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<h1 class="title">QML Transition Element</h1>
<span class="subtitle"></span>
<!-- $$$Transition-brief -->
<p>The Transition element defines animated transitions that occur on state changes. <a href="#details">More...</a></p>
<!-- @@@Transition -->
<p>This element was introduced in Qt 4.7.</p>
<ul>
<li><a href="qml-transition-members.html">List of all members, including inherited members</a></li>
</ul>
<a name="properties"></a>
<h2>Properties</h2>
<ul>
<li class="fn"><b><b><a href="qml-transition.html#animations-prop">animations</a></b></b> : list&lt;Animation&gt;</li>
<li class="fn"><b><b><a href="qml-transition.html#from-prop">from</a></b></b> : string</li>
<li class="fn"><b><b><a href="qml-transition.html#reversible-prop">reversible</a></b></b> : bool</li>
<li class="fn"><b><b><a href="qml-transition.html#to-prop">to</a></b></b> : string</li>
</ul>
<!-- $$$Transition-description -->
<a name="details"></a>
<h2>Detailed Description</h2>
<p>A Transition defines the animations to be applied when a <a href="qml-state.html">State</a> change occurs.</p>
<p>For example, the following <a href="qml-rectangle.html">Rectangle</a> has two states: the default state, and an added &quot;moved&quot; state. In the &quot;moved state, the rectangle's position changes to (50, 50). The added Transition specifies that when the rectangle changes between the default and the &quot;moved&quot; state, any changes to the <tt>x</tt> and <tt>y</tt> properties should be animated, using an <tt>Easing.InOutQuad</tt>.</p>
<pre class="qml"> import QtQuick 1.0
<span class="type"><a href="qml-rectangle.html">Rectangle</a></span> {
<span class="name">id</span>: <span class="name">rect</span>
<span class="name">width</span>: <span class="number">100</span>; <span class="name">height</span>: <span class="number">100</span>
<span class="name">color</span>: <span class="string">&quot;red&quot;</span>
<span class="type"><a href="qml-mousearea.html">MouseArea</a></span> {
<span class="name">id</span>: <span class="name">mouseArea</span>
<span class="name">anchors</span>.fill: <span class="name">parent</span>
}
<span class="name">states</span>: <span class="name">State</span> {
<span class="name">name</span>: <span class="string">&quot;moved&quot;</span>; <span class="name">when</span>: <span class="name">mouseArea</span>.<span class="name">pressed</span>
<span class="type"><a href="qml-propertychanges.html">PropertyChanges</a></span> { <span class="name">target</span>: <span class="name">rect</span>; <span class="name">x</span>: <span class="number">50</span>; <span class="name">y</span>: <span class="number">50</span> }
}
<span class="name">transitions</span>: <span class="name">Transition</span> {
<span class="type"><a href="qml-numberanimation.html">NumberAnimation</a></span> { <span class="name">properties</span>: <span class="string">&quot;x,y&quot;</span>; <span class="name">easing</span>.type: <span class="name">Easing</span>.<span class="name">InOutQuad</span> }
}
}</pre>
<p>Notice the example does not require <a href="qml-propertyanimation.html#to-prop">to</a> and <a href="qml-propertyanimation.html#from-prop">from</a> values for the <a href="qml-numberanimation.html">NumberAnimation</a>. As a convenience, these properties are automatically set to the values of <tt>x</tt> and <tt>y</tt> before and after the state change; the <tt>from</tt> values are provided by the current values of <tt>x</tt> and <tt>y</tt>, and the <tt>to</tt> values are provided by the <a href="qml-propertychanges.html">PropertyChanges</a> object. If you wish, you can provide <a href="qml-propertyanimation.html#to-prop">to</a> and <a href="qml-propertyanimation.html#from-prop">from</a> values anyway to override the default values.</p>
<p>By default, a Transition's animations are applied for any state change in the parent item. The Transition <a href="qml-transition.html#from-prop">from</a> and <a href="qml-transition.html#to-prop">to</a> values can be set to restrict the animations to only be applied when changing from one particular state to another.</p>
<p>To define multiple transitions, specify <a href="qml-item.html#transitions-prop">Item::transitions</a> as a list:</p>
<pre class="qml"> <span class="name">transitions</span>: [
<span class="type">Transition</span> {
<span class="name">from</span>: <span class="string">&quot;stop&quot;</span>; <span class="name">to</span>: <span class="string">&quot;go&quot;</span>
<span class="type"><a href="qml-propertyanimation.html">PropertyAnimation</a></span> { <span class="name">target</span>: <span class="name">stopLight</span>
