[scribus-dev] Fwd: Great meeting you in Saarbrücken

[Andreas Vox]

Tamir Hassan <dev at tamirhassan.com> schrieb am Do., 13. Juni 2019, 09:14:

> Hi Andreas,
>
> On 6/11/19 8:20 AM, Andreas Vox wrote:
> > I think it's only possible to achieve two of the following: editable,
> > stable layout and optimal layout. If you modify a document in another
> > application than the one which produced it, there will always be
> > difference in appearance, functionality or both.
>
> I'm not quite sure what you mean by "optimal layout", but of course, I
> am trying to achieve the first two here. Opening a document for editing
> should not cause any reflow changes until the content has been edited,
>

That would imply that applications support a "frozen text layout" in
addition to their usual layout algorithm. Doable, but I'm not convinced
that the benefits outweigh the drawbacks. For one, users have to be aware
which frames are frozen and which ones use the application's native layout.

and then it should reflow in a predictable manner.
>
>

That would mean standardizing the layout algorithm. On a per-application
basis the reflow is already predictable - I'm not aware of any software
that randomizes text layout :-)

Optimal layout for me is not only the use of local and global
> optimization algorithms such as Knuth-Plass on the paragraph level, but
> also stuff such as pagination and figure placement on the global level.
>

Agreed.

Combining this with interactive, WYSIWYG editing is a different problem,
> as everything would be jumping about from page to page every time a
> single character is typed, assuming the computation can be done fast
> enough.


Scribus already does it that way.

It would probably make the most sense to carry out global
> optimizations on demand once the content is known, and only locally
> optimize during editing (if at all.)
>
> > But there's definitely a lot of opportunity to improve editing PDF if
> > you accept adequate layout changes. IMHO, reflow, font substitution,
> > change of color model, change of resolution and scaling are acceptable
> > layout changes. Missing content, inconsistent line breaking or
> > distortion are obviously not acceptable.
>
> I wouldn't describe some of these as layout changes at all. But yes, if
> a font is substituted (PDF already provides mechanisms for this), this
> should not cause reflow and, in fact, if the font later becomes
> available again it should be substituted back.
>
>
Substituting the font without reflow usually makes the document useless for
professional use. Scribus allows editing with substituted fonts and changes
them back when they become available, but text layout is always done with
the substituted font's metrics.
Editing a document without having the used fonts available is always
suboptimal and should not be encouraged. Permanently substituting missing
fonts with an available one is the better choice unless you have a workflow
where users have  different font sets and the final layout is done by
someone who has all the fonts.

Speaking of workflows: what kind of workflow do you want to support with
editable PDF? Touching up a document at the print shop? Providing
collaboration between authors who use different page layout applications?
Allowing to reuse an existing PDF later for a new project?
To me, avoiding reflow only makes sense for the first of those.


>
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