I want to dynamically change the number of sliders on my application window, in dependence of the number of checked items in a QStandardItemModel structure.
My application window has an instance of QVBoxLayout called sliders, which I update when a button is pressed:
first removing all sliders eventually in there:
self.sliders.removeWidget(slider)
And then creating a new set.
The relevant code:
def create_sliders(self):
if len(self.sliders_list):
for sl in self.sliders_list:
self.sliders.removeWidget(sl)
self.sliders_list = []
for index in range(self.model.rowCount()):
if self.model.item(index).checkState():
slid = QSlider(Qt.Horizontal)
self.sliders.addWidget(slid)
self.sliders_list.append(slid)
The principle seems to work, however what happens is weird as the deleted sliders do not really disappear but it is as they were 'disconnected' from the underlying layout.
When created, the sliders keep their position among other elements while I resize the main window.
However, once they've been removed, they occupy a fixed position and can for instance disappear if I reduce the size of the window.
Unfortunately I'm having difficulties in linking images (it says the format is not supported when I try to link from pasteboard), so I hope this description is enough to highlight the issue.
Do I have to remove the sliders using a different procedure?
EDIT
Thanks to #eyllansec for his reply, it condenses a bunch of other replies around the topic, which I wasn't able to find as I did not know the method deleteLater() which is the key to get rid of widgets inside a QLayout.
I am marking it as my chosen (hey, it's the only one and it works, after all!), however I want to propose my own code which also works with minimal changes w.r.t. to what I proposed in the beginning.
The key point here is that I was using the metod QLayout.removeWidget(QWidget) which I was wrongly thinking, it would..er..Remove the widget! But actually what it does is (if I understood it right) remove it from the layout instance.
That is why it was still hanging in my window, although it seemed disconnected
Manual reference
Also, the proposed code is far more general than what I need, as it is a recursion over layout contents, which could in principle be both other QLayout objects or QWidgets (or even Qspacer), and be organized in a hierarchy (i.e., a QWidget QLayout within a QLayout and so on).
check this other answer
From there, the use of recursion and the series of if-then constructs.
My case is much simpler though, as I use this QVLayout instance to just place my QSliders and this will be all. So, for me, I stick to my list for now as I do not like the formalism of QLayout.TakeAt(n) and I don't need it. I was glad that the references I build in a list are absolutely fine to work with.
In the end, this is the slightly changed code that works for me in this case:
def create_sliders(self):
if len(self.sliders_list):
for sl in self.sliders_list:
sl.deleteLater()
self.sliders_list = []
for index in range(self.model.rowCount()):
if self.model.item(index).checkState():
slid = QSlider(Qt.Horizontal)
self.sliders.addWidget(slid)
self.sliders_list.append(slid)
It is not necessary to save the sliders in a list, they can be accessed through the layout where it is contained. I have implemented a function that deletes the elements within a layout. The solution is as follows:
def create_sliders(self):
self.clearLayout(self.sliders)
for index in range(self.model.rowCount()):
if self.model.item(index).checkState():
slid = QSlider(Qt.Horizontal)
self.sliders.addWidget(slid)
def clearLayout(self, layout):
if layout:
while layout.count():
item = layout.takeAt(0)
widget = item.widget()
if widget:
widget.deleteLater()
else :
self.clearLayout(item.layout())
layout.removeItem(item)
Related
I have been fighting with custom widgets and lists for weeks now.
I have the ability to add a custom widget to a QListWidget. My issue is the insertItem seems to be buggy as it always drops it to the bottom of the list no matter what row I tell it to go to.
def AddToInitiative(self):
creature = self.comboBoxSelectCharacter.currentText()
if(creature):
widget = self.NewItemWidget()
customWidgetItem = QtGui.QListWidgetItem(self.initiativeList)
customWidgetItem.setSizeHint(QtCore.QSize(400,50))
self.initiativeList.addItem(customWidgetItem)
self.initiativeList.setItemWidget(customWidgetItem, widget)
widget.lineName.setText(creature)
return
def NewItemWidget(self):
customWidget = creature_initiative_object.InitCreatureObject()
customWidget.btnRemove.clicked.connect(self.ItemButtonClicked)
customWidget.btnInfo.clicked.connect(self.ItemButtonClicked)
customWidget.btnIncreaseInitOrder.clicked.connect(self.ItemButtonClicked)
customWidget.btnDecreaseInitOrder.clicked.connect(self.ItemButtonClicked)
return customWidget
def ChangeInit(self, row, direction, oldwidget):
item = self.initiativeList.takeItem(row)
widget = self.NewItemWidget()
widget.lineName.setText(oldwidget.lineName.text())
customWidgetItem = QtGui.QListWidgetItem(self.initiativeList)
customWidgetItem.setSizeHint(QtCore.QSize(400,50))
self.initiativeList.insertItem((row + direction), customWidgetItem)
self.initiativeList.setItemWidget(customWidgetItem, widget)
self.initiativeList.setCurrentRow(row+direction)
If I try to move the item up or down the list it always just goes straight to the bottom despite assigning the row number. I've output the row number and count to verify it should be saying the right row.
