Develop Reference

QPainter draw lines inside a QScrollArea

I raised a problem earlier on how to draw lines between widgets. and #eyllanesc solves it very well. But I faced another problem. I try to make the widget with QScrollarea. But the lines are not shown.
When using Widget it works fine with drawing lines, but seems QScrollArea need another paint_event. Don't know how to do that.
Can anyone help me to show lines with QScrollarea.
import functools
import sys
from PyQt5.QtCore import QEvent, QLine
from PyQt5.QtGui import QPainter
from PyQt5.QtWidgets import QApplication, QPushButton, QVBoxLayout, QWidget, QScrollArea
class Drawer:
def __init__(self):
self._lines = []
#property
def lines(self):
return self._lines
#lines.setter
def lines(self, l):
self._lines = l[:]
self.update()
def paintEvent(self, event):
painter = QPainter(self)
for line in self.lines:
painter.drawLine(line)
class Example(QScrollArea, Drawer):
def __init__(self, parent=None):
super().__init__(parent)
self.initUI()
def initUI(self):
self.AddButton = QPushButton("Add")
self.AddButton.clicked.connect(self.addbuttonwithline)
self.w = QWidget()
self.setWidget(self.w)
self.setWidgetResizable(True)
self.vbox = QVBoxLayout(self.w)
self.vbox.addWidget(self.AddButton)
self.setGeometry(300, 300, 300, 150)
self.setWindowTitle("Buttons")
self.buttons = []
def addbuttonwithline(self):
button = QPushButton("delete")
button.clicked.connect(functools.partial(self.remove_button, button))
button.installEventFilter(self)
self.vbox.addWidget(button)
self.buttons.append(button)
self.recalculate_position()
def remove_button(self, button):
self.buttons.remove(button)
button.deleteLater()
self.recalculate_position()
def recalculate_position(self):
lines = []
for last_button, next_button in zip(self.buttons, self.buttons[1:]):
l = QLine(last_button.pos().x()+50, last_button.pos().y(), next_button.pos().x()+50, next_button.pos().y())
lines.append(l)
self.lines = lines
def eventFilter(self, o, e):
if e.type() == QEvent.Move and o in self.buttons:
self.recalculate_position()
return super().eventFilter(o, e)
if __name__ == "__main__":
app = QApplication(sys.argv)
ex = Example()
ex.show()
sys.exit(app.exec_())

QScrollArea is designed to be a container so you should not paint over that item since the content covers it, instead it sets the painting in the content widget.
Based on my code from my previous answer then just change to:
if __name__ == "__main__":
app = QApplication(sys.argv)
ex = Example()
w = QScrollArea(widgetResizable=True)
w.setWidget(ex)
w.show()
sys.exit(app.exec_())

Have QScrollArea react on wheelEvent, also in space taken up by children?

Consider this example:
#!/usr/bin/env python
import sys,os
from PyQt5 import QtCore, QtWidgets, QtGui
from PyQt5.QtCore import Qt
class MainWindow(QtWidgets.QMainWindow):
class ScrollAreaWheel(QtWidgets.QScrollArea): # SO:9475772
def __init__(self, parent=None):
super(MainWindow.ScrollAreaWheel, self).__init__(parent)
self.parent = parent
def wheelEvent(self, event):
print("wheelEvent", event.angleDelta().y())
def __init__(self):
#~ self.do_init = QtCore.QEvent.registerEventType()
QtWidgets.QMainWindow.__init__(self)
self.setMinimumWidth(1000)
self.setMinimumHeight(400)
self.frame1 = QtWidgets.QFrame(self)
self.frame1.setFrameShape(QtWidgets.QFrame.StyledPanel)
self.frame1layout = QtWidgets.QGridLayout(self.frame1)
self.frame1layout.setSpacing(0);
self.frame1layout.setContentsMargins(0,0,0,0);
self.frame1widget = QtWidgets.QWidget()
self.frame1widget.setLayout(QtWidgets.QGridLayout())
self.frame1layout.addWidget(self.frame1widget)
self.frame1scroll = MainWindow.ScrollAreaWheel(self) #QtWidgets.QScrollArea()
self.frame1scroll.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
self.frame1scroll.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
self.frame1widget.layout().addWidget(self.frame1scroll, 0, 0) #, Qt.AlignCenter)
#self.frame1scrolllayout = QtWidgets.QHBoxLayout(self.frame1scroll)
self.frame1scrolllayout = QtWidgets.QGridLayout(self.frame1scroll)
self.frame1scroll.setWidget(self.frame1scrolllayout.widget())
self.frame1scroll.setWidgetResizable(True)
self.frame1scroll.setAlignment(Qt.AlignCenter)
self.frame1label = QtWidgets.QLabel()
self.frame1scrolllayout.addWidget(self.frame1label, 0, 0, Qt.AlignCenter) ##
pixmap = QtGui.QPixmap(200, 100)
pixmap.fill(Qt.red)
self.frame1label.setPixmap(pixmap)
self.frame2 = QtWidgets.QFrame(self)
self.frame2.setFrameShape(QtWidgets.QFrame.StyledPanel)
self.frame2layout = QtWidgets.QHBoxLayout(self.frame2)
self.frame2layout.setSpacing(0);
self.frame2layout.setContentsMargins(0,0,0,0);
self.frame2scroll = QtWidgets.QScrollArea(self)
self.frame2scroll.setWidgetResizable(True)
self.frame2widget = QtWidgets.QWidget()
self.frame2widget.setLayout(QtWidgets.QGridLayout())
self.frame2scroll.setWidget(self.frame2widget)
self.frame2layout.addWidget(self.frame2scroll)
self.mainwid = QtWidgets.QWidget()
self.mainwid.setLayout(QtWidgets.QGridLayout())
self.setCentralWidget(self.mainwid)
self.splitter1 = QtWidgets.QSplitter(Qt.Horizontal)
self.splitter1.addWidget(self.frame1)
self.splitter1.addWidget(self.frame2)
self.splitter1.setSizes([600, 600]); # equal splitter at start
self.mainwid.layout().addWidget(self.splitter1)
self.mainwid.layout().update()
if __name__ == "__main__":
app = QtWidgets.QApplication([])
main = MainWindow()
main.show()
sys.exit(app.exec_())
It generates this (Ubuntu 18.04):
I want to use mousewheel only on the left QScrollArea, for which I've made a separate class. However, its wheelEvent fires only when I'm outside the red box, not when I hover over it. How can I make ScrollAreaWheel.wheelEvent fire even when mouse is over the child label (the red box)?

