<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- tutorial.qdoc --> <title>QML Tutorial 3 - States and Transitions | Qt Quick 5.11</title> <link rel="stylesheet" type="text/css" href="style/offline-simple.css" /> <script type="text/javascript"> document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css"); // loading style sheet breaks anchors that were jumped to before // so force jumping to anchor again setTimeout(function() { var anchor = location.hash; // need to jump to different anchor first (e.g. none) location.hash = "#"; setTimeout(function() { location.hash = anchor; }, 0); }, 0); </script> </head> <body> <div class="header" id="qtdocheader"> <div class="main"> <div class="main-rounded"> <div class="navigationbar"> <table><tr> <td ><a href="../qtdoc/index.html">Qt 5.11</a></td><td ><a href="qtquick-index.html">Qt Quick</a></td><td >QML Tutorial 3 - States and Transitions</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right">Qt 5.11.2 Reference Documentation</td> </tr></table> </div> </div> <div class="content"> <div class="line"> <div class="content mainContent"> <link rel="prev" href="qml-tutorial2.html" /> <p class="naviNextPrevious headerNavi"> <a class="prevPage" href="qml-tutorial2.html">QML Tutorial 2 - QML Components</a> </p><p/> <div class="sidebar"> <div class="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#walkthrough">Walkthrough</a></li> </ul> </div> <div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">QML Tutorial 3 - States and Transitions</h1> <span class="subtitle"></span> <!-- $$$qml-tutorial3.html-description --> <div class="descr"> <a name="details"></a> <p>In this chapter, we make this example a little bit more dynamic by introducing states and transitions.</p> <p>We want our text to move to the bottom of the screen, rotate and become red when clicked.</p> <p class="centerAlign"><img src="images/declarative-tutorial3_animation.gif" alt="" /></p><p>Here is the QML code:</p> <pre class="qml"> import QtQuick 2.0 <span class="type"><a href="qml-qtquick-rectangle.html">Rectangle</a></span> { <span class="name">id</span>: <span class="name">page</span> <span class="name">width</span>: <span class="number">320</span>; <span class="name">height</span>: <span class="number">480</span> <span class="name">color</span>: <span class="string">"lightgray"</span> <span class="type"><a href="qml-qtquick-text.html">Text</a></span> { <span class="name">id</span>: <span class="name">helloText</span> <span class="name">text</span>: <span class="string">"Hello world!"</span> <span class="name">y</span>: <span class="number">30</span> <span class="name">anchors</span>.horizontalCenter: <span class="name">page</span>.<span class="name">horizontalCenter</span> <span class="name">font</span>.pointSize: <span class="number">24</span>; <span class="name">font</span>.bold: <span class="number">true</span> <span class="type"><a href="qml-qtquick-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">"down"</span>; <span class="name">when</span>: <span class="name">mouseArea</span>.<span class="name">pressed</span> <span class="operator">==</span> <span class="number">true</span> <span class="type"><a href="qml-qtquick-propertychanges.html">PropertyChanges</a></span> { <span class="name">target</span>: <span class="name">helloText</span>; <span class="name">y</span>: <span class="number">160</span>; <span class="name">rotation</span>: <span class="number">180</span>; <span class="name">color</span>: <span class="string">"red"</span> } } <span class="name">transitions</span>: <span class="name">Transition</span> { <span class="name">from</span>: <span class="string">""</span>; <span class="name">to</span>: <span class="string">"down"</span>; <span class="name">reversible</span>: <span class="number">true</span> <span class="type"><a href="qml-qtquick-parallelanimation.html">ParallelAnimation</a></span> { <span class="type"><a href="qml-qtquick-numberanimation.html">NumberAnimation</a></span> { <span class="name">properties</span>: <span class="string">"y,rotation"</span>; <span class="name">duration</span>: <span class="number">500</span>; <span class="name">easing</span>.type: <span class="name">Easing</span>.<span class="name">InOutQuad</span> } <span class="type"><a href="qml-qtquick-coloranimation.html">ColorAnimation</a></span> { <span class="name">duration</span>: <span class="number">500</span> } } } } <span class="type"><a href="qml-qtquick-grid.html">Grid</a></span> { <span class="name">id</span>: <span class="name">colorPicker</span> <span class="name">x</span>: <span class="number">4</span>; <span class="name">anchors</span>.bottom: <span class="name">page</span>.<span class="name">bottom</span>; <span class="name">anchors</span>.bottomMargin: <span class="number">4</span> <span class="name">rows</span>: <span class="number">2</span>; <span class="name">columns</span>: <span class="number">3</span>; <span class="name">spacing</span>: <span class="number">3</span> <span class="type">Cell</span> { <span class="name">cellColor</span>: <span class="string">"red"</span>; <span class="name">onClicked</span>: <span class="name">helloText</span>.