Do you know a way to do this with QListWidget for custom widgets that need to preserve data? Is there a better module to use?
I've looked at QListView, QBoxLayout, and a few others without being able to get it to work as well as QListWidget.
I'm using the Qt framework to build my graphical user interface. I use a QGridLayout to position my QWidgets neatly.
The GUI looks like this:
My application regularly adds new widgets to the GUI at runtime. These new widgets are usually not added at the end of the QLayout, but somewhere in the middle.
The procedure to do this is a bit cumbersome. Applied on the figure above, I would need to take out widg_C, widg_D, ... from the QGridLayout. Next, I add widg_xand widg_y, and finally I put the other widgets back again.
This is how I remove widgets from the QGridLayout:
for i in reversed(range(myGridLayout.count())):
self.itemAt(i).widget().setParent(None)
###
As long as you're dealing with a small amount of widgets, this procedure is not a disaster. But in my application I display a lot of small widgets - perhaps 50 or more! The application freezes a second while this procedure is ongoing, which is very annoying to the user.
Is there a way to insert widgets somewhere in a QLayout, without the need to take out other widgets?
EDIT: Apparently the solution for the QVBoxLayout is very simple. Just use the function insertWidget(..) instead of addWidget(..). The docs can be found a this link: http://doc.qt.io/qt-5/qboxlayout.html#insertWidget
Unfortunately, I couldn't find a similar function for the QGridLayout.
EDIT: Many people rightly mentioned that putting back a lot of widgets shouldn't cause a performance issue - it is very fast indeed (thank you #ekhumoro to point that out). Apparently, the performance issue I faced had to do with the algorithm putting the widgets back. It is a fairly complicated recursive algorithm that puts every widget on the right coordinates in the QGridLayout. This resulted in a "flicker" on my display. The widgets are taken out, and put back inside with some delay (due to the algorithm) - causing the flicker.
EDIT: I found a solution such that I can easily insert new rows into the QGridLayout. Inserting new rows means that I don't need to take out and replace all the widgets from scratch - hence I avoid the expensive recursive algorithm to run.
The solution can be found in my answer below.
Thank you #ekhumoro, #Stuart Fisher, #vahancho and #mbjoe for your help. I eventually found a way to solve the issue. I no longer use the QGridLayout(). Instead, I built a wrapper around the QVBoxLayout to behave as if it was a GridLayout, with an extra function to insert new rows:
class CustomGridLayout(QVBoxLayout):
def __init__(self):
super(CustomGridLayout, self).__init__()
self.setAlignment(Qt.AlignTop) # !!!
self.setSpacing(20)
def addWidget(self, widget, row, col):
# 1. How many horizontal layouts (rows) are present?
horLaysNr = self.count()
# 2. Add rows if necessary
if row < horLaysNr:
pass
else:
while row >= horLaysNr:
lyt = QHBoxLayout()
lyt.setAlignment(Qt.AlignLeft)
self.addLayout(lyt)
horLaysNr = self.count()
###
###
# 3. Insert the widget at specified column
self.itemAt(row).insertWidget(col, widget)
''''''
def insertRow(self, row):
lyt = QHBoxLayout()
lyt.setAlignment(Qt.AlignLeft)
self.insertLayout(row, lyt)
''''''
def deleteRow(self, row):
for j in reversed(range(self.itemAt(row).count())):
self.itemAt(row).itemAt(j).widget().setParent(None)
###
self.itemAt(row).setParent(None)
def clear(self):
for i in reversed(range(self.count())):
for j in reversed(range(self.itemAt(i).count())):
self.itemAt(i).itemAt(j).widget().setParent(None)
###
###
for i in reversed(range(self.count())):
self.itemAt(i).setParent(None)
###
''''''
well I'm using Pyqt4 in Maya2012 to make a reference editor alike ui. I working with a QtableWidget to make the reference list and i have subwidgets in each cell. One of the widgets is a checkbox that unload or reload the reference.