You are the QLabel placing on top of the QScrollArea instead of placing it inside, visually it is the same but at the level of events it is not.
from PyQt5 import QtCore, QtGui, QtWidgets
class ScrollAreaWheel(QtWidgets.QScrollArea):
def wheelEvent(self, event):
print("wheelEvent", event.angleDelta().y())
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.setMinimumSize(1000, 400)
frame1 = QtWidgets.QFrame(frameShape=QtWidgets.QFrame.StyledPanel)
scrollarea1 = ScrollAreaWheel(widgetResizable=True)
scrollarea1.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
scrollarea1.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
widget1 = QtWidgets.QWidget()
scrollarea1.setWidget(widget1)
label_lay = QtWidgets.QGridLayout(widget1)
lay1 = QtWidgets.QVBoxLayout(frame1)
lay1.addWidget(scrollarea1)
pixmap = QtGui.QPixmap(200, 100)
pixmap.fill(QtCore.Qt.red)
label = QtWidgets.QLabel(pixmap=pixmap)
label_lay.addWidget(label, 0, 0, QtCore.Qt.AlignCenter)
#==============================
frame2 = QtWidgets.QFrame(frameShape=QtWidgets.QFrame.StyledPanel)
scrollarea2 = QtWidgets.QScrollArea(widgetResizable=True)
scrollarea2.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
scrollarea2.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
widget2 = QtWidgets.QWidget()
scrollarea2.setWidget(widget2)
splitter = QtWidgets.QSplitter(QtCore.Qt.Horizontal)
splitter.addWidget(frame1)
splitter.addWidget(frame2)
splitter.setSizes([600, 600])
self.setCentralWidget(splitter)
if __name__ == '__main__':
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.resize(640, 480)
w.show()
sys.exit(app.exec_())

QListView Selected Index not updated when embedding a QWidget

I have embedded a QPushbutton in a Qwidget in a QListView:
QPushbutton >> QWidget >> QListView
list_widget = QWidget()
list_widget.layout(QHBoxLayout())
btn = QPushButton()
btn.pressed.connect(clicked)
list_widget.layout().addWidget(QPushButton())
list_view.setIndexWidget(self.list_model.index(row, 0), list_widget)
def clicked():
row = list_view.selectedIndexes()
The problem is now list_view.selectedIndexes() does not return the row of the pressed button, when pressed.
This seems to work only when the QPushbutton is embedded in the QListView directly: QPushbutton >> QListView.
Does anyone have an idea how to delegate the focus of the pushbutton to the QListView?

