<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- calculator-qml.qdoc --> <title>Qt SCXML Calculator QML Example | Qt SCXML 5.9</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 >Qt 5.9</td><td ><a href="qtscxml-index.html">Qt SCXML</a></td><td ><a href="examples-qtscxml.html">Qt SCXML Examples</a></td><td >Qt SCXML Calculator QML Example</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right">Qt 5.9.4 Reference Documentation</td> </tr></table> </div> </div> <div class="content"> <div class="line"> <div class="content mainContent"> <div class="sidebar"> <div class="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#running-the-example">Running the Example</a></li> <li class="level1"><a href="#compiling-the-state-machine">Compiling the State Machine</a></li> <li class="level1"><a href="#instantiating-the-state-machine">Instantiating the State Machine</a></li> </ul> </div> <div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">Qt SCXML Calculator QML Example</h1> <span class="subtitle"></span> <!-- $$$calculator-qml-description --> <div class="descr"> <a name="details"></a> <p class="centerAlign"><img src="images/calculator-qml.png" alt="" /></p><p><i>Calculator</i> uses Qt SCXML to implement the <a href="http://www.w3.org/TR/scxml/#N11630">Calculator Example</a> presented in the SCXML Specification.</p> <p>The state machine is specified in the <i>statemachine.scxml</i> file and compiled into the <code>CalculatorStateMachine</code> class. The user interface is created using Qt Quick.</p> <a name="running-the-example"></a> <h2 id="running-the-example">Running the Example</h2> <p>To run the example from Qt Creator, open the <b>Welcome</b> mode and select the example from <b>Examples</b>. For more information, visit Building and Running an Example.</p> <a name="compiling-the-state-machine"></a> <h2 id="compiling-the-state-machine">Compiling the State Machine</h2> <p>We link against the Qt SCXML module by adding the following line to the <i>.pro</i> file:</p> <pre class="qml"> QT += widgets scxml </pre> <p>We then specify the state machine to compile:</p> <pre class="qml"> STATECHARTS = ../calculator-common/statemachine.scxml </pre> <p>The Qt SCXML Compiler, <code>qscxmlc</code>, is run automatically to generate <i>statemachine.h</i> and <i>statemachine.cpp</i>, and to add them to the <code>HEADERS</code> and <code>SOURCES</code> variables for compilation.</p> <a name="instantiating-the-state-machine"></a> <h2 id="instantiating-the-state-machine">Instantiating the State Machine</h2> <p>We make the generated <code>CalculatorStateMachine</code> class available to QML by registering it as a QML type in the <i>calculator-qml.cpp</i> file:</p> <pre class="qml"> <span class="preprocessor">#include "statemachine.h"</span> <span class="type">int</span> main(<span class="type">int</span> argc<span class="operator">,</span> <span class="type">char</span> <span class="operator">*</span>argv<span class="operator">[</span><span class="operator">]</span>) { <span class="type">QGuiApplication</span> app(argc<span class="operator">,</span> argv); qmlRegisterType<span class="operator"><</span>CalculatorStateMachine<span class="operator">></span>(<span class="string">"CalculatorStateMachine"</span><span class="operator">,</span> <span class="number">1</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="string">"CalculatorStateMachine"</span>); <span class="type">QQmlApplicationEngine</span> engine; engine<span class="operator">.</span>load(<span class="type">QUrl</span>(<span class="type">QStringLiteral</span>(<span class="string">"qrc:/calculator-qml.qml"</span>))); <span class="keyword">if</span> (engine<span class="operator">.</span>rootObjects()<span class="operator">.</span>isEmpty()) <span class="keyword">return</span> <span class="operator">-</span><span class="number">1</span>; <span class="keyword">return</span> app<span class="operator">.</span>exec(); } </pre> <p>To use the CalculatorStateMachine type in a QML file, we import it:</p> <pre class="qml"> import CalculatorStateMachine 1.0 </pre> <p>We instantiate a CalculatorStateMachine and listen to the <code>updateDisplay</code> event. When it occurs, we change the text on the calculator display:</p> <pre class="qml"> <span class="type">CalculatorStateMachine</span> { <span class="name">id</span>: <span class="name">statemachine</span> <span class="name">running</span>: <span class="number">true</span> <span class="type"><a href="qml-qtscxml-eventconnection.html">EventConnection</a></span> { <span class="name">events</span>: [<span class="string">"updateDisplay"</span>] <span class="name">onOccurred</span>: <span class="name">resultText</span>.<span class="name">text</span> <span class="operator">=</span> <span class="name">event</span>.<span class="name">data</span>.<span class="name">display</span> } } </pre> <p>When users press the calculator buttons, the buttons submit events to the state machine:</p> <pre class="qml"> <span class="type">Button</span> { <span class="name">id</span>: <span class="name">resultButton</span> <span class="name">x</span>: <span class="number">3</span> <span class="operator">*</span> <span class="name">width</span> <span class="name">y</span>: <span class="name">parent</span>.<span class="name">height</span> <span class="operator">/</span> <span class="number">5</span> <span class="name">textHeight</span>: <span class="name">y</span> <span class="operator">-</span> <span class="number">2</span> <span class="name">fontHeight</span>: <span class="number">0.4</span> <span class="name">width</span>: <span class="name">parent</span>.<span class="name">width</span> <span class="operator">/</span> <span class="number">4</span> <span class="name">height</span>: <span class="name">y</span> <span class="operator">*</span> <span class="number">4</span> <span class="name">color</span>: <span class="name">pressed</span> ? <span class="string">"#e0b91c"</span> : <span class="string">"#face20"</span> <span class="name">text</span>: <span class="string">"="</span> <span class="name">onClicked</span>: <span class="name">statemachine</span>.<span class="name">submitEvent</span>(<span class="string">"EQUALS"</span>) } </pre> <p>Files:</p> <ul> <li><a href="qtscxml-calculator-qml-button-qml.html">calculator-qml/Button.qml</a></li> <li><a href="qtscxml-calculator-qml-calculator-qml-cpp.html">calculator-qml/calculator-qml.cpp</a></li> <li><a href="qtscxml-calculator-qml-calculator-qml-qml.html">calculator-qml/calculator-qml.qml</a></li> <li><a href="qtscxml-calculator-qml-statemachine-cpp.html">calculator-qml/statemachine.cpp</a></li> <li><a href="qtscxml-calculator-qml-statemachine-h.html">calculator-qml/statemachine.h</a></li> <li><a href="qtscxml-calculator-qml-calculator-qml-pro.html">calculator-qml/calculator-qml.pro</a></li> <li><a href="qtscxml-calculator-qml-calculator-qml-qrc.html">calculator-qml/calculator-qml.qrc</a></li> </ul> </div> <!-- @@@calculator-qml --> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2017 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners.<br> 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.<br> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners. </p> </div> </body> </html>