[NTG-pdftex] Creating identical PDF files with different pdfTeX runs

[Hans Hagen]

>
> 3. Regression testing in pdfTeX: A change that only aims at
>    e.g. performance enhancements should not alter the document.  Many
>    other changes of course will change it.
>   
i think that you must define different levels of similarity:

- pure text: in that case a bitmap as already discussed is needed
- functionality (annotations and such): that need to take place at the 
pdf level, i.e. filtering resources and descriptions and compare them 
(e.g. annotation names, rectangles, etc)
- font resources

i can imagine that your test of text similarity is run with disabled 
interactive features

the second one could be an add=on for pdftex: a special log mode, where 
pdftex writes a file with all annotations (name, page, rectangle, maybe 
also the while dict) and a second one which lists all the used fonts, 
encoding files, map lines and glyphs (encoding subset)

Hans

 

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