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https://issues.apache.org/jira/browse/PDFBOX-615?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12837614#action_12837614
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Daniel Wilson commented on PDFBOX-615:
--------------------------------------
I'll note my "progress" here in hopes that if I'm way off base in the concept,
one of you can throw a flag.
It does seem that there should be a class to represent a Shading Dictionary.
Conceptually it is parallel to PDPattern, so I now have a PDShading class. I
haven't committed this code as it's really not doing anything yet ... but it
looks like part of the solution.
The piece I completely overlooked in last night's comment was the _sh_
operator. I'm implementing it as o.a.p.util.operator.pagedrawer.SHFill.
At this point its process method is simply logging the argument list.
This operator is getting a single name argument -- just like the spec says it
should. In my case it's:
[COSName{Sh0}]
I must say I'm a little confused regarding how to take that name and get the
Shading Dictionary.
The relevant section of the PDF file looks like this:
<</Parent 2 0 R
/Contents 178 0 R
/BleedBox[0.0 0.0 1152.0 1656.0]
/PieceInfo
<</Illustrator 142 0 R>>
/ArtBox[39.6431 171.689 963.828 1655.02]
/MediaBox[0.0 0.0 1152.0 1656.0]
/Thumb 183 0 R
/TrimBox[0.0 0.0 1152.0 1656.0]
/Resources
<</Shading
<</Sh0 170 0 R>>
/ColorSpace
<</CS0 174 0 R/CS1 162 0 R/CS2 175 0 R/CS3 168 0 R/CS4 163 0
R/CS5 169 0 R>>
/Font
<</T1_0 176 0 R>>
/ProcSet[/PDF/Text]
/Properties
<</MC0 158 0 R>>
/ExtGState
<</GS0 161 0 R>>
>>
/Type
/Page
/LastModified(D:20090602144525-05'00')
>>
The Sh0 name is clearly there ... and it refers to object 170 if I'm reading it
right. Object 170 appears to be:
170 0 obj
<</ColorSpace 162 0 R/AntiAlias false/Coords[0.0 0.0 1.0 0.0]/Function 171 0
R/Extend[true true]/Domain[0.0 1.0]/ShadingType 2>>
endobj
This contains the required entries for a shading dictionary of ShadingType 2
(Axial) as well as a couple of the optional ones.
Which all brings me back to trying to get the Shading Dictionary from the name
Sh0.
Again, pointers are MUCH appreciated.
> shfill operator needs implementation
> ------------------------------------
>
> Key: PDFBOX-615
> URL: https://issues.apache.org/jira/browse/PDFBOX-615
> Project: PDFBox
> Issue Type: New Feature
> Components: PDModel
> Reporter: Daniel Wilson
> Assignee: Daniel Wilson
>
> I have a PDF file (for which I do not yet have release permission) that uses
> the "sh" operator, equivalent to PostScript's shfill (per PDF spec 1.7 page
> 987).
> Adobe provides implementation guidance in a 78-page document at
> http://www.adobe.com/devnet/postscript/pdfs/TN5600.SmoothShading.pdf#17
> I will be trying to add this functionality this week, but if anyone has
> hints, suggestions, etc. they are most certainly welcome!
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