Develop Reference

PyQt5 drawing lines that have mouse events

I have an application where I draw 2 custom widgets and then draw a line between them. I want to add a mousePressEvent to the line.
What would be the best way to do this?
I suppose I could create a QWidget of x pixel thickness and y length and then fill in the whole widget with the colour I want the line to have. Then the QWidget has the mousePressEvent that I can override. This doesn't seem like the most elegant solution and feels more like a workaround. Is there a better way?
import sys
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QPaintEvent, QPainter, QPen, QFont
from PyQt5.QtWidgets import QApplication, QMainWindow, QWidget, QLabel
class MyWidget(QWidget):
def __init__(self, name, parent):
super().__init__(parent)
self.setAutoFillBackground(True)
self.setFixedSize(300, 100)
p = self.palette()
p.setColor(self.backgroundRole(), Qt.white)
self.setPalette(p)
lbl_name = QLabel(name, self)
lbl_name.setFont(QFont('Arial', 16))
lbl_name.move((self.width() - lbl_name.width()) / 2, self.height()/2 - lbl_name.height()/2)
class MainWindow(QMainWindow):
def __init__(self, parent=None):
super().__init__(parent)
self.main_widget = QWidget(self)
self.widget_1 = MyWidget("Widget 1", self)
self.widget_1.move(50, 50)
self.widget_2 = MyWidget("Widget 2", self)
self.widget_2.move(700, 600)
self.resize(1200, 800)
self.setCentralWidget(self.main_widget)
def paintEvent(self, a0: QPaintEvent) -> None:
super().paintEvent(a0)
painter = QPainter(self)
painter.setPen(QPen(Qt.red, 3, Qt.SolidLine))
widget_1_x = self.widget_1.pos().x() + self.widget_1.size().width()
widget_1_y = self.widget_1.pos().y() + self.widget_1.size().height() / 2
widget_2_x = self.widget_2.pos().x()
widget_2_y = self.widget_2.pos().y() + self.widget_2.size().height() / 2
halfway_x = widget_1_x + (widget_2_x - widget_1_x) / 2
# add mousePressEvents to these lines:
painter.drawLine(widget_1_x, widget_1_y, halfway_x, widget_1_y)
painter.drawLine(halfway_x, widget_1_y, halfway_x, widget_2_y)
painter.drawLine(halfway_x, widget_2_y, widget_2_x, widget_2_y)
if __name__ == "__main__":
app = QApplication(sys.argv)
myapp = MainWindow()
myapp.show()
sys.exit(app.exec_())
How the above code looks like when run

PyQt5: How to click a button to move the paint?

In the following code, one rectangle is made when the "Paint" button is clicked. It contains also a "Move" button. By clicking the "Move" button I want to move the rectangle 1px in both x and y directions. But I failed here.
I can understand the question is about how to transfer variable values wenn a button is clicked. To a beginner it is very difficult for me. Any help will be highly appreciated!
# -*- coding: utf-8 -*-
from PyQt5.QtWidgets import QWidget, QApplication, QPushButton, QHBoxLayout, QDoubleSpinBox
from PyQt5.QtGui import QPainter, QColor, QBrush
import sys
class Example(QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
self.flag = False
def initUI(self):
self.setFixedSize(400, 400)
self.setWindowTitle('Colours')
self.btnPaint = QPushButton("Paint", self)
self.btnMove = QPushButton("Move x+1 y+1", self)
self.deltax = 0 # original value
self.deltay = 0 # original value
self.btnPaint.clicked.connect(self.onPaint)
self.btnMove.clicked.connect(self.onMove)
self.hlayout = QHBoxLayout()
self.hlayout.addWidget(self.btnPaint)
self.hlayout.addWidget(self.btnMove)
self.hlayout.addStretch(1)
self.setLayout(self.hlayout)
self.show()
def onPaint(self):
self.flag = True
self.update()
def onMove(self):
self.deltax = self.deltax + 1 # button clicked, value +1
self.deltay = self.deltay + 1 # button clicked, value +1
self.flag_move = True
self.update()
def paintEvent(self, e):
if self.flag:
qp = QPainter()
qp.begin(self)
self.drawRectangles(qp)
qp.end()
if self.flag_move:
qp = QPainter()
qp.begin(self)
self.drawRectangles(qp)
qp.end()
def drawRectangles(self, qp):
x1 = 10
y1 = 15
x2 = 90
y2 = 60
col = QColor(0, 0, 0)
col.setNamedColor('#d4d4d4')
qp.setPen(col)
qp.setBrush(QColor(200, 0, 0))
qp.drawRect(x1+self.deltax, y1+self.deltay, x2+self.deltax, y2+self.deltay)
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())

