[poppler] Reading code for FUN

[thomas.huxhorn at web.de]

The answer to my question can be found in the reference document Section
F.2:
Linearized Parameter L - The length of the entire files in bytes. This
must be exactly equal to the actual length of the PDF file.

Reading the manual works XD

Thomas

On 6/18/21 11:40 AM, thomas.huxhorn at web.de wrote:
> Progress! :)
> I now know what a linearized PDF is and I found the code.
> class Dokument -> DokumentData -> PDFDoc -> isLinearized() ->
> Linearization -> Parser -> Lexer -> Object
>
> Here is my question:
> In function isLinearized() PDFDoc.cc line 731 from poppler 21.06.0
> getLinearization()->getLength() == str->getLength()
> It test if length given bei \L in the PDF document equals the PDF file
> size. It is 1830148 in both cases for my test file. But why is this a
> reason for a linearized PDF?
>
> The PDF could be linearized and corrupt so the sized are not equal.
>
> Yes, I read a few more lines and if variable "tryingToReconstruct" is
> true, only the \L size is tested. Im not familiar with this concept.
>
> Thomas
>
> On 6/13/21 11:51 AM, thomas.huxhorn at web.de wrote:
>> Hello,
>>
>> I always wonder why it takes so long to display big pictures in PDF
>> files on linux. So I recompile poppler with release+debug symbols and
>> use valgrind profile to get an idea what is happening there. As I can
>> see, 50% of the CPU ticks are used to copy data from A to B. But without
>> knowing the code, its hard to say if this is good or not.
>> So I start reading the code. Puh it's hard to understand, so I start
>> reading the PDF reference too.
>>
>> As far I can see, there a linearized PDFs and and a table called xref.
>> Not much for one week of reading ;)
>>
>> Perhaps I should start from scratch and write my own PDF reader to
>> understand things better.
>>
>> If you are interested in, I can inform you about my progress. I'll do
>> this in my free time, so no hurry.
>>
>> Thomas H.
>> _______________________________________________
>> poppler mailing list
>> poppler at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/poppler
>
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