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PySide2: How to keep QTreeWidgetItem widgets?

I have a problem with my custom QTreeWidget losing the associated widgets for each QTreeWidgetItem when it gets dragged and dropped. I understand that this is due to the item being destroyed and re-created at it's new position, and that it has something to do with the QMimeType, I believe? But I'm not sure how to work around this to get it to work and preserve/re-create these widgets? Could I possibly un-parent & reparent them, somehow? The examples I've been able to find have largely been in QT, which I can read, but I'm not really sure how to implement a solution in PySide2/PyQt. Would anybody be able to give me any pointers?
My code is written for Maya, but hopefully it should be able to work outside of Maya as well. (The custom dropEvent is needed due to a Maya/Mac bug that causes drag and drop actions to completely remove the item on drop.) You can see that item5 has been re-ordered, but lost it's associated button.
import sys
from PySide2 import QtCore, QtWidgets
def main():
try:
app = QtWidgets.QApplication(sys.argv)
ui = TreeUI()
ui.show()
app.exec_()
except RuntimeError:
from maya import OpenMayaUI as omui
try:
import shiboken2 as shiboken
except ImportError:
import shiboken
pointer = omui.MQtUtil.mainWindow()
win = shiboken.wrapInstance(long(pointer), QtWidgets.QWidget)
ui = TreeUI(parent=win)
ui.show()
class Tree(QtWidgets.QTreeWidget):
def __init__(self, parent=None):
super(Tree, self).__init__(parent)
self.setHeaderLabels(('name', 'widget'))
self.setSelectionMode(self.SingleSelection)
self.setDragEnabled(True)
self.setDropIndicatorShown(True)
self.setDragDropMode(self.InternalMove)
self.reparented_widgets = {}
def dropEvent(self, event):
index = self.indexAt(event.pos())
parent = index.parent()
self.model().dropMimeData(
event.mimeData(),
event.dropAction(),
index.row(),
index.column(),
parent
)
event.accept()
class TreeUI(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(TreeUI, self).__init__(parent)
widget = QtWidgets.QWidget(self)
self.setCentralWidget(widget)
tree = Tree()
for x in range(0, 6):
item = QtWidgets.QTreeWidgetItem(tree, ('item{}'.format(x), None))
item.setFlags(item.flags() & ~QtCore.Qt.ItemIsDropEnabled)
button = QtWidgets.QPushButton('Button{}'.format(x))
tree.setItemWidget(item, 1, button)
layout = QtWidgets.QVBoxLayout(widget)
layout.addWidget(tree)
main()
UPDATE #1:
I'm able to store the widgets for the QTreeWidgetItem within the startDrag function, while removing them from the item. But then, when I go to add them back to the new QTreeWidgetItem, the application crashes, unfortunately...
def startDrag(self, actions):
column_count = self.columnCount()
items = self.selectedItems()
for item in items:
for x in range(column_count):
widget = self.itemWidget(item, x)
if widget:
self.removeItemWidget(item, x)
self.reparent_widgets[x] = widget
super(Tree, self).startDrag(actions)
def dropEvent(self, event):
# Fix Mac/Maya drag and drop bug
index = self.indexAt(event.pos())
parent = index.parent()
self.model().dropMimeData(
event.mimeData(),
event.dropAction(),
index.row(),
index.column(),
parent
)
event.accept()
# Re-create widget(s)
pos = event.pos()
item = self.itemAt(pos)
for x in self.reparent_widgets.keys():
self.setItemWidget(item, x, self.reparent_widgets[x])

