[scribus-dev] Tables GSoC - Weekly Report #6

[Andreas Vox]

Hi Elvis!

Yes, listening to the StyleContext is the way to go.
For listening to an Observable you can just derive from this class and
implement ist changed() method:

// in observabe.h:

template<class OBSERVED>
class SCRIBUS_API Observer {
public:
	virtual void changed(OBSERVED) = 0;
	virtual ~Observer() {}
};

or you use 
      bool Observable::connectObserver(QObject* o, const char* slot);
	bool Observable::disconnectObserver(QObject* o, const char* slot =
0);

to connect an Observable to an QObject-observer; in that case deriving from
QObject is enough.
The Observable::update() method will notify both kinds of observers.

/Andreas	

> -----Ursprüngliche Nachricht-----
> Von: Elvis Stansvik [mailto:elvstone at gmail.com]
> Gesendet: Montag, 11. Juli 2011 14:20
> An: Scribus Development Mailing List
> Betreff: Re: [scribus-dev] Tables GSoC - Weekly Report #6
> 
> 2011/7/11 Elvis Stansvik <elvstone at gmail.com>:
> > 2011/7/11 Elvis Stansvik <elvstone at gmail.com>:
> >> 2011/7/11 Elvis Stansvik <elvstone at gmail.com>:
> >>> ...
> >>> ===Question 2===
> >>> I've now finally hit some problems relating to painting outside of
> the
> >>> table frame (before I didn't have any artifacts because of this,
> but
> >>> now they've started to appear sometimes when changing the border
> >>> through UI).
> >>
> >> I should note that this happens when the border reaches a certain
> >> width, probably when it goes outside the area around the frame that
> is
> >> actually repainted. So I really do think the table should never
> paint
> >> outside its frame. Is it OK if I try to implement the offset thing
> >> (and also at the same time finally get around to setting the
> cliprect
> >> properly, I think I did try early on with using the PoLine but it
> >> wasn't working, I'll try again).
> >>
> >> If it is OK, then my old question from the mid-week mini report is
> >> still valid; How can I be notified of style changes? Since the table
> >> needs to have this offset correctly set at all times, it needs to be
> >> notified of the following style changes, whether they came as a
> result
> >> of a change in a parent style or as a change in the locally stored
> >> style used for direct formatting:
> >>
> >> 1) Table top border changes.
> >> 2) Table left border changes.
> >> 3) Cell top border changes (on cells in row 0)
> >> 4) Cell left border changes (on cells in col 0)
> >
> > After some more investigation I realize that it's not possible to
> > listen to individual style changes, but that it's possible to listen
> > to changes in the StyleContext. That means I should be able to listen
> > to the StyleContexts I have for table and cell styles in ScribusDoc
> > (docTableStyles and docCellStyles) to get notified of possible
> changes
> > in relevant parent styles. And for direct formatting I can just
> ensure
> > that the offset is also recalculated when setters are called on
> > PageItem_Table. Does that sound sane?
> >
> > Listening to the style context like that will notify me of all style
> > changes, which is a bit liberal, but it's OK I think since it's not
> > time critical and besided the recalculation of the offsets should be
> > quite quick.
> 
> Many questions at once now. Sorry about that ;) Here's another one; I
> noticed that it's not using regular Qt signals/slots but that
> StyleContext implements Observable<StyleContext>. What requirement are
> there on a class that wants to be an observer in the observer pattern
> implementation in Scribus? Does it need to be a QObject? Or implement
> some Observer interface?
> 
> Elvis
> 
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