Your code has an error because the self.flag_move is not initially defined, but it is not necessary to use so many variables either.
Qt has the QRect class that has several methods that make the task easier, initially we create a null QRect, and when the btnPaint button is pressed we will enable QRect to a non-null one. in the case of pressing the btnMove button we will use the translate method that moves the rectangle:
import sys
from PyQt5.QtWidgets import QWidget, QApplication, QPushButton, QHBoxLayout
from PyQt5.QtGui import QPainter, QColor, QBrush
from PyQt5.QtCore import QRect, QPoint
class Example(QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
self.setFixedSize(400, 400)
self.setWindowTitle('Colours')
self.btnPaint = QPushButton("Paint", self)
self.btnMove = QPushButton("Move x+1 y+1", self)
self.rect = QRect()
self.btnPaint.clicked.connect(self.onPaint)
self.btnMove.clicked.connect(self.onMove)
self.hlayout = QHBoxLayout(self)
self.hlayout.addWidget(self.btnPaint)
self.hlayout.addWidget(self.btnMove)
self.hlayout.addStretch(1)
self.show()
def onPaint(self):
if self.rect.isNull():
self.rect = QRect(10, 15, 80, 45)
self.update()
def onMove(self):
if not self.rect.isNull():
self.rect.translate(QPoint(1, 1))
self.update()
def paintEvent(self, e):
qp = QPainter(self)
qp.setPen(QColor("#d4d4d4"))
qp.setBrush(QColor(200, 0, 0))
qp.drawRect(self.rect)

PySide/PyQT5: How to emit signals from a QGraphicsItem?

I want to emit a signal from a QGraphicsItem when it is doubled-clicked, in order to change a widget in the main window. The graphics-scene/-item does not provide an emit() method, but I was just wondering if there is an alternate way to do this. The code below has a function within a QGraphicsView class that will print to the terminal when an item is double-clicked. How can I make that into a slot/signal instead (if QGraphicsItem does not support signal/slots)?
import sys
from PySide.QtCore import *
from PySide.QtGui import *
class MyFrame(QGraphicsView):
def __init__( self, parent = None ):
super(MyFrame, self).__init__(parent)
scene = QGraphicsScene()
self.setScene(scene)
self.setFixedSize(500, 500)
pen = QPen(QColor(Qt.green))
brush = QBrush(pen.color().darker(150))
item = scene.addEllipse(0, 0, 45, 45, pen, brush)
item.setPos(0,0)
def mouseDoubleClickEvent(self, event):
print("Circle Clicked!")
# this double click event prints to terminal but how to setup
# signal/slot to update the QWidget QLabel text instead?
class Example(QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
hbox = QHBoxLayout(self)
top = QLabel("Double Click Green Circle (Howto change this QWidget Label with signals?)")
bottom = MyFrame()
splitter = QSplitter(Qt.Vertical)
splitter.addWidget(top)
splitter.addWidget(bottom)
hbox.addWidget(splitter)
self.setLayout(hbox)
self.setGeometry(0, 0, 500, 600)
self.show()
def main():
app = QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
if __name__ == '__main__':
main()

