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How to add notification number to a button icon?

I am trying to make a GUI with PyQt5. It will have a notification button with an icon. I want to add a small bubble with the number of notifications on the icon.
If a number is not possible, I would like to use a red dot as a backup method.
But how should I keep track of the new notifications (like a listener for notification) and change the icon while the window is running?
I have been googling about this problem, but only mobile development stuff and non-PyQt5 related results come up.
Expected result: Let's say we have a list. And the icon of the button will automatically change when a new item is added to the list. Then when the button is clicked, the icon will change back.

A possible solution is to create a widget that has a layout where you place a QToolButton and at the top right a QLabel with a QPixmap that has the number
from PyQt5 import QtCore, QtGui, QtWidgets
def create_pixmap(point, radius=64):
rect = QtCore.QRect(QtCore.QPoint(), 2 * radius * QtCore.QSize(1, 1))
pixmap = QtGui.QPixmap(rect.size())
rect.adjust(1, 1, -1, -1)
pixmap.fill(QtCore.Qt.transparent)
painter = QtGui.QPainter(pixmap)
painter.setRenderHints(
QtGui.QPainter.Antialiasing | QtGui.QPainter.TextAntialiasing
)
pen = painter.pen()
painter.setPen(QtCore.Qt.NoPen)
gradient = QtGui.QLinearGradient()
gradient.setColorAt(1, QtGui.QColor("#FD6684"))
gradient.setColorAt(0, QtGui.QColor("#E0253F"))
gradient.setStart(0, rect.height())
gradient.setFinalStop(0, 0)
painter.setBrush(QtGui.QBrush(gradient))
painter.drawEllipse(rect)
painter.setPen(pen)
painter.drawText(rect, QtCore.Qt.AlignCenter, str(point))
painter.end()
return pixmap
class NotificationButton(QtWidgets.QWidget):
scoreChanged = QtCore.pyqtSignal(int)
def __init__(self, score=0, icon=QtGui.QIcon(), radius=12, parent=None):
super(NotificationButton, self).__init__(parent)
self.m_score = score
self.m_radius = radius
self.setContentsMargins(0, self.m_radius, self.m_radius, 0)
self.m_button = QtWidgets.QToolButton(clicked=self.clear)
self.m_button.setContentsMargins(0, 0, 0, 0)
self.m_button.setIcon(icon)
self.m_button.setIconSize(QtCore.QSize(18, 18))
lay = QtWidgets.QVBoxLayout(self)
lay.setContentsMargins(0, 0, 0, 0)
lay.addWidget(self.m_button)
self.m_label = QtWidgets.QLabel(self)
self.m_label.setAttribute(QtCore.Qt.WA_TransparentForMouseEvents)
self.m_label.raise_()
self.setSizePolicy(self.m_button.sizePolicy())
self.update_notification()
#QtCore.pyqtProperty(int, notify=scoreChanged)
def score(self):
return self.m_score
#score.setter
def score(self, score):
if self.m_score != score:
self.m_score = score
self.update_notification()
self.scoreChanged.emit(score)
#QtCore.pyqtSlot()
def clear(self):
self.score = 0
#QtCore.pyqtProperty(int)
def radius(self):
return self.m_radius
#radius.setter
def radius(self, radius):
self.m_radius = radius
self.update_notification()
def update_notification(self):
self.setContentsMargins(0, self.m_radius, self.m_radius, 0)
self.m_label.setPixmap(create_pixmap(self.m_score, self.m_radius))
self.m_label.adjustSize()
def resizeEvent(self, event):
self.m_label.move(self.width() - self.m_label.width(), 0)
super(NotificationButton, self).resizeEvent(event)
class Widget(QtWidgets.QWidget):
def __init__(self, parent=None):
super(Widget, self).__init__(parent)
self.m_item_le = QtWidgets.QLineEdit("Stack Overflow")
add_button = QtWidgets.QPushButton("Add", clicked=self.add_item)
self.m_notification_button = NotificationButton(
icon=QtGui.QIcon("image.png")
)
self.m_list_widget = QtWidgets.QListWidget()
vlay = QtWidgets.QVBoxLayout(self)
hlay = QtWidgets.QHBoxLayout()
hlay.addWidget(self.m_item_le)
hlay.addWidget(add_button)
vlay.addLayout(hlay)
vlay.addWidget(
self.m_notification_button, alignment=QtCore.Qt.AlignRight
)
vlay.addWidget(self.m_list_widget)
#QtCore.pyqtSlot()
def add_item(self):
text = self.m_item_le.text()
self.m_list_widget.addItem(
"%s: %s" % (self.m_list_widget.count(), text)
)
self.m_notification_button.score += 1
self.m_list_widget.scrollToBottom()
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
w = Widget()
w.show()
sys.exit(app.exec_())

