QML Button - How to check that button is pressed with Control modifier? - qt

Question

How we can detect the QML button is clicked (checked) with "Control" key button pressed simultaniously?

Answer 1

AFAIK there's no way to check if the CTRL key is pressed while you're in an onPressed handler of a button, but you could work around that:
Let QML inform you when the CTRL key is pressed/released. Save that status in a property and use it in the onPressed handler of the button.
// Example code
Item {
id: rootItem
anchors.fill: parent
focus: true
property bool ctrlPressed: false
Keys.onPressed: {
if (event.key === Qt.Key_Control) {
ctrlPressed = true
}
}
Keys.onReleased: {
if (event.key === Qt.Key_Control) {
ctrlPressed = false
}
}
Button {
anchors.centerIn: parent
text: "Press me"
onPressed: {
if (rootItem.ctrlPressed)
console.log("Click with CTRL")
else
console.log("Click without CTRL")
}
}
}
This is just a 'workaround' and has some issues:
The rootItem has to have the focus
when the Application loses focus (ALT+TAB or minimize) while the CTRL button is pressed you might get unexpected behaviour

Answer 2

Another option is simply adding your own MouseArea on top of the button. You could use propogateComposedEvents to allow the Button's default mouse handling to still occur, or you could manually regenerate things like the clicked signal yourself. Neither option is ideal, but maybe one works for you.
Button {
MouseArea {
anchors.fill: parent
propagateComposedEvents: true
onClicked: {
if ((mouse.button == Qt.LeftButton) && (mouse.modifiers & Qt.ControlModifier)) {
doSomething();
}
}
}
}

Answer 3

I used #ParkerHalo's answer. The issue he noticed when the app loses focus with ctrl pressed can be avoided by placing this in the top level Window:
onActiveChanged: if( ! active ) rootItem.ctrlPressed = false;

Answer 4

One more solution is to use a TapHandler (a relatively new feature, see blog post).
There's an example in the docs for a new TreeViewDelegate which can be modified for your case with Button (they both inherit AbstractButton).
This way you won't have to remember any state or propagate events to underlying internal mouse area of the button:
Button {
text: "Test"
TapHandler {
acceptedModifiers: Qt.ControlModifier
onTapped: console.log("tapped with Qt.ControlModifier")
}
TapHandler {
acceptedModifiers: Qt.NoModifier
onTapped: console.log("tapped with Qt.NoModifier")
}
}