PointHandler QML Type

The mouse buttons that can activate this PointHandler.

By default, this property is set to Qt.LeftButton. It can be set to an OR combination of mouse buttons, and will ignore events in which other buttons are pressed or held.

 import QtQuick

 Item {
     width: 480; height: 320

     Rectangle {
         color: handler.active ? "tomato" : "wheat"
         x: handler.point.position.x - width / 2
         y: handler.point.position.y - height / 2
         width: 20; height: width; radius: width / 2
     }

     PointHandler {
         id: handler
         acceptedButtons: Qt.MiddleButton | Qt.RightButton
     }
 }

The types of pointing devices that can activate this PointHandler.

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:

 PointHandler {
     id: handler
     acceptedDevices: PointerDevice.TouchScreen | PointerDevice.TouchPad
     target: Rectangle {
         parent: glassPane
         color: "red"
         visible: handler.active
         x: handler.point.position.x - width / 2
         y: handler.point.position.y - height / 2
         width: 20; height: width; radius: width / 2
     }
 }

If this property is set, PointHandler requires the given keyboard modifiers to be pressed in order to react to PointerEvents, and otherwise ignores them.

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

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

 import QtQuick

 Item {
     id: feedbackPane
     width: 480; height: 320

     PointHandler {
         id: control
         acceptedModifiers: Qt.ControlModifier
         cursorShape: Qt.PointingHandCursor
         target: Rectangle {
             parent: feedbackPane
             color: control.active ? "indianred" : "khaki"
             x: control.point.position.x - width / 2
             y: control.point.position.y - height / 2
             width: 20; height: width; radius: width / 2
         }
     }

     PointHandler {
         id: shift
         acceptedModifiers: Qt.ShiftModifier | Qt.MetaModifier
         cursorShape: Qt.CrossCursor
         target: Rectangle {
             parent: feedbackPane
             color: shift.active ? "darkslateblue" : "lightseagreen"
             x: shift.point.position.x - width / 2
             y: shift.point.position.y - height / 2
             width: 30; height: width; radius: width / 2
         }
     }
 }

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

The available modifiers are as follows:

See also Qt::KeyboardModifier.

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

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 devices:

 import QtQuick

 Canvas {
     id: canvas
     width: 800
     height: 600
     antialiasing: true
     renderTarget: Canvas.FramebufferObject
     property var points: []
     onPaint: {
         if (points.length < 2)
             return
         var ctx = canvas.getContext('2d');
         ctx.save()
         ctx.strokeStyle = stylusHandler.active ? "blue" : "white"
         ctx.lineCap = "round"
         ctx.beginPath()
         ctx.moveTo(points[0].x, points[0].y)
         for (var i = 1; i < points.length; i++)
             ctx.lineTo(points[i].x, points[i].y)
         ctx.lineWidth = 3
         ctx.stroke()
         points = points.slice(points.length - 2, 1)
         ctx.restore()
     }

     PointHandler {
         id: stylusHandler
         acceptedPointerTypes: PointerDevice.Pen
         onPointChanged: {
             canvas.points.push(point.position)
             canvas.requestPaint()
         }
     }

     PointHandler {
         id: eraserHandler
         acceptedPointerTypes: PointerDevice.Eraser
         onPointChanged: {
             canvas.points.push(point.position)
             canvas.requestPaint()
         }
     }

     Rectangle {
         width: 10; height: 10
         color: stylusHandler.active ? "green" : eraserHandler.active ? "red" : "beige"
     }
 }

The Qt Quick Examples - Pointer Handlers includes a more complex example for drawing on a Canvas with a graphics tablet.

This holds true whenever the constraints are satisfied and this PointHandler is reacting. This means that it is keeping its properties up-to-date according to the movements of the eventPoints that satisfy the constraints.

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.

See also Qt::CursorShape, QQuickItem::cursor(), and HoverHandler::cursorShape.

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

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 margin beyond the bounds of the parent item within which an eventPoint can activate this handler.

The default value is 0.

 import QtQuick

 Item {
     width: 480; height: 320

     Rectangle {
         anchors.fill: handlingContainer
         anchors.margins: -handler.margin
         color: "beige"
     }

     Rectangle {
         id: handlingContainer
         width: 200; height: 200
         anchors.centerIn: parent
         border.color: "green"
         color: handler.active ? "lightsteelblue" : "khaki"

         Text {
             text: "X"
             x: handler.point.position.x - width / 2
             y: handler.point.position.y - height / 2
             visible: handler.active
         }

         PointHandler {
             id: handler
             margin: 30
         }
     }

 }

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 eventPoints occurs within the Item's interior. Initially target() is the same, but it can be reassigned.

See also target and QObject::parent().

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

A property that can conveniently hold an Item to be manipulated or to show feedback. Unlike other Pointer Handlers, PointHandler does not do anything with the target on its own: you usually need to create reactive bindings to properties such as SinglePointHandler::point and PointHandler::active. If you declare an Item instance here, you need to explicitly set its parent, because PointHandler is not an Item.

By default, it is the same as the parent, the Item within which the handler is declared.

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 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.

Valid values for transition are: