Can you see what I mean. The Decode function requires a pointer argument. I
have to provide it with a PdfDictionary so getting the Decode Parms directly is
of no use in this case.
dict->HasKey("Columns") and dict->HasKey("Predictor") both indicate true, so
when I load the dictionary it is definitely seeing those parms.
I can't seem to decode a stream with parms using this function so I'm not sure
what is going wrong. If I use this very same code (without parms) on other
streams, it decompresses them fine. When I need to use Parms it doesn't
decompress the stream. Just outputs jumble.
That's all I am trying to do, just using the Decode Function from PdfFilter.
From: [email protected]
To: [email protected]; [email protected]
Date: Tue, 19 Aug 2014 17:11:23 +0930
Subject: Re: [Podofo-users] DecodeParms, how to use?
Hi
Thanks very much for the response. I suppose then my question is with regards
to the function below.
PdfFilter->Decode (const char *pInBuffer, pdf_long lInLen, char **ppOutBuffer,
pdf_long *plOutLen, const PdfDictionary *pDecodeParms) const
If I have to do this every time I want to decode a stream, what is the const
PdfDictionary *pDecodeParms what would go here if there is a sub_Dictionary?
It is certainly easy enough to get the individual values, but from the
explanation in the documentation it says the below so I am assuming a complete
dictionary must go here.Should it only be the Sub_Dictionary though?
In page 175 of the PDF Version of the PODOFO documentation.
'pDictionary pointer to a dictionary that might contain additional parameters
fordecoding the stream. CreateDecodeStream will look for a key named
DecodeParmsin this dictionary and pass the information found in this
dictionaryto the filters.'
> From: [email protected]
> To: [email protected]
> Date: Tue, 19 Aug 2014 09:02:51 +0200
> Subject: Re: [Podofo-users] DecodeParms, how to use?
>
> On Tue, 2014-08-19 at 13:17 +0930, Domonic Tom wrote:
> > ...
> >
> > <</DecodeParms<</Columns 4/Predictor
> > 12>>/Filter/FlateDecode/ID[<6647557224A6C102A60F6D82BB22C18D><AA383B5CF85B7F4BACB9D502B93343E9>]/Index[10
> >
> > 20]/Info 9 0 R/Length 64/Prev 23381/Root 11 0 R/Size
> > 30/Type/XRef/W[1 2 1]>>
> >
> > If I know which object this is and extract the dictionary then I
> > can't see why it won't work.
>
> Hi,
> I do not think I can help you much here, also because I'm unsure what
> you are trying to do, but maybe this will help a little bit:
>
> Once you have a PdfDictionary, you can get its keys (and values) by:
> if (dict->HasKey("Columns"))
> columns = dict->GetKey("Columns");
>
> See the base/PdfDictionary.h for more GetKey...() variants.
>
> If yours 'dict' points to:
> <</DecodeParms<</Columns 4/Predictor 12>>...>>
> then the way to get into the inner/sub-dictionary might be:
> columns = dict->GetKey("DecodeParams")->GetDictionary().GetKey("Columns");
> Some safety checks like HasKey() and IsDictionary() will make your
> code more error proof.
>
> > PdfDictionary *dict = new PdfDictionary;
> > *dict = obj->GetDictionary();
> >
>
> The above construction is incorrect by many means. It might be done
> either directly, like in the snippets I wrote above (not assigning to a
> variable) or by:
> const PdfDictionary &dict = obj->GetDictionary();
> if (dict.HasKey(...)) ...
>
> Hope it helps,
> zyx
>
>
> --
> http://www.litePDF.cz [email protected]
>
>
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