Updated Question
I think my original quandary might be a result of the structure of my PyQt app. The way I've approached creating a GUI is to divide the larger widget into smaller pieces, each given their own class until the parts are simple enough. Because of this, I end up with a ton of nesting, as a large widget holds instances of smaller widgets, and those hold their own even smaller widgets. It makes it hard to navigate data around the app.
How should a PyQt app be structured so that it is simple to understand in code and yet has a structure containing very little nesting? I haven't found many examples of this around, so I'm sort of stuck. The code example in my original question shows a pretty good example of the structure I'm currently using, which has a large amount of nesting.
Info on program
The GUI is used to create a set of parameters for running a test. The options in each setting should correspond to a binary number, and all of the binary numbers indicated by each set of options are collected, formed into a single sequence of binary numbers, and passed on. Changes to settings do not have to be carried over between sessions, as each new session will most likely correspond to a new test (and thus a new set of choices for settings).
The basic flow of the app should be that upon opening it, all available settings (about 20 total) are set to their default values. A user can go through and change whatever settings they would like, and once they're done they can press a "Generate" button to gather all of the binary numbers corresponding to the settings and create the command. It would be very helpful to have a live preview of individual bits that updates as settings are changed, which is why updates must be immediate.
Some settings are dependent on other; for instance, Setting A has 4 options, and if option 3 is selected, Setting B should be made visible, otherwise it is invisible.
Original Question
I'm definitely a beginner to PyQt, so I don't quite know if I've worded my question correctly, but here goes. I've got a GUI wherein I'm attempting to take a bunch of different settings, keep track of what number was selected from each setting, and then pass the number up to an object that keeps track of all of the numbers from all of the settings. The trouble is that I don't know the best way to get all the individual settings values up my tree of classes, so to speak. Here's the structure of my GUI so far:
Bottom: individual custom QWidgets, each responsible for a single setting. Each has a signal that fires whenever the value it returns changes.
Middle: a QWidget containing ~7-10 individual settings each. These collect settings into related groups.
Top: a QTabWidget that places each instance of a setting group into an individual tab. This widget also contains an object that should ideally collect all of the settings from individual groups into it.
My question is how do I get the values from the bottom layer signals to the top layer widget? My only idea is to connect all of the signals from those small setting widgets to a signal in the middle layer, and connect the middle layer signal to something in the top layer. This sort of chaining seems crazy, though.
I'm running PyQt5 and Python 3.7.
Here's some stripped down code which hopefully shows what I want to do.
class TabWindow(QTabWidget):
def __init__(self):
super().__init__()
self.tabs = [SettingsGroup1, SettingsGroup2, SettingsGroup3]
self.setting_storage = { # dictionary is where I'd like to store all settings values
# 'setting name': setting value
}
for tab in self.tabs:
self.addTab(tab, 'Example')
class SettingsGroup(QWidget):
def __init__(self):
super().__init__()
# not shown: layout created for widget
self.settings = []
def add_to_group(self, new_setting):
self.settings.append(new_setting)
# not shown: add setting to the layout
class SettingsGroup1(SettingsGroup):
def __init__(self):
super().__init__()
self.add_to_group([Setting1, Setting2, Setting3])
class SettingsGroup2(SettingsGroup):...
class SettingsGroup3(SettingsGroup):...
class Setting(QWidget):
val_signal = pyqtSignal([int], name='valChanged')
def __init__(self, name):
self.val = None
self.name = name
def set_val(self, new_val):
self.val = new_val
self.val_signal.emit(self.val) # <-- the signal I want to pass up
class Setting1(Setting):
def __init__(self, name):
super().__init__(name)
# not shown: create custom setting layout/interface
class Setting2(Setting):...
class Setting3(Setting):...
I use a lot of inheritance (SettingsGroup -> SettingsGroup1, 2, 3) because each subclass will have its own functions and internal dependencies that are unique to it. For each Setting subclass, for instance, there is a different user interface.
Thanks for any help provided!
EDIT: The question has been updated in the meantime, I've added a solution that's more specific at the bottom of this answer.
I feel like this question is slightly "opinion based", but since I've had my share of similar situations I'd like to propose my suggestions. In these situations it's important to understand that there's not one good way to do things, but many ways to do it wrong.
Original answer
An idea could be to create a common signal interface for every "level", which will get that signal and send it back to its parent by adding its own name to keep track of the setting "path"; the topmost widget will then evaluate the changes accordingly.