Overriding QCompleter popup position

There have been similar questions asked about overriding the QCompleter popup position but i'll still not found a working solution. I simply want to move the popup down around 5px (I have some specific styling requirements)
I've tried subclassing a QListView and using that as my popup using setPopup(). I then override the showEvent and move the popup down in Y. I also do this on the resizeEvent since I believe this is triggered when items are filtered and the popup resizes. However this doesn't work.. I then used a singleshot timer to trigger the move after 1ms. This does kind of work but it seems quite inconsistent - the first time it shows is different to subsequent times or resizing.
Below is my latest attempt (trying to hack it by counting the number of popups..), hopefully someone can show me what i'm doing wrong or a better solution
import sys
import os
from PySide2 import QtCore, QtWidgets, QtGui
class QPopup(QtWidgets.QListView):
def __init__(self, parent=None):
super(QPopup, self).__init__(parent)
self.popups = 0
def offset(self):
y = 3 if self.popups < 2 else 7
print('y: {}'.format(y))
self.move(self.pos().x(), self.pos().y() + y)
self.popups += 1
def showEvent(self, event):
print('show')
# self.offset()
QtCore.QTimer.singleShot(1, self.offset)
def resizeEvent(self, event):
print('resize')
# self.offset()
QtCore.QTimer.singleShot(1, self.offset)
class MyDialog(QtWidgets.QDialog):
def __init__(self, parent=None):
super(MyDialog, self).__init__(parent)
self.create_widgets()
self.create_layout()
self.create_connections()
def create_widgets(self):
self.le = QtWidgets.QLineEdit('')
self.completer = QtWidgets.QCompleter(self)
self.completer.setCaseSensitivity(QtCore.Qt.CaseInsensitive)
self.completer.setCompletionMode(QtWidgets.QCompleter.PopupCompletion)
self.completer.setMaxVisibleItems(10)
self.completer.setFilterMode(QtCore.Qt.MatchContains)
self.completer.setPopup(QPopup())
popup = QPopup(self)
self.completer.setPopup(popup)
self.model = QtCore.QStringListModel()
self.completer.setModel(self.model)
self.le.setCompleter(self.completer)
self.completer.model().setStringList(['one','two','three'])
def create_layout(self):
main_layout = QtWidgets.QVBoxLayout(self)
main_layout.addWidget(self.le)
def create_connections(self):
pass
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
my_dialog = MyDialog()
my_dialog.show() # Show the UI
sys.exit(app.exec_())

One solution could be to make a subclass of QLineEdit and override keyPressEvent to display the popup with an offset:
PySide2.QtWidgets.QCompleter.complete([rect=QRect()])
For PopupCompletion and QCompletion::UnfilteredPopupCompletion modes, calling this function displays the popup displaying the current completions. By default, if rect is not specified, the popup is displayed on the bottom of the widget() . If rect is specified the popup is displayed on the left edge of the rectangle.
see doc.qt.io -> QCompleter.complete.
Complete, self-contained example
The rect is calculated based on the y-position of the cursor rect. The height of the popup window is not changed. The width is adjusted to the width of the ZLineEdit widget.
rect = QtCore.QRect(0,
self.cursorRect().y() + 4,
self.width(),
self.completer().widget().height())
Your code, slightly modified using the points mentioned above, could look like this:
import sys
from PySide2 import QtCore, QtWidgets
from PySide2.QtWidgets import QLineEdit, QDialog, QCompleter
class ZLineEdit(QLineEdit):
def __init__(self, string, parent=None):
super().__init__(string, parent)
def keyPressEvent(self, event):
super().keyPressEvent(event)
if len(self.text()) > 0:
rect = QtCore.QRect(0,
self.cursorRect().y() + 4,
self.width(),
self.completer().widget().height())
self.completer().complete(rect)
class MyDialog(QDialog):
def __init__(self, parent=None):
super().__init__(parent)
self.le = ZLineEdit('')
autoList = ['one', 'two', 'three']
self.completer = QCompleter(autoList, self)
self.setup_widgets()
self.create_layout()
self.create_connections()
def setup_widgets(self):
self.completer.setCaseSensitivity(QtCore.Qt.CaseInsensitive)
self.completer.setCompletionMode(QtWidgets.QCompleter.PopupCompletion)
self.completer.setMaxVisibleItems(10)
self.completer.setFilterMode(QtCore.Qt.MatchContains)
self.le.setCompleter(self.completer)
def create_layout(self):
main_layout = QtWidgets.QVBoxLayout(self)
main_layout.addWidget(self.le)
def create_connections(self):
pass
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
my_dialog = MyDialog()
my_dialog.show()
sys.exit(app.exec_())
Test
On the left side you see the default behavior. On the right side the popup is moved down 4px:

