
    End If
Else
    MessageBox.Show("The file can't be loaded.", caption)
End If
gdpictureImaging.Dispose()
gdpicturePDF.Dispose()

string caption = "Example: SetFormFieldsNeedAppearances";
GdPicturePDF gdpicturePDF = new GdPicturePDF();
GdPictureImaging gdpictureImaging = new GdPictureImaging();
if (gdpicturePDF.LoadFromFile("test.pdf", false) == GdPictureStatus.OK)
{
    int formsCount = gdpicturePDF.GetFormFieldsCount();
    if (gdpicturePDF.GetStat() == GdPictureStatus.OK)
    {
        if (formsCount > 0)
        {
            if ((gdpicturePDF.GetFormFieldsNeedAppearances() == false) &&
                (gdpicturePDF.GetStat() == GdPictureStatus.OK))
                //Forcing the toolkit to construct form fields appearances for proper rendering.
                gdpicturePDF.SetFormFieldsNeedAppearances(true);
        }
        if (gdpicturePDF.GetStat() == GdPictureStatus.OK)
        {
            int count = gdpicturePDF.GetPageCount();
            if (gdpicturePDF.GetStat() == GdPictureStatus.OK)
            {
                string message = "";
                int image_index = 0;
                string filename = "image_page0.png";
                for (int i = 1; i <= count; i++)
                {
                    if (gdpicturePDF.SelectPage(i) == GdPictureStatus.OK)
                    {
                        image_index = gdpicturePDF.RenderPageToGdPictureImage(200, true);
                        if (gdpicturePDF.GetStat() == GdPictureStatus.OK)
                        {
                            filename = filename.Replace((i - 1).ToString(), i.ToString());
                            if (gdpictureImaging.SaveAsPNG(image_index, filename) == GdPictureStatus.OK)
                                message = message + "The image of the page nr." + i.ToString() + " has been successfully saved.\n";
                            else
                                message = message + "The SaveAsPNG() method has failed for the page nr." + i.ToString() + " with the status: " + gdpicturePDF.GetStat().ToString() + "\n";
                            gdpictureImaging.ReleaseGdPictureImage(image_index);
                            //Or you can use this one:
                            //GdPictureDocumentUtilities.DisposeImage(image_index)
                        }
                        else
                            message = message + "The RenderPageToGdPictureImage() method has failed for the page nr." + i.ToString() + " with the status: " + gdpicturePDF.GetStat().ToString() + "\n";
                    }
                    else
                        message = message + "The SelectPage() method has failed for the page nr." + i.ToString() + " with the status: " + gdpicturePDF.GetStat().ToString() + "\n";
                }
                MessageBox.Show(message, caption);
            }
            else
                MessageBox.Show("The GetPageCount() method has failed with the status: " + gdpicturePDF.GetStat().ToString(), caption);
        }
        else
            MessageBox.Show("The handling of form fields appearance flag has failed with the status: " + gdpicturePDF.GetStat().ToString(), caption);
    }
    else
        MessageBox.Show("The GetFormFieldsCount() method has failed with the status: " + gdpicturePDF.GetStat().ToString(), caption);
}
else
    MessageBox.Show("The file can't be loaded.", caption);
gdpictureImaging.Dispose();
gdpicturePDF.Dispose();

Reference

GdPicturePDF Class
GdPicturePDF Members
GetFormFieldsNeedAppearances Method
GetFormFieldsCount Method
RemoveFormFields Method
FlattenFormFields Method