It would be nice if you show your code so far. Anyhow, these may help you solve your question:
You'll need two different icons: one to represent a dirty (just loaded) list and the other for the "clean" list
class YourClass(Dialog):
def __init__(self)
super().__init__()
self.lst = []
# ...
def setUI(self):
# ...
self.notButton = QPushButton(icon_off, '0')
self.notButton.clicked.connect(self.clearButton)
# ...
#pyqtSlot()
def clearButton(self):
self.notButton.setIcon(icon_clean)
def addToList(self, item):
self.lst.append(item)
self.notButton.setIcon(icon_dirty)
self.notButton.setText(str(len(self.lst)

A possible solution to updating the icon would be to have a separate image file for each icon and its associated notification number. You can keep track of the number of current notifications in a counter variable. Use that number to call the corresponding icon.

Center subwindows in qmdiarea

Is there an attribute to position subwindows in qmdiarea? I’m trying to center subwindow in middle of mainwindow on startup (mdiarea)
I’m working on a mcve but haven’t finished it, wanted to see if anyone has tried doing this, and how they did it
Subwindows are randomly placed on startup when initialized
class App(QMainWindow, Ui_MainWindow):
def __init__(self, parent=None):
QMainWindow.__init__(self, parent=parent)
self.setupUi(self)
self.screenShape = QDesktopWidget().screenGeometry()
self.width = self.screenShape.width()
self.height = self.screenShape.height()
self.resize(self.width * .6, self.height * .6)
self.new = []
#calls GUI's in other modules
self.lw = Login()
self.vs = VS()
self.ms = MS()
self.hw = HomeWindow()
self.mw = MainWindow()
self.ga = GA()
self.sGUI = Settings()
# shows subwindow
self.CreateLogin()
self.CreateVS()
self.CreateMS()
self.CreateGA()
self.CreateSettings()
def CreateLogin(self):
self.subwindow = QMdiSubWindow()
self.subwindow.setWidget(self.lw)
self.subwindow.setAttribute(Qt.WA_DeleteOnClose, True)
self.mdiArea.addSubWindow(self.subwindow)
self.subwindow.setMaximumSize(520, 300)
self.subwindow.setMinimumSize(520, 300)
self.lw.showNormal()
def CreateVS(self):
self.subwindow = QMdiSubWindow()
self.subwindow.setWidget(self.vs)
self.mdiArea.addSubWindow(self.subwindow)
self.vs.showMinimized()
def CreateMS(self):
self.subwindow = QMdiSubWindow()
self.subwindow.setWidget(self.ms)
self.mdiArea.addSubWindow(self.subwindow)
self.ms.showMinimized()
self.ms.tabWidget.setCurrentIndex(0)
def CreateGA(self):
self.subwindow = QMdiSubWindow()
self.subwindow.setWidget(self.ga)
self.mdiArea.addSubWindow(self.subwindow)
self.ga.showMinimized()
self.subwindow.setMaximumSize(820, 650)
def CreateSettings(self):
self.subwindow = QMdiSubWindow()
self.subwindow.setWidget(self.sGUI)
self.mdiArea.addSubWindow(self.subwindow)
self.sGUI.showMinimized()
def CreateWindow(self):
self.hw.pushButton.clicked.connect(self.vs.showNormal)
self.hw.pushButton_2.clicked.connect(self.Moduleprogram)
self.hw.pushButton_3.clicked.connect(self.ms.showNormal)
self.hw.pushButton_4.clicked.connect(self.ga.showNormal)
self.subwindow = QMdiSubWindow()
self.subwindow.setWindowFlags(Qt.CustomizeWindowHint | Qt.Tool)
self.subwindow.setWidget(self.hw)
self.subwindow.setMaximumSize(258, 264)
self.subwindow.move(self.newwidth*.35, self.newheight*.25)
self.mdiArea.addSubWindow(self.subwindow)