Qt: Prevent drag-and-drop on child widgets and show forbidden cursor

I want to enable drag and drop functionality in some custom widgets, to allow reordering and rearranging the widgets within a layout. The basic functionality is working, but I'd like to prevent dropping a widget on itself, or on a child of itself. This is straightforward in the dropEvent method, but I can't find a way to also show the "forbidden" cursor while dragging, such that the user is aware that a drop will not be allowed.
The example below shows a test implementation, where the widgets "One" to "Five" can be dragged and dropped (no rearrangement will happen, only a message will be printed on the terminal, you may need to press Ctrl or something to initiate a drag). The problem line is the first ev.accept() in the dragEnterEvent method. By accepting the event, the cursor is shown in an "allowed" state (a grabbing hand for me). For example, trying to drag "One" and drop it onto "Three" appears as allowed, although nothing will happen. However, ignoring the event results in the event being propagated to the parent, so in that case dragging "Three" and dropping it onto "Three" results in "One" getting the drop instead. Setting the WA_NoMousePropagation attribute does not seem to make any difference.
So, what I would need is a way to "accept" the event, so that it will not be propagated to the parent, but still show a "forbidden" cursor, as if nobody accepted the event. Any ideas?
#!/usr/bin/env python3
import sys
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
class WidgetMimeData(QtCore.QMimeData):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.itemObject = None
def hasFormat(self, mime):
if (self.itemObject and (mime == 'widgetitem')):
return True
return super().hasFormat(mime)
def setItem(self, obj):
self.itemObject = obj
def item(self):
return self.itemObject
class DraggableWidget(QGroupBox):
def __init__(self):
QWidget.__init__(self)
layout = QVBoxLayout()
self.setLayout(layout)
self.setAcceptDrops(True)
def addWidget(self, widget):
return self.layout().addWidget(widget)
def mouseMoveEvent(self, ev):
pixmap = QPixmap(self.size())
pixmap.fill(QtCore.Qt.transparent)
painter = QPainter()
painter.begin(pixmap)
painter.setOpacity(0.8)
painter.drawPixmap(0, 0, self.grab())
painter.end()
drag = QDrag(self)
mimedata = WidgetMimeData()
mimedata.setItem(self)
drag.setMimeData(mimedata)
drag.setPixmap(pixmap)
drag.setHotSpot(ev.pos())
drag.exec_(QtCore.Qt.MoveAction)
def dragEnterEvent(self, ev):
item = ev.mimeData().item()
if item.isAncestorOf(self):
#ev.ignore()
ev.accept()
else:
ev.accept()
def dropEvent(self, ev):
item = ev.mimeData().item()
if not item.isAncestorOf(self):
print('dropped on', self.layout().itemAt(0).widget().text())
ev.accept()
class HelloWindow(QMainWindow):
def __init__(self):
QMainWindow.__init__(self)
w1 = DraggableWidget()
w1.addWidget(QLabel('One'))
w2 = DraggableWidget()
w2.addWidget(QLabel('Two'))
w3 = DraggableWidget()
w3.addWidget(QLabel('Three'))
w4 = DraggableWidget()
w4.addWidget(QLabel('Four'))
w5 = DraggableWidget()
w5.addWidget(QLabel('Five'))
w1.addWidget(w3)
w1.addWidget(w4)
w2.addWidget(w5)
layout = QVBoxLayout()
layout.addWidget(w1)
layout.addWidget(w2)
layout.addStretch(1)
centralWidget = QWidget(self)
centralWidget.setLayout(layout)
self.setCentralWidget(centralWidget)
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
mainWin = HelloWindow()
mainWin.show()
sys.exit( app.exec_() )

Probably the easiest way is to always accept the event in dragEnterEvent and in dragMoveEvent ignore it when the source of the event is an ancestor of self, i.e.
def dragEnterEvent(self, ev):
ev.accept()
def dragMoveEvent(self, ev):
item = ev.source()
if item.isAncestorOf(self):
ev.ignore()
By ignoring the event in dragMoveEvent you wouldn't need the check in dropEvent either and can simply do
def dropEvent(self, ev):
print('Dropped of', self.layout().itemAt(0).widget().text())
ev.accept()