The problem i have is if a click directly in the checkbox without have the cell selected it doesn't do anything
this is my code:
def listConnections(self):
self.pos=self.sender().currentRow()
wid = self.list.ref_l.cellWidget(self.pos, 0).children()
self.text = self.list.list[self.pos]
self.ref()
for wt in wid:
if type(wt)== type(QCheckBox()):
wt.stateChanged.connect(self.changeState)
if type(wt)== type(QComboBox()):
wt.currentIndexChanged.connect(self.changeType)
I'm calling the function with a "itemSlectionChanged" signal because is the only way i knew i could detect the subwidgets.
All the subwidgets are made in the moment i fill the list.
Is there a way to make what i want?
Edit:
This is how i called the function
self.list.ref_l.itemSelectionChanged.connect(self.listConnections)
and this is how i create all the subwidgets in the cells
def fillList(self):
mayaRef = self.findRef()
if len(mayaRef)>0:
for count in range(0,len(mayaRef)):
self.ref_l.insertRow(count)
wid=QWidget()
cLayout=QHBoxLayout()
wid.setLayout(cLayout)
checkWid=QCheckBox()
nameWid=QLabel()
cLayout.addWidget(nameWid)
nameWid2=QLabel()
cLayout.addWidget(nameWid2)
comWid=QComboBox()
cLayout.addWidget(comWid)
self.ref_l.setCellWidget(count,0,wid)
self.ref_l is my QTable Widget, this is in another code that i'm calling with self.list in the original
You should set up all your connections right after you create the check boxes in fillList. Each item is associated with the path of the reference. You can use a QSignalMapper to map each check box to the path, then connect the signal mapper to your changeState slot. The signal mapper then calls that slot with the path you specified.
I have a window containing multiple QRowWidgets, which are custom widgets defined by me. These QRowWidgets contain QLineEdits and other standard widgets. To show or hide certain parts of a QRowWidget, I overdefined the focusInEvent() methodes of all the widgets within it. It works perfectly, when I click on the QRowWidget, the hidden elements appear.
The weird thing is that the blinking cursor line hovewer doesn't appear in the QLineEdits within the custom widgets. I can select them both by a mouse click or with Tab, and a glow effect indicates that the QLineEdit is selected in it, I can select a text in it, or start typing at any location wherever I clicked, but the cursor never appears and it's quite annoying.
My 1st thought was that it is a bug on Mac, but I have the same experience on SuSe Linux.
I'm using python 2.7 and PyQt4.
This is in the __init__() of the QRowWidget:
for i in self.findChildren(QWidget):
i.focusInEvent = self.focusInEvent
And then this is the own focusInEvent():
def focusInEvent(self, event):
if self.pself.focusedLine:
self.pself.focusedLine.setStyleSheet("color: #666;")
self.pself.focusedLine.desc.hide()
self.pself.focusedLine.closebutton.hide()
self.setStyleSheet("color: #000;")
self.desc.show()
self.closebutton.show()
self.pself.focusedLine = self
I suspect you do not make a call to the original focusInEvent() when you override it. Your function should look something like:
def focusInEvent(self,...):
QParent.focusInEvent(self,...)
# the rest of your code
where QParent is the nearest base class for your widgets is.
Either that, or make sure you call focusInEvent() on your QLineEdit widgets as part of your function.
Given the comments, it sounds like you are dynamically reassigning the focusInEvent function on the insantiatations in your custom widget. I would either make a derived class for each of the widgets you use that just overrides focusInEvent as above, or include a line like
type(self).focusInEvent(self,..)
in you function.
Is there a way to clear (delete) all the widgets in a layout?
self.plot_layout = QtGui.QGridLayout()
self.plot_layout.setGeometry(QtCore.QRect(200,200,200,200))
self.root_layout.addLayout(self.plot_layout)
self.plot_layout.addWidget(MyWidget())
Now I want to replace the widget in plot_layout with a new widget. Is there an easy way to clear all the widgets in plot_layout? I don't see any method such.
After a lot of research (and this one took quite time, so I add it here for future reference), this is the way I found to really clear and delete the widgets in a layout:
for i in reversed(range(layout.count())):
layout.itemAt(i).widget().setParent(None)
What the documentation says about the QWidget is that:
The new widget is deleted when its parent is deleted.
Important note: You need to loop backwards because removing things from the beginning shifts items and changes the order of items in the layout.
