Re: [gs-cvs] gs/lib

I don't think that this patch is conforming,
because 0x0 bbox is not same as an empty path :

    0 0 moveto closepath clip

In this case we must paint nothing rather than ignore the clipping.
The correct condition is :

    { currentpoint pop pop } stopped

Igor.

----- Original Message ----- 
From: "Ray Johnston" <[email protected]>
To: <[email protected]>
Sent: Thursday, November 13, 2003 10:20 PM
Subject: [gs-cvs] gs/lib


> Update of /cvs/ghostscript/gs/lib
> In directory casper:/tmp/cvs-serv4207/lib
>
> Modified Files:
> pdf_ops.ps
> Log Message:
> Fix: Adobe Acrobat Reader ignores an empty path when setting the clip
> path. Bug #687136.
>
> DETAILS:
>
> We never encountered this problem in a 'real' file, but one of Raph's
> test files showed the difference in the way our PDF interpreter handled
> an zero area path to setting clipping versus the way Adobe does.
>
> Igor tested CPSI and determined that PostScript results in a zero area
> clipping box, but Acrobat Reader works differently, so the patch detects
> a zero area path and does not change the clipping path in that case.
>
> The details of the determination of 0 area is commented here:
>
> pathbbox % get the path bounding box
> 3 -1 roll % roll to get upper and lower Y coordinates together
> sub abs % form absolute delta Y of path bbox
> 3 1 roll % roll upper and lower X coordinates to TOS
> sub abs % form absolute delta X of path bbox
> add % sum abs delta X and abs delta Y
> 0 ne % if it is non-zero, then perform the clip/eoclip
>
>
>
> Index: pdf_ops.ps
> ===================================================================
> RCS file: /cvs/ghostscript/gs/lib/pdf_ops.ps,v
> retrieving revision 1.32
> retrieving revision 1.33
> diff -u -d -r1.32 -r1.33
> --- pdf_ops.ps 14 Oct 2003 10:15:38 -0000 1.32
> +++ pdf_ops.ps 13 Nov 2003 19:20:36 -0000 1.33
> @@ -368,12 +368,14 @@
>  /S { gsave setstrokestate stroke grestore n } bdef
>  /f { gsave setfillstate fill grestore n } bdef
>  /f* { gsave setfillstate eofill grestore n } bdef
> -/n { end clip newpath } bdef
> +% Adobe PDF Rendering doesn't change clipping if path is 0 area
> +/n { end pathbbox 3 -1 roll sub abs 3 1 roll sub abs add 0 ne { clip } if
newpath } bdef
>  end readonly def
>  /W { //Wdict begin } bdef
>  /W*dict 4 dict dup begin
>  Wdict { def } forall
> -/n { end eoclip newpath } bdef
> +% Adobe PDF Rendering doesn't change clipping if path is 0 area
> +/n { end pathbbox 3 -1 roll sub abs 3 1 roll sub abs add 0 ne { eoclip }
if newpath } bdef
>  end readonly def
>  /W* { //W*dict begin } bdef
>
>
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