Mouse Input

Listing 18 scripts/PYQT4/02_mouse_event/main.py:

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QLabel
from PyQt5.QtCore import Qt

class MouseDetectionApp(QMainWindow):
    def __init__(self):
        super(MouseDetectionApp, self).__init__()

        self.label = QLabel(self)
        self.label.setAlignment(Qt.AlignCenter)
        self.label.setText("Click or move the mouse!")
        self.label.setMouseTracking(True)
        self.setCentralWidget(self.label)

        self.init_ui()

    def init_ui(self):
        self.setWindowTitle('Mouse Event Detection')
        self.setGeometry(100, 100, 400, 300)

    def mousePressEvent(self, event):
        self.label.setText("Mouse Pressed: Button {} at {}".format(event.button(), event.pos()))

    def mouseReleaseEvent(self, event):
        self.label.setText("Mouse Released: Button {} at {}".format(event.button(), event.pos()))

    def mouseMoveEvent(self, event):
        self.label.setText("Mouse Moved: Position {}".format(event.pos()))

    def mouseDoubleClickEvent(self, event):
        self.label.setText("Mouse Double Clicked: Button {} at {}".format(event.button(), event.pos()))

• mousePressEvent(event): This method is called when a mouse button is pressed. It displays the pressed button and the position of the click.

• mouseReleaseEvent(event): Called when a mouse button is released. It displays the released button and its position.

• mouseMoveEvent(event): This is triggered when the mouse moves, displaying its current position.

• mouseDoubleClickEvent(event): Activated upon a mouse double click. It displays the button double clicked and its position.

• self.label.setMouseTracking(True): This line ensures that the mouseMoveEvent is invoked whenever the mouse is moved over the widget. If setMouseTracking is set to False, the mouseMoveEvent is only invoked when a mouse button is pressed.

• event.button(): Returns information about the button (left, right, center) related to the mouse event.

• event.pos(): Returns the coordinate information where the mouse event occurred.