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/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
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****************************************************************************/
/*!
\page qmlanimation.html
\title QML Animation
Animation in QML is done by animating properties of objects. Properties of type
real, int, color, rect, point, size, and vector3d can all be animated.
QML supports three main forms of animation - basic property animation,
transitions, and property behaviors.
\tableofcontents
\section1 Basic Property Animation
The simplest form of animation is directly using \l PropertyAnimation, which can animate all of the property
types listed above. If the property you are animating is a number or color, you can alternatively use
NumberAnimation or ColorAnimation. These elements don't add any additional functionality,
but will help enforce type correctness and are slightly more efficient.
A property animation can be specified as a value source. This is especially useful for repeating animations.
The following example creates a bouncing effect:
\qml
Rectangle {
id: rect
width: 120; height: 200;
Image {
id: img
source: "qt-logo.png"
x: 60-img.width/2
y: 0
y: SequentialAnimation {
repeat: true
NumberAnimation { to: 200-img.height; easing: "easeOutBounce"; duration: 2000 }
PauseAnimation { duration: 1000 }
NumberAnimation { to: 0; easing: "easeOutQuad"; duration: 1000 }
}
}
}
\endqml
\image propanim.gif
When you assign an animation as a value source, you do not need to specify \c property
or \c target; they are automatically selected for you. You do, however, need to specify \c to.
An animation specified as a value source will be \c running by default.
\qml
Rectangle {
id: rect
width: 200; height: 200;
Rectangle {
color: "red"
width: 50; height: 50
x: NumberAnimation { to: 50; }
}
}
\endqml
A property animation can also be specified as a resource that is manipulated from script.
\qml
PropertyAnimation {
id: animation
target: image
property: "scale"
from: 1; to: .5
}
Image {
id: image
source: "image.png"
MouseRegion {
anchors.fill: parent
onPressed: animation.start()
}
}
\endqml
As can be seen, when an animation is used like this (as opposed to as a value source) you will need
to explicitly set the \c target and \c property to animate.
Animations can be joined into a group using SequentialAnimation and ParallelAnimation.
\target state-transitions
\section1 Transitions
QML transitions describe animations to perform when \l{qmlstates}{state} changes occur. A transition
can only be triggered by a state change.
For example, a transition could describe how an item moves from its initial position to its new position:
\code
transitions: [
Transition {
NumberAnimation {
properties: "x,y"
easing: "easeOutBounce"
duration: 200
}
}
]
\endcode
As can be seen, transitions make use of the same basic animation classes introduced above.
In the above example we have specified that we want to animate the \c x and \c y properties, but have not
specified the objects to animate or the \c to values. By default these values are supplied by the framework --
the animation will animate any \c targets whose \c x and \c y have changed, and the \c to values will be those
defined in the end state. You can always supply explicit values to override these implicit values when needed.
\code
Transition {
from: "*"
to: "MyState"
reversible: true
SequentialAnimation {
NumberAnimation {
duration: 1000
easing: "easeOutBounce"
// animate myItem's x and y if they have changed in the state
target: myItem
properties: "x,y"
}
NumberAnimation {
duration: 1000
// animate myItem2's y to 200, regardless of what happens in the state
target: myItem2
property: "y"
to: 200
}
}
}
\endcode
QML transitions have selectors to determine which state changes a transition should apply to.
The following transition will only be triggered when we enter into the \c "details" state.
\code
Transition {
from: "*"
to: "details"
...
}
\endcode
Transitions can happen in parallel, in sequence, or in any combination of the two. By default, the top-level
animations in a transition will happen in parallel. The following example shows a rather complex transition
making use of both sequential and parallel animations:
\code
Transition {
from: "*"
to: "MyState"
reversible: true
SequentialAnimation {
ColorAnimation { duration: 1000 }
PauseAnimation { duration: 1000 }
ParallelAnimation {
NumberAnimation {
duration: 1000
easing: "easeOutBounce"
targets: box1
properties: "x,y"
}
NumberAnimation {
duration: 1000
targets: box2
properties: "x,y"
}
}
}
}
\endcode
\section1 Property Behaviors
A \l{Behavior}{property behavior} specifies a default animation to run whenever the property's value changes, regardless
of what caused the change. The \c enabled property can be used to force a \l Behavior
to only apply under certain circumstances.
In the following snippet, we specify that we want the x position of redRect to be animated
whenever it changes. The animation will last 300 milliseconds and use an InOutQuad easing curve.
\qml
Rectangle {
id: redRect
color: "red"
width: 100; height: 100
x: Behavior { NumberAnimation { duration: 300; easing: "InOutQuad" } }
}
\endqml
Like using an animation as a value source, when used in a Behavior and animation does not need to specify
a \c target or \c property.
To trigger this behavior, we could:
\list
\o Enter a state that changes x
\qml
State {
name: "myState"
PropertyChanges {
target: redRect
x: 200
...
}
}
\endqml
\o Update x from a script
\qml
MouseRegion {
....
onClicked: redRect.x = 24;
}
\endqml
\endlist
If x were bound to another property, triggering the binding would also trigger the behavior.
If a state change has a transition animation matching a property with a Behavior, the transition animation
will override the Behavior for that state change.
*/
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