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tinnews@isbd.co.uk 07-16-2012 03:51 PM

PyQt QCalendarWidget events question
 
I am trying to use the PyQt4 calendar widget to perform some different
actions on specific dates. There are three events available:-

selectionChanged()
activated(QDate)
clicked(QDate)

On trying all these out it would appear that the event handlers get
called as follows:-

The clicked(QDate) event gets called if you click on an already
selected date.

The selectionChanged() and then the clicked(QDate) events are
called when you click on a new date.

The selectionChanged(), then the clicked(QDate) and then the
activated(QDate) events are called if you double-click on a new date.

The clicked(QDate) and then the activated(QDate) events are called
if you double-click on an already selected date.


How can I get a single-click on a date to get 'Action1' and double-click
on a date to get 'Action2'?

--
Chris Green

tinnews@isbd.co.uk 07-16-2012 04:28 PM

Re: PyQt QCalendarWidget events question
 
tinnews@isbd.co.uk wrote:
> I am trying to use the PyQt4 calendar widget to perform some different
> actions on specific dates. There are three events available:-
>
> selectionChanged()
> activated(QDate)
> clicked(QDate)
>
> On trying all these out it would appear that the event handlers get
> called as follows:-
>
> The clicked(QDate) event gets called if you click on an already
> selected date.
>
> The selectionChanged() and then the clicked(QDate) events are
> called when you click on a new date.
>
> The selectionChanged(), then the clicked(QDate) and then the
> activated(QDate) events are called if you double-click on a new date.
>
> The clicked(QDate) and then the activated(QDate) events are called
> if you double-click on an already selected date.
>
>
> How can I get a single-click on a date to get 'Action1' and double-click
> on a date to get 'Action2'?


I'm sorry, this got sent a bit before I'd completed it. The trouble
is that I want to run Action1 if I single-click on a date whether or
not it's a changed date and I want to run Action2 if I double-click on
a date whether or not it's a changed date. However I don't see how I
can do this because of the order in which the event handlers are
called.

Is there any way to manipulate this so I can get the result I want?
At the moment the only way I can see to do it is to wait a while after
a click and then look at what actions occurred but this seems a real
bodge.

--
Chris Green

John Posner 07-16-2012 07:58 PM

Re: Re: PyQt QCalendarWidget events question
 
On 7/16/2012 12:28 PM, tinnews@isbd.co.uk wrote:
> tinnews@isbd.co.uk wrote:
>> I am trying to use the PyQt4 calendar widget to perform some different
>> actions on specific dates. There are three events available:-
>>
>> selectionChanged()
>> activated(QDate)
>> clicked(QDate)
>>
>> On trying all these out it would appear that the event handlers get
>> called as follows:-
>>
>> The clicked(QDate) event gets called if you click on an already
>> selected date.
>>
>> The selectionChanged() and then the clicked(QDate) events are
>> called when you click on a new date.
>>
>> The selectionChanged(), then the clicked(QDate) and then the
>> activated(QDate) events are called if you double-click on a new date.
>>
>> The clicked(QDate) and then the activated(QDate) events are called
>> if you double-click on an already selected date.
>>
>>
>> How can I get a single-click on a date to get 'Action1' and double-click
>> on a date to get 'Action2'?

> I'm sorry, this got sent a bit before I'd completed it. The trouble
> is that I want to run Action1 if I single-click on a date whether or
> not it's a changed date and I want to run Action2 if I double-click on
> a date whether or not it's a changed date. However I don't see how I
> can do this because of the order in which the event handlers are
> called.
>
> Is there any way to manipulate this so I can get the result I want?
> At the moment the only way I can see to do it is to wait a while after
> a click and then look at what actions occurred but this seems a real
> bodge.


I suspect that the consensus would be "don't do that" -- having
single-click and double click perform unrelated actions. But here's an
implementation based on the advice at
http://www.qtcentre.org/threads/7858...lick-Capturing

(use Ctrl-Break to break out of the event loop)

import PyQt4.QtCore as C
import PyQt4.QtGui as G

class Button(G.QPushButton):
def __init__(self, text):
G.QPushButton.__init__(self, text)

# flag to suppress second mouseReleaseEvent
# in this double-click event sequence:
# 1. mousePressEvent
# 2. mouseReleaseEvent
# 3. mouseDoubleClickEvent
# 4. mouseReleaseEvent
self.double_clicked = False

def mouseReleaseEvent(self, evt):
# executed for first mouseReleaseEvent
if not self.double_clicked:
self.first_click_timer = C.QTimer()
self.first_click_timer.setSingleShot(True)
# double-click must occur within 1/4 second of first-click
release
self.first_click_timer.setInterval(250)
self.first_click_timer.timeout.connect(self.single _click_action)
self.first_click_timer.start()
# executed for second mouseReleaseEvent
else:
# reset the flag
self.double_clicked = False

def single_click_action(self):
print "Performing single-click action"

def mouseDoubleClickEvent(self, evt):
# suppress the single-click action; perform double-click action
instead
self.first_click_timer.stop()
print "Performing double-click action"