To test and confirm that the layout is empty:
for i in range(layout.count()): print i
There seems to be another way to do it. Instead of using the setParent function, use the deleteLater() function like this:
for i in reversed(range(layout.count())):
layout.itemAt(i).widget().deleteLater()
The documentation says that QObject.deleteLater (self)
Schedules this object for deletion.
However, if you run the test code specified above, it prints some values. This indicates that the layout still has items, as opposed to the code with setParent.
This may be a bit too late but just wanted to add this for future reference:
def clearLayout(layout):
while layout.count():
child = layout.takeAt(0)
if child.widget():
child.widget().deleteLater()
Adapted from Qt docs http://doc.qt.io/qt-5/qlayout.html#takeAt. Remember that when you are removing children from the layout in a while or for loop, you are effectively modifying the index # of each child item in the layout. That's why you'll run into problems using a for i in range() loop.
The answer from PALEN works well if you do not need to put new widgets to your layout.
for i in reversed(range(layout.count())):
layout.itemAt(i).widget().setParent(None)
But you will get a "Segmentation fault (core dumped)" at some point if you empty and fill the layout many times or with many widgets. It seems that the layout keeps a list of widget and that this list is limited in size.
If you remove the widgets that way:
for i in reversed(range(layout.count())):
widgetToRemove = layout.itemAt(i).widget()
# remove it from the layout list
layout.removeWidget(widgetToRemove)
# remove it from the gui
widgetToRemove.setParent(None)
You won't get that problem.
That's how I clear a layout :
def clearLayout(layout):
if layout is not None:
while layout.count():
child = layout.takeAt(0)
if child.widget() is not None:
child.widget().deleteLater()
elif child.layout() is not None:
clearLayout(child.layout())
You can use the close() method of widget:
for i in range(layout.count()): layout.itemAt(i).widget().close()
I use:
while layout.count() > 0:
layout.itemAt(0).setParent(None)
My solution to this problem is to override the setLayout method of QWidget. The following code updates the layout to the new layout which may or may not contain items that are already displayed. You can simply create a new layout object, add whatever you want to it, then call setLayout. Of course, you can also just call clearLayout to remove everything.
def setLayout(self, layout):
self.clearLayout()
QWidget.setLayout(self, layout)
def clearLayout(self):
if self.layout() is not None:
old_layout = self.layout()
for i in reversed(range(old_layout.count())):
old_layout.itemAt(i).widget().setParent(None)
import sip
sip.delete(old_layout)
Most of the existing answers don't account for nested layouts, so I made a recursive function, that given a layout it will recursively delete everything inside it, and all the layouts inside of it. here it is:
def clearLayout(layout):
print("-- -- input layout: "+str(layout))
for i in reversed(range(layout.count())):
layoutItem = layout.itemAt(i)
if layoutItem.widget() is not None:
widgetToRemove = layoutItem.widget()
print("found widget: " + str(widgetToRemove))
widgetToRemove.setParent(None)
layout.removeWidget(widgetToRemove)
elif layoutItem.spacerItem() is not None:
print("found spacer: " + str(layoutItem.spacerItem()))
else:
layoutToRemove = layout.itemAt(i)
print("-- found Layout: "+str(layoutToRemove))
clearLayout(layoutToRemove)
I might not have accounted for all UI types, not sure. Hope this helps!
From the docs:
To remove a widget from a layout, call removeWidget(). Calling QWidget.hide() on a widget also effectively removes the widget from the layout until QWidget.show() is called.
removeWidget is inherited from QLayout, that's why it's not listed among the QGridLayout methods.
I had issues with solutions previously mentioned. There were lingering widgets that were causing problems; I suspect deletion was scheduled, but not finihsed. I also had to set the widgets parent to None.
this was my solution:
def clearLayout(layout):
while layout.count():
child = layout.takeAt(0)
childWidget = child.widget()
if childWidget:
childWidget.setParent(None)
childWidget.deleteLater()
A couple of solutions, if you are swapping between known views using a stacked widget and just flipping the shown index might be a lot easier than adding and removing single widgets from a layout.
If you want to replace all the children of a widget then the QObject functions findChildren should get you there e.g. I don't know how the template functions are wrapped in pyqt though. But you could also search for the widgets by name if you know them.
for i in reversed(range(layout.count())):
if layout.itemAt(i).widget():
layout.itemAt(i).widget().setParent(None)
else:
layout.removeItem(layout.itemAt(i))
for i in reversed (range(layout.count())):
layout.itemAt(i).widget().close()
layout.takeAt(i)
or
for i in range(layout.count()):
layout.itemAt(0).widget().close()
layout.takeAt(0)