Drag and drop columns between QHeaderView and QListWidget

I am having troubled using the QHeaderView drag & drop feature. When I subclass a QHeaderView, I am able to accept drops with no issue. However, when I click on the QHeaderView and try to drag from one of the columns, nothing appears to happen.
Below I have re-implemented several drag events to simply print if they were called. However, only the dragEnterEvent is successful. No other event such as startDrag is ever called. My ultimate goal is to have a QTableView where I can drag columns from and to a QListWidget (essentially hiding the column) and the user can then drag the QListWidget item back onto the QTableView if they want the column and its data to be visible again. However, I can’t move forward until I can understand why the QHeaderView is not allowing me to drag. Any help would be greatly appreciated.
class MyHeader(QHeaderView):
def __init__(self, parent=None):
super().__init__(Qt.Horizontal, parent)
self.setDragEnabled(True)
self.setAcceptDrops(True)
def startDrag(self, *args, **kwargs):
print('start drag success')
def dragEnterEvent(self, event):
print('drag enter success')
def dragLeaveEvent(self, event):
print('drag leave success')
def dragMoveEvent(self, event):
print('drag move success')
class Form(QDialog):
def __init__(self, parent=None):
super().__init__(parent)
listWidget = QListWidget()
listWidget.setDragEnabled(True)
listWidget.setAcceptDrops(True)
listWidget.addItem('item #1')
listWidget.addItem('item #2')
tableWidget = QTableWidget()
header = MyHeader()
tableWidget.setHorizontalHeader(header)
tableWidget.setRowCount(5)
tableWidget.setColumnCount(2)
tableWidget.setHorizontalHeaderLabels(["Column 1", "Column 2"])
splitter = QSplitter(Qt.Horizontal)
splitter.addWidget(listWidget)
splitter.addWidget(tableWidget)
layout = QHBoxLayout()
layout.addWidget(splitter)
self.setLayout(layout)
if __name__=='__main__':
import sys
app = QApplication(sys.argv)
form= Form()
form.show()
sys.exit(app.exec_())