In this example every tab "group" has its own valueChanged signal, which includes the group name, setting name and value; the source signal is fired from the "source" (a spinbox, in this case), then it follows its parents which, in turn "add" their name in turn.
Keep in mind that you can also just use a generalized pyqtSignal(object) for every parent and connect it with widget.valueChanged.connect(self.valueChanged), and then track its group and setting by walking by self.sender() parents backwards.
As a final notice, if you are using these values for application settings, remember that Qt already provides the QSettings API, which can be used as a common and OS-transparent interface for every configuration you need to set (and remember between sessions) in your application. I implemented it in the example, but I suggest you to read its documentation to better understand how it works.
import sys
from PyQt5 import QtCore, QtWidgets
class SettingWidget(QtWidgets.QWidget):
valueChanged = QtCore.pyqtSignal(int)
def __init__(self, name):
super().__init__()
self.settings = QtCore.QSettings()
self.val = 0
self.name = name
layout = QtWidgets.QVBoxLayout()
self.setLayout(layout)
layout.addWidget(QtWidgets.QLabel(self.name))
self.spinBox = QtWidgets.QSpinBox()
layout.addWidget(self.spinBox)
self.spinBox.valueChanged.connect(self.set_val)
def set_val(self, new_val):
if self.val != new_val:
self.val = new_val
self.valueChanged.emit(self.val)
# enter a setting group, ensuring that same name settings won't
# be mismatched; this allows a single sub level setting only
self.settings.beginGroup(self.parent().name)
self.settings.setValue(self.name, new_val)
# leave the setting group. THIS IS IMPORTANT!!!
self.settings.endGroup()
class SettingWidget1(SettingWidget):
def __init__(self):
super().__init__('Setting1')
class SettingWidget2(SettingWidget):
def __init__(self):
super().__init__('Setting2')
class SettingWidget3(SettingWidget):
def __init__(self):
super().__init__('Setting3')
class SettingsGroup(QtWidgets.QWidget):
# create two signal signatures, the first sends the full "path",
# while the last will just send the value
valueChanged = QtCore.pyqtSignal([str, str, int], [int])
def __init__(self, name):
super().__init__()
self.name = name
layout = QtWidgets.QHBoxLayout()
self.setLayout(layout)
def add_to_group(self, new_setting):
widget = new_setting()
# emit both signal signatures
widget.valueChanged.connect(
lambda value, name=widget.name: self.valueChanged.emit(
self.name, name, value))
widget.valueChanged.connect(self.valueChanged[int])
self.layout().addWidget(widget)
class SettingsGroup1(SettingsGroup):
def __init__(self):
super().__init__('Group1')
self.add_to_group(SettingWidget1)
self.add_to_group(SettingWidget2)
class SettingsGroup2(SettingsGroup):
def __init__(self):
super().__init__('Group2')
self.add_to_group(SettingWidget3)
class TabWidget(QtWidgets.QTabWidget):
def __init__(self):
QtWidgets.QTabWidget.__init__(self)
self.settings = QtCore.QSettings()
self.tabs = [SettingsGroup1, SettingsGroup2]
self.settingsDict = {}
for tab in self.tabs:
widget = tab()
self.addTab(widget, widget.__class__.__name__)
widget.valueChanged[str, str, int].connect(self.valueChangedFullPath)
widget.valueChanged[int].connect(self.valueChangedOnly)
def valueChangedFullPath(self, group, setting, value):
# update the settings dict; if the group key doesn't exist, create it
try:
self.settingsDict[group][setting] = value
except:
self.settingsDict[group] = {setting: value}
settingsData = [group, setting, value]
print('Full path result: {}'.format(settingsData))
# Apply setting from here, instead of using the SettingWidget
# settings.setValue() option; this allows a single sub level only
# self.applySetting(data)
def valueChangedOnly(self, value):
parent = sender = self.sender()
# sender() returns the last signal sender, so we need to track down its
# source; keep in mind that this is *not* a suggested approach, as
# tracking the source might result in recursion if the sender's sender
# is not one of its children; this system also has issues if you're
# using a Qt.DirectConnection from a thread different from the one that
# emitted it
while parent.sender() in sender.children():
parent = sender.sender()
widgetPath = []
while parent not in self.children():
widgetPath.insert(0, parent)
parent = parent.parent()
settingsData = [w.name for w in widgetPath] + [value]
print('Single value result: {}'.format(settingsData))
# similar to valueChangedFullPath(), but with this implementation more
# nested "levels" can be used instead
# self.applySetting(settingsData)
def applySetting(self, settingsData):
# walk up to the next to last of settingsData levels, assuming they are
# all parent group section names
for count, group in enumerate(settingsData[:-2], 1):
self.settings.beginGroup(group)
# set the setting name settingsData[-2] to its value settingsData[-1]
self.settings.setValue(*settingsData[-2:])
for g in range(count):
self.settings.endGroup()
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
# set both Organization and Application name to make settings persistent
app.setOrganizationName('StackOverflow')
app.setApplicationName('Example')
w = TabWidget()
w.show()
sys.exit(app.exec_())
Alternate solution, based on updated answer
Since the answer has become more specific in its update, I'm adding another suggestion.
