SetBlendMode Method (GdPicturePDF)

In This Topic

Sets the blending mode, that defines the function used in the compositing formula to customize the blending operation for all subsequent drawing operations. The initial value is set to normal.

Blending modes are used to determine how two layers are blended into each other (affect one another) through more complex methods. Some blending modes exist to create special effects, some are used to give you more control when using adjustment layers to correct photographs.

The blend mode parameter is one of the graphics state parameters. These parameters are initialized to their default values at the beginning of each page (see PDF Reference, Section "Graphics State").

Syntax

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

'Declaration
 
Public Function SetBlendMode( _
   ByVal BlendMode As PdfBlendMode _
) As GdPictureStatus

public GdPictureStatus SetBlendMode( 
   PdfBlendMode BlendMode
)

public function SetBlendMode( 
    BlendMode: PdfBlendMode
): GdPictureStatus;

public function SetBlendMode( 
   BlendMode : PdfBlendMode
) : GdPictureStatus;

public: GdPictureStatus SetBlendMode( 
   PdfBlendMode BlendMode
)

public:
GdPictureStatus SetBlendMode( 
   PdfBlendMode BlendMode
)

Parameters

BlendMode: A member of the PdfBlendMode enumeration. The current blend mode to be used in the transparent imaging model. Initial value is PdfBlendMode.PdfBlendModeNormal.

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.

Be aware also that graphics state parameters are initialized to their default values at the beginning of each page.

Example

How to set different blending modes to be used to draw text.

VB.NET
C#

Dim caption As String = "Example: SetBlendMode"
Dim gdpicturePDF As New GdPicturePDF()
Dim status As GdPictureStatus = gdpicturePDF.NewPDF()
If status = GdPictureStatus.OK Then
    gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft)
    gdpicturePDF.SetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitMillimeter)
    Dim fontName As String = gdpicturePDF.AddStandardFont(PdfStandardFont.PdfStandardFontCourierBold)
    status = gdpicturePDF.GetStat()
    If (status <> GdPictureStatus.OK) OrElse (gdpicturePDF.SetTextSize(60) <> GdPictureStatus.OK) Then
        MessageBox.Show("The standard font can't be add correctly.", caption)
        GoTo [error]
    End If
    Dim text As String = "Mode = "
    If (gdpicturePDF.NewPage(210, 297) = GdPictureStatus.OK) AndAlso
       (gdpicturePDF.SetFillColor(255, 255, 0) = GdPictureStatus.OK) AndAlso
       (gdpicturePDF.DrawRectangle(80, 0, 130, 297, True, False) = GdPictureStatus.OK) AndAlso
       (gdpicturePDF.SetFillColor(173, 216, 230) = GdPictureStatus.OK) AndAlso
       (gdpicturePDF.SetBlendMode(PdfBlendMode.PdfBlendModeNormal) = GdPictureStatus.OK) AndAlso
       (gdpicturePDF.DrawText(fontName, 10, 30, text + "normal") = GdPictureStatus.OK) AndAlso
       (gdpicturePDF.SetBlendMode(PdfBlendMode.PdfBlendModeScreen) = GdPictureStatus.OK) AndAlso
       (gdpicturePDF.DrawText(fontName, 10, 60, text + "screen") = GdPictureStatus.OK) AndAlso
       (gdpicturePDF.SetBlendMode(PdfBlendMode.PdfBlendModeMultiply) = GdPictureStatus.OK) AndAlso
       (gdpicturePDF.DrawText(fontName, 10, 90, text + "multiply") = GdPictureStatus.OK) Then
        status = gdpicturePDF.SaveToFile("test_BlendMode.pdf")
        If status = GdPictureStatus.OK Then
            MessageBox.Show("The example has been followed successfully and the file has been saved.", caption)
        Else
            MessageBox.Show("The example has been followed successfully, but the file can't be saved. Status: " + status.ToString(), caption)
        End If
    Else
        MessageBox.Show("The example has not been followed successfully." + vbCrLf + "The last known status is " + gdpicturePDF.GetStat().ToString(), caption)
    End If
Else
    MessageBox.Show("The NewPDF() method has failed with the status: " + status.ToString(), caption)
End If
[error]:
gdpicturePDF.Dispose()

string caption = "Example: SetBlendMode";
GdPicturePDF gdpicturePDF = new GdPicturePDF();
GdPictureStatus status = gdpicturePDF.NewPDF();
if (status == GdPictureStatus.OK)
{
    gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft);
    gdpicturePDF.SetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitMillimeter);
    string fontName = gdpicturePDF.AddStandardFont(PdfStandardFont.PdfStandardFontCourierBold);
    status = gdpicturePDF.GetStat();
    if ((status != GdPictureStatus.OK) ||
        (gdpicturePDF.SetTextSize(60) != GdPictureStatus.OK))
    {
        MessageBox.Show("The standard font can't be add correctly.", caption);
        goto error;
    }
    string text = "Mode = ";
    if ((gdpicturePDF.NewPage(210, 297) == GdPictureStatus.OK) &&
        (gdpicturePDF.SetFillColor(255, 255, 0) == GdPictureStatus.OK) &&
        (gdpicturePDF.DrawRectangle(80, 0, 130, 297, true, false) == GdPictureStatus.OK) &&
        (gdpicturePDF.SetFillColor(173, 216, 230) == GdPictureStatus.OK) &&
        (gdpicturePDF.SetBlendMode(PdfBlendMode.PdfBlendModeNormal) == GdPictureStatus.OK) &&
        (gdpicturePDF.DrawText(fontName, 10, 30, text+"normal") == GdPictureStatus.OK) &&
        (gdpicturePDF.SetBlendMode(PdfBlendMode.PdfBlendModeScreen) == GdPictureStatus.OK) &&
        (gdpicturePDF.DrawText(fontName, 10, 60, text + "screen") == GdPictureStatus.OK) &&
        (gdpicturePDF.SetBlendMode(PdfBlendMode.PdfBlendModeMultiply) == GdPictureStatus.OK) &&
        (gdpicturePDF.DrawText(fontName, 10, 90, text + "multiply") == GdPictureStatus.OK))
    {
        status = gdpicturePDF.SaveToFile("test_BlendMode.pdf");
        if (status == GdPictureStatus.OK)
            MessageBox.Show("The example has been followed successfully and the file has been saved.", caption);
        else
            MessageBox.Show("The example has been followed successfully, but the file can't be saved. Status: " + status.ToString(), caption);
    }
    else
        MessageBox.Show("The example has not been followed successfully.\nThe last known status is " + gdpicturePDF.GetStat().ToString(), caption);
}
else
    MessageBox.Show("The NewPDF() method has failed with the status: " + status.ToString(), caption);
error:
gdpicturePDF.Dispose();

Reference

GdPicturePDF Class
GdPicturePDF Members
SetMeasurementUnit Method
SetOrigin Method
SetFillColor(Byte,Byte,Byte) Method
DrawText Method
DrawRectangle Method
ResetGraphicsState Method