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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
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** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
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**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at qt-sales@nokia.com.
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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, and size can all be animated.
QML supports three different forms of animation - basic property animation,
transitions, and property behaviors.
\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 {
running: true
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, and explicitly
start the animation (usually via the \c running property).
\qml
Rectangle {
id: rect
width: 200; height: 200;
Rectangle {
color: "red"
width: 50; height: 50
x: NumberAnimation { to: 50; running: true }
}
}
\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 {
matchProperties: "x,y"
easing: "easeOutBounce"
duration: 200
}
}
]
\endcode
As you can see from the above example, transitions make use of the same basic animation classes introduced
above. However, you generally use a different set of properties when working with transitions. In the example,
no \c target or \c property has been specified. Instead, we have specified \c matchProperties,
which (along with \c matchTargets) acts as a selector to determine which property changes to animate;
in this case, we will animate any x,y properties that have changed on any objects.
QML transitions also have selectors to determine which state changes a transition should apply to:
\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"
matchTargets: box1
matchProperties: "x,y"
}
NumberAnimation {
duration: 1000
matchTargets: box2
matchProperties: "x,y"
}
}
}
}
\endcode
To insert an explicit animation into your transition, you can use \target and \property as normal.
\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
matchTargets: myItem
matchProperties: "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
\section1 Property Behaviors
A property behavior specifies a default animation to run whenever the property's value changes, regardless
of what caused the change. Unlike Transition, Behavior doesn't provide a way to indicate that a Behavior
should 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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