Shadow generation in the PDF Language.

Question

I am working on an application that needs to create PDF files from vector-based imagery.
There appears to be an extension to the language (which may be Mac-specific) that allows
paths to have drop-shadows; however, I can find no discussion of this feature anywhere.
I have checked the PDF reference, the addendums and waded through countless web
pages trying to find more information.
I can create files on the Mac which use the extension through Quartz 2D.  Please forgive
my ignorance in some of these matters, but I believe the relevant data from the PDF file is
the following (much is culled for simple viewing):
6 0 obj
<< /ProcSet [ /PDF /Text /ImageB /ImageC /ImageI ] /ColorSpace << /Cs2 8 0 R
/Cs1 7 0 R >> /ExtGState << /Gs1 20 0 R >> /Font << /F1.0 13 0 R >> /XObject
<< /Im2 11 0 R /Im4 16 0 R /Im3 14 0 R /Im5 18 0 R /Im1 9 0 R >> /Properties
<< /Pl1 21 0 R /Pl2 22 0 R >> >>
endobj
21 0 obj
<< /Type /PropertyList /Style << /Type /Style /Subtype /Shadow /Offset [ 10.22150
-17.19072 ] /Radius 7.543859 /ColorSpace 8 0 R /Color [ 1 0 0 1 ] >> >>
endobj
I am guessing this "/Shadow" and its parameters control a vector-based shadow.
This is clearly not Mac-specific.  Viewers, even on the PC, recognize this and render
the file appropriately.
Although the example above is condensed, essentiallly it is drawing a filled rectangle
which has a red shadow beneath it.
Can someone give me some information on this feature, or at least point me in the right
direction to using any API to manufacture it?
Thanks,
Phil

Answer 1

Thank you for the prompt reply.
So the values for Offset and Radius are communicated to some other object in the file
that renders the shadow from that?  They can be changed textually (yes, I am aware that
isn't recommended), but trivially changing say the "10.22150" to "40.22150" does translate
the shadow appropriately.
I could post a more complete example; however, I am pretty sure the PDF content operations
are encoded.  This file is the result of a "Save as PDF" from the generic Print dialog in Mac
OS X and I don't think I have detailed control over that process.
It sounds like I need to learn more about the PDF content operators and how to use them
to manufacture something like a shadow.  I didn't realize they were that powerful.  I am
guessing it is doing some sort of filtering with the intensity of the effect being handled through
"Radius".
Phil