In Qt the geometry is only effective when the window is visible so if you want to center something it must be in the showEvent method. On the other hand to center the QMdiSubWindow you must first get the center of the viewport of the QMdiArea, and according to that modify the geometry of the QMdiSubWindow.
Because the code you provide is complicated to execute, I have created my own code
from PyQt5 import QtCore, QtGui, QtWidgets
import random
def create_widget():
widget = QtWidgets.QLabel(
str(random.randint(0, 100)), alignment=QtCore.Qt.AlignCenter
)
widget.setStyleSheet(
"""background-color: {};""".format(
QtGui.QColor(*random.sample(range(255), 3)).name()
)
)
widget.setMinimumSize(*random.sample(range(100, 300), 2))
return widget
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super().__init__(parent)
add_button = QtWidgets.QPushButton(
"Add subwindow", clicked=self.add_subwindow
)
self._mdiarea = QtWidgets.QMdiArea()
central_widget = QtWidgets.QWidget()
self.setCentralWidget(central_widget)
lay = QtWidgets.QVBoxLayout(central_widget)
lay.addWidget(add_button)
lay.addWidget(self._mdiarea)
self._is_first_time = True
for _ in range(4):
self.add_subwindow()
#QtCore.pyqtSlot()
def add_subwindow(self):
widget = create_widget()
subwindow = QtWidgets.QMdiSubWindow(self._mdiarea)
subwindow.setWidget(widget)
subwindow.setAttribute(QtCore.Qt.WA_DeleteOnClose, True)
subwindow.show()
self._mdiarea.addSubWindow(subwindow)
# self.center_subwindow(subwindow)
def showEvent(self, event):
if self.isVisible() and self._is_first_time:
for subwindow in self._mdiarea.subWindowList():
self.center_subwindow(subwindow)
self._is_first_time = False
def center_subwindow(self, subwindow):
center = self._mdiarea.viewport().rect().center()
geo = subwindow.geometry()
geo.moveCenter(center)
subwindow.setGeometry(geo)
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
Update:
If you want the subwindow to be centered then with the following code you have to create a property center to True:
def add_subwindow(self):
widget = create_widget()
subwindow = QtWidgets.QMdiSubWindow(self._mdiarea)
subwindow.setWidget(widget)
subwindow.setAttribute(QtCore.Qt.WA_DeleteOnClose, True)
subwindow.show()
subwindow.setProperty("center", True) # <----
self._mdiarea.addSubWindow(subwindow)
def showEvent(self, event):
if self.isVisible() and self._is_first_time:
for subwindow in self._mdiarea.subWindowList():
if subwindow.property("center"): # <---
self.center_subwindow(subwindow)
self._is_first_time = False

