I have a QTreeView with a QStyledItemDelegate inside of it. When a certain action occurs to the delegate, its size is supposed to change. However I haven't figured out how to get the QTreeView's rows to resize in response to the delegate's editor size changing. I tried QTreeView.updateGeometry and QTreeView.repaint and a couple other things but it doesn't seem to work. Could someone point me in the right direction?
Here's a minimal reproduction (note: The code is hacky in a few places, it's just meant to be a demonstration of the problem, not a demonstration of good MVC).
Steps:
Run the code below
Press either "Add a label" button
Note that the height of the row in the QTreeView does not change no matter how many times either button is clicked.
from PySide2 import QtCore, QtWidgets
_VALUE = 100
class _Clicker(QtWidgets.QWidget):
clicked = QtCore.Signal()
def __init__(self, parent=None):
super(_Clicker, self).__init__(parent=parent)
self.setLayout(QtWidgets.QVBoxLayout())
self._button = QtWidgets.QPushButton("Add a label")
self.layout().addWidget(self._button)
self._button.clicked.connect(self._add_label)
self._button.clicked.connect(self.clicked.emit)
def _add_label(self):
global _VALUE
_VALUE += 10
self.layout().addWidget(QtWidgets.QLabel("Add a label"))
self.updateGeometry() # Note: I didn't expect this to work but added it regardless
class _Delegate(QtWidgets.QStyledItemDelegate):
def createEditor(self, parent, option, index):
widget = _Clicker(parent=parent)
viewer = self.parent()
widget.clicked.connect(viewer.updateGeometries) # Note: I expected this to work
return widget
def paint(self, painter, option, index):
super(_Delegate, self).paint(painter, option, index)
viewer = self.parent()
if not viewer.isPersistentEditorOpen(index):
viewer.openPersistentEditor(index)
def setEditorData(self, editor, index):
pass
def updateEditorGeometry(self, editor, option, index):
editor.setGeometry(option.rect)
def sizeHint(self, option, index):
hint = index.data(QtCore.Qt.SizeHintRole)
if hint:
return hint
return super(_Delegate, self).sizeHint(option, index)
class _Model(QtCore.QAbstractItemModel):
def __init__(self, parent=None):
super(_Model, self).__init__(parent=parent)
self._labels = ["foo", "bar"]
def columnCount(self, parent=QtCore.QModelIndex()):
return 1
def data(self, index, role):
if role == QtCore.Qt.SizeHintRole:
return QtCore.QSize(200, _VALUE)
if role != QtCore.Qt.DisplayRole:
return None
return self._labels[index.row()]
def index(self, row, column, parent=QtCore.QModelIndex()):
child = self._labels[row]
return self.createIndex(row, column, child)
def parent(self, index):
return QtCore.QModelIndex()
def rowCount(self, parent=QtCore.QModelIndex()):
if parent.isValid():
return 0
return len(self._labels)
application = QtWidgets.QApplication([])
view = QtWidgets.QTreeView()
view.setModel(_Model())
view.setItemDelegate(_Delegate(parent=view))
view.show()
application.exec_()
How do I get a single row in a QTreeView, which has a persistent editor applied already to it, to tell Qt to resize in response to some change in the editor?
Note: One possible solution would be to close the persistent editor and re-open it to force Qt to redraw the editor widget. This would be generally very slow and not work in my specific situation. Keeping the same persistent editor is important.
As the documentation about updateGeometries() explains, it:
Updates the geometry of the child widgets of the view.
This is used to update the widgets (editors, scroll bars, headers, etc) based on the current view state. It doesn't consider the editor size hints, so that call or the attempt to update the size hint is useless (and, it should go without saying, using global for this is wrong).
In order to properly notify the view that a specific index has updated its size hint, you must use the delegate's sizeHintChanged signal, which should also be emitted when the editor is created in order to ensure that the view makes enough room for it; note that this is normally not required for standard editors (as, being they temporary, they should not try to change the layout of the view), but for persistent editors that are potentially big, it may be necessary.
Other notes:
calling updateGeometry() on the widget is pointless in this case, as adding a widget to a layout automatically results in a LayoutRequest event (which is what updateGeometry() does, among other things);
as explained in createEditor(), "the view's background will shine through unless the editor paints its own background (e.g., with setAutoFillBackground())";
the SizeHintRole of the model should always return a size important for the model (if any), not based on the editor; it's the delegate responsibility to do that, and the model should never be influenced by any of its views;
opening a persistent editor in a paint event is wrong; only drawing related aspects should ever happen in a paint function, most importantly because they are called very often (even hundreds of times per second for item views) so they should be as fast as possible, but also because doing anything that might affect a change in geometry will cause (at least) a recursive call;
signals can be "chained" without using emit: self._button.clicked.connect(self.clicked) would have sufficed;
Considering all the above, there are two possibilities. The problem is that there is no direct correlation between the editor widget and the index it's referred to, so we need to find a way to emit sizeHintChanged with its correct index when the editor is updated.