As far as we can understand now, you don't need that level of "nested" classes, but more specifically designed code that can be reused according to your purposes. Also, since you're using binary based data, it makes things a bit (pun intended) easier, as long as you know how bit operation works (which I assume you do) and the setting "widgets" don't require specific GUI customization.
In this example I created just one "setting" class and one "group" class, and their instancies are created only according to their names and default values.
import sys
from PyQt5 import QtCore, QtWidgets
defaultValues = '0010101', '1001010', '000111'
# set bit lengths for each setting; be careful in ensuring that each
# setting group has the full default value bit length!
groups = [
['Group 1', [1, 3, 2, 1]],
['Group 2', [1, 2, 2, 1, 1]],
['Group 1', [2, 1, 2, 1]],
]
class BinaryWidget(QtWidgets.QFrame):
changed = QtCore.pyqtSignal()
def __init__(self, name, index, defaults='0'):
QtWidgets.QFrame.__init__(self)
self.setFrameShape(self.StyledPanel|self.Sunken)
layout = QtWidgets.QGridLayout()
self.setLayout(layout)
self.index = index
self.defaults = defaults
self.buttons = []
# use the "defaults" length to create buttons
for i in range(len(defaults)):
value = int(defaults[i], 2) & 1
# I used QToolButtons as they're usually smaller than QPushButtons
btn = QtWidgets.QToolButton()
btn.setText(str(value))
layout.addWidget(btn, 1, i)
btn.setCheckable(True)
btn.setChecked(value)
btn.toggled.connect(self.changed)
# show the binary value on change, just for conveniency
btn.toggled.connect(lambda v, btn=btn: btn.setText(str(int(v))))
self.buttons.append(btn)
layout.addWidget(QtWidgets.QLabel(name), 0, 0, 1, layout.columnCount())
def value(self):
# return the correct value of all widget's buttons; they're reversed
# because of how bit shifting works
v = 0
for i, btn in enumerate(reversed(self.buttons)):
v += btn.isChecked() << i
# bit shift again, according to the actual "setting" bit index
return v << self.index
def resetValues(self):
oldValue = self.value()
self.blockSignals(True)
for i, value in enumerate(self.defaults):
self.buttons[i].setChecked(int(self.defaults[i], 2) & 1)
self.blockSignals(False)
newValue = self.value()
# emit the changed signal only once, and only if values actually changed
if oldValue != newValue:
self.changed.emit()
class Group(QtWidgets.QWidget):
changed = QtCore.pyqtSignal()
def __init__(self, name, defaults=None, lenghts=None):
QtWidgets.QWidget.__init__(self)
layout = QtWidgets.QHBoxLayout()
self.setLayout(layout)
self.name = name
self.bitLength = 0
self.widgets = []
if defaults is not None:
self.addOptions(defaults, lenghts)
def value(self):
v = 0
for widget in self.widgets:
v += widget.value()
return v
def addOption(self, name, index, default='0'):
widget = BinaryWidget(name, index, default)
self.layout().addWidget(widget)
self.widgets.append(widget)
widget.changed.connect(self.changed)
self.bitLength += len(default)
def addOptions(self, defaults, lenghts = None):
if lenghts is None:
lenghts = [1] * len(defaults)
# reverse bit order for per-setting indexing
defaultsIndex = 0
bitIndex = len(defaults)
for i, l in enumerate(lenghts):
self.addOption(
'Setting {}'.format(i + 1),
bitIndex - l,
defaults[defaultsIndex:defaultsIndex + l])
bitIndex -= l
defaultsIndex += l
def resetValues(self):
for widget in self.widgets:
widget.resetValues()
class Tester(QtWidgets.QWidget):
def __init__(self):
QtWidgets.QWidget.__init__(self)
layout = QtWidgets.QGridLayout()
self.setLayout(layout)
