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Breadcrumbs go here --> <li><a href="all-examples.html">Examples</a></li> <li>Hello Script Example</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"> <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> <h1 class="title">Hello Script Example</h1> <span class="subtitle"></span> <!-- $$$script/helloscript-description --> <div class="descr"> <a name="details"></a> <p>Files:</p> <ul> <li><a href="script-helloscript-helloscript-js.html">script/helloscript/helloscript.js</a></li> <li><a href="script-helloscript-main-cpp.html">script/helloscript/main.cpp</a></li> <li><a href="script-helloscript-helloscript-pro.html">script/helloscript/helloscript.pro</a></li> <li><a href="script-helloscript-helloscript-qrc.html">script/helloscript/helloscript.qrc</a></li> </ul> <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.<p>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="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="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="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, <tt>button</tt>. Scripts will be able to access properties, signals and slots of the button as properties of the <tt>button</tt> script object; the script object acts as a proxy to the C++ button object.</p> <pre class="cpp"> <span class="type"><a href="qstring.html">QString</a></span> fileName(<span class="string">":/helloscript.js"</span>); <span class="type"><a href="qfile.html">QFile</a></span> scriptFile(fileName); scriptFile<span class="operator">.</span>open(<span class="type"><a href="qiodevice.html">QIODevice</a></span><span class="operator">::</span>ReadOnly); <span class="type"><a href="qtextstream.html">QTextStream</a></span> stream(<span class="operator">&</span>scriptFile); <span class="type"><a href="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 <tt>text</tt> (note that the qTr() function is used to allow for translation) and <tt>styleSheet</tt> properties of the button, and calls the button's <tt>show()</tt> 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="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="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>Translating the Application</h2> <p>The Qt Script internalization support builds on what Qt already provides for C++; see the <a href="linguist-hellotr.html">Hello tr</a>() Example for an introduction.</p> <p>Since we haven't made the translation file <tt>helloscript_la.qm</tt>, the source text is shown when we run the application ("Hello world!").</p> <p>To generate the translation file, run <tt>lupdate</tt> 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 <tt>helloscript_la.ts</tt> in the current directory. Run <tt>linguist</tt> 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"> <translation type='unfinished'></translation></pre> <p>but instead will have</p> <pre class="cpp"> <translation>Orbis, te saluto!</translation></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 <tt>lrelease</tt> which will produce one QM file for each of the TS files listed in the project file. Generate <tt>hellotr_la.qm</tt> from <tt>hellotr_la.ts</tt> 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 <tt>helloscript</tt> program again. This time the button will be labelled "Orbis, te saluto!".</p> </div> <!-- @@@script/helloscript --> </div> </div> </div> <div class="ft"> <span></span> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2015 The Qt Company Ltd. 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