This can only be done by creating a reference of the index for the editor, but it's important that we use a QPersistentModelIndex for that, as the indexes might change while a persistent editor is opened (for example, when sorting or filtering), and the index provided in the arguments of delegate functions is not able to track these changes.
Emit a custom signal
In this case, we only use a custom signal that is emitted whenever we know that the layout is changed, and we create a local function in createEditor that will eventually emit the sizeHintChanged signal by "reconstructing" the valid index:
class _Clicker(QtWidgets.QWidget):
sizeHintChanged = QtCore.Signal()
def __init__(self, parent=None):
super().__init__(parent)
self.setAutoFillBackground(True)
layout = QtWidgets.QVBoxLayout(self)
self._button = QtWidgets.QPushButton("Add a label")
layout.addWidget(self._button)
self._button.clicked.connect(self._add_label)
def _add_label(self):
self.layout().addWidget(QtWidgets.QLabel("Add a label"))
self.sizeHintChanged.emit()
class _Delegate(QtWidgets.QStyledItemDelegate):
def createEditor(self, parent, option, index):
widget = _Clicker(parent)
persistent = QtCore.QPersistentModelIndex(index)
def emitSizeHintChanged():
index = persistent.model().index(
persistent.row(), persistent.column(),
persistent.parent())
self.sizeHintChanged.emit(index)
widget.sizeHintChanged.connect(emitSizeHintChanged)
self.sizeHintChanged.emit(index)
return widget
# no other functions implemented here
Use the delegate's event filter
We can create a reference for the persistent index in the editor, and then emit the sizeHintChanged signal in the event filter of the delegate whenever a LayoutRequest event is received from the editor:
class _Clicker(QtWidgets.QWidget):
def __init__(self, parent=None):
super().__init__(parent)
self.setAutoFillBackground(True)
layout = QtWidgets.QVBoxLayout(self)
self._button = QtWidgets.QPushButton("Add a label")
layout.addWidget(self._button)
self._button.clicked.connect(self._add_label)
def _add_label(self):
self.layout().addWidget(QtWidgets.QLabel("Add a label"))
class _Delegate(QtWidgets.QStyledItemDelegate):
def createEditor(self, parent, option, index):
widget = _Clicker(parent)
widget.index = QtCore.QPersistentModelIndex(index)
return widget
def eventFilter(self, editor, event):
if event.type() == event.LayoutRequest:
persistent = editor.index
index = persistent.model().index(
persistent.row(), persistent.column(),
persistent.parent())
self.sizeHintChanged.emit(index)
return super().eventFilter(editor, event)
Finally, you should obviously remove the SizeHintRole return in data(), and in order to open all persistent editors you could do something like this:
def openEditors(view, parent=None):
model = view.model()
if parent is None:
parent = QtCore.QModelIndex()
for row in range(model.rowCount(parent)):
for column in range(model.columnCount(parent)):
index = model.index(row, column, parent)
view.openPersistentEditor(index)
if model.rowCount(index):
openEditors(view, index)
# ...
openEditors(view)
I had a similar problem when I was adding new widgets to a QFrame, because the dumb thing was not updating the value of its sizeHint( ) after adding each new widget. It seems that QWidgets (including QFrames) only update their sizeHint( ) when the children widgets are "visible". Somehow, in some occassions Qt sets new children to "not visible" when they are added, don't ask me why. You can see if a widget is visible by calling isVisible( ), and change its visibility status with setVisible(...). I solved my problem by telling to the QFrame that they new child widgets were intended to be visible, by calling setVisible( True ) with each of each child after adding them to the QFrame. Some Qt fundamentalists may say that this is a blasphemous hack that breaks the fabric of space time or something and that I should be burnt at the stake, but I don't care, it works, and it works very well in a quite complex GUI that I have built.
Related
In a QlistWidget, When using listItem.setIcon(qIcon) the icon is put on the left of the list item. How can I make it show up on the right as shown below?
Also another question. How can I remove the icon from the item?
