<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en_US" lang="en_US"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- tutorial.qdoc --> <title>Qt 4.8: QML Tutorial 3 - States and Transitions</title> <link rel="stylesheet" type="text/css" href="style/style.css" /> <script src="scripts/jquery.js" type="text/javascript"></script> <script src="scripts/functions.js" type="text/javascript"></script> <link rel="stylesheet" type="text/css" href="style/superfish.css" /> <link rel="stylesheet" type="text/css" href="style/narrow.css" /> <!--[if IE]> <meta name="MSSmartTagsPreventParsing" content="true"> <meta http-equiv="imagetoolbar" content="no"> <![endif]--> <!--[if lt IE 7]> <link rel="stylesheet" type="text/css" href="style/style_ie6.css"> <![endif]--> <!--[if IE 7]> <link rel="stylesheet" type="text/css" href="style/style_ie7.css"> <![endif]--> <!--[if IE 8]> <link rel="stylesheet" type="text/css" href="style/style_ie8.css"> <![endif]--> <script src="scripts/superfish.js" type="text/javascript"></script> <script src="scripts/narrow.js" type="text/javascript"></script> </head> <body class="" onload="CheckEmptyAndLoadList();"> <div class="header" id="qtdocheader"> <div class="content"> <div id="nav-logo"> <a href="index.html">Home</a></div> <a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a> <div id="narrowsearch"></div> <div id="nav-topright"> <ul> <li class="nav-topright-home"><a href="http://qt.digia.com/">Qt HOME</a></li> <li class="nav-topright-dev"><a href="http://qt-project.org/">DEV</a></li> <li class="nav-topright-doc nav-topright-doc-active"><a href="http://qt-project.org/doc/"> DOC</a></li> <li class="nav-topright-blog"><a href="http://blog.qt.digia.com/">BLOG</a></li> </ul> </div> <div id="shortCut"> <ul> <li class="shortCut-topleft-inactive"><span><a href="index.html">Qt 4.8</a></span></li> <li class="shortCut-topleft-active"><a href="http://qt-project.org/doc/">ALL VERSIONS </a></li> </ul> </div> <ul class="sf-menu" id="narrowmenu"> <li><a href="#">API Lookup</a> <ul> <li><a href="classes.html">Class index</a></li> <li><a href="functions.html">Function index</a></li> <li><a href="modules.html">Modules</a></li> <li><a href="namespaces.html">Namespaces</a></li> <li><a href="qtglobal.html">Global Declarations</a></li> <li><a href="qdeclarativeelements.html">QML elements</a></li> </ul> </li> <li><a href="#">Qt Topics</a> <ul> <li><a href="qt-basic-concepts.html">Programming with Qt</a></li> <li><a href="qtquick.html">Device UIs & Qt Quick</a></li> <li><a href="qt-gui-concepts.html">UI Design with Qt</a></li> <li><a href="supported-platforms.html">Supported Platforms</a></li> <li><a href="technology-apis.html">Qt and Key Technologies</a></li> <li><a href="best-practices.html">How-To's and Best Practices</a></li> </ul> </li> <li><a href="#">Examples</a> <ul> <li><a href="all-examples.html">Examples</a></li> <li><a href="tutorials.html">Tutorials</a></li> <li><a href="demos.html">Demos</a></li> <li><a href="qdeclarativeexamples.html">QML Examples</a></li> </ul> </li> </ul> </div> </div> <div class="wrapper"> <div class="hd"> <span></span> </div> <div class="bd group"> <div class="sidebar"> <div class="searchlabel"> Search index:</div> <div class="search" id="sidebarsearch"> <form id="qtdocsearch" action="" onsubmit="return false;"> <fieldset> <input type="text" name="searchstring" id="pageType" value="" /> <div id="resultdialog"> <a href="#" id="resultclose">Close</a> <p id="resultlinks" class="all"><a href="#" id="showallresults">All</a> | <a href="#" id="showapiresults">API</a> | <a href="#" id="showarticleresults">Articles</a> | <a href="#" id="showexampleresults">Examples</a></p> <p id="searchcount" class="all"><span id="resultcount"></span><span id="apicount"></span><span id="articlecount"></span><span id="examplecount"></span> results:</p> <ul id="resultlist" class="all"> </ul> </div> </fieldset> </form> </div> <div class="box first bottombar" id="lookup"> <h2 title="API Lookup"><span></span> API Lookup</h2> <div id="list001" class="list"> <ul id="ul001" > <li class="defaultLink"><a href="classes.html">Class index</a></li> <li class="defaultLink"><a href="functions.html">Function index</a></li> <li class="defaultLink"><a href="modules.html">Modules</a></li> <li class="defaultLink"><a href="namespaces.html">Namespaces</a></li> <li class="defaultLink"><a href="qtglobal.html">Global Declarations</a></li> <li class="defaultLink"><a href="qdeclarativeelements.html">QML elements</a></li> </ul> </div> </div> <div class="box bottombar" id="topics"> <h2 title="Qt