Qt 5.11 | Qt Quick | QML Types | MultiPointHandler QML Type

Qt 5.11.3 Reference Documentation

# MultiPointHandler QML Type

Abstract handler for multi-point Pointer Events. More...

Import Statement: | import Qt.labs.handlers 1.0
Since: | Qt 5.10
Inherits: | PointerDeviceHandler
Inherited By: | PinchHandler

- List of all members, including inherited members

## Properties

- acceptedDevices : int
- acceptedModifiers : int
- acceptedPointerTypes : int
- active : bool
- enabled : bool
- grabPermission : bool
- maximumPointCount : int
- minimumPointCount : int
- parent : Item
- pointDistanceThreshold : real
- target : Item

## Signals

- canceled(EventPoint point)
- grabChanged(EventPoint point)

## Detailed Description

An intermediate class (not registered as a QML type) for any type of handler which requires and acts upon a specific number of multiple touchpoints.

## Property Documentation

acceptedDevices : int

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")
         }
      }

acceptedModifiers : int

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")
         }
      }

acceptedPointerTypes : int

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()
         }
      }

[read-only] active : bool

This holds true whenever this PointerHandler 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).

enabled : bool

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

grabPermission : bool

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

maximumPointCount : int

The maximum number of touchpoints this handler can utilize.

If a larger number of touchpoints are in contact with the parent, the required number of points will be chosen in the order that they are pressed, and the remaining points will be ignored.

Any ignored points are eligible to activate other Pointer Handlers that have different constraints, on the same Item or on other Items.

The default value is the same as minimumPointCount.

minimumPointCount : int

The minimum number of touchpoints required to activate this handler.

If a smaller number of touchpoints are in contact with the parent, they will be ignored.

Any ignored points are eligible to activate other Pointer Handlers that have different constraints, on the same Item or on other Items.

The default value is 2.

[read-only] parent : Item

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 target and QObject::parent().

pointDistanceThreshold : real

The margin beyond the bounds of the parent item within which a touch 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.

The default value is 0.

target : Item

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.

## Signal Documentation

canceled(EventPoint point)

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.

grabChanged(EventPoint point)

This signal is emitted when this handler has acquired or relinquished a passive or exclusive grab of the given point.