This can be done quite easily with a simple custom item-delegate:
class ItemDelegate(QtGui.QStyledItemDelegate):
def paint(self, painter, option, index):
option.decorationPosition = QtGui.QStyleOptionViewItem.Right
super(ItemDelegate, self).paint(painter, option, index)
class MainWindow(QtGui.QMainWindow, Ui_MainWindow):
def __init__(self):
...
self.delegate = ItemDelegate()
self.listWidget.setItemDelegate(self.delegate)
To remove an icon from an item, just set it to a null QIcon:
listItem.setIcon(QtGui.QIcon())
For this you will need to provide your own item delegate that draws the item data like you want.
See QAbstractItemView::setItemDelegate().
You can likely use QStyledItemDelegate as your base class and let its paint() handle all aspects other than the Qt::DecorationRole (the icon) and draw that yourself.
I am looking for the clean way to use a multi line text edit in the my QStyledItemDelegate. The createEditor implementation is pretty straight forward by returning a QTextEdit instance
def createEditor(self, parent, option, index):
return QtGui.QTextEdit("Some text")
But setModelData expects a Edit Widget derived from QWidget as a parameter instead of QTextEdits base QScrollArea. The Qt Documentation also tells me (at least in the PyQt Doc) that the setModelData function tries to get the data from the QWidget UserData field. But without having an Edit Widget derived from QWidget there is no option in setting the data. Currently it throws a AttributeError because it can't find text() on the editor.
Is there some proven way to use a non-QWidget editor? Or am I just missing some Widget to do that?
Currently I quick fixed the issue by instanciating a QLineEdit with the QTextEdit data from toPlainText() and passing this to setModelData. Very Hacky!! I could also use duck typing and just implement a text() method on a QTextEdit derivate. But still not a nice way, isn't it? What is a way to do this in C++?
The minimum requirements for an item-delegate are very simple. All you need to do is reimplement createEditor, setEditorData, and setModelData:
class Delegate(QStyledItemDelegate):
def createEditor(self, parent, options, index):
return QtGui.QTextEdit(parent)
def setEditorData(self, editor, index):
editor.setText(index.data())
def setModelData(self, editor, model, index):
model.setData(index, editor.toPlainText())
With this solution, it is easy to support several different types of editor via the same delegate. For example, an isinstance check could be used to decide which type of editor to use:
def setModelData(self, editor, model, index):
if isinstance(editor, QtGui.QTextEdit):
model.setData(index, editor.toPlainText())
elif isinstance(editor, QtGui.QComboBox):
model.setData(index, editor.currentText())
else:
super(Delegate, self).setModelData(editor, model, index)
See the section A Simple Delegate in the Model/View Overview for some C++ examples.
So I took some time and digged deeper into the problem. There are in fact multiple cleaner solutions:
Implementing a Property
I got it to work properly by implementing a QProperty on a subclass of QTextEdit which adds the text property as USER property to the object. Here is my code:
class DelegatableTextEdit(QtGui.QTextEdit):
#pyqtProperty(str, user=True)
def text(self):
return self.toPlainText()
#text.setter
def text(self, text):
self.setText(text)
Using the Factory
There seems to be an way to solve this by using the Delegates setDefaultFactory() method which then takes a QItemEditorFactory which has registered a custom editor creator by using the registerEditor() function. You can register a custom implementation of the QItemEditorCreatorBase class there which has a overriden createWidget method (and if needed a valuePropertyName function as well). But I haven't tried this one yet
I decided to take the first solution which only needs the custom QTextEdit and the overriden createEditor() function. Both should work in C++
The idea is to emit the index so I can catch it somewhere else and update information from that index. It works great - except when I scroll (while keeping the mouse still) the correct indices are not emitted. I'm guessing this is because the wheelEvent is firing before the actual scrolling happens. I'm a little stuck here though.
class View(QtGui.QTreeView):
hovered = QtCore.Signal(QtCore.QModelIndex)
def __init__(self, parent=None):
super(View, self).__init__(parent)
self.setMouseTracking(True)
def mouseMoveEvent(self, event):
index = QtCore.QPersistentModelIndex(self.indexAt(event.pos()))
if index.isValid():
self.hovered.emit(index)
super(TreeView, self).mouseMoveEvent(event)
def wheelEvent(self, event):
index = QtCore.QPersistentModelIndex(self.indexAt(event.pos()))
if index.isValid():
self.hovered.emit(index)
super(TreeView, self).wheelEvent(event)
It is not safe to save QModelIndex between different event. You need to use QPersistentModelIndex instead.
I feel a little dumb now. The problem was exactly what I was saying earlier. The actual scrolling was happening after I was grabbing the index because I was calling the super class method last (duh!). All I had to do was move the super class method to the top.