<span class="name">properties</span>: <span class="string">&quot;color&quot;</span>; <span class="name">duration</span>: <span class="number">1000</span> }
},
<span class="type">Transition</span> {
<span class="name">from</span>: <span class="string">&quot;go&quot;</span>; <span class="name">to</span>: <span class="string">&quot;stop&quot;</span>
<span class="type"><a href="qml-propertyanimation.html">PropertyAnimation</a></span> { <span class="name">target</span>: <span class="name">goLight</span>
<span class="name">properties</span>: <span class="string">&quot;color&quot;</span>; <span class="name">duration</span>: <span class="number">1000</span> }
} ]</pre>
<p>If multiple Transitions are specified, only a single (best-matching) Transition will be applied for any particular state change. In the example above, when changing to <tt>state1</tt>, the first transition will be used, rather than the more generic second transition.</p>
<p>If a state change has a Transition that matches the same property as a <a href="qml-behavior.html">Behavior</a>, the Transition animation overrides the <a href="qml-behavior.html">Behavior</a> for that state change.</p>
<p><b>See also </b><a href="qdeclarativeanimation.html">QML Animation and Transitions</a>, <a href="declarative-animation-states.html">states example</a>, <a href="qdeclarativestates.html#qmlstates">States</a>, and <a href="qtdeclarative.html">QtDeclarative</a>.</p>
<!-- @@@Transition -->
<h2>Property Documentation</h2>
<!-- $$$animations -->
<div class="qmlitem"><div class="qmlproto"><table class="qmlname"><tr valign="top" class="odd"><td class="tblQmlPropNode"><p><a name="animations-prop"></a><span class="qmlreadonly">read-only</span><span class="qmldefault">default</span><span class="name">animations</span> : <span class="type"><a href="qml-list.html">list</a></span>&lt;<span class="type"><a href="qml-animation.html">Animation</a></span>&gt;</p></td></tr></table></div><div class="qmldoc"><p>This property holds a list of the animations to be run for this transition.</p>
<pre class="qml"></pre>
<p>The top-level animations are run in parallel. To run them sequentially, define them within a <a href="qml-sequentialanimation.html">SequentialAnimation</a>:</p>
<pre class="qml"> <span class="name">transitions</span>: <span class="name">Transition</span> {
<span class="type"><a href="qml-sequentialanimation.html">SequentialAnimation</a></span> {
<span class="type"><a href="qml-propertyanimation.html">PropertyAnimation</a></span> { <span class="name">property</span>: <span class="string">&quot;x&quot;</span>; <span class="name">duration</span>: <span class="number">1000</span> }
<span class="type"><a href="qml-coloranimation.html">ColorAnimation</a></span> { <span class="name">duration</span>: <span class="number">1000</span> }
}
}</pre>
</div></div><!-- @@@animations -->
<br/>
<!-- $$$from -->
<div class="qmlitem"><div class="qmlproto"><table class="qmlname"><tr valign="top" class="odd"><td class="tblQmlPropNode"><p><a name="from-prop"></a><span class="name">from</span> : <span class="type"><a href="qml-string.html">string</a></span></p></td></tr><tr valign="top" class="even"><td class="tblQmlPropNode"><p><a name="to-prop"></a><span class="name">to</span> : <span class="type"><a href="qml-string.html">string</a></span></p></td></tr></table></div><div class="qmldoc"><p>These properties indicate the state changes that trigger the transition.</p>
<p>The default values for these properties is &quot;*&quot; (that is, any state).</p>
<p>For example, the following transition has not set the <tt>to</tt> and <tt>from</tt> properties, so the animation is always applied when changing between the two states (i.e&#x2e; when the mouse is pressed and released).</p>
<pre class="qml"> <span class="type"><a href="qml-rectangle.html">Rectangle</a></span> {
<span class="name">id</span>: <span class="name">rect</span>
<span class="name">width</span>: <span class="number">100</span>; <span class="name">height</span>: <span class="number">100</span>
<span class="name">color</span>: <span class="string">&quot;red&quot;</span>
<span class="type"><a href="qml-mousearea.html">MouseArea</a></span> { <span class="name">id</span>: <span class="name">mouseArea</span>; <span class="name">anchors</span>.fill: <span class="name">parent</span> }
<span class="name">states</span>: <span class="name">State</span> {
<span class="name">name</span>: <span class="string">&quot;brighter&quot;</span>; <span class="name">when</span>: <span class="name">mouseArea</span>.<span class="name">pressed</span>
