[PULL REQUEST] table print implementation

[Dirk Hohndel]

On Thu, 2013-07-11 at 14:28 +0300, Lubomir I. Ivanov wrote:
> On 11 July 2013 13:56, Dirk Hohndel <dirk at hohndel.org> wrote:
> >> the approach of doing the table print is by using the QTextDocument class
> >> with HTML/CSS with table/tr/th tags. it allows some freedom of what can be done
> >> in the table, but not as much as if you draw it manually with cairo/pango
> >> or with QPainter and this HTML/CSS implementation REALLY is as subset.
> >>
> >> but as you have already guessed it is much easier to maintain, which
> >> perhaps can be seen in printlayout.cpp...
> >
> > I think I like this approach. If we do this right it should make it
> > quite easy to support custom templates that users can create and share.
> > I know that almost every country has their own preferred logbook format,
> > and often even more than one. So having the ability for users who just
> > know a bit of html/css to be able to contribute layouts would be a real
> > strength for Subsurface...
> >
> 
> i was thinking about designing a template based structure, where
> programmatically the table columns can be preset.
> this could be based on a custom format specified in the preferences
> with a parseable string, for example:
> 
> nr,15|divemaster,30|location,50|gps,15
> would only create a table with these dive properties in columns with
> certain width (name, %).

This will work for the table, but what about the 6up, 4up, 2up, 1up
layouts. You'll have to design a complex "language" to describe which
element goes where... that's why I was hoping for something more
generic 

> the real problem that i've encountered is the limitation of the Qt
> HTML/CSS subset..
> a good example would be that the table border and color can only be
> controlled via the <table> tag style and not from the inner <th>, <tr>
> tags. and there are a lot of missing, common CSS properties which
> means that users trying to create a style template will have to be
> aware of the Qt specific limitations in this case otherwise their
> style sheets will be broken.

I'm sure those are documented somewhere. Right? Thiago?
And then we can point users to that documentation. Still seems easier
than creating a new description language that we need to parse.

> the preferred columns to be printed is something that can be done at
> this stage, but if we plan to allow table style mods (like colors) we
> really need to 'sandbox' the user outside of the actual Qt CSS, with a
> list print dialog options/controls i'd think.

Why?

> >> it detects a new page by a rather expensive (i think) operation, but it seems
> >> to work OK, so far.
> >
> > For 230 or so dives it easily took 13 seconds before the preview came
> > up. That seems rather long :-)
> >
> 
> i found reports on the web that QTextDocument is slow in general.
> after each row added, the current algorithm requires passing a new
> string to the QTextDocument object (with setHtml()) and then calling
> pageCount() to determine if a new page has occurred. this is the only
> way i found out how to do it so far, so that table headers are
> inserted on that new page.
> if someone has tips for a better solution i would be happy to apply it.

Thiago, Tomaz, any suggestions?

> >> to test go to File->Print (all 'print types' modes do a table print for now),
> >> 'print selected' should work, press 'print'..
> >>
> >> comments are welcome.
> >
> > Thanks for the code. This is one of the major missing pieces and I'm
> > glad to see progress. It would be really nice to design it early on with
> > the idea of reading templates and using those to do the layout...
> >
> 
> i will start thinking on this part, perhaps after a short discussion /
> plan on the direction. if someone is interested, please look at the
> above comments.

Great.

> >> p.s. i think i saw a couple of divelist bugs, in the lines of dives were
> >> reported as dive->selected, but weren't selected in the divelist.
> >> will try to replicate again later.
> >
> > That would be great. I've seen and fixed some in the past but I'm sure
> > there are many more lurking everywhere.
> >
> 
> i think i also found some visual glitches in the divelist on ubuntu
> and will report in trac soon.

Even better.

/D