self.tabWidget = QtWidgets.QTabWidget()
layout.addWidget(self.tabWidget)
resultLayout = QtWidgets.QHBoxLayout()
layout.addLayout(resultLayout, layout.rowCount(), 0, 1, layout.columnCount())
self.tabs = []
self.labels = []
for (group, lenghts), defaults in zip(groups, defaultValues):
tab = Group(group, defaults, lenghts)
self.tabWidget.addTab(tab, group)
tab.changed.connect(self.updateResults)
self.tabs.append(tab)
tabLabel = QtWidgets.QLabel()
self.labels.append(tabLabel)
resultLayout.addWidget(tabLabel)
self.resetButton = QtWidgets.QPushButton('Reset values')
layout.addWidget(self.resetButton)
self.resetButton.clicked.connect(lambda: [tab.resetValues() for tab in self.tabs])
self.updateResults()
def values(self):
return [tab.value() for tab in self.tabs]
def updateResults(self):
for value, tab, label in zip(self.values(), self.tabs, self.labels):
label.setText('''
{0}: <span style="font-family:monospace;">{1} <b>{1:0{2}b}</b></span>
'''.format(tab.name, value, tab.bitLength))
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
w = Tester()
w.show()
sys.exit(app.exec_())
I am designing a program composed of a 3D viewer and a table with Python 3.4 and PySide bindings.
I have created a TableView with this class:
from PySide import QtGui
from PySide.QtCore import Qt
class MyTableView(QtGui.QWidget):
def __init__(self, parent=None):
super(MyTableView, self).__init__()
self.parent = parent
self.title = "Results"
self.initUI()
def initUI(self):
self.grid = QtGui.QGridLayout(self)
self.table = QtGui.QTableView()
self.grid.addWidget(self.table, 0, 0)
# Configure table
self.table.verticalHeader().setVisible(False)
self.table.horizontalHeader().setDefaultAlignment(Qt.AlignLeft)
self.table.setSortingEnabled(True)
self.table.setAlternatingRowColors(True)
self.table.setShowGrid(False)
self.table.setEditTriggers(QtGui.QAbstractItemView.NoEditTriggers)
self.table.setSelectionBehavior(QtGui.QAbstractItemView.SelectRows)
and the model with this other class:
class MyModel(QStandardItemModel):
def __init__(self, path, *args, **kwargs):
super(MyModel, self).__init__()
self.path = path
self.parse()
def parse(self):
with open(self.path) as f:
self.mydata = yaml.load(f)
self.setColumnCount(len(self.mydata['headers']) + 1)
self.setHorizontalHeaderLabels(
['ID'] + self.mydata['headers'])
row = 0
for ind, val in self.mydata['rows'].items():
col = 0
self.insertRow(row)
self.setItem(row, col, QStandardItem(ind))
for v in val:
col += 1
self.setItem(row, col, QStandardItem(str(v)))
row += 1
which are then tied together in this controller:
from PySide.QtCore import Qt
class MyController(object):
def __init__(self, model, view):
self.model = model
self.tableview = view.table
self.fill_table()
self.connect_signals()
def fill_table(self):
self.tableview.setModel(self.model)
self.tableview.sortByColumn(0, Qt.AscendingOrder)
def connect_signals(self):
selectionModel = self.tableview.selectionModel()
selectionModel.selectionChanged.connect(self.selection_changed)
def selection_changed(self, selected, deselected):
print("Selection changed.")
Then, the program is executed through this script:
def main():
app = QtGui.QApplication(sys.argv)
MyController(MyModel(sys.argv[1]), MyView())
sys.exit(app.exec_())
if __name__ == '__main__':
main()
(Note that I haven't posted the main window class, but you get the idea)
The table gets rendered OK, but I am not able to connect the selectionChanged signal to the handler (which should udpate the viewer, but for testing purposes it's only a print statement).
What am I doing wrong? Thanks!