<span class="type"><a href="qml-propertychanges.html">PropertyChanges</a></span> { <span class="name">target</span>: <span class="name">rect</span>; <span class="name">color</span>: <span class="string">&quot;yellow&quot;</span> }
}
<span class="name">transitions</span>: <span class="name">Transition</span> {
<span class="type"><a href="qml-coloranimation.html">ColorAnimation</a></span> { <span class="name">duration</span>: <span class="number">1000</span> }
}
}</pre>
<p>If the transition was changed to this:</p>
<pre class="qml"> <span class="name">transitions</span>: <span class="name">Transition</span> {
<span class="name">to</span>: <span class="string">&quot;brighter&quot;</span>
<span class="type"><a href="qml-coloranimation.html">ColorAnimation</a></span> { <span class="name">duration</span>: <span class="number">1000</span> }
}</pre>
<p>The animation would only be applied when changing from the default state to the &quot;brighter&quot; state (i.e&#x2e; when the mouse is pressed, but not on release).</p>
<p><b>See also </b><a href="qml-transition.html#reversible-prop">reversible</a>.</p>
</div></div><!-- @@@from -->
<br/>
<!-- $$$reversible -->
<div class="qmlitem"><div class="qmlproto"><table class="qmlname"><tr valign="top" class="odd"><td class="tblQmlPropNode"><p><a name="reversible-prop"></a><span class="name">reversible</span> : <span class="type"><a href="qml-bool.html">bool</a></span></p></td></tr></table></div><div class="qmldoc"><p>This property holds whether the transition should be automatically reversed when the conditions that triggered this transition are reversed.</p>
<p>The default value is false.</p>
<p>By default, transitions run in parallel and are applied to all state changes if the <a href="qml-transition.html#from-prop">from</a> and <a href="qml-transition.html#to-prop">to</a> states have not been set. In this situation, the transition is automatically applied when a state change is reversed, and it is not necessary to set this property to reverse the transition.</p>
<p>However, if a <a href="qml-sequentialanimation.html">SequentialAnimation</a> is used, or if the <a href="qml-transition.html#from-prop">from</a> or <a href="qml-transition.html#to-prop">to</a> properties have been set, this property will need to be set to reverse a transition when a state change is reverted. For example, the following transition applies a sequential animation when the mouse is pressed, and reverses the sequence of the animation when the mouse is released:</p>
<pre class="qml"> <span class="type"><a href="qml-rectangle.html">Rectangle</a></span> {
<span class="name">id</span>: <span class="name">rect</span>
<span class="name">width</span>: <span class="number">100</span>; <span class="name">height</span>: <span class="number">100</span>
<span class="name">color</span>: <span class="string">&quot;red&quot;</span>
<span class="type"><a href="qml-mousearea.html">MouseArea</a></span> { <span class="name">id</span>: <span class="name">mouseArea</span>; <span class="name">anchors</span>.fill: <span class="name">parent</span> }
<span class="name">states</span>: <span class="name">State</span> {
<span class="name">name</span>: <span class="string">&quot;brighter&quot;</span>
<span class="name">when</span>: <span class="name">mouseArea</span>.<span class="name">pressed</span>
<span class="type"><a href="qml-propertychanges.html">PropertyChanges</a></span> { <span class="name">target</span>: <span class="name">rect</span>; <span class="name">color</span>: <span class="string">&quot;yellow&quot;</span>; <span class="name">x</span>: <span class="number">50</span> }
}
<span class="name">transitions</span>: <span class="name">Transition</span> {
<span class="type"><a href="qml-sequentialanimation.html">SequentialAnimation</a></span> {
<span class="type"><a href="qml-propertyanimation.html">PropertyAnimation</a></span> { <span class="name">property</span>: <span class="string">&quot;x&quot;</span>; <span class="name">duration</span>: <span class="number">1000</span> }
<span class="type"><a href="qml-coloranimation.html">ColorAnimation</a></span> { <span class="name">duration</span>: <span class="number">1000</span> }
}
}
}</pre>
<p>If the transition did not set the <tt>to</tt> and <tt>reversible</tt> values, then on the mouse release, the transition would play the <a href="qml-propertyanimation.html">PropertyAnimation</a> before the <a href="qml-coloranimation.html">ColorAnimation</a> instead of reversing the sequence.</p>
</div></div><!-- @@@reversible -->
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