PyQt QCalendarWidget events question

[tinnews]

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'?

 

[tinnews]

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.

 

[John Posner]

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-Double-Click-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]

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-Double-Click-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 Angelico]

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