# prepare for second mouseReleaseEvent
self.double_clicked = True

# main program

app = G.QApplication([])
button = Button("Click or double-click me")
button.show()
app.exec_()


HTH,
John


tinnews@isbd.co.uk 07-17-2012 09:34 AM

Re: PyQt QCalendarWidget events question
 
John Posner <jjposner@optimum.net> wrote:
> On 7/16/2012 12:28 PM, tinnews@isbd.co.uk wrote:
> > tinnews@isbd.co.uk wrote:
> >> I am trying to use the PyQt4 calendar widget to perform some different
> >> actions on specific dates. There are three events available:-
> >>
> >> selectionChanged()
> >> activated(QDate)
> >> clicked(QDate)
> >>
> >> On trying all these out it would appear that the event handlers get
> >> called as follows:-
> >>
> >> The clicked(QDate) event gets called if you click on an already
> >> selected date.
> >>
> >> The selectionChanged() and then the clicked(QDate) events are
> >> called when you click on a new date.
> >>
> >> The selectionChanged(), then the clicked(QDate) and then the
> >> activated(QDate) events are called if you double-click on a new date.
> >>
> >> The clicked(QDate) and then the activated(QDate) events are called
> >> if you double-click on an already selected date.
> >>
> >>
> >> How can I get a single-click on a date to get 'Action1' and double-click
> >> on a date to get 'Action2'?

> > I'm sorry, this got sent a bit before I'd completed it. The trouble
> > is that I want to run Action1 if I single-click on a date whether or
> > not it's a changed date and I want to run Action2 if I double-click on
> > a date whether or not it's a changed date. However I don't see how I
> > can do this because of the order in which the event handlers are
> > called.
> >
> > Is there any way to manipulate this so I can get the result I want?
> > At the moment the only way I can see to do it is to wait a while after
> > a click and then look at what actions occurred but this seems a real
> > bodge.

>
> I suspect that the consensus would be "don't do that" -- having
> single-click and double click perform unrelated actions.


They're not actually unrelated, one will edit an existing entry in a
file for the given date, the other will add a new entry in the file
for that date. I.e. single-click means open file at specified date,
double-click means open file at specified date and insert a new entry
for that date.


> But here's an
> implementation based on the advice at
> http://www.qtcentre.org/threads/7858...lick-Capturing
>
> (use Ctrl-Break to break out of the event loop)
>
> import PyQt4.QtCore as C
> import PyQt4.QtGui as G
>
> class Button(G.QPushButton):
> def __init__(self, text):
> G.QPushButton.__init__(self, text)
>
> # flag to suppress second mouseReleaseEvent
> # in this double-click event sequence:
> # 1. mousePressEvent
> # 2. mouseReleaseEvent
> # 3. mouseDoubleClickEvent
> # 4. mouseReleaseEvent
> self.double_clicked = False
>
> def mouseReleaseEvent(self, evt):
> # executed for first mouseReleaseEvent
> if not self.double_clicked:
> self.first_click_timer = C.QTimer()
> self.first_click_timer.setSingleShot(True)
> # double-click must occur within 1/4 second of first-click
> release
> self.first_click_timer.setInterval(250)
> self.first_click_timer.timeout.connect(self.single _click_action)
> self.first_click_timer.start()
> # executed for second mouseReleaseEvent
> else:
> # reset the flag
> self.double_clicked = False
>
> def single_click_action(self):
> print "Performing single-click action"
>
> def mouseDoubleClickEvent(self, evt):
> # suppress the single-click action; perform double-click action
> instead
> self.first_click_timer.stop()
> print "Performing double-click action"
>
> # prepare for second mouseReleaseEvent
> self.double_clicked = True
>
> # main program
>
> app = G.QApplication([])
> button = Button("Click or double-click me")
> button.show()
> app.exec_()
>
>

Yes, thanks, though it is basically the bodge using timing that I was
trying to avoid. It's so fundamental to most GUIs that single-click
and double-click allow one to do different things with the same object
I'm surprised that pyqt makes it so difficult to implement.

--
Chris Green

Chris Angelico 07-17-2012 05:41 PM

Re: PyQt QCalendarWidget events question
 
On Tue, Jul 17, 2012 at 7:34 PM, <tinnews@isbd.co.uk> wrote:
> It's so fundamental to most GUIs that single-click
> and double-click allow one to do different things with the same object


Kinda yes, kinda no. Most GUIs and GUI recommendations would either
enforce or strongly suggest that the double-click action incorporate
the click action; for instance, click to select, double-click to open.

The series of events usually goes:

Mouse down
Mouse up
Click
Mouse down
Mouse up
Double-click

They're fired as things happen and in that order. (Some systems insert
another Click just before the Double-click, but that's generally
unhelpful.) Please code your application so that this isn't a problem
to it, because anything else causes untold confusion to the users.

ChrisA


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