4

I'm trying to detect mouse clicks for anywhere inside an area with several widgets. For this I'm using the following code:

custom_widget = CustomWidget()
custom_widget.mouse_pressed_signal.connect(self.on_custom_label_mouse_pressed)
main_layout_vbox.addWidget(custom_widget)

hbox = QtWidgets.QHBoxLayout()
custom_widget.setLayout(hbox)

# Adding several widgets to hbox_l6

class CustomWidget(QtWidgets.QWidget):
    mouse_pressed_signal = QtCore.pyqtSignal(QtGui.QMouseEvent)

    def __init__(self):
        super().__init__()

    def mousePressEvent(self, i_qmouseevent):
        super(CustomWidget, self).mousePressEvent(i_qmouseevent)
        logging.debug("======== CustomWidget - mousePressEvent ========")
        self.mouse_pressed_signal.emit(i_qmouseevent)

Problem

This works when clicking in any of the child widgets, but there's a problem: If I click between widgets (so in the area of the hbox layout that is not covered by a widget) the mousePressEvent is not captured

Question

How can I solve this problem? (Or is there another approach that you can recommend?) The important thing is that I am able to capture mouse clicks anywhere inside of custom_widget / hbox (see code above)

sunyata
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1 Answers1

3

If you want to listen to other widget's mousePressEvent you can use an eventFilter as I show below:

from PyQt5 import QtCore, QtGui, QtWidgets
import random


class Widget(QtWidgets.QWidget):
    mouse_clicked_signal = QtCore.pyqtSignal(QtGui.QMouseEvent, QtWidgets.QWidget)

    def __init__(self, parent=None):
        super(Widget, self).__init__(parent)

        hlay = QtWidgets.QHBoxLayout(self)

        for cls in (QtWidgets.QLabel,  QtWidgets.QPushButton, QtWidgets.QFrame, QtWidgets.QWidget):
            widget = cls()
            color = QtGui.QColor(*random.sample(range(255), 3))
            widget.setStyleSheet("background-color: {}".format(color.name()))
            hlay.addWidget(widget)

        for w in self.findChildren(QtWidgets.QWidget) +  [self]:
            w.installEventFilter(self)

        self.resize(640, 480)

    def eventFilter(self, watched, event):
        if event.type() == QtCore.QEvent.MouseButtonPress:
            self.mouse_clicked_signal.emit(event, watched)
        return super(Widget, self).eventFilter(watched, event)


if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.mouse_clicked_signal.connect(print)
    w.show()
    sys.exit(app.exec_())
eyllanesc
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  • That works, thank you. I don't understand why my approach wasn't working though, maybe because layouts can handle event filters but not mouse signals? – sunyata Nov 03 '18 at 23:20
  • @sunyata the layouts are not visual elements, the problem is that you are not overwriting the mousePressEvent event of `self` (which I think is a widget) and therefore you do not listen to the mousePressEvent of the same window but only of the children widgets. – eyllanesc Nov 03 '18 at 23:23