DragHandler QML Type
Handler for dragging. More...
Properties
- activeTranslation : QVector2D
- persistentTranslation : QVector2D
- snapMode : enumeration
- translation : QVector2D
- xAxis
- xAxis.activeValue : real
- xAxis.enabled : bool
- xAxis.maximum : real
- xAxis.minimum : real
- yAxis
- yAxis.activeValue : real
- yAxis.enabled : bool
- yAxis.maximum : real
- yAxis.minimum : real
Detailed Description
\inherits
MultiPointHandler \inqmlmodule
QtQuick \ingroup
qtquick-input-handlers
DragHandler is a handler that is used to interactively move an Item. Like other Input Handlers, by default it is fully functional, and manipulates its target.
import QtQuick Rectangle { width: 100 height: 100 color: "lightsteelblue" DragHandler { } }
It has properties to restrict the range of dragging.
If it is declared within one Item but is assigned a different target, then it handles events within the bounds of the parent Item but manipulates the target
Item instead:
import QtQuick Item { width: 640 height: 480 Rectangle { id: feedback border.color: "red" width: Math.max(10, handler.centroid.ellipseDiameters.width) height: Math.max(10, handler.centroid.ellipseDiameters.height) radius: Math.max(width, height) / 2 visible: handler.active } DragHandler { id: handler target: feedback } }
A third way to use it is to set target to null
and react to property changes in some other way:
import QtQuick Item { width: 640 height: 480 DragHandler { id: handler target: null } Text { color: handler.active ? "darkgreen" : "black" text: handler.centroid.position.x.toFixed(1) + "," + handler.centroid.position.y.toFixed(1) x: handler.centroid.position.x - width / 2 y: handler.centroid.position.y - height } }
If minimumPointCount and maximumPointCount are set to values larger than 1, the user will need to drag that many fingers in the same direction to start dragging. A multi-finger drag gesture can be detected independently of both a (default) single-finger DragHandler and a PinchHandler on the same Item, and thus can be used to adjust some other feature independently of the usual pinch behavior: for example adjust a tilt transformation, or adjust some other numeric value, if the target
is set to null. But if the target
is an Item, centroid
is the point at which the drag begins and to which the target
will be moved (subject to constraints).
At this time, drag-and-drop is not yet supported.
See also Drag, MouseArea, and Qt Quick Examples - Pointer Handlers.
Property Documentation
[read-only] activeTranslation : QVector2D |
\readonly
The translation while the drag gesture is being performed. It is 0, 0
when the gesture begins, and increases as the event point(s) are dragged downward and to the right. After the gesture ends, it stays the same; and when the next drag gesture begins, it is reset to 0, 0
again.
persistentTranslation : QVector2D |
The translation to be applied to the target if it is not null
. Otherwise, bindings can be used to do arbitrary things with this value. While the drag gesture is being performed, activeTranslation is continuously added to it; after the gesture ends, it stays the same.
snapMode : enumeration |
This property holds the snap mode.
The snap mode configures snapping of the target item's center to the eventPoint.
Possible values:
Constant | Description |
---|---|
DragHandler.SnapNever | Never snap |
DragHandler.SnapAuto | The target snaps if the eventPoint was pressed outside of the target item and the target is a descendant of parent item (default) |
DragHandler.SnapWhenPressedOutsideTarget | The target snaps if the eventPoint was pressed outside of the target |
DragHandler.SnapAlways | Always snap |
[read-only] translation : QVector2D |
\readonly
\deprecated
[6.2] Use activeTranslation
xAxis
controls the constraints for horizontal dragging.
minimum
is the minimum acceptable value of x to be applied to the target. maximum
is the maximum acceptable value of x to be applied to the target. If enabled
is true, horizontal dragging is allowed. activeValue
is the same as activeTranslation.x.
The activeValueChanged
signal is emitted when activeValue
changes, to provide the increment by which it changed. This is intended for incrementally adjusting one property via multiple handlers.
yAxis
controls the constraints for vertical dragging.
minimum
is the minimum acceptable value of y to be applied to the target. maximum
is the maximum acceptable value of y to be applied to the target. If enabled
is true, vertical dragging is allowed. activeValue
is the same as activeTranslation.y.
The activeValueChanged
signal is emitted when activeValue
changes, to provide the increment by which it changed. This is intended for incrementally adjusting one property via multiple handlers:
import QtQuick Rectangle { width: 50; height: 200 Rectangle { id: knob width: parent.width; height: width; radius: width / 2 anchors.centerIn: parent color: "lightsteelblue" Rectangle { antialiasing: true width: 4; height: 20 x: parent.width / 2 - 2 } WheelHandler { property: "rotation" } } DragHandler { target: null dragThreshold: 0 yAxis.onActiveValueChanged: (delta)=> { knob.rotation -= delta } } }