Adjust GraphicView according to any image geometry

My QGraphicsView should show an image of a large resolution. The size should fit inside a resizable window. Currently, the image is viewed in a way that I want it to but only by providing some manually adjusted values to the initial view geometry. This doe not look neat. I also tried to refer to the solutions posted here: Graphics View and Pixmap Size
My current Window looks like this:
class ImageCheck(Ui_ImageCheck.Ui_MainWindow, QMainWindow):
def __init__(self, parent=None):
super(ImageCheck, self).__init__()
self.setupUi(self)
self.setWindowTitle("Image Analyzer")
self.crop_ratio_w = 1
self.crop_ratio_h = 1
self.path = None
self.scene = QGraphicsScene()
self.scene.clear()
self.image_item = QGraphicsPixmapItem()
# This is the approximate shift in coordinates of my initial view from the window
self.view.setGeometry(self.geometry().x()+ 10, self.geometry().y()+ 39,
self.geometry().width()- 55, self.geometry().height()- 110)
self.view.setAlignment(Qt.AlignCenter)
self.view.setFrameShape(QFrame.NoFrame)
def setImage(self, path):
self.path = path
self.crop_ratio_w = self.pixmap.width() / self.view.width()
self.crop_ratio_h = self.pixmap.height() / self.view.height()
pixmap = QPixmap(path)
smaller_pixmap = pixmap.scaled(self.view.width(), self.view.height(),
Qt.IgnoreAspectRatio, t.FastTransformation)
self.image_item.setPixmap(smaller_pixmap)
self.scene.addItem(self.image_item)
self.scene.setSceneRect(0, 0, self.view.width(), self.view.height())
self.view.setGeometry(0, 0, self.view.width(), self.view.height())
self.view.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
self.view.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
self.view.setScene(self.scene)
self.view.setSceneSize()
def resizeEvent(self, event):
self.view.setGeometry(self.geometry().x()+ 10, self.geometry().y()+ 39,
self.geometry().width()- 55, self.geometry().height()- 110)
self.setImage(self.path)
My manual override was probably not a good idea when I tried to determine distances between two points. Even the scaled distance gives me a slightly wrong value.

I can not use your code because there are many hidden things so I will propose the next solution that is to rescale the view based on the scene each time the window changes its size. I have also implemented a signal that transports the clicked information in the image based on the coordinates of the image.
from PyQt5 import QtCore, QtGui, QtWidgets
class ClickableGraphicsView(QtWidgets.QGraphicsView):
clicked = QtCore.pyqtSignal(QtCore.QPoint)
def __init__(self, parent=None):
super(ClickableGraphicsView, self).__init__(parent)
scene = QtWidgets.QGraphicsScene(self)
self.setScene(scene)
self.pixmap_item = None
def setImage(self, path):
pixmap = QtGui.QPixmap(path)
self.pixmap_item = self.scene().addPixmap(pixmap)
self.pixmap_item.setShapeMode(
QtWidgets.QGraphicsPixmapItem.BoundingRectShape
)
def mousePressEvent(self, event):
if self.pixmap_item is not None:
if self.pixmap_item == self.itemAt(event.pos()):
sp = self.mapToScene(event.pos())
lp = self.pixmap_item.mapToItem(self.pixmap_item, sp)
p = lp.toPoint()
if self.pixmap_item.pixmap().rect().contains(p):
self.clicked.emit(p)
super(ClickableGraphicsView, self).mousePressEvent(event)
def resizeEvent(self, event):
self.fitInView(self.sceneRect(), QtCore.Qt.IgnoreAspectRatio)
super(ClickableGraphicsView, self).resizeEvent(event)
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.setWindowTitle("Image Analyzer")
view = ClickableGraphicsView()
view.clicked.connect(print)
view.setImage("image.jpg")
label = QtWidgets.QLabel("Distance")
display = QtWidgets.QLCDNumber()
buttonbox = QtWidgets.QDialogButtonBox(
QtWidgets.QDialogButtonBox.Ok | QtWidgets.QDialogButtonBox.Cancel
)
widget = QtWidgets.QWidget()
self.setCentralWidget(widget)
lay = QtWidgets.QGridLayout(widget)
lay.addWidget(view, 0, 0, 1, 2)
hlay = QtWidgets.QHBoxLayout()
hlay.addWidget(label)
hlay.addWidget(display)
hlay.addStretch()
lay.addLayout(hlay, 1, 0)
lay.addWidget(buttonbox, 1, 1)
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())

Position internal widget inside QStackedWidget object

I have several tabs and inside the "admin" tab I want to display two pages: one locked page (before entering credentials) and another unlocked page (after successful login). To do this, I'm using a QStackedWidget() to switch between the two pages. I have created a locked login screen but can't seem to move the object to the center of the page.
I have looked at moving widgets inside QStackedWidget and centering widgets in the center of the screen but my objects do not seem to change position. I've tried to move the entire internal widget using move() to the center of the screen using the desktop dimension and the parent widget to no avail. How would I be able to move the login fields to the center of the page? Thanks!
Current:
Desired:
Code:
from PyQt4 import QtGui, QtCore
# from load_CSS import load_CSS
# from widgets import UniversalPlotWidget
import sys
import time
def exit_application():
"""Exit program event handler"""
sys.exit(1)
class VerticalTabBar(QtGui.QTabBar):
def __init__(self, width, height, parent=None):
super(VerticalTabBar, self).__init__(parent)
self.width = width
self.height = height
def tabSizeHint(self, index):
return QtCore.QSize(self.width, self.height)
def paintEvent(self, event):
painter = QtGui.QStylePainter(self)
tab_options = QtGui.QStyleOptionTab()
for tab in range(self.count()):
self.initStyleOption(tab_options, tab)
painter.drawControl(QtGui.QStyle.CE_TabBarTabShape, tab_options)
painter.save()
size = tab_options.rect.size()
size.transpose()
rectangle = QtCore.QRect(QtCore.QPoint(), size)
rectangle.moveCenter(tab_options.rect.center())
tab_options.rect = rectangle
center = self.tabRect(tab).center()
painter.translate(center)
painter.rotate(90)
painter.translate(-center)
painter.drawControl(QtGui.QStyle.CE_TabBarTabLabel, tab_options);
painter.restore()
class TabWidget(QtGui.QTabWidget):
def __init__(self, *args, **kwargs):
QtGui.QTabWidget.__init__(self, *args, **kwargs)
self.setTabBar(VerticalTabBar(kwargs.pop('width'), kwargs.pop('height')))
self.setTabPosition(QtGui.QTabWidget.West)
self.setTabShape(QtGui.QTabWidget.Rounded)
class AdminTabWidget(QtGui.QWidget):
def __init__(self, parent=None):
super(AdminTabWidget, self).__init__(parent)
self.setWindowModality(QtCore.Qt.ApplicationModal)
self.setWindowFlags(QtCore.Qt.FramelessWindowHint)
self.admin_page_locked_init()
self.admin_page_unlocked_init()
self.admin_page_layout = QtGui.QGridLayout()
self.admin_page_switch = QtGui.QStackedWidget()
self.admin_page_switch.addWidget(self.admin_locked_tab)
self.admin_page_switch.addWidget(self.admin_unlocked_tab)
self.admin_page_switch.setCurrentIndex(0)
self.admin_page_layout.addWidget(self.admin_page_switch,0,0)
def admin_page_locked_init(self):
self.admin_locked_tab = QtGui.QWidget()
self.admin_locked_tab.setFixedSize(550,225)
self.admin_locked_layout = QtGui.QGridLayout()
self.username_label = QtGui.QLabel('Username: ')
self.username_field = QtGui.QLineEdit()
self.username_field.returnPressed.connect(self.verify_credentials)
self.space_label = QtGui.QLabel(' ')
self.space_label.setFixedHeight(25)
self.password_label = QtGui.QLabel('Password: ')
self.password_field = QtGui.QLineEdit()
self.password_field.returnPressed.connect(self.verify_credentials)
