How to create mouse press or click events in QML/Pyside2 without actually pressing the mouse

Question

For the project that I am doing, I need to be able to create "artificial" mouse events that only QML can see without physically pressing the mouse down.

In my current implementation, I am trying to use "key pressed" events to trigger these artificial mouse events. I am currently using the function "Qt.createQmlObject" to create a MouseEvent and then feed that as parameter for a mouse clicked signal. However, I keep getting an error back saying that "MouseEvent is not a type." I am open to different implementations.

import QtQuick.Controls 2.12
import QtQuick.Controls.Styles 1.4
import QtQuick.Layouts 1.11
import QtGraphicalEffects 1.12
import QtMultimedia 5.12
import QtQml.Models 2.12
import "../components"

Item{
   id: widget
   width: 600
   height: 600

   //MouseArea
   MouseArea{
       id: mouseArea
       anchors.fill: parent
       propagateComposedEvents: true
       hoverEnabled: true
       
       onClicked: {
           console.log("The mouse was clicked")
           widget.focus = true 
           mouse.accepted = false
       }

       onPressed: {
           console.log("The mouse was pressed")
           mouse.accept = false
       }

       onEntered:{
           widget.focus = true               
       }
   }

   //Defines key event changes
   Keys.onPressed: {
       if(event.key == Qt.Key_0){
           var mouEvent = Qt.createQmlObject('import QtQuick 2.12; import QtQuick.Controls 2.12; MouseEvent{x: 0; y: 0; accepted: false; button: Qt.LeftButton; buttons: Qt.LeftButton; flags: 0; modifiers: Qt.NoModifier; source: Qt.MouseEventSynthesizedByApplication; wasHeld: false}', mouseArea, "error")
           mouseArea.clicked(mouEvent)
       }
   }
}

Answer 1

MouseEvent is not an element that can or should be created, in simple terms MouseEvent is a wrapper over QMouseEvent that allows obtaining the event information.

Nor does invoking a signal imply that the event will be transmitted, instead you have to use the Qt Event System which cannot be used from QML but from C++ (in your case it is equivalent to python).

So the logic is to create a class that notifies the event to Qt, and Qt has to send the event to the item through the window as shown below:

from PySide2.QtCore import (
    QCoreApplication,
    QEvent,
    QObject,
    QPointF,
    Qt,
    QTimer,
    QUrl,
    Slot,
)
from PySide2.QtGui import QGuiApplication, QMouseEvent
from PySide2.QtQuick import QQuickItem, QQuickView


class MouseEmulator(QObject):
    @Slot(QQuickItem, Qt.MouseButton)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier, QPointF)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier, QPointF, int)
    def mouseClick(self, item, button, modifier=Qt.NoModifier, pos=QPointF(), delay=-1):
        self.mousePress(item, button, modifier, pos, delay)
        self.mouseRelease(item, button, modifier, pos, 2 * delay)

    @Slot(QQuickItem, Qt.MouseButton)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier, QPointF)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier, QPointF, int)
    def mousePress(self, item, button, modifier=Qt.NoModifier, pos=QPointF(), delay=-1):
        self._send_mouse_events(
            QEvent.MouseButtonPress, item, button, modifier, pos, delay
        )

    @Slot(QQuickItem, Qt.MouseButton)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier, QPointF)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier, QPointF, int)
    def mouseRelease(
        self, item, button, modifier=Qt.NoModifier, pos=QPointF(), delay=-1
    ):
        self._send_mouse_events(
            QEvent.MouseButtonRelease, item, button, modifier, pos, delay
        )

    @Slot(QQuickItem, Qt.MouseButton)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier, QPointF)
    @Slot(QQuickItem, Qt.MouseButton, Qt.KeyboardModifier, QPointF, int)
    def mouseDClick(
        self, item, button, modifier=Qt.NoModifier, pos=QPointF(), delay=-1
    ):
        self.mousePress(item, button, modifier, pos, delay)
        self.mouseRelease(item, button, modifier, pos, 2 * delay)
        self.mousePress(item, button, modifier, pos, 3 * delay)
        self._send_mouse_events(
            QEvent.MouseButtonDblClick, item, button, pos, 4 * delay
        )
        self.mouseRelease(item, button, modifier, pos, 5 * delay)

    def _send_mouse_events(self, type_, item, button, modifier, pos, delay):
        window = item.window()
        if pos.isNull():
            pos = item.boundingRect().center()
        sp = item.mapToScene(pos).toPoint()
        event = QMouseEvent(
            type_, pos, window.mapToGlobal(sp), button, button, modifier
        )
        if delay < 0:
            delay = 0

        def on_timeout():
            QCoreApplication.instance().notify(window, event)

        QTimer.singleShot(delay, on_timeout)


def main():
    import os
    import sys

    CURRENT_DIR = os.path.dirname(os.path.realpath(__file__))

    app = QGuiApplication(sys.argv)
    mouse_emulator = MouseEmulator()
    view = QQuickView()
    view.rootContext().setContextProperty("mouse_emulator", mouse_emulator)
    filename = os.path.join(CURRENT_DIR, "main.qml")
    view.setSource(QUrl.fromLocalFile(filename))
    view.show()

    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

import QtQuick 2.12

Item{
   id: widget
   width: 600
   height: 600

   MouseArea{
       id: mouseArea
       anchors.fill: parent
       propagateComposedEvents: true
       hoverEnabled: true
       
       onClicked: {
           console.log("The mouse was clicked")
           widget.focus = true 
           mouse.accepted = false
       }

       onPressed: {
           console.log("The mouse was pressed")
           mouse.accept = false
       }

       onEntered:{
           widget.focus = true               
       }
   }

   Keys.onPressed: {
        if(event.key == Qt.Key_0){
            mouse_emulator.mouseClick(widget, Qt.LeftButton)
        }
   }
}