Behavior QML Type▲
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Import Statement: import QtQuick
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Group: Behavior is part of qtquick-transitions-animations, qtquick-interceptors
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 2.0
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▲
Property Documentation▲
[default] animation : Animation▲
This property holds the animation to run when the behavior is triggered.
enabled : bool▲
This property holds whether the behavior will be triggered when the tracked property changes value.
By default a Behavior is enabled.
targetProperty group▲
[read-only, since QtQuick 2.15] targetProperty.name : string
[read-only, since QtQuick 2.15] targetProperty.object : QtObject
|
Property |
Description |
|---|---|
|
name |
This property holds the name of the property being controlled by this Behavior. |
|
object |
This property holds the object of the property being controlled by this Behavior. |
This property can be used to define custom behaviors based on the name or the object of the property being controlled.
The following example defines a Behavior fading out and fading in its target object when the property it controls changes:
// 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
}
}
}This can be used to animate a text when it changes:
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
}
}This QML property was introduced in QtQuick 2.15.
[read-only, since QtQuick 2.13] targetValue : Variant▲
This property holds the target value of the property being controlled by the Behavior. This value is set by the Behavior before the animation is started.
This property was introduced in QtQuick 2.13.