The QHeaderView class does not use the drag and drop methods inherited from QAbstractItemView, because it never needs to initiate a drag operation. Drag and drop is only used for rearranging columns, and it is not necessary to use the QDrag mechanism for that.
Given this, it will be necessary to implement custom drag and drop handling (using mousePressEvent, mouseMoveEvent and dropEvent), and also provide functions for encoding and decoding the mime-data format that Qt uses to pass items between views. An event-filter will be needed for the table-widget, so that dropping is still possible when all columns are hidden; and also for the list-widget, to stop it copying items to itself.
The demo script below implements all of that. There are probably some more refinements needed, but it should be enough to get you started:
import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
class MyHeader(QHeaderView):
MimeType = 'application/x-qabstractitemmodeldatalist'
columnsChanged = pyqtSignal(int)
def __init__(self, parent=None):
super().__init__(Qt.Horizontal, parent)
self.setDragEnabled(True)
self.setAcceptDrops(True)
self._dragstartpos = None
def encodeMimeData(self, items):
data = QByteArray()
stream = QDataStream(data, QIODevice.WriteOnly)
for column, label in items:
stream.writeInt32(0)
stream.writeInt32(column)
stream.writeInt32(2)
stream.writeInt32(int(Qt.DisplayRole))
stream.writeQVariant(label)
stream.writeInt32(int(Qt.UserRole))
stream.writeQVariant(column)
mimedata = QMimeData()
mimedata.setData(MyHeader.MimeType, data)
return mimedata
def decodeMimeData(self, mimedata):
data = []
stream = QDataStream(mimedata.data(MyHeader.MimeType))
while not stream.atEnd():
row = stream.readInt32()
column = stream.readInt32()
item = {}
for count in range(stream.readInt32()):
key = stream.readInt32()
item[key] = stream.readQVariant()
data.append([item[Qt.UserRole], item[Qt.DisplayRole]])
return data
def mousePressEvent(self, event):
if event.button() == Qt.LeftButton:
self._dragstartpos = event.pos()
super().mousePressEvent(event)
def mouseMoveEvent(self, event):
if (event.buttons() & Qt.LeftButton and
self._dragstartpos is not None and
(event.pos() - self._dragstartpos).manhattanLength() >=
QApplication.startDragDistance()):
column = self.logicalIndexAt(self._dragstartpos)
data = [column, self.model().headerData(column, Qt.Horizontal)]
self._dragstartpos = None
drag = QDrag(self)
drag.setMimeData(self.encodeMimeData([data]))
action = drag.exec(Qt.MoveAction)
if action != Qt.IgnoreAction:
self.setColumnHidden(column, True)
def dropEvent(self, event):
mimedata = event.mimeData()
if mimedata.hasFormat(MyHeader.MimeType):
if event.source() is not self:
for column, label in self.decodeMimeData(mimedata):
self.setColumnHidden(column, False)
event.setDropAction(Qt.MoveAction)
event.accept()
else:
event.ignore()
else:
super().dropEvent(event)
def setColumnHidden(self, column, hide=True):
count = self.count()
if 0 <= column < count and hide != self.isSectionHidden(column):
if hide:
self.hideSection(column)
else:
self.showSection(column)
self.columnsChanged.emit(count - self.hiddenSectionCount())
class Form(QDialog):
def __init__(self, parent=None):
super().__init__(parent)
self.listWidget = QListWidget()
self.listWidget.setAcceptDrops(True)
self.listWidget.setDragEnabled(True)
self.listWidget.viewport().installEventFilter(self)
self.tableWidget = QTableWidget()
header = MyHeader(self)
self.tableWidget.setHorizontalHeader(header)
self.tableWidget.setRowCount(5)
self.tableWidget.setColumnCount(4)
labels = ["Column 1", "Column 2", "Column 3", "Column 4"]
self.tableWidget.setHorizontalHeaderLabels(labels)
for column, label in enumerate(labels):
if column > 1:
item = QListWidgetItem(label)
item.setData(Qt.UserRole, column)
self.listWidget.addItem(item)
header.hideSection(column)
header.columnsChanged.connect(
lambda count: self.tableWidget.setAcceptDrops(not count))
self.tableWidget.viewport().installEventFilter(self)
splitter = QSplitter(Qt.Horizontal)
splitter.addWidget(self.listWidget)
splitter.addWidget(self.tableWidget)
layout = QHBoxLayout()
layout.addWidget(splitter)
self.setLayout(layout)
def eventFilter(self, source, event):
if event.type() == QEvent.Drop:
if source is self.tableWidget.viewport():
self.tableWidget.horizontalHeader().dropEvent(event)
return True
else:
event.setDropAction(Qt.MoveAction)
return super().eventFilter(source, event)
if __name__=='__main__':
app = QApplication(sys.argv)
form = Form()
form.setGeometry(600, 50, 600, 200)
form.show()
sys.exit(app.exec_())

