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.
Example





In This Topic
GdPicture14 Namespace / GdPicturePDF Class / SetFormFieldsNeedAppearances Method

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
'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 GdPicturePDF.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. 
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();
Example
How to force form fields appearance reconstruction during the rendering process. 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();
See Also

Reference

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