GdPictureImaging.PdfSetAlpha Method

Specifies the level of transparency to use for the next drawing operations with a PDF.

public PdfSetAlpha(
    int PdfID, 
    Single Alpha
);

Visual Basic

Public Sub PdfSetAlpha(
    ByVal PdfID As Integer, 
    ByVal Alpha As Single
)

Parameters

Parameters	Description
PdfID	A PDF identifier returned by the PdfNewPdf(), PdfOCRStart(), PdfOcrStartStream(), TwainPDFStart() or TwainPdfStartStream() function.
Alpha	A value in the range [0;1]. 0 means full transparency, 1 means full opacity.

Example

Drawing 3 circles with Alpha bending.

Copy Code

Dim PdfID As Integer
 
PdfID = oGdPictureImaging.PdfNewPdf("c:\test.pdf")
oGdPictureImaging.PdfSetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitMillimeter)
oGdPictureImaging.PdfNewPage(PdfID, 210, 297) 'A4 format
oGdPictureImaging.PdfDrawFilledCircle(PdfID, 105, 148.5, 80, Color.Blue)
oGdPictureImaging.PdfSetAlpha(PdfID, 0.5)
oGdPictureImaging.PdfDrawFilledCircle(PdfID, 120, 160.5, 80, Color.Red)
 
oGdPictureImaging.PdfSetAlpha(PdfID, 0.1)
oGdPictureImaging.PdfDrawFilledCircle(PdfID, 140, 180.5, 80, Color.Green)
oGdPictureImaging.PdfEndPdf(PdfID)