Hi Bret et al,
On Tue, 23 Oct 2001 10:07:45 -0400
Brett Viren <bv@bnl.gov> wrote
concerning "Re: [ROOT] Qt ROOT":
> Christian Holm Christensen writes:
> > All though it may seem like reinventing the wheel, and without knowing
> > a lot about it, I think ROOT would benefiet from being able to use
> > various graphics abstraction layers like GNOME and Qt, and I think
> > that was what Valery was suggesting and working on (but I may be
> > wrong).
>
> I have a couple points about this.
>
> First, one thing to add to your ASCII UML is a "TPostScript" low level
> GUI so as to allow scalable/printable output of the entire
> application.
Ok, I should have put some more '...' in that diagram, since, after
all, that's what it's all about: Code reuse and extensibility :-)
> Second, I actually prefer the approach that QtROOT takes (replace high
> level GUI code instead of providing low level implementation).
Which however has the disadvantage that you write code explicitly for
Qt, Gtk, X11, Win32, AtheOS, MacOS, ladida, rather than writting for
all of them at once, not caring what the user really prefers.
> This approach lets you write Qt code directly. You don't need to go
> through the TG classes nor rely on Rt for sig/slot.
Well, that's really the point of it: Rely on one API - not 4, 5, or
6.
> You can benefit from a library which has had thousands of eyes on
> its design and implementation, which is thoroughly documented, and
> which is quite frankly much much more easy to work with than TG +
> Rt.
Well, the idea was to have something like
class TGButton {
private:
TGVirtualButton* fImplmentation;
...
public:
TGButton(...) {
fImplmentation = TVirtualX::Instance()->MakeButton(...);
...
}
...
};
class TQt {
public:
TGQtButton* MakeButton(...);
...
};
class TGQtButton : public TGVirtualButton {
private:
QtButton fLowLevel;
...
};
and so you will use the QtButton/Gtk::Button/ladida (stable)
implementation, and if you need additional elements, all you need to
do is make the wrapper and methods in the interfaces. Drawing the
stuff is done by the backend.
> I wait eagerly for QtROOT to be finished so I can look through it and
> steal all their hard work for GtkROOT!
The fact that you can probably do that, really implies (at least to
me) that a 'backend' implmentation is possible, although, as I said
needs a big effort.
Also, a second thing to learn from that is that OpenSource (as defined
by the OSD) is a Good Thing!
I do realise that by the time ROOT started thier GUI stuff, Qt, Gtk,
and so on were not nearly as complete as these libraries are today,
and hence the option of using those libraries was not really there.
In that context, ROOT was very good at providing a nice abstract GUI
library, which in many respects were ahead of Qt and Gtk.
Today, some 4-5 years down the line, things look different (very
different - heck, most my friends think I'm running Windoze with some
weird skin, when I'm really using GNOME), and maybe it's time to
revisit the approach.
Yours,
Christian Holm Christensen -------------------------------------------
Address: Sankt Hansgade 23, 1. th. Phone: (+45) 35 35 96 91
DK-2200 Copenhagen N Cell: (+45) 28 82 16 23
Denmark Office: (+45) 353 25 305
Email: cholm@nbi.dk Web: www.nbi.dk/~cholm
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