Custom Titlebar with frame in PyQt5

I'm working on an opensource markdown supported minimal note taking application for Windows/Linux. I'm trying to remove the title bar and add my own buttons. I want something like, a title bar with only two custom buttons as shown in the figure
Currently I have this:
I've tried modifying the window flags:
With not window flags, the window is both re-sizable and movable. But no custom buttons.
Using self.setWindowFlags(QtCore.Qt.FramelessWindowHint), the window has no borders, but cant move or resize the window
Using self.setWindowFlags(QtCore.Qt.CustomizeWindowHint), the window is resizable but cannot move and also cant get rid of the white part at the top of the window.
Any help appreciated. You can find the project on GitHub here.
Thanks..
This is my python code:
from PyQt5 import QtCore, QtWidgets, QtWebEngineWidgets, uic
import sys
import os
import markdown2 # https://github.com/trentm/python-markdown2
from PyQt5.QtCore import QRect
from PyQt5.QtGui import QFont
simpleUiForm = uic.loadUiType("Simple.ui")[0]
class SimpleWindow(QtWidgets.QMainWindow, simpleUiForm):
def __init__(self, parent=None):
QtWidgets.QMainWindow.__init__(self, parent)
self.setupUi(self)
self.markdown = markdown2.Markdown()
self.css = open(os.path.join("css", "default.css")).read()
self.editNote.setPlainText("")
#self.noteView = QtWebEngineWidgets.QWebEngineView(self)
self.installEventFilter(self)
self.displayNote.setContextMenuPolicy(QtCore.Qt.NoContextMenu)
#self.setWindowFlags(QtCore.Qt.FramelessWindowHint)
def eventFilter(self, object, event):
if event.type() == QtCore.QEvent.WindowActivate:
print("widget window has gained focus")
self.editNote.show()
self.displayNote.hide()
elif event.type() == QtCore.QEvent.WindowDeactivate:
print("widget window has lost focus")
note = self.editNote.toPlainText()
htmlNote = self.getStyledPage(note)
# print(note)
self.editNote.hide()
self.displayNote.show()
# print(htmlNote)
self.displayNote.setHtml(htmlNote)
elif event.type() == QtCore.QEvent.FocusIn:
print("widget has gained keyboard focus")
elif event.type() == QtCore.QEvent.FocusOut:
print("widget has lost keyboard focus")
return False
The UI file is created in the following hierarchy

Here are the steps you just gotta follow:
Have your MainWindow, be it a QMainWindow, or QWidget, or whatever [widget] you want to inherit.
Set its flag, self.setWindowFlags(Qt.FramelessWindowHint)
Implement your own moving around.
Implement your own buttons (close, max, min)
Implement your own resize.
Here is a small example with move around, and buttons implemented. You should still have to implement the resize using the same logic.
import sys
from PyQt5.QtCore import QPoint
from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QApplication
from PyQt5.QtWidgets import QHBoxLayout
from PyQt5.QtWidgets import QLabel
from PyQt5.QtWidgets import QPushButton
from PyQt5.QtWidgets import QVBoxLayout
from PyQt5.QtWidgets import QWidget
class MainWindow(QWidget):
def __init__(self):
super(MainWindow, self).__init__()
self.layout = QVBoxLayout()
self.layout.addWidget(MyBar(self))
self.setLayout(self.layout)
self.layout.setContentsMargins(0,0,0,0)
self.layout.addStretch(-1)
self.setMinimumSize(800,400)
self.setWindowFlags(Qt.FramelessWindowHint)
self.pressing = False
class MyBar(QWidget):
def __init__(self, parent):
super(MyBar, self).__init__()
self.parent = parent
print(self.parent.width())
self.layout = QHBoxLayout()
self.layout.setContentsMargins(0,0,0,0)
self.title = QLabel("My Own Bar")
