RE: Fix for 688018 (PreserveHalftones in pdfwrite)

Ray,

Peter is the culprit for the code in gdevpdfj.c

Dan

-----Original Message-----
From: Ray Johnston [mailto:[email protected]]
Sent: Tuesday, April 12, 2005 9:34 PM
To: [email protected]
Cc: GS Code Review List
Subject: Re: [gs-code-review] Fix for 688018 (PreserveHalftones in
pdfwrite) (xefitra)


Dan,

Abject apology.

I didn't create this -- I copied it from another file -- gdevpdfj.c.

Since it is really localized and in the 'style' created by someone
else, I just 'followed'. I guess I've mucked around in ghostscript
code to have my tolerance to objectionable coding styles reduced.

Besides, as a father of five year olds, I've learned the value of the
expression "do what I say, not what I do". ;-)

If someone objects strenusously, I my feelings won't be hurt if the
macro is replaced with code (but only if they do it in gdevpdfj.c as
well as gdevpdfg.c -- and  all the other places where control flow
is embedded in a macro).

Regards,
Ray
_________________________________________________________________________

Dan Coby wrote:

> Ray,
> 
> + #define CHECK(expr)\
> +   BEGIN if ((code = (expr)) < 0) return code; END
> 
> I remember a long discussion in which we (including you) specifically
> told Igor not to create a macro like this one which hides the control
> flow.
> 
> 
> Dan
> 
> 
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Ray Johnston
> Sent: Tuesday, April 12, 2005 2:20 PM
> To: GS Code Review List
> Cc: Raph Levien
> Subject: [gs-code-review] Fix for 688018 (PreserveHalftones in pdfwrite)
> | 
> 
> 
> All,
> 
> I know this is usually Igor's area, but he's busy right now and
> rather than divert his attention, I decided to look into this
> SEGV in pdfwrite. Good learning oppurtunity for me :-)
> 
> The patch is attached.
> 
> Log message:
> 
> Fix for SEGV when PreserveHalftoneInfo=true is given as a
> pdfwrite option. Bug 688018.
> 
> DETAILS:
> 
> The initial problem was that the num_comp was not being looked at
> when HalftoneType 5 was written and if num_comp was 3, the 4th
> element of ht_ids[] was being used (UMR-wise). The solution to
> this was to only write the three halftones and to use the 'Green'
> halftone (arbitrarily) for Default.
> 
> After fixing the SEGV, another problem surfaced because the object
> dictionary was not being terminated with the ">>".
> 
> Since I suspected that the threshold_halftone writers were also
> broken I tested with 258-01.ps and found more problems. This
> code was also quite broken. Since the Threshold array is the
> stream data for HalftoneType 6 and 16, I changed this a lot to
> emit valid PDF.
> 
> EXPECTED DIFFERENCES:
> 
> None, since we don't set PreserveHalftoneInfo.