Below is a simple example showing one way to emit signals from a graphics-item. This defines a custom signal on a subclass of QGraphicsScene and then uses the scene() method of graphics-items to emit it:
import sys
from PySide import QtCore, QtGui
class GraphicsScene(QtGui.QGraphicsScene):
itemDoubleClicked = QtCore.Signal(object)
class GraphicsRectangle(QtGui.QGraphicsRectItem):
def mouseDoubleClickEvent(self, event):
self.scene().itemDoubleClicked.emit(self)
class Window(QtGui.QWidget):
def __init__(self):
super(Window, self).__init__()
self.view = QtGui.QGraphicsView()
self.scene = GraphicsScene(self)
self.view.setScene(self.scene)
layout = QtGui.QVBoxLayout(self)
layout.addWidget(self.view)
for i in range(1, 4):
self.scene.addItem(GraphicsRectangle(50 * i, 50 * i, 20, 20))
self.scene.itemDoubleClicked.connect(self.handleItemDoubleClicked)
def handleItemDoubleClicked(self, item):
print(item.boundingRect())
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
window = Window()
window.setGeometry(600, 100, 300, 200)
window.show()
sys.exit(app.exec_())
UPDATE:
Below is a an example based on the code in your question. The basic idea is the same: define a custom signal on an available QObject (the graphics-view in this case), and use that to emit the double-click notification.
import sys
from PySide.QtCore import *
from PySide.QtGui import *
class MyFrame(QGraphicsView):
itemDoubleClicked = Signal(object)
def __init__(self, parent=None):
super(MyFrame, self).__init__(parent)
scene = QGraphicsScene()
self.setScene(scene)
self.setFixedSize(500, 500)
for i, color in enumerate('red blue green'.split()):
pen = QPen(QColor(color))
brush = QBrush(pen.color().darker(150))
item = scene.addEllipse(i * 50, i * 50, 45, 45, pen, brush)
item.setData(0, color.upper())
def mouseDoubleClickEvent(self, event):
item = self.itemAt(event.pos())
if item is not None:
self.itemDoubleClicked.emit(item)
class Example(QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
hbox = QHBoxLayout(self)
top = QLabel('Double Click a Circle')
bottom = MyFrame()
bottom.itemDoubleClicked.connect(
lambda item, top=top:
top.setText('Double Clicked: %s' % item.data(0)))
splitter = QSplitter(Qt.Vertical)
splitter.addWidget(top)
splitter.addWidget(bottom)
hbox.addWidget(splitter)
self.setLayout(hbox)
self.setGeometry(0, 0, 500, 600)
self.show()
def main():
app = QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
if __name__ == '__main__':
main()

How to return mouse coordinates in realtime?

I'm new to PyQt and I'm trying to use it to create a widget that returns the position of the mouse in real time.
Here's what I have:
import sys
from PyQt5.QtWidgets import (QWidget, QToolTip,
QPushButton, QApplication)
from PyQt5.QtGui import QFont
class MouseTracker(QWidget):
def __init__(self):
super().__init__()
self.initUI()
self.setMouseTracking(True)
self.installEventFilter(self)
def initUI(self):
self.setGeometry(300, 300, 300, 200)
self.setWindowTitle('Mouse Tracker')
self.show()
def eventFilter(self, source, event):
if (event.type() == QtCore.QEvent.MouseMove and
event.buttons() == QtCore.Qt.NoButton):
pos = event.pos()
print('Mouse coords: ( %d : %d )' % (pos.x(), pos.y()))
return QtGui.QWidget.eventFilter(self, source, event)
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = MouseTracker()
sys.exit(app.exec_())
I'm confused on how to make this work. I set mouse tracking to True but I'm not sure how to apply the event filter. Any help?

