<?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.qdoc --> <title>Qt SCXML Calculator Example | Qt SCXML 5.12.6</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 5.12</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 Example</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right"><a href="qtscxml-index.html">Qt 5.12.6 Reference Documentation</a></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> <li class="level1"><a href="#connecting-to-active-properties">Connecting to Active Properties</a></li> </ul> </div> <div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">Qt SCXML Calculator Example</h1> <span class="subtitle"></span> <!-- $$$calculator-widgets-brief --> <p>A widget-based application that implements the Calculator example presented in the SCXML Specification.</p> <!-- @@@calculator-widgets --> <!-- $$$calculator-widgets-description --> <div class="descr"> <a name="details"></a> <p class="centerAlign"><img src="images/calculator.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 Widgets.</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="cpp"> QT += widgets scxml </pre> <p>We then specify the state machine to compile:</p> <pre class="cpp"> 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 instantiate the generated <code>CalculatorStateMachine</code> class in the <i>calculator-widgets.cpp</i> file, as follows:</p> <pre class="cpp"> <span class="preprocessor">#include "statemachine.h"</span> <span class="preprocessor">#include "mainwindow.h"</span> <span class="preprocessor">#include <QApplication></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><span class="operator">*</span>argv) { <span class="type">QApplication</span> app(argc<span class="operator">,</span> argv); CalculatorStateMachine machine; MainWindow mainWindow(<span class="operator">&</span>machine); machine<span class="operator">.</span>start(); mainWindow<span class="operator">.</span>show(); <span class="keyword">return</span> app<span class="operator">.</span>exec(); } </pre> <a name="connecting-to-active-properties"></a> <h2 id="connecting-to-active-properties">Connecting to Active Properties</h2> <p>After instantiating the state machine, we can connect to the active properties of the states, as follows:</p> <pre class="cpp"> connect(ui<span class="operator">-</span><span class="operator">></span>digit0<span class="operator">,</span> <span class="operator">&</span><span class="type">QAbstractButton</span><span class="operator">::</span>clicked<span class="operator">,</span> <span class="operator">[</span><span class="keyword">this</span><span class="operator">]</span> { m_machine<span class="operator">-</span><span class="operator">></span>submitEvent(<span class="string">"DIGIT.0"</span>); }); connect(ui<span class="operator">-</span><span class="operator">></span>digit1<span class="operator">,</span> <span class="operator">&</span><span class="type">QAbstractButton</span><span class="operator">::</span>clicked<span class="operator">,</span> <span class="operator">[</span><span class="keyword">this</span><span class="operator">]</span> { m_machine<span class="operator">-</span><span class="operator">></span>submitEvent(<span class="string">"DIGIT.1"</span>); }); connect(ui<span class="operator">-</span><span class="operator">></span>digit2<span class="operator">,</span> <span class="operator">&</span><span class="type">QAbstractButton</span><span class="operator">::</span>clicked<span class="operator">,</span> <span class="operator">[</span><span class="keyword">this</span><span class="operator">]</span> { m_machine<span class="operator">-</span><span class="operator">></span>submitEvent(<span class="string">"DIGIT.2"</span>); }); </pre> <p>The state machine can notify other code when events occur:</p> <pre class="cpp"> <transition event="DISPLAY.UPDATE"> <log label="'result'" expr="short_expr==''?res:short_expr" /> <send event="updateDisplay"> <param name="display" expr="short_expr==''?res:short_expr"/> </send> </transition> </pre> <p>We connect to the <code>updateDisplay</code> event to display the data passed by the events:</p> <pre class="cpp"> m_machine<span class="operator">-</span><span class="operator">></span>connectToEvent(QLatin1String(<span class="string">"updateDisplay"</span>)<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">[</span><span class="keyword">this</span><span class="operator">]</span>(<span class="keyword">const</span> <span class="type"><a href="qscxmlevent.html">QScxmlEvent</a></span> <span class="operator">&</span>event) { <span class="keyword">const</span> <span class="type">QString</span> display <span class="operator">=</span> event<span class="operator">.</span>data()<span class="operator">.</span>toMap() <span class="operator">.</span>value(<span class="string">"display"</span>)<span class="operator">.</span>toString(); ui<span class="operator">-</span><span class="operator">></span>display<span class="operator">-</span><span class="operator">></span>setText(display); }); </pre> <p>Files:</p> <ul> <li><a href="qtscxml-calculator-widgets-calculator-widgets-cpp.html">calculator-widgets/calculator-widgets.cpp</a></li> <li><a href="qtscxml-calculator-widgets-calculator-widgets-pro.html">calculator-widgets/calculator-widgets.pro</a></li> <li><a href="qtscxml-calculator-widgets-mainwindow-cpp.html">calculator-widgets/mainwindow.cpp</a></li> <li><a href="qtscxml-calculator-widgets-mainwindow-h.html">calculator-widgets/mainwindow.h</a></li> <li><a href="qtscxml-calculator-widgets-mainwindow-ui.html">calculator-widgets/mainwindow.ui</a></li> <li><a href="qtscxml-calculator-widgets-statemachine-cpp.html">calculator-widgets/statemachine.cpp</a></li> <li><a href="qtscxml-calculator-widgets-statemachine-h.html">calculator-widgets/statemachine.h</a></li> </ul> </div> <!-- @@@calculator-widgets --> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2019 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>