self.password_field.setEchoMode(QtGui.QLineEdit.Password)
self.verify_button = QtGui.QPushButton('Ok')
self.verify_button.clicked.connect(self.verify_credentials)
self.cancel_button = QtGui.QPushButton('Cancel')
self.cancel_button.clicked.connect(self.unauthorized)
self.status_label = QtGui.QLabel('')
self.status_label.setAlignment(QtCore.Qt.AlignCenter)
self.button_layout = QtGui.QGridLayout()
self.button_layout.addWidget(self.verify_button,0,0,1,1)
self.button_layout.addWidget(self.cancel_button,0,1,1,1)
self.admin_locked_layout.addWidget(self.username_label,0,0,1,1)
self.admin_locked_layout.addWidget(self.username_field,0,1,1,1)
self.admin_locked_layout.addWidget(self.space_label,1,0,1,3)
self.admin_locked_layout.addWidget(self.password_label,2,0,1,1)
self.admin_locked_layout.addWidget(self.password_field,2,1,1,1)
self.admin_locked_layout.addWidget(self.status_label,3,0,1,3)
self.admin_locked_layout.addLayout(self.button_layout,4,0,1,3)
self.admin_locked_tab.setLayout(self.admin_locked_layout)
def verify_credentials(self):
print('button pressed')
# Grab username/password from input fields
self.username = str(self.username_field.text())
self.password = str(self.password_field.text())
self.status_label.setText('Verifying')
self.status_label.setStyleSheet('QLabel {color: rgb(117,255,161)}')
self.spin(.001)
print('verified')
def spin(self, seconds):
"""Pause for set amount of seconds, replaces time.sleep so program doesnt stall"""
time_end = time.time() + seconds
while time.time() < time_end:
QtGui.QApplication.processEvents()
def unauthorized(self):
print('unauthorized')
self.status_label.setText('Invalid username and/or password')
self.status_label.setStyleSheet('QLabel {color: rgb(255,65,106)}')
def admin_page_unlocked_init(self):
self.admin_unlocked_tab = QtGui.QWidget()
admin_unlocked_layout = QtGui.QGridLayout()
admin_unlocked_button = QtGui.QPushButton('unlocked')
admin_unlocked_layout.addWidget(admin_unlocked_button)
self.admin_unlocked_tab.setLayout(admin_unlocked_layout)
def get_admin_page_layout(self):
return self.admin_page_layout
if __name__ == '__main__':
# Create main application window
app = QtGui.QApplication(sys.argv)
# app.setStyleSheet(load_CSS(1))
app.setStyle(QtGui.QStyleFactory.create("Cleanlooks"))
font = QtGui.QFont('Ubuntu', 20)
font.setWeight(70)
app.setFont(font)
screen_height = QtGui.QApplication.desktop().screenGeometry().height()
main_window_tab = TabWidget(width=300, height=screen_height/8)
main_window_tab.setWindowTitle("Tab Layout")
main_window_tab.setWindowFlags(QtCore.Qt.FramelessWindowHint)
main_window_tab.showMaximized()
tab1 = QtGui.QWidget()
tab2 = QtGui.QWidget()
tab3 = QtGui.QWidget()
tab4 = QtGui.QWidget()
tab5 = QtGui.QWidget()
tab6 = QtGui.QWidget()
tab7 = QtGui.QWidget()
admin_tab = QtGui.QWidget()
admin_tab_widget = AdminTabWidget()
admin_tab.setLayout(admin_tab_widget.get_admin_page_layout())
main_window_tab.addTab(admin_tab, "Admin")
main_window_tab.addTab(tab1, "tab1")
main_window_tab.addTab(tab2, "tab2")
main_window_tab.addTab(tab3, "tab3")
main_window_tab.addTab(tab4, "tab4")
main_window_tab.addTab(tab5, "tab5")
main_window_tab.addTab(tab6, "tab6")
main_window_tab.addTab(tab7, "tab7")
main_window_tab.show()
QtGui.QShortcut(QtGui.QKeySequence('Ctrl+Q'), main_window_tab, exit_application)
sys.exit(app.exec_())