The QMouseEvent function must be implemented since it is executed when the mouse is moved.
import sys
from PyQt5.QtWidgets import (QApplication, QLabel, QWidget)
class MouseTracker(QWidget):
def __init__(self):
super().__init__()
self.initUI()
self.setMouseTracking(True)
def initUI(self):
self.setGeometry(300, 300, 300, 200)
self.setWindowTitle('Mouse Tracker')
self.label = QLabel(self)
self.label.resize(200, 40)
self.show()
def mouseMoveEvent(self, event):
self.label.setText('Mouse coords: ( %d : %d )' % (event.x(), event.y()))
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = MouseTracker()
sys.exit(app.exec_())

Python count How many Clicks are in a second

Would someone mind helping me with this? I'm trying to make a clicks per second test like this one on this website.
I've tried many different things, but I couldn't figure it out
Here are my imports
from PyQt4.QtCore import QSize
from PyQt4.QtGui import QApplication, QMainWindow, QPushButton, QWidget, QIcon, QLabel, QPainter, QPixmap
here is my code
class UICPS(QWidget): #||| CPS TAB |||
def __init__(self, parent=None):
super(UICPS, self).__init__(parent)
clicks = 0
self.Back = QPushButton("<- Back", self)
self.Back.resize(50,25)
self.Back.move(0, 425)
self.Clicked = QLabel(str(clicks), self)
self.Clicked.move(200, 200)
self.CPSBTN = QPushButton("Click Me!", self)
self.CPSBTN.resize(400, 175)
self.CPSBTN.move(0, 250)
if self.Clicked:
clicks +1

My Solution:
import sys
from PyQt4.QtCore import QTimer
from PyQt4.QtGui import QApplication, QLabel, QPushButton, QWidget
class UICPS(QWidget):
def __init__(self, parent=None):
super(UICPS, self).__init__(parent)
self.clicks = 0
self.Back = QPushButton("<- Back", self)
self.Back.resize(50, 25)
self.Back.move(0, 425)
self.ClickedLB = QLabel(str(self.clicks), self)
self.ClickedLB.resize(400, 20)
self.ClickedLB.move(200, 100)
self.ClickedLB2 = QLabel(str(self.clicks), self)
self.ClickedLB2.resize(400, 20)
self.ClickedLB2.move(200, 150)
self.ClickedLB3 = QLabel(str(self.clicks), self)
self.ClickedLB3.resize(400, 20)
self.ClickedLB3.move(200, 200)
self.CPSBTN = QPushButton("Click Me!", self)
self.CPSBTN.clicked.connect(self.Clicked)
self.CPSBTN.resize(400, 175)
self.CPSBTN.move(0, 250)
self.resize(400, 450)
self.starting = False
self.timer = QTimer(self)
self.timer.timeout.connect(self.updateClock)
self.counter = 0
self.isFist = True
def updateClock(self):
self.counter += 0.01
self.ClickedLB2.setText("%.2f s" % self.counter)
if self.counter >= 9.99:
self.starting = False
cps = self.clicks/10
self.ClickedLB3.setText("%.2f CPS" % cps)
self.timer.stop()
def Clicked(self):
if self.starting:
self.clicks += 1
self.ClickedLB.setText(str(self.clicks))
else:
if self.isFist:
self.timer.start(10)
self.starting = True
self.isFist = False
if __name__ == '__main__':
app = QApplication(sys.argv)
w = UICPS()
w.show()
sys.exit(app.exec_())
After clicked:

You have to assign function to button
from PyQt4 import QtGui
import sys
class MyWindow(QtGui.QWidget):
def __init__(self, parent=None):
super(MyWindow, self).__init__()
self.clicks = 0
self.vbox = QtGui.QVBoxLayout()
self.setLayout(self.vbox)
self.label = QtGui.QLabel(str(self.clicks), self)
self.vbox.addWidget(self.label)
self.button = QtGui.QPushButton("Click Me!", self)
self.vbox.addWidget(self.button)
# assign function to button
self.button.clicked.connect(self.on_click)
self.show()
def on_click(self):
self.clicks += 1
self.label.setText(str(self.clicks))
app = QtGui.QApplication(sys.argv)
win = MyWindow()
app.exec_()