Behavior QML Type

Defines a default animation for a property change. More...

• List of all members, including inherited members

Properties

• animation : Animation
• enabled : bool
• targetProperty (since QtQuick 2.15)
  • targetProperty.name : string (since QtQuick 2.15)
  • targetProperty.object : QtObject (since QtQuick 2.15)
• targetValue : Variant (since QtQuick 2.13)

Detailed Description

A Behavior defines the default animation to be applied whenever a particular property value changes.

For example, the following Behavior defines a NumberAnimation to be run whenever the Rectangle's width value changes. When the MouseArea is clicked, the width is changed, triggering the behavior's animation:

import QtQuick

Rectangle {
    id: rect
    width: 100; height: 100
    color: "red"

    Behavior on width {
        NumberAnimation { duration: 1000 }
    }

    MouseArea {
        anchors.fill: parent
        onClicked: rect.width = 50
    }
}

Note that a property cannot have more than one assigned Behavior. To provide multiple animations within a Behavior, use ParallelAnimation or SequentialAnimation.

If a state change has a Transition that matches the same property as a Behavior, the Transition animation overrides the Behavior for that state change. For general advice on using Behaviors to animate state changes, see Using Qt Quick Behaviors with States.

See also Animation and Transitions in Qt Quick, Behavior example, and Qt Qml.

Property Documentation

// FadeBehavior.qml
import QtQuick 2.15

Behavior {
    id: root
    property Item fadeTarget: targetProperty.object
    SequentialAnimation {
        NumberAnimation {
            target: root.fadeTarget
            property: "opacity"
            to: 0
            easing.type: Easing.InQuad
        }
        PropertyAction { } // actually change the controlled property between the 2 other animations
        NumberAnimation {
            target: root.fadeTarget
            property: "opacity"
            to: 1
            easing.type: Easing.OutQuad
        }
    }
}

import QtQuick 2.15

Text {
    id: root
    property int counter
    text: counter
    FadeBehavior on text {}
    Timer {
        running: true
        repeat: true
        interval: 1000
        onTriggered: ++root.counter
    }
}