/*! 
\page qmlanimation.html
\target qmlanimation
\title QML Animation

QML supports three different forms of animation - basic property animation, 
states and transitions and property behaviors.  

\section1 Property Animation

Animation in QML is done by animating properties of objects.

Any property of a recognizable type can be animated. Currently those types include:
\list
\o qreal
\o int
\o Most of QVariant's built-in types
\endlist

Animations can also involve numerous properties on numerous objects.

Other Features:
\list
\o Support for a large set of parameterized easing curves. (based on the Penner easing equations)
\o Animation synchronization
\endlist

The simplest form of animation is using \c <NumericAnimation/>

The following example creates a bouncing effect:
\code
<Rect id="rect" width="120" height="200" color="white">
    <Image id="img" file="pics/qtlogo.png"
            x="{60-img.width/2}" y="{200-img.height}">
        <y>
            <SequentialAnimation running="true" repeat="true">
                <NumericAnimation to="{200-img.height}"
                    easing="easeOutBounce(amplitude:100)"
                    duration="2000" />
                <PauseAnimation duration="1000" />
            </SequentialAnimation>
        </y>
    </Image>
</Rect>
\endcode

\image propanim.gif

\target states-transitions
\section1 States and Transitions

\section2 States

QML states describe user interface configurations, including:
\list
\o What UI elements are present
\o The properties of those elements (including how they behave)
\o What actions are available
\endlist

A state can also be thought of as a set of batched changes from a default configuration.

Examples of states in modern UI:
\list
\o A Contacts application has a 'View Contact' state and an 'Edit Contact' State. In the first state the information presented is static (using labels), and in the second it is editable (using editors).
\o A button has a pressed and unpressed state. When pressed the text moves down and to the right, and the button has a slightly darker appearance.
\endlist

In QML:
\list
\o Any object can use states.
\o There is a default state. The default state can be explicitly set.
\o A state can affect other the properties of other objects, not just the object owning the state (and not just that object's children).
\endlist

The following example shows a simple use of states. In the default state \c myrect is positioned at 0,0. In the 'moved' state it is positioned at 50,50.

\code
<Item>
    <Rect id="myrect" width="100" height="100"/>
    <states>
        <State name="moved">
            <SetProperty target="{myrect}" property="x" value="50"/>
            <SetProperty target="{myrect}" property="y" value="50"/>
        </State>
    </states>
</Item>
\endcode

\section2 Transitions

QML transitions describe animations to perform when state changes occur.

For the previous example, a transition could describe how \c myrect moved from its initial position to its new position:

\code
<transitions>
    <Transition>
        <NumericAnimation properties="x,y" easing="easeOutBounce" duration="200" />
    </Transition>
</transitions>
\endcode

QML transitions can use selectors to determine which state changes a transition should apply to:

\code
<Transition fromState="*" toState="Details">
...
</Transition>
\endcode

Transitions can happen in parallel, in sequence, or in any combination of the two:;

\code
<Transition fromState="*" toState="MyState" reversible="true" >
    <SequentialAnimation>
        <ColorAnimation duration="1000" />
        <PauseAnimation duration="1000" />
        <ParallelAnimation>
            <NumericAnimation duration="1000" easing="easeOutBounce" target="{box1}" properties="x,y" />
            <NumericAnimation duration="1000" target="{box2}" properties="x,y" />
        </ParallelAnimation>
    </SequentialAnimation>
</Transition>
\endcode

\section1 Property Behaviors

\note Property behaviors are currently experimental.
*/