Qt-interest Archive, March 2002
Toggle buttons
Message 1 in thread
- Subject: Toggle buttons
- From: George Ogata <g_ogata@xxxxxxxxxxx>
- Date: Thu, 14 Mar 2002 02:08:25 +1100
- Organization: Committee for the Liberation and Integration of Terrifying Organisms and their Rehabilitation Into Society
- To: qt-interest@xxxxxxxxxxxxx
Hello,
I'd like a togglable toolbutton which checks a predicate before been set to
"on" (and remains off and appears undepressed if the predicate is false).
After seeing that QButton::setState(bool) was virtual, I figured that this
could just be overriden in a subclass and would get run each time the state
of the button was changed, similar to the way QListViewItem::setOpen(bool)
gets called no matter how it's opened; that is, that internally, the state
was only ever set through setState(). Alternatively, the same deal with
QToolButton::setOn(bool).
However, neither seems to be the case; clicking a togglable button
doesn't call setState() nor setOn(), unless of course you wire up the right
signals. But I want to intercept the click _before_ it sets the state, so
hooking onto some signal is no good since I can't stop the signal propagating
(let alone ensure that no other connected slots get run).
So I have two questions:
1.
Is there a good reason why either QButton::setState() or QToolButton::setOn()
isn't used as a "bookkeeping" method like QListViewItem::setOpen()? In fact,
is there any reason why QButton::setState(bool) is virtual to begin with? No
subclass of QButton in the library seems to use it (based on a quick grep).
Ditto with QToolButton::setOn(bool).
2.
Is there an easy way to achieve what I want? Overriding the QWidget event
methods is messy due to all the checks and making sure that every way of
onning a button is caught.
Cheers.
(Running Qt Free 2.3.1)
