TapHandler QML Type

See also MouseArea

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:

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

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:

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

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:

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:

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

The available modifiers are as follows:

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:

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.modifiers);
                break;
            }
    }
}

See Also▲

The types of pointing instruments (finger, stylus, eraser, etc.) that can activate this Pointer Handler.

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

For example, a control could be made to respond to mouse, touch, and stylus clicks in some way, but delete itself if tapped with an eraser tool on a graphics tablet, with two handlers:

Rectangle {
   id: rect
   TapHandler {
       acceptedPointerTypes: PointerDevice.GenericPointer | PointerDevice.Finger | PointerDevice.Pen
       onTapped: console.log("clicked")
   }
   TapHandler {
       acceptedPointerTypes: PointerDevice.Eraser
       onTapped: rect.destroy()
   }
}

This holds true whenever this Input Handler has taken sole responsibility for handing one or more EventPoints, by successfully taking an exclusive grab of those points. This means that it is keeping its properties up-to-date according to the movements of those Event Points and actively manipulating its target (if any).

This property holds the cursor shape that will appear whenever the mouse is hovering over the parent item while active is true.

The available cursor shapes are:

• Qt.ArrowCursor

• Qt.UpArrowCursor

• Qt.CrossCursor

• Qt.WaitCursor

• Qt.IBeamCursor

• Qt.SizeVerCursor

• Qt.SizeHorCursor

• Qt.SizeBDiagCursor

• Qt.SizeFDiagCursor

• Qt.SizeAllCursor

• Qt.BlankCursor

• Qt.SplitVCursor

• Qt.SplitHCursor

• Qt.PointingHandCursor

• Qt.ForbiddenCursor

• Qt.WhatsThisCursor

• Qt.BusyCursor

• Qt.OpenHandCursor

• Qt.ClosedHandCursor

• Qt.DragCopyCursor

• Qt.DragMoveCursor

• Qt.DragLinkCursor

The default value is not set, which allows the cursor of parent item to appear. This property can be reset to the same initial condition by setting it to undefined.

This property was introduced in Qt 5.15.

See Also▲

The distance in pixels that the user must drag an event point in order to have it treated as a drag gesture.

The default value depends on the platform and screen resolution. It can be reset back to the default value by setting it to undefined. The behavior when a drag gesture begins varies in different handlers.

This property was introduced in Qt 5.15.

If a PointerHandler is disabled, it will reject all events and no signals will be emitted.

The spatial constraint for a tap or long press gesture to be recognized, in addition to the constraint that the release must occur before longPressThreshold has elapsed. If these constraints are not satisfied, the tapped signal is not emitted, and tapCount is not incremented. If the spatial constraint is violated, pressed transitions immediately from true to false, regardless of the time held.

The gesturePolicy also affects grab behavior as described below.

This property specifies the permissions when this handler's logic decides to take over the exclusive grab, or when it is asked to approve grab takeover or cancellation by another handler.

The default is PointerHandler.CanTakeOverFromItems | PointerHandler.CanTakeOverFromHandlersOfDifferentType | PointerHandler.ApprovesTakeOverByAnything which allows most takeover scenarios but avoids e.g. two PinchHandlers fighting over the same touchpoints.

The time in seconds that an event point must be pressed in order to trigger a long press gesture and emit the longPressed() signal. If the point is released before this time limit, a tap can be detected if the gesturePolicy constraint is satisfied. The default value is QStyleHints::mousePressAndHoldInterval() converted to seconds.

The margin beyond the bounds of the parent item within which an event point can activate this handler. For example, on a PinchHandler where the target is also the parent, it's useful to set this to a distance at least half the width of a typical user's finger, so that if the parent has been scaled down to a very small size, the pinch gesture is still possible. Or, if a TapHandler-based button is placed near the screen edge, it can be used to comply with Fitts's Law: react to mouse clicks at the screen edge even though the button is visually spaced away from the edge by a few pixels.

The default value is 0.

The Item which is the scope of the handler; the Item in which it was declared. The handler will handle events on behalf of this Item, which means a pointer event is relevant if at least one of its event points occurs within the Item's interior. Initially target() is the same, but it can be reassigned.

See Also▲

The event point currently being handled. When no point is currently being handled, this object is reset to default values (all coordinates are 0).

Holds true whenever the mouse or touch point is pressed, and any movement since the press is compliant with the current gesturePolicy. When the event point is released or the policy is violated, pressed will change to false.

The number of taps which have occurred within the time and space constraints to be considered a single gesture. For example, to detect a triple-tap, you can write:

Rectangle {
    width: 100; height: 30
    signal tripleTap
    TapHandler {
        acceptedButtons: Qt.AllButtons
        onTapped: if (tapCount == 3) tripleTap()
    }
}

The Item which this handler will manipulate.

By default, it is the same as the parent, the Item within which the handler is declared. However, it can sometimes be useful to set the target to a different Item, in order to handle events within one item but manipulate another; or to null, to disable the default behavior and do something else instead.

The amount of time in seconds that a pressed point has been held, without moving beyond the drag threshold. It will be updated at least once per frame rendered, which enables rendering an animation showing the progress towards an action which will be triggered by a long-press. It is also possible to trigger one of a series of actions depending on how long the press is held.

A value of less than zero means no point is being held within this handler's Item.

If this handler has already grabbed the given point, this signal is emitted when the grab is stolen by a different Pointer Handler or Item.

This signal is emitted when the parent Item is tapped twice within a short span of time (QStyleHints::mouseDoubleClickInterval()) and distance (QStyleHints::mouseDoubleClickDistance() or QStyleHints::touchDoubleTapDistance()). This signal always occurs after singleTapped, tapped, and tapCountChanged. The eventPoint signal parameter contains information from the release event about the point that was tapped, and button is the mouse button that was clicked, or NoButton on a touchscreen.

This signal was introduced in Qt 5.11.

This signal is emitted when the grab has changed in some way which is relevant to this handler.

The transition (verb) tells what happened. The point (object) is the point that was grabbed or ungrabbed.

This signal is emitted when the parent Item is pressed and held for a time period greater than longPressThreshold. That is, if you press and hold a touchpoint or button, while any movement does not exceed the drag threshold, then the longPressed signal will be emitted at the time that timeHeld exceeds longPressThreshold.

This signal is emitted when the parent Item is tapped once. After an amount of time greater than QStyleHints::mouseDoubleClickInterval, it can be tapped again; but if the time until the next tap is less, tapCount will increase. The eventPoint signal parameter contains information from the release event about the point that was tapped, and button is the mouse button that was clicked, or NoButton on a touchscreen.

This signal was introduced in Qt 5.11.

This signal is emitted when the parent Item is tapped once or more (within a specified time and distance span) and when the present tapCount differs from the previous tapCount.

This signal is emitted each time the parent Item is tapped.

That is, if you press and release a touchpoint or button within a time period less than longPressThreshold, while any movement does not exceed the drag threshold, then the tapped signal will be emitted at the time of release. The eventPoint signal parameter contains information from the release event about the point that was tapped, and button is the mouse button that was clicked, or NoButton on a touchscreen.

import QtQuick

Rectangle {
    width: 100
    height: 100

    TapHandler {
        acceptedButtons: Qt.LeftButton | Qt.RightButton
        onTapped: (eventPoint, button)=> console.log("tapped", eventPoint.device.name,
                                             "button", button,
                                             "@", eventPoint.scenePosition)
    }
}