<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- helloscript.qdoc --> <title>Hello Script Example | Qt Script</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="qtscript-index.html">Qt Script</a></td><td >Hello Script Example</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"> <div class="sidebar"> <div class="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#translating-the-application">Translating the Application</a></li> </ul> </div> <div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">Hello Script Example</h1> <span class="subtitle"></span> <!-- $$$script/helloscript-description --> <div class="descr"> <a name="details"></a> <p>The Hello Script example shows the basic use of Qt Script: How to embed a script engine into the application, how to evaluate a script, and how to process the result of the evaluation. The example also shows how to apply internationalization to scripts.</p> <pre class="cpp"> <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>) { Q_INIT_RESOURCE(helloscript); </pre> <p>The application will load the script file to evaluate from a resource, so we first make sure that the resource is initialized.</p> <pre class="cpp"> <span class="type"><a href="../qtwidgets/qapplication.html">QApplication</a></span> app(argc<span class="operator">,</span> argv); <span class="type"><a href="qscriptengine.html">QScriptEngine</a></span> engine; <span class="type"><a href="../qtcore/qtranslator.html">QTranslator</a></span> translator; translator<span class="operator">.</span>load(<span class="string">"helloscript_la"</span>); app<span class="operator">.</span>installTranslator(<span class="operator">&</span>translator); engine<span class="operator">.</span>installTranslatorFunctions(); </pre> <p>We attempt to load a translation, and install translation functions in the script engine. How to produce a translation is explained later.</p> <pre class="cpp"> <span class="type"><a href="../qtwidgets/qpushbutton.html">QPushButton</a></span> button; <span class="type"><a href="qscriptvalue.html">QScriptValue</a></span> scriptButton <span class="operator">=</span> engine<span class="operator">.</span>newQObject(<span class="operator">&</span>button); engine<span class="operator">.</span>globalObject()<span class="operator">.</span>setProperty(<span class="string">"button"</span><span class="operator">,</span> scriptButton); </pre> <p>A push button is created and exported to the script environment as a global variable, <code>button</code>. Scripts will be able to access properties, signals and slots of the button as properties of the <code>button</code> script object; the script object acts as a proxy to the C++ button object.</p> <pre class="cpp"> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> fileName(<span class="string">":/helloscript.js"</span>); <span class="type"><a href="../qtcore/qfile.html">QFile</a></span> scriptFile(fileName); scriptFile<span class="operator">.</span>open(<span class="type"><a href="../qtcore/qiodevice.html">QIODevice</a></span><span class="operator">::</span>ReadOnly); <span class="type"><a href="../qtcore/qtextstream.html">QTextStream</a></span> stream(<span class="operator">&</span>scriptFile); <span class="type"><a href="../qtcore/qstring.html">QString</a></span> contents <span class="operator">=</span> stream<span class="operator">.</span>readAll(); scriptFile<span class="operator">.</span>close(); </pre> <p>The contents of the script file are read.</p> <pre class="js"> <span class="name">button</span>.<span class="name">text</span> <span class="operator">=</span> <span class="name">qsTr</span>(<span class="string">'Hello World!'</span>); <span class="name">button</span>.<span class="name">styleSheet</span> <span class="operator">=</span> <span class="string">'font-style: italic'</span>; <span class="name">button</span>.<span class="name">show</span>(); </pre> <p>The script sets the <code>text</code> (note that the qTr() function is used to allow for translation) and <code>styleSheet</code> properties of the button, and calls the button's <code>show()</code> slot.</p> <pre class="cpp"> <span class="type"><a href="qscriptvalue.html">QScriptValue</a></span> result <span class="operator">=</span> engine<span class="operator">.</span>evaluate(contents<span class="operator">,</span> fileName); </pre> <p>The script is evaluated. Note that the file name is passed as the (optional) second parameter; this makes it possible for the script engine to produce a meaningful backtrace if something goes wrong, and makes the qTr() function be able to resolve the translations that are associated with this script.