[EDIT]
I have discovered that it works if I use a lambda function to call the handler method. Can someone explain why?!
selectionModel.selectionChanged.connect(lambda: self.selection_changed(selectionModel.selectedRows()))
I tried to implement what you wrote and it worked - so I can't be 100% sure of why you are having trouble. But I suspect it is because of what I had to fix to get it to work at all: I had to sort out some problems you have with garbage collection.
In the example code you give, you create a MyController, a MyModel and a MyView. But they will all then be garbage collected (in CPython) since you don't keep a reference to them. If you add a reference to MyController
my_controller = MyController(MyModel(sys.argv[1]), MyView())
you are almost there, but I think the MyTableView might also then be garbage collected since the controller only keeps a reference to the QTableVIew not the MyTableView.
Presumably using the lanbda function changes the references you are preserving - it preserves the controller and the selection model - and that may be why it is working in that case.
Generally it's a good idea to use the Qt parenting mechanism. If you simply parented all these objects on the main window (or their natural parent widget) that would have prevented most of these problems.
Short version
How do you implement undo functionality for edits made on QListWidgetItems in PySide/PyQt?
Hint from a Qt tutorial?
The following tutorial written for Qt users (c++) likely has the answer, but I am not a c++ person, so get a bit lost: Using Undo/Redo with Item Views
Longer version
I am using a QListWidget to learn my way around PyQt's Undo Framework (with the help of an article on the topic). I am fine with undo/redo when I implement a command myself (like deleting an item from the list).
I also want to make the QListWidgetItems in the widget editable. This is easy enough: just add the ItemIsEditable flag to each item. The problem is, how can I push such edits onto the undo stack, so I can then undo/redo them?
Below is a simple working example that shows a list, lets you delete items,and undo/redo such deletions. The application displays both the list and the the undo stack. What needs to be done to get edits onto that stack?
Simple working example
from PySide import QtGui, QtCore
class TodoList(QtGui.QWidget):
def __init__(self):
QtGui.QWidget.__init__(self)
self.setAttribute(QtCore.Qt.WA_DeleteOnClose)
self.initUI()
self.show()
def initUI(self):
self.todoList = self.makeTodoList()
self.undoStack = QtGui.QUndoStack(self)
undoView = QtGui.QUndoView(self.undoStack)
buttonLayout = self.buttonSetup()
mainLayout = QtGui.QHBoxLayout(self)
mainLayout.addWidget(undoView)
mainLayout.addWidget(self.todoList)
mainLayout.addLayout(buttonLayout)
self.setLayout(mainLayout)
self.makeConnections()
def buttonSetup(self):
#Make buttons
self.deleteButton = QtGui.QPushButton("Delete")
self.undoButton = QtGui.QPushButton("Undo")
self.redoButton = QtGui.QPushButton("Redo")
self.quitButton = QtGui.QPushButton("Quit")
#Lay them out
buttonLayout = QtGui.QVBoxLayout()
buttonLayout.addWidget(self.deleteButton)
buttonLayout.addStretch()
buttonLayout.addWidget(self.undoButton)
buttonLayout.addWidget(self.redoButton)
buttonLayout.addStretch()
buttonLayout.addWidget(self.quitButton)
return buttonLayout
def makeConnections(self):
self.deleteButton.clicked.connect(self.deleteItem)
self.quitButton.clicked.connect(self.close)
self.undoButton.clicked.connect(self.undoStack.undo)
self.redoButton.clicked.connect(self.undoStack.redo)
def deleteItem(self):
rowSelected=self.todoList.currentRow()
rowItem = self.todoList.item(rowSelected)
if rowItem is None:
return
command = CommandDelete(self.todoList, rowItem, rowSelected,
"Delete item '{0}'".format(rowItem.text()))
self.undoStack.push(command)
def makeTodoList(self):
todoList = QtGui.QListWidget()
allTasks = ('Fix door', 'Make dinner', 'Read',
'Program in PySide', 'Be nice to everyone')
for task in allTasks:
todoItem=QtGui.QListWidgetItem(task)
todoList.addItem(todoItem)
todoItem.setFlags(QtCore.Qt.ItemIsSelectable | QtCore.Qt.ItemIsEnabled)
return todoList
class CommandDelete(QtGui.QUndoCommand):
def __init__(self, listWidget, item, row, description):
super(CommandDelete, self).__init__(description)
self.listWidget = listWidget
self.string = item.text()
self.row = row
def redo(self):
self.listWidget.takeItem(self.row)
def undo(self):
addItem = QtGui.QListWidgetItem(self.string)
addItem.setFlags(QtCore.Qt.ItemIsSelectable | QtCore.Qt.ItemIsEnabled)
self.listWidget.insertItem(self.row, addItem)
if __name__ == "__main__":
import sys
app = QtGui.QApplication(sys.argv)
myList=TodoList()
sys.exit(app.exec_())
Note I posted an earlier version of this question at QtCentre.