When you click on the button it is not transmitted to the QListView because the button consumes it and does not transmit it to other widgets so if you want to obtain the row it must be obtained indirectly, a possible solution is to use the geometry for it you must obtain the sender , in this case the button, and then for its topleft to global positions, then convert it to a local position with respect to the viewport of QListView, using that position with the method indexAt() you get the QModelIndex.
from PyQt5 import QtCore, QtGui, QtWidgets
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.list_model = QtGui.QStandardItemModel(200, 1)
self.list_view = QtWidgets.QListView()
self.list_view.setModel(self.list_model)
self.setCentralWidget(self.list_view)
for row in range(self.list_model.rowCount()):
list_widget = QtWidgets.QWidget()
hlay = QtWidgets.QHBoxLayout(list_widget)
btn = QtWidgets.QPushButton(str(row))
btn.pressed.connect(self.clicked)
hlay.addWidget(btn)
hlay.setContentsMargins(0, 0, 0, 0)
self.list_view.setIndexWidget(self.list_model.index(row, 0), list_widget)
#QtCore.pyqtSlot()
def clicked(self):
btn = self.sender()
gp = btn.mapToGlobal(QtCore.QPoint())
lp = self.list_view.viewport().mapFromGlobal(gp)
ix = self.list_view.indexAt(lp)
print("row", ix.row())
if __name__ == '__main__':
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
Another much simpler way is to pass the row as an argument using functools.partial():
from functools import partial
from PyQt5 import QtCore, QtGui, QtWidgets
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.list_model = QtGui.QStandardItemModel(200, 1)
self.list_view = QtWidgets.QListView()
self.list_view.setModel(self.list_model)
self.setCentralWidget(self.list_view)
for row in range(self.list_model.rowCount()):
list_widget = QtWidgets.QWidget()
hlay = QtWidgets.QHBoxLayout(list_widget)
btn = QtWidgets.QPushButton(str(row))
btn.pressed.connect(partial(self.clicked, row))
hlay.addWidget(btn)
hlay.setContentsMargins(0, 0, 0, 0)
self.list_view.setIndexWidget(self.list_model.index(row, 0), list_widget)
#QtCore.pyqtSlot(int)
def clicked(self, row):
print(row)
if __name__ == '__main__':
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
Or using a lambda method:
from PyQt5 import QtCore, QtGui, QtWidgets
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.list_model = QtGui.QStandardItemModel(200, 1)
self.list_view = QtWidgets.QListView()
self.list_view.setModel(self.list_model)
self.setCentralWidget(self.list_view)
for row in range(self.list_model.rowCount()):
list_widget = QtWidgets.QWidget()
hlay = QtWidgets.QHBoxLayout(list_widget)
btn = QtWidgets.QPushButton(str(row))
btn.pressed.connect(lambda *args, row=row: self.clicked(row))
hlay.addWidget(btn)
hlay.setContentsMargins(0, 0, 0, 0)
self.list_view.setIndexWidget(self.list_model.index(row, 0), list_widget)
#QtCore.pyqtSlot(int)
def clicked(self, row):
print(row)
if __name__ == '__main__':
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
In my case I prefer to use partials since you do not need to write a lot of logic and it's thread-safe.

pyqt5 Is there a limit to loading widgets using clicked.connect?

I'm using the QPushButton to load the UI. First -> Jumin -> Department -> next -> next I want to create the UI in order. The problem is that I can not load the third Department into the QMainwindow window. I do not know why
When you create a widget in QVBoxLayout, it changes the size of the widget according to the wallpaper like wxpython layout (wx.all). Can not change the position (move) and size (resize) by automatic centering?
import sys
from PyQt5.QtWidgets import *
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.center_widget = QWidget()
self.setCentralWidget(self.center_widget)
self.FirstUI()
def FirstUI(self):
self.btn1 = QPushButton('test1', self)
self.btn1.move(50, 50)
self.btn1.clicked.connect(self.btn1_click)
def JuminUI(self):
self.ju1 = QLineEdit('13')
self.btn2 = QPushButton('^^^^^^^^^^')
self.ju_text = QLabel('asd')
self.jumim_layout = QVBoxLayout()
self.jumim_layout.addWidget(self.ju_text)
self.jumim_layout.addWidget(self.ju1)
self.jumim_layout.addWidget(self.btn2)
self.centralWidget().setLayout(self.jumim_layout)
self.btn2.clicked.connect(self.btn2_click)
def DepartmentUI(self):
self.depart_layout = QVBoxLayout()
self.depart_layout.addWidget(QPushButton('sdfsdf'))
self.centralWidget().setLayout(self.depart_layout)
def btn1_click(self):
self.btn1.deleteLater()
self.JuminUI()
def btn2_click(self):
self.ju1.deleteLater()
self.btn2.deleteLater()
self.ju_text.deleteLater()
self.DepartmentUI()
if __name__ == "__main__":
app = QApplication(sys.argv)
fream = MainWindow()
fream.show()
app.exec_()