btn_size = 35
self.btn_close = QPushButton("x")
self.btn_close.clicked.connect(self.btn_close_clicked)
self.btn_close.setFixedSize(btn_size,btn_size)
self.btn_close.setStyleSheet("background-color: red;")
self.btn_min = QPushButton("-")
self.btn_min.clicked.connect(self.btn_min_clicked)
self.btn_min.setFixedSize(btn_size, btn_size)
self.btn_min.setStyleSheet("background-color: gray;")
self.btn_max = QPushButton("+")
self.btn_max.clicked.connect(self.btn_max_clicked)
self.btn_max.setFixedSize(btn_size, btn_size)
self.btn_max.setStyleSheet("background-color: gray;")
self.title.setFixedHeight(35)
self.title.setAlignment(Qt.AlignCenter)
self.layout.addWidget(self.title)
self.layout.addWidget(self.btn_min)
self.layout.addWidget(self.btn_max)
self.layout.addWidget(self.btn_close)
self.title.setStyleSheet("""
background-color: black;
color: white;
""")
self.setLayout(self.layout)
self.start = QPoint(0, 0)
self.pressing = False
def resizeEvent(self, QResizeEvent):
super(MyBar, self).resizeEvent(QResizeEvent)
self.title.setFixedWidth(self.parent.width())
def mousePressEvent(self, event):
self.start = self.mapToGlobal(event.pos())
self.pressing = True
def mouseMoveEvent(self, event):
if self.pressing:
self.end = self.mapToGlobal(event.pos())
self.movement = self.end-self.start
self.parent.setGeometry(self.mapToGlobal(self.movement).x(),
self.mapToGlobal(self.movement).y(),
self.parent.width(),
self.parent.height())
self.start = self.end
def mouseReleaseEvent(self, QMouseEvent):
self.pressing = False
def btn_close_clicked(self):
self.parent.close()
def btn_max_clicked(self):
self.parent.showMaximized()
def btn_min_clicked(self):
self.parent.showMinimized()
if __name__ == "__main__":
app = QApplication(sys.argv)
mw = MainWindow()
mw.show()
sys.exit(app.exec_())
Here are some tips:
Option 1:
Have a QGridLayout with widget in each corner and side(e.g. left, top-left, menubar, top-right, right, bottom-right, bottom and bottom left)
With the approach (1) you would know when you are clicking in each border, you just got to define each one size and add each one on their place.
When you click on each one treat them in their respective ways, for example, if you click in the left one and drag to the left, you gotta resize it larger and at the same time move it to the left so it will appear to be stopped at the right place and grow width.
Apply this reasoning to each edge, each one behaving in the way it has to.
Option 2:
Instead of having a QGridLayout you can detect in which place you are clicking by the click pos.
Verify if the x of the click is smaller than the x of the moving pos to know if it's moving left or right and where it's being clicked.
The calculation is made in the same way of the Option1
Option 3:
Probably there are other ways, but those are the ones I just thought of. For example using the CustomizeWindowHint you said you are able to resize, so you just would have to implement what I gave you as example. BEAUTIFUL!
Tips:
Be careful with the localPos(inside own widget), globalPos(related to your screen). For example: If you click in the very left of your left widget its 'x' will be zero, if you click in the very left of the middle(content)it will be also zero, although if you mapToGlobal you will having different values according to the pos of the screen.
Pay attention when resizing, or moving, when you have to add width or subtract, or just move, or both, I'd recommend you to draw on a paper and figure out how the logic of resizing works before implementing it out of blue.
GOOD LUCK :D

