TapHandler QML Type▲

  • Import Statement: import QtQuick 2.13

  • Inherits: SinglePointHandler

  • Group: TapHandler is part of qtquick-input-handlers

Detailed Description▲

TapHandler is a handler for taps on a touchscreen or clicks on a mouse.

Detection of a valid tap gesture depends on gesturePolicy. The default value is DragThreshold, which requires the press and release to be close together in both space and time. In this case, DragHandler is able to function using only a passive grab, and therefore does not interfere with event delivery to any other Items or Input Handlers. So the default gesturePolicy is useful when you want to modify behavior of an existing control or Item by adding a TapHandler with bindings and/or JavaScript callbacks.

Note that buttons (such as QPushButton) are often implemented not to care whether the press and release occur close together: if you press the button and then change your mind, you need to drag all the way off the edge of the button in order to cancel the click. For this use case, set the gesturePolicy to TapHandler.ReleaseWithinBounds.

For multi-tap gestures (double-tap, triple-tap etc.), the distance moved must not exceed QPlatformTheme::MouseDoubleClickDistance with mouse and QPlatformTheme::TouchDoubleTapDistance with touch, and the time between taps must not exceed QStyleHints::mouseDoubleClickInterval().

See Also▲

See also MouseArea

Property Documentation▲

 

acceptedButtons : flags▲

The mouse buttons which can activate this Pointer Handler.

By default, this property is set to Qt.LeftButton. It can be set to an OR combination of mouse buttons, and will ignore events from other buttons.

For example, a control could be made to respond to left and right clicks in different ways, with two handlers:

 
Sélectionnez
Item {
    TapHandler {
        onTapped: console.log("left clicked")
    }
    TapHandler {
        acceptedButtons: Qt.RightButton
        onTapped: console.log("right clicked")
    }
}

Tapping on a touchscreen or tapping the stylus on a graphics tablet emulates clicking the left mouse button. This behavior can be altered via acceptedDevices or acceptedPointerTypes.

acceptedDevices : flags▲

The types of pointing devices that can activate this Pointer Handler.

By default, this property is set to PointerDevice.AllDevices. If you set it to an OR combination of device types, it will ignore events from non-matching devices.

For example, a control could be made to respond to mouse and stylus clicks in one way, and touchscreen taps in another way, with two handlers:

 
Sélectionnez
Item {
   TapHandler {
       acceptedDevices: PointerDevice.Mouse | PointerDevice.Stylus
       onTapped: console.log("clicked")
   }
   TapHandler {
       acceptedDevices: PointerDevice.TouchScreen
       onTapped: console.log("tapped")
   }
}

acceptedModifiers : flags▲

If this property is set, it will require the given keyboard modifiers to be pressed in order to react to pointer events, and otherwise ignore them.

If this property is set to Qt.KeyboardModifierMask (the default value), then the PointerHandler ignores the modifier keys.

For example, an Item could have two handlers of the same type, one of which is enabled only if the required keyboard modifiers are pressed:

 
Sélectionnez
Item {
   TapHandler {
       acceptedModifiers: Qt.ControlModifier
       onTapped: console.log("control-tapped")
   }
   TapHandler {
       acceptedModifiers: Qt.NoModifier
       onTapped: console.log("tapped")
   }
}

If you set acceptedModifiers to an OR combination of modifier keys, it means all of those modifiers must be pressed to activate the handler:

 
Sélectionnez
Item {
   TapHandler {
       acceptedModifiers: Qt.ControlModifier | Qt.AltModifier | Qt.ShiftModifier
       onTapped: console.log("control-alt-shift-tapped")
   }
}

The available modifiers are as follows:

Constant

Description

NoModifier

No modifier key is allowed.

ShiftModifier

A Shift key on the keyboard must be pressed.

ControlModifier

A Ctrl key on the keyboard must be pressed.

AltModifier

An Alt key on the keyboard must be pressed.

MetaModifier

A Meta key on the keyboard must be pressed.

KeypadModifier

A keypad button must be pressed.

GroupSwitchModifier

X11 only (unless activated on Windows by a command line argument). A Mode_switch key on the keyboard must be pressed.

KeyboardModifierMask

The handler does not care which modifiers are pressed.

If you need even more complex behavior than can be achieved with combinations of multiple handlers with multiple modifier flags, you can check the modifiers in JavaScript code:

 
Sélectionnez
Item {
    TapHandler {
        onTapped:
            switch (point.modifiers) {
            case Qt.ControlModifier | Qt.AltModifier:
                console.log("CTRL+ALT");
                break;
            case Qt.ControlModifier | Qt.AltModifier | Qt.MetaModifier:
                console.log("CTRL+META+ALT");
                break;
            default:
                console.log("other modifiers", point.modif