Signals and Slots
Remarks:
In the following example, two QPushButton objects (b1 and b2) are added in QDialog window. We want to call functions b1_clicked() and b2_clicked() on clicking b1 and b2 respectively.
When b1 is clicked, the clicked() signal is connected to b1_clicked() function
b1.clicked.connect(b1_clicked())
When b2 is clicked, the clicked() signal is connected to b2_clicked() function
QObject.connect(b2, SIGNAL("clicked()"), b2_clicked)
Widgets used to build the GUI interface act as the source of such events.
Each PyQt widget, which is derived from QObject class, is designed to emit signal in response to one or more events. The signal on its own does not perform any action. Instead, it is connected to a slot. The slot can be any callable Python function.
An Example Using Signals and Slots
import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *
def window():
app = QApplication(sys.argv)
win = QDialog()
b1 = QPushButton(win)
b1.setText("Button1")
b1.move(50,20)
b1.clicked.connect(b1_clicked)
b2 = QPushButton(win)
b2.setText("Button2")
b2.move(50,50)
QObject.connect(b2,SIGNAL("clicked()"),b2_clicked)
win.setGeometry(100,100,200,100)
win.setWindowTitle("PyQt")
win.show()
sys.exit(app.exec_())
def b1_clicked():
print ("Button 1 clicked")
def b2_clicked():
print ("Button 2 clicked")
if __name__ == '__main__':
window()
The following example will produce two buttons, if you click them, then function b1_clicked or b2_clicked will be called.
Contributors
Topic Id: 9270
Example Ids: 28735
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