Im making a QTableWidget in Pyqt and ran into a bit of an annoying hiccup.
I need to use widgets in my table for its functionality, so im using setCellWidget to add them to the table. However, widgets dont have the same methods available as QTableWidgetItem's do (especially regarding selection in the table).
Im wondering if its possible to do something subclassing both items, so i can have the methods of both, and how i woulda dd that to the table.
Something like:
class TableItem(QtGui.QTableWidgetItem, QtGui.QWidget):
def __init__(self, parent=None):
super(TableItem, self).__init__(parent)
self.check = QtGui.QCheckBox()
self.label = QtGui.QLabel('Some Text')
self.h_box = QtGui.QHBoxLayout()
self.h_box.addWidget(self.check)
self.h_box.addWidget(self.label)
and then somehow add that to my table as a TableWidgetItem so it displays widgets and also has selection methods available.
Any ideas here?
For reference:
setCellWidget: http://pyqt.sourceforge.net/Docs/PyQt4/qtablewidget.html#setCellWidget
QWidget: (easy to find, i cant post more than 2 links)
-Which doesnt have the nice methods for a table
QTableWidgetItem: http://pyqt.sourceforge.net/Docs/PyQt4/qtablewidgetitem.html#type
with isSelected and setSelected (Methods not avialble from a widget used in setCellWidget.
To return the widget in a cell you can use table.cellWidget(row, column) and then use your widgets methods on that. But beacuse setSelected and isSelected arent methods of a widget, you cant check for selection. I was hoping to subclass the two together to allow for both
--Basically I need to know how to get my class to 'return' the proper type when i call it to add to the table with setItem
I am not sure what you want to do but you could "inject" a method like:
class TableWidgetItem(QtGui.QTableWidgetItem):
def __init__(self, parent=None):
QtGui.QTableWidgetItem.__init__(self)
def doSomething(self):
print "doing something in TableWidgetItem"
class Widget(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self)
tableWidgetItem = TableWidgetItem()
widget = Widget()
def widgetFunction(self):
tableWidgetItem.doSomething()
# as an instance method
settatr(widget, "widgetFunction", MethodType(widgetFunction, widget, type(widget)))
# or as a class method
settatr(widget, "widgetFunction", widgetFunction)
Then you can:
>>>widget.widgetFunction()
doing something in TableWidgetItem
(not tested)
QLineEdit has a textEdited signal which is emitted whenever the text is changed by user interaction, but not when the text is changed programatically. However, QDateTimeEdit has only a general dateTimeChanged signal that does not distinguish between these two types of changes. Since my app depends on knowing if the field was edited by the user or not, I'm looking for ways to implement it.
My (currently working) strategy was to create an eventFilter to the edit field, intercept key press and mouse wheel events and use them to determine if the field was modified by the user (storing this info in an object), and finally connecting the dateTimeChanged signal to a function that decides if the change was by the user or done programatically. Here are the relevant parts of the code (python):
class UserFilter(QObject):
def __init__(self, parent):
QObject.__init__(self, parent)
self.parent = parent
def eventFilter(self, object, event):
if event.type() == QEvent.KeyPress or event.type() == QEvent.Wheel:
self.parent.edited = True
else:
pass
return False
class DockThumb(QWidget):
def __init__(self, parent):
QWidget.__init__(self, parent)
self.parent = parent
self.edited = False
self.dateedit = QDateTimeEdit(self)
self.userfilter = UserFilter(self)
self.dateedit.installEventFilter(self.userfilter)
...
self.connect(self.dateedit,
SIGNAL('dateTimeChanged(QDateTime)'),
self.edited_or_not)
def edited_or_not(self):
if self.edited:
# User interacted! Go for it.
self.parent.runtimer()
# self.edited returns to False once data is saved.
else:
# User did not edited. Wait.
pass
Is there a more objective way of doing it? I tried subclasssing QDateTimeEdit, but failed to deal with events... Expected user interactions are direct typing, up/down arrow keys to spin through dates and copy/pasting the whole string.
The idiomatic Qt way of achieving this is indeed subclassing QDateTimeEdit and adding the functionality you require. I understand you tried it and "failed to deal with events", but that's a separate issue, and perhaps you should describe those problems - since they should be solvable.
Since I'm not entirely sure about what you are trying to do, I would agree with Eli Bendersky. Short of that, if you know when you will be programatically changing the QDateTimeEdit, set some flag that you can check in the slot handler that will indicate a programatic change is occurring and clear it when you are done.