= Adding custom signals to a simple painted widget =

On the `#pyqt` channel on [[http://freenode.net|freenode]], `magicblaze007` asked for an example that showed how to declare and use custom signals.

{{{
#!python

import sys
from PyQt4.QtCore import pyqtSignal, QSize, Qt
from PyQt4.QtGui import *

class MyWidget(QWidget):

    clicked = pyqtSignal()
    keyPressed = pyqtSignal(unicode)
    
    def __init__(self, parent = None):
    
        QWidget.__init__(self, parent)
        self.color = QColor(0, 0, 0)
    
    def paintEvent(self, event):
    
        painter = QPainter()
        painter.begin(self)
        painter.fillRect(event.rect(), QBrush(self.color))
        painter.end()
    
    def keyPressEvent(self, event):
    
        self.keyPressed.emit(event.text())
        event.accept()
    
    def mousePressEvent(self, event):
    
        self.setFocus(Qt.OtherFocusReason)
        event.accept()
    
    def mouseReleaseEvent(self, event):
    
        if event.button() == Qt.LeftButton:
        
            self.color = QColor(self.color.green(), self.color.blue(),
                                127 - self.color.red())
            self.update()
            self.clicked.emit()
            event.accept()
    
    def sizeHint(self):
    
        return QSize(100, 100)


if __name__ == "__main__":

    app = QApplication(sys.argv)
    window = QWidget()
    
    mywidget = MyWidget()
    label = QLabel()
    
    mywidget.clicked.connect(label.clear)
    mywidget.keyPressed.connect(label.setText)
    
    layout = QVBoxLayout()
    layout.addWidget(mywidget)
    layout.addWidget(label)
    window.setLayout(layout)
    
    window.show()
    sys.exit(app.exec_())
}}}