creating and removing widgets is almost always a bad idea, and your code falls into those bad ideas, it's always best to hide the widgets and for that you should use the QStackedWidget, what QStackedWidget does is just make a widget visible on all widgets that you have been assigned by changing the currentIndex.
import sys
from functools import partial
from PyQt5 import QtWidgets
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.center_widget = QtWidgets.QStackedWidget()
self.setCentralWidget(self.center_widget)
self.FirstUI()
self.JuminUI()
self.DepartmentUI()
def FirstUI(self):
widget = QtWidgets.QWidget()
self.btn1 = QtWidgets.QPushButton('test1', widget)
self.btn1.move(50, 50)
self.center_widget.addWidget(widget)
self.btn1.clicked.connect(partial(self.center_widget.setCurrentIndex, 1))
def JuminUI(self):
widget = QtWidgets.QWidget()
lay = QtWidgets.QVBoxLayout(widget)
self.ju1 = QtWidgets.QLineEdit('13')
self.btn2 = QtWidgets.QPushButton('^^^^^^^^^^')
self.ju_text = QtWidgets.QLabel('asd')
lay.addWidget(self.ju_text)
lay.addWidget(self.ju1)
lay.addWidget(self.btn2)
self.center_widget.addWidget(widget)
self.btn2.clicked.connect(partial(self.center_widget.setCurrentIndex, 2))
def DepartmentUI(self):
widget = QtWidgets.QWidget()
lay = QtWidgets.QVBoxLayout(widget)
lay.addWidget(QtWidgets.QPushButton('sdfsdf'))
self.center_widget.addWidget(widget)
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
fream = MainWindow()
fream.show()
sys.exit(app.exec_())

PyQt: How to create a scrollable window

I think it should be much easier to create a scrollable window in PyQt.
I have a list of labels that goes out of the window and I would like to scroll down to view them. At the moment the code does not give me an error, but the window just doesn't appear:
class Example(QWidget):
def __init__(self):
super().__init__()
layout = QVBoxLayout()
lbl_arr = makeLabelArr()
for i in range(1,8):
qb = lbl_arr[i]
# qb.setFixedWidth(300)
layout.addWidget(qb)
layout.setAlignment(Qt.AlignTop)
scroll = QScrollArea()
scroll.setWidget(self)
scroll.setWidgetResizable(True)
scroll.setFixedHeight(400)
layout.addWidget(scroll)
self.setLayout(layout)
self.setGeometry(0, 0, 600, 220)
self.setWindowTitle('SnP watchlist')
self.show()
if __name__ == '__main__':
app = QApplication(sys.argv)
#print(QDesktopWidget().availableGeometry())
ex = Example()
sys.exit(app.exec_())

Make the window itself a QScrollArea, like this:
class Window(QScrollArea):
def __init__(self):
super(Window, self).__init__()
widget = QWidget()
layout = QVBoxLayout(widget)
layout.setAlignment(Qt.AlignTop)
for index in range(100):
layout.addWidget(QLabel('Label %02d' % index))
self.setWidget(widget)
self.setWidgetResizable(True)

There is an example here: https://www.learnpyqt.com/tutorials/qscrollarea/
from PyQt5.QtWidgets import (QWidget, QSlider, QLineEdit, QLabel, QPushButton, QScrollArea,QApplication,
QHBoxLayout, QVBoxLayout, QMainWindow)
from PyQt5.QtCore import Qt, QSize
from PyQt5 import QtWidgets, uic
import sys
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
self.scroll = QScrollArea() # Scroll Area which contains the widgets, set as the centralWidget
self.widget = QWidget() # Widget that contains the collection of Vertical Box
self.vbox = QVBoxLayout() # The Vertical Box that contains the Horizontal Boxes of labels and buttons
for i in range(1,50):
object = QLabel("TextLabel: "+str(i))
self.vbox.addWidget(object)
self.widget.setLayout(self.vbox)
#Scroll Area Properties
self.scroll.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
self.scroll.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
self.scroll.setWidgetResizable(True)
self.scroll.setWidget(self.widget)
self.setCentralWidget(self.scroll)
self.setGeometry(600, 100, 1000, 900)
self.setWindowTitle('Scroll Area Demonstration')
self.show()
return
def main():
app = QtWidgets.QApplication(sys.argv)
main = MainWindow()
sys.exit(app.exec_())
if __name__ == '__main__':
main()

You should set layout after adding the scroll bar widget.
class Example(QWidget):
def __init__(self):
super().__init__()
layout = QVBoxLayout()
lbl_arr = makeArrayOfLabelsHTML()
for i in range(1,8):
qb = lbl_arr[i]
layout.addWidget(qb)
layout.setAlignment(Qt.AlignTop)
scroll = QScrollArea()
scroll.setWidget(self)
scroll.setWidgetResizable(True)
scroll.setFixedHeight(400)
layout.addWidget(scroll)
# set layout after adding scroll bar
self.setLayout(layout)
self.setGeometry(0, 0, 600, 220)
self.setWindowTitle('SnP watchlist')
self.show()
if __name__ == '__main__':
app = QApplication(sys.argv)
#print(QDesktopWidget().availableGeometry())
ex = Example()
sys.exit(app.exec_())