Draw transparent image on PDF

[MarcVeit]

Hi,

I would like to draw a transparent image on a pdf. I'm using the following code:

Code: Select all

  Dim ImageID As Integer = oGdPictureImaging.CreateGdPictureImageFromFile("c:\test.jpg")
  oGdPicturePDF.SelectPage(1) 'Selecting first page
  oGdPictureImaging.SetTransparency(ImageID, -100)

  Dim image_res_name As String = oGdPicturePDF.AddImageFromGdPictureImage(ImageID, False, False)
  oGdPicturePDF.DrawImage(image_res_name, 10, 10, imageWidth, imageHeight)
  oGdPictureImaging.ReleaseGdPictureImage(ImageID)
  oGdPicturePDF.SaveToFileInc("c:\test.pdf")
  oGdPicturePDF.CloseDocument()



This draws the image on the pdf, however, the transparency is lost. What am I doing wrong?

Any help is appreciated. Best regards,

Marc

[Loïc]

Hello Marc,

The transparency model in PDF is not the same at all as in raster image. While in image you just "play' with an alpha channel, in PDF you have to deal with softmask, blending mode, groups, composting mode and some other hell.

Currently we support only mask image. Therefore, you will not blend your image to a PDF page in an other way than defining a single fully transparent color.

We are already working on the full transparency support since 6 months now ,for rasterization, printing & writing purpose. The task is 50-60% done, and we expect to be ready for GdPicture 9.

Kind regards,

Loïc