<span class="name">color</span> <span class="operator">=</span> <span class="name">cellColor</span> } <span class="type">Cell</span> { <span class="name">cellColor</span>: <span class="string">"green"</span>; <span class="name">onClicked</span>: <span class="name">helloText</span>.<span class="name">color</span> <span class="operator">=</span> <span class="name">cellColor</span> } <span class="type">Cell</span> { <span class="name">cellColor</span>: <span class="string">"blue"</span>; <span class="name">onClicked</span>: <span class="name">helloText</span>.<span class="name">color</span> <span class="operator">=</span> <span class="name">cellColor</span> } <span class="type">Cell</span> { <span class="name">cellColor</span>: <span class="string">"yellow"</span>; <span class="name">onClicked</span>: <span class="name">helloText</span>.<span class="name">color</span> <span class="operator">=</span> <span class="name">cellColor</span> } <span class="type">Cell</span> { <span class="name">cellColor</span>: <span class="string">"steelblue"</span>; <span class="name">onClicked</span>: <span class="name">helloText</span>.<span class="name">color</span> <span class="operator">=</span> <span class="name">cellColor</span> } <span class="type">Cell</span> { <span class="name">cellColor</span>: <span class="string">"black"</span>; <span class="name">onClicked</span>: <span class="name">helloText</span>.<span class="name">color</span> <span class="operator">=</span> <span class="name">cellColor</span> } } } </pre> <a name="walkthrough"></a> <h2 id="walkthrough">Walkthrough</h2> <pre class="qml"> <span class="name">states</span>: <span class="name">State</span> { <span class="name">name</span>: <span class="string">"down"</span>; <span class="name">when</span>: <span class="name">mouseArea</span>.<span class="name">pressed</span> <span class="operator">==</span> <span class="number">true</span> <span class="type"><a href="qml-qtquick-propertychanges.html">PropertyChanges</a></span> { <span class="name">target</span>: <span class="name">helloText</span>; <span class="name">y</span>: <span class="number">160</span>; <span class="name">rotation</span>: <span class="number">180</span>; <span class="name">color</span>: <span class="string">"red"</span> } } </pre> <p>First, we create a new <i>down</i> state for our text type. This state will be activated when the <a href="qml-qtquick-mousearea.html">MouseArea</a> is pressed, and deactivated when it is released.</p> <p>The <i>down</i> state includes a set of property changes from our implicit <i>default state</i> (the items as they were initially defined in the QML). Specifically, we set the <code>y</code> property of the text to <code>160</code>, the rotation to <code>180</code> and the <code>color</code> to red.</p> <pre class="qml"> <span class="name">transitions</span>: <span class="name">Transition</span> { <span class="name">from</span>: <span class="string">""</span>; <span class="name">to</span>: <span class="string">"down"</span>; <span class="name">reversible</span>: <span class="number">true</span> <span class="type"><a href="qml-qtquick-parallelanimation.html">ParallelAnimation</a></span> { <span class="type"><a href="qml-qtquick-numberanimation.html">NumberAnimation</a></span> { <span class="name">properties</span>: <span class="string">"y,rotation"</span>; <span class="name">duration</span>: <span class="number">500</span>; <span class="name">easing</span>.type: <span class="name">Easing</span>.<span class="name">InOutQuad</span> } <span class="type"><a href="qml-qtquick-coloranimation.html">ColorAnimation</a></span> { <span class="name">duration</span>: <span class="number">500</span> } } } </pre> <p>Because we don't want the text to appear at the bottom instantly but rather move smoothly, we add a transition between our two states.</p> <p><code>from</code> and <code>to</code> define the states between which the transition will run. In this case, we want a transition from the default state to our <i>down</i> state.</p> <p>Because we want the same transition to be run in reverse when changing back from the <i>down</i> state to the default state, we set <code>reversible</code> to <code>true</code>. This is equivalent to writing the two transitions separately.</p> <p>The <a href="qml-qtquick-parallelanimation.html">ParallelAnimation</a> type makes sure that the two types of animations (number and color) start at the same time. We could also run them one after the other by using <a href="qml-qtquick-sequentialanimation.html">SequentialAnimation</a> instead.</p> <p>For more details on states and transitions, see <a href="qtquick-statesanimations-states.html">Qt Quick States</a> and the <a href="../qtwidgets/qtwidgets-animation-states-example.html">states and transitions example</a>.</p> </div> <!-- @@@qml-tutorial3.html --> <p class="naviNextPrevious footerNavi"> <a class="prevPage" href="qml-tutorial2.html">QML Tutorial 2 - QML Components</a> </p> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2018 The Qt Company Ltd. 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