That tutorial you mentioned is really not very helpful. There are indeed many approaches to undo-redo implementation for views, we just need to choose the simplest one. If you deal with small lists, the simpliest way is to save all data on each change and restore full list from scratch on each undo or redo operation.
If you still want atomic changes list, you can track user-made edits with QListWidget::itemChanged signal. There are two problems with that:
Any other item change in the list will also trigger this signal, so you need to wrap any code that changes items into QObject::blockSignals calls to block unwanted signals.
There is no way to get previous text, you can only get new text. The solution is either save all list data to variable, use and update it on change or save the edited item's text before it's edited. QListWidget is pretty reticent about its internal editor state, so I decided to use QListWidget::currentItemChanged assuming that user won't find a way to edit an item without making is current first.
So this is the changes that will make it work (besides adding ItemIsEditable flag in two places):
def __init__(self):
#...
self.todoList.itemChanged.connect(self.itemChanged)
self.todoList.currentItemChanged.connect(self.currentItemChanged)
self.textBeforeEdit = ""
def itemChanged(self, item):
command = CommandEdit(self.todoList, item, self.todoList.row(item),
self.textBeforeEdit,
"Rename item '{0}' to '{1}'".format(self.textBeforeEdit, item.text()))
self.undoStack.push(command)
def currentItemChanged(self, item):
self.textBeforeEdit = item.text()
And the new change class:
class CommandEdit(QtGui.QUndoCommand):
def __init__(self, listWidget, item, row, textBeforeEdit, description):
super(CommandEdit, self).__init__(description)
self.listWidget = listWidget
self.textBeforeEdit = textBeforeEdit
self.textAfterEdit = item.text()
self.row = row
def redo(self):
self.listWidget.blockSignals(True)
self.listWidget.item(self.row).setText(self.textAfterEdit)
self.listWidget.blockSignals(False)
def undo(self):
self.listWidget.blockSignals(True)
self.listWidget.item(self.row).setText(self.textBeforeEdit)
self.listWidget.blockSignals(False)
I would do it like this:
Create a custom QItemDelegate and use these two signals:
editorEvent
closeEditor
On editorEvent: Save current state
On closeEditor: Get new state and create a QUndoCommand that set the new state for Redo and the old state for Undo.
Each time you verify and accept the new text of the item, save it as list item data. Quasi-semi-pseudo-code:
OnItemEdited(Item* item)
{
int dataRole{ 32 }; //or greater (see ItemDataRole documentation)
if (Validate(item->text()) {
item->setData(dataRole, item->text());
} else { //Restore previous value
item->setText(item->data(dataRole).toString());
}
}
I'm sorry if it looks too much like C++.
I need to determine which rows are selected in a QTableView associated with a QStandardItemModel. From the view, I call the function selectionModel() to get the selection. This function returns a QSelectionModel object. From that object, I want to call isRowSelected() function. This function takes two arguments: the row I want to test, and a parent argument, which is a QModelIndex. This is where I'm lost. What is this parent argument for? Where does it come from? Conceptually, I don't understand why I'd need this parameter, and concretely, I don't know what value I should pass to the function to make it work.
You'll find the parent useful in a QTreeView, for example. For your use case, this are the relevant parts of the documentation:
The index is used by item views, delegates, and selection models to
locate an item in the model... Invalid indexes are often used as parent indexes when referring to top-level items in a model."