Topics"><span></span> Qt Topics</h2> <div id="list002" class="list"> <ul id="ul002" > <li class="defaultLink"><a href="qt-basic-concepts.html">Programming with Qt</a></li> <li class="defaultLink"><a href="qtquick.html">Device UIs & Qt Quick</a></li> <li class="defaultLink"><a href="qt-gui-concepts.html">UI Design with Qt</a></li> <li class="defaultLink"><a href="supported-platforms.html">Supported Platforms</a></li> <li class="defaultLink"><a href="technology-apis.html">Qt and Key Technologies</a></li> <li class="defaultLink"><a href="best-practices.html">How-To's and Best Practices</a></li> </ul> </div> </div> <div class="box" id="examples"> <h2 title="Examples"><span></span> Examples</h2> <div id="list003" class="list"> <ul id="ul003"> <li class="defaultLink"><a href="all-examples.html">Examples</a></li> <li class="defaultLink"><a href="tutorials.html">Tutorials</a></li> <li class="defaultLink"><a href="demos.html">Demos</a></li> <li class="defaultLink"><a href="qdeclarativeexamples.html">QML Examples</a></li> </ul> </div> </div> </div> <div class="wrap"> <div class="toolbar"> <div class="breadcrumb toolblock"> <ul> <li class="first"><a href="index.html">Home</a></li> <!-- Breadcrumbs go here --> <li>QML Tutorial 3 - States and Transitions</li> </ul> </div> <div class="toolbuttons toolblock"> <ul> <li id="smallA" class="t_button">A</li> <li id="medA" class="t_button active">A</li> <li id="bigA" class="t_button">A</li> <li id="print" class="t_button"><a href="javascript:this.print();"> <span>Print</span></a></li> </ul> </div> </div> <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="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#walkthrough">Walkthrough</a></li> </ul> </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 1.0 <span class="type"><a href="qml-rectangle.html">Rectangle</a></span> { <span class="name">id</span>: <span class="name">page</span> <span class="name">width</span>: <span class="number">500</span>; <span class="name">height</span>: <span class="number">200</span> <span class="name">color</span>: <span class="string">"lightgray"</span> <span class="type"><a href="qml-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-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-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-parallelanimation.html">ParallelAnimation</a></span> { <span class="type"><a href="qml-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-coloranimation.html">ColorAnimation</a></span> { <span class="name">duration</span>: <span class="number">500</span> } } } } <span class="type"><a href="qml-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>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-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 element. This state will be activated when the <a href="qml-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 <tt>y</tt> property of the text to <tt>160</tt>, the rotation to <tt>180</tt> and the <tt>color</tt> 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-parallelanimation.html">ParallelAnimation</a></span> { <span class="type"><a href="qml-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-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><tt>from</tt> and <tt>to</tt> 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 <tt>reversible</tt> to <tt>true</tt>. This is equivalent to writing the two transitions separately.</p> <p>The <a href="qml-parallelanimation.html">ParallelAnimation</a> element 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-sequentialanimation.html">SequentialAnimation</a> instead.</p> <p>For more details on states and transitions, see <a href="qdeclarativestates.html">QML States</a> and the <a href="declarative-animation-states.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 class="ft"> <span></span> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2013 Digia Plc and/or its subsidiaries. Documentation contributions included herein are the copyrights of their respective owners.</p> <br /> <p> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.</p> <p> Documentation sources may be obtained from <a href="http://www.qt-project.org"> www.qt-project.org</a>.</p> <br /> <p> Digia, Qt and their respective logos are trademarks of Digia Plc in Finland and/or other countries worldwide. All other trademarks are property of their respective owners. <a title="Privacy Policy" href="http://en.gitorious.org/privacy_policy/">Privacy Policy</a></p> </div> <script src="scripts/functions.js" type="text/javascript"></script> </body> </html>