While the accepted answer can be considered valid, it has some issues.
using setGeometry() is not appropriate (and the reason for using it was wrong) since it doesn't consider possible frame margins set by the style;
the position computation is unnecessarily complex;
resizing the title bar to the total width is wrong, since it doesn't consider the buttons and can also cause recursion problems in certain situations (like not setting the minimum size of the main window); also, if the title is too big, it makes impossible to resize the main window;
buttons should not accept focus;
setting a layout creates a restraint for the "main widget" or layout, so the title should not be added, but the contents margins of the widget should be used instead;
I revised the code to provide a better base for the main window, simplify the moving code, and add other features like the Qt windowTitle() property support, standard QStyle icons for buttons (instead of text), and proper maximize/normal button icons. Note that the title label is not added to the layout.
class MainWindow(QWidget):
def __init__(self):
super(MainWindow, self).__init__()
self.setWindowFlags(self.windowFlags() | Qt.FramelessWindowHint)
self.titleBar = MyBar(self)
self.setContentsMargins(0, self.titleBar.height(), 0, 0)
self.resize(640, self.titleBar.height() + 480)
def changeEvent(self, event):
if event.type() == event.WindowStateChange:
self.titleBar.windowStateChanged(self.windowState())
def resizeEvent(self, event):
self.titleBar.resize(self.width(), self.titleBar.height())
class MyBar(QWidget):
clickPos = None
def __init__(self, parent):
super(MyBar, self).__init__(parent)
self.setAutoFillBackground(True)
self.setBackgroundRole(QPalette.Shadow)
# alternatively:
# palette = self.palette()
# palette.setColor(palette.Window, Qt.black)
# palette.setColor(palette.WindowText, Qt.white)
# self.setPalette(palette)
layout = QHBoxLayout(self)
layout.setContentsMargins(1, 1, 1, 1)
layout.addStretch()
self.title = QLabel("My Own Bar", self, alignment=Qt.AlignCenter)
# if setPalette() was used above, this is not required
self.title.setForegroundRole(QPalette.Light)
style = self.style()
ref_size = self.fontMetrics().height()
ref_size += style.pixelMetric(style.PM_ButtonMargin) * 2
self.setMaximumHeight(ref_size + 2)
btn_size = QSize(ref_size, ref_size)
for target in ('min', 'normal', 'max', 'close'):
btn = QToolButton(self, focusPolicy=Qt.NoFocus)
layout.addWidget(btn)
btn.setFixedSize(btn_size)
iconType = getattr(style,
'SP_TitleBar{}Button'.format(target.capitalize()))
btn.setIcon(style.standardIcon(iconType))
if target == 'close':
colorNormal = 'red'
colorHover = 'orangered'
else:
colorNormal = 'palette(mid)'
colorHover = 'palette(light)'
btn.setStyleSheet('''
QToolButton {{
background-color: {};
}}
QToolButton:hover {{
background-color: {}
}}
'''.format(colorNormal, colorHover))
signal = getattr(self, target + 'Clicked')
btn.clicked.connect(signal)
setattr(self, target + 'Button', btn)
self.normalButton.hide()
self.updateTitle(parent.windowTitle())
parent.windowTitleChanged.connect(self.updateTitle)
def updateTitle(self, title=None):
if title is None:
title = self.window().windowTitle()
width = self.title.width()
width -= self.style().pixelMetric(QStyle.PM_LayoutHorizontalSpacing) * 2
self.title.setText(self.fontMetrics().elidedText(
title, Qt.ElideRight, width))
def windowStateChanged(self, state):
self.normalButton.setVisible(state == Qt.WindowMaximized)
self.maxButton.setVisible(state != Qt.WindowMaximized)
def mousePressEvent(self, event):
if event.button() == Qt.LeftButton:
self.clickPos = event.windowPos().toPoint()
def mouseMoveEvent(self, event):
if self.clickPos is not None:
self.window().move(event.globalPos() - self.clickPos)
def mouseReleaseEvent(self, QMouseEvent):
self.clickPos = None
def closeClicked(self):
self.window().close()
def maxClicked(self):
self.window().showMaximized()
def normalClicked(self):
self.window().showNormal()
def minClicked(self):
self.window().showMinimized()
def resizeEvent(self, event):
self.title.resize(self.minButton.x(), self.height())
self.updateTitle()
if __name__ == "__main__":
app = QApplication(sys.argv)
mw = MainWindow()
layout = QVBoxLayout(mw)
widget = QTextEdit()
layout.addWidget(widget)
mw.show()
mw.setWindowTitle('My custom window with a very, very long title')
sys.exit(app.exec_())

This is for the people who are going to implement custom title bar in PyQt6 or PySide6
The below changes should be done in the answer given by #musicamante
def mousePressEvent(self, event):
if event.button() == Qt.LeftButton:
# self.clickPos = event.windowPos().toPoint()
self.clickPos = event.scenePosition().toPoint()
def mouseMoveEvent(self, event):
if self.clickPos is not None:
# self.window().move(event.globalPos() - self.clickPos)
self.window().move(event.globalPosition().toPoint() - self.clickPos)
if __name__ == "__main__":
app = QApplication(sys.argv)
mw = MainWindow()
mw.show()
# sys.exit(app.exec_())
sys.exit(app.exec())
References:
QMouseEvent.globalPosition(),
QMouseEvent.scenePosition()
This method of moving Windows with Custom Widget doesn't work with WAYLAND. If anybody has a solution for that please post it here for future reference

Working functions for WAYLAND and PyQT6/PySide6 :
def mousePressEvent(self, event):
if event.button() == Qt.MouseButton.LeftButton:
self._move()
return super().mousePressEvent(event)
def _move(self):
window = self.window().windowHandle()
window.startSystemMove()
Please check.