With QtCore.QModelIndex() you'll create an invalid index, that's the argument you are looking for. In this example, you can use the context menu to print the selection state of the rows:
#!/usr/bin/env python
#-*- coding:utf-8 -*-
from PyQt4 import QtGui, QtCore
class MyWindow(QtGui.QTableView):
def __init__(self, parent=None):
super(MyWindow, self).__init__(parent)
self.modelSource = QtGui.QStandardItemModel(self)
for rowNumber in range(3):
items = []
for columnNumber in range(3):
item = QtGui.QStandardItem()
item.setText("row: {0} column: {0}".format(rowNumber, columnNumber))
items.append(item)
self.modelSource.appendRow(items)
self.actionSelectedRows = QtGui.QAction(self)
self.actionSelectedRows.setText("Get Selected Rows")
self.actionSelectedRows.triggered.connect(self.on_actionSelectedRows_triggered)
self.contextMenu = QtGui.QMenu(self)
self.contextMenu.addAction(self.actionSelectedRows)
self.setModel(self.modelSource)
self.setContextMenuPolicy(QtCore.Qt.CustomContextMenu)
self.setSelectionBehavior(QtGui.QAbstractItemView.SelectRows)
self.horizontalHeader().setStretchLastSection(True)
self.customContextMenuRequested.connect(self.on_customContextMenuRequested)
#QtCore.pyqtSlot(bool)
def on_actionSelectedRows_triggered(self, state):
for rowNumber in range(self.model().rowCount()):
info = "Row {0} is ".format(rowNumber)
if self.selectionModel().isRowSelected(rowNumber, QtCore.QModelIndex()):
info += "selected"
else:
info += "not selected"
print info
#QtCore.pyqtSlot(QtCore.QPoint)
def on_customContextMenuRequested(self, pos):
self.contextMenu.exec_(self.mapToGlobal(pos))
if __name__ == "__main__":
import sys
app = QtGui.QApplication(sys.argv)
app.setApplicationName('MyWindow')
main = MyWindow()
main.resize(333, 222)
main.show()
sys.exit(app.exec_())
I want to create a doublespin box that changes values in steps of 0.2. But when the user enters a value that is not correct according to the steps. I normalizes that to the nearest correct value.
I tried something like the code shown below but I don't know how to stop values like 0.5 to be entered. Please help me on this.
from PyQt4.QtCore import *
from PyQt4.QtGui import *
class SigSlot(QWidget):
def __init__(self, parent=None):
QWidget.__init__(self, parent)
self.setWindowTitle('spinbox value')
self.resize(250,150)
self.lcd1 = QLCDNumber(self)
self.spinbox1 = QDoubleSpinBox(self)
self.spinbox1.setSingleStep(0.2)
self.spinbox1.setCorrectionMode(1)
# create a Grid Layout
grid = QGridLayout()
grid.addWidget(self.lcd1, 0, 0)
grid.addWidget(self.spinbox1, 1, 0)
self.setLayout(grid)
# allows access to the spinbox value as it changes
self.connect(self.spinbox1, SIGNAL('valueChanged(double)'), self.change_value1)
def change_value1(self, event):
val = self.spinbox1.value()
self.lcd1.display(val)
app = QApplication([])
qb = SigSlot()
qb.show()
app.exec_()
You have two choices:
You can subclass the QSpinBox, override validate method and use an appropriate Q*Validator (e.g. QRegExpValidator) inside.
You can check the value in slot connected to valueChanged before using and correct it if necessary.
Since you are already using the valueChanged signal, second option should be fairly easy to implement. Just change your change_value method like this:
def change_value1(self, val): # new value is passed as an argument
# so no need for this
# val = self.spinbox1.value()
new_val = round(val*5)/5 # one way to fix
if val != new_val: # if value is changed, put it in the spinbox
self.spinbox1.setValue(new_val)
self.lcd1.display(new_val)
By the way, since you are using only one decimal precision, it might be logical to also use:
self.spinbox1.setDecimals(1)
in your __init__. And try to use the new style signals and slots. i.e.:
self.connect(self.spinbox1, SIGNAL('valueChanged(double)'), self.change_value1)
could be written as:
self.spinbox1.valueChanged[float].connect(self.change_value1)
Edit
Subclassing:
class MySpinBox(QDoubleSpinBox):
def __init__(self, parent=None):
super(MySpinBox, self).__init__(parent)
# any RegExp that matches the allowed input
self.validator = QRegExpValidator(QRegExp("\\d+[\\.]{0,1}[02468]{0,1}"), self)
def validate(self, text, pos):
# this decides if the entered value should be accepted
return self.validator.validate(text, pos)
then instead of using QDoubleSpinBox you would use MySpinBox and leave the input checking to this class.
In your change value method you can do something like this
val = round(self.spinbox1.value(), 1)
if val/2*10 - int(val/2*10):
val = round(val, 1) + .1
It's probably not the best way but it works.