</p> <pre class="cpp"> <span class="keyword">if</span> (result<span class="operator">.</span>isError()) { <span class="type"><a href="../qtwidgets/qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>critical(<span class="number">0</span><span class="operator">,</span> <span class="string">"Hello Script"</span><span class="operator">,</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span><span class="operator">::</span>fromLatin1(<span class="string">"%0:%1: %2"</span>) <span class="operator">.</span>arg(fileName) <span class="operator">.</span>arg(result<span class="operator">.</span>property(<span class="string">"lineNumber"</span>)<span class="operator">.</span>toInt32()) <span class="operator">.</span>arg(result<span class="operator">.</span>toString())); <span class="keyword">return</span> <span class="operator">-</span><span class="number">1</span>; } </pre> <p>If the result is an Error object (e.g. the script contained a syntax error, or tried to call a function that doesn't exist), we obtain the line number and string representation of the error and display it in a message box.</p> <pre class="cpp"> <span class="keyword">return</span> app<span class="operator">.</span>exec(); } </pre> <p>If the evaluation went well, the application event loop is entered.</p> <a name="translating-the-application"></a> <h2 id="translating-the-application">Translating the Application</h2> <p>The Qt Script internalization support builds on what Qt already provides for C++; see the <a href="../qtlinguist/qtlinguist-hellotr-example.html">Hello tr</a>() Example for an introduction.</p> <p>Since we haven't made the translation file <code>helloscript_la.qm</code>, the source text is shown when we run the application ("Hello world!").</p> <p>To generate the translation file, run <code>lupdate</code> as follows:</p> <pre class="cpp"> lupdate helloscript<span class="operator">.</span>js <span class="operator">-</span>ts helloscript_la<span class="operator">.</span>ts </pre> <p>You should now have a file <code>helloscript_la.ts</code> in the current directory. Run <code>linguist</code> to edit the translation:</p> <pre class="cpp"> linguist helloscript_la<span class="operator">.</span>ts </pre> <p>You should now see the text "helloscript.js" in the top left pane. Double-click it, then click on "Hello world!" and enter "Orbis, te saluto!" in the <b>Translation</b> pane (the middle right of the window). Don't forget the exclamation mark!</p> <p>Click the <b>Done</b> checkbox and choose <b>File|Save</b> from the menu bar. The TS file will no longer contain</p> <pre class="cpp"> <span class="operator"><</span>translation type<span class="operator">=</span><span class="char">'unfinished'</span><span class="operator">></span><span class="operator"><</span><span class="operator">/</span>translation<span class="operator">></span> </pre> <p>but instead will have</p> <pre class="cpp"> <span class="operator"><</span>translation<span class="operator">></span>Orbis<span class="operator">,</span> te saluto<span class="operator">!</span><span class="operator"><</span><span class="operator">/</span>translation<span class="operator">></span> </pre> <p>To see the application running in Latin, we have to generate a QM file from the TS file. Generating a QM file can be achieved either from within <i>Qt Linguist</i> (for a single TS file), or by using the command line program <code>lrelease</code> which will produce one QM file for each of the TS files listed in the project file. Generate <code>hellotr_la.qm</code> from <code>hellotr_la.ts</code> by choosing <b>File|Release</b> from <i>Qt Linguist</i>'s menu bar and pressing <b>Save</b> in the file save dialog that pops up. Now run the <code>helloscript</code> program again. This time the button will be labelled "Orbis, te saluto!".</p> <p>Files:</p> <ul> <li><a href="qtscript-script-helloscript-helloscript-js.html">script/helloscript/helloscript.js</a></li> <li><a href="qtscript-script-helloscript-helloscript-pro.html">script/helloscript/helloscript.pro</a></li> <li><a href="qtscript-script-helloscript-helloscript-qrc.html">script/helloscript/helloscript.qrc</a></li> <li><a href="qtscript-script-helloscript-main-cpp.html">script/helloscript/main.cpp</a></li> </ul> </div> <!-- @@@script/helloscript --> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2018 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>