DragHandler QML Type▲
-
Import Statement: import QtQuick 2.13
-
Inherits: MultiPointHandler
-
Group: DragHandler is part of qtquick-input-handlers
Detailed Description▲
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 2.12
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 2.12
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 2.12
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▲
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:
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:
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:
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"
)
}
}