The idea is to set the QStackedWidget with the Qt::AlignCenter alignment in the layout so it changes:
self.admin_page_layout.addWidget(self.admin_page_switch, 0, 0)
to:
self.admin_page_layout.addWidget(self.admin_page_switch, 0, 0, alignment=QtCore.Qt.AlignCenter)

QGraphics Item Creates a delay in painting

I tried to create a 2D plot using QGraphicsItem, I was successful in doing that but when I drag the QGraphicsItem there is a delay and the view is distorted.
Searching for a solution, I came across this QGraphicsItem paint delay. I applied the mouseMoveEvent to my QGraphicsView but it did not resolve the problem.
Could someone tell me what is causing the problem and how can I fix it?
Here is my code:
from PyQt4 import QtGui, QtCore
import sys
import numpy as np
class MyGraphicsItem(QtGui.QGraphicsItem):
def __init__(self,dataX,dataY):
super(MyGraphicsItem,self).__init__()
self.Xval = dataX
self.Yval = dataY
self.Xvalmin = np.min(self.Xval)
self.Xvalmax = np.max(self.Xval)
self.Yvalmin = np.min(self.Yval)
self.Yvalmax = np.max(self.Yval)
self.rect = QtCore.QRectF(0,0,100,2)
self.points = []
self._picture = None
def paint(self, QPainter, QStyleOptionGraphicsItem, QWidget_widget=None):
if self._picture is None:
self._picture = QtGui.QPicture()
QPainter.begin(self._picture)
startPoint = QtCore.QPointF(0, 0)
cubicPath = QtGui.QPainterPath()
cubicPath.moveTo(startPoint)
for i in range(len(self.points) - 2):
points_ = self.points[i:i+3]
cubicPath.cubicTo(*points_)
QPainter.setPen(QtGui.QPen(QtCore.Qt.red))
QPainter.drawLine(0,10,100,10)
QPainter.drawLine(0,-10,0,10)
QPainter.setPen(QtGui.QPen(QtCore.Qt.black))
QPainter.drawPath(cubicPath)
QPainter.end()
else:
self._picture.play(QPainter)
def boundingRect(self):
return self.rect
class mygraphicsview(QtGui.QGraphicsView):
def __init__(self):
super(mygraphicsview,self).__init__()
def mouseMoveEvent(self, event):
QtGui.QGraphicsView.mouseMoveEvent(self,event)
if self.scene().selectedItems():
self.update()
class Mainwindow(QtGui.QMainWindow):
def __init__(self):
super(Mainwindow,self).__init__()
self.main_widget = QtGui.QWidget()
self.vl = QtGui.QVBoxLayout()
self.scene = QtGui.QGraphicsScene()
self.view = mygraphicsview()
self.Xval = np.linspace(0,100,1000)
self.Yval = np.sin(self.Xval)
self.painter = QtGui.QPainter()
self.style = QtGui.QStyleOptionGraphicsItem()
self.item = MyGraphicsItem(self.Xval, self.Yval)
self.item.paint(self.painter, self.style,self.main_widget)
self.item.setFlag(QtGui.QGraphicsItem.ItemIsMovable,True)
self.trans = QtGui.QTransform()
self.trans.scale(5,5)
self.item.setTransform(self.trans)
self.scene = QtGui.QGraphicsScene()
self.scene.addItem(self.item)
self.view.setScene(self.scene)
self.vl.addWidget(self.view)
self.main_widget.setLayout(self.vl)
self.setCentralWidget(self.main_widget)
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
window = Mainwindow()
window.show()
sys.exit(app.exec_())

I fixed the issue of dragging delay.
The reason for the occurrence of such a delay is due to the boundinRect() function. The boudingRect was too tight around the item designed.
Adding some marigin to the boundingRect(), solved the problem.
self.rect = QtCore.QRectF(-10,-10,120,25)