<?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" /> <!-- designer-manual.qdoc --> <title>Qt 4.8: Creating Custom Widget Extensions</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>Creating Custom Widget Extensions</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="designer-creating-custom-widgets.html" /> <link rel="next" href="designer-ui-file-format.html" /> <p class="naviNextPrevious headerNavi"> <a class="prevPage" href="designer-creating-custom-widgets.html">Creating Custom Widgets for Qt Designer</a> <a class="nextPage" href="designer-ui-file-format.html">Qt Designer's UI File Format</a> </p><p/> <div class="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#extension-types">Extension Types</a></li> <li class="level1"><a href="#creating-an-extension">Creating an Extension</a></li> <li class="level1"><a href="#exposing-an-extension-to-qt-designer">Exposing an Extension to Qt Designer</a></li> <li class="level2"><a href="#creating-an-extension-factory">Creating an Extension Factory</a></li> <li class="level2"><a href="#accessing-qt-designer-s-extension-manager">Accessing Qt Designer's Extension Manager</a></li> <li class="level1"><a href="#related-examples">Related Examples</a></li> </ul> </div> <h1 class="title">Creating Custom Widget Extensions</h1> <span class="subtitle"></span> <!-- $$$designer-creating-custom-widgets-extensions.html-description --> <div class="descr"> <a name="details"></a> <p>Once you have a custom widget plugin for <i>Qt Designer</i>, you can provide it with the expected behavior and functionality within <i>Qt Designer</i>'s workspace, using custom widget extensions.</p> <a name="extension-types"></a> <h2>Extension Types</h2> <p>There are several available types of extensions in <i>Qt Designer</i>. You can use all of these extensions in the same pattern, only replacing the respective extension base class.</p> <p><a href="qdesignercontainerextension.html">QDesignerContainerExtension</a> is necessary when implementing a custom multi-page container.</p> <table class="generic"> <tr valign="top" class="odd"><td ><img src="images/designer-manual-taskmenuextension.png" alt="" /></td><td ><b><a href="qdesignertaskmenuextension.html">QDesignerTaskMenuExtension</a></b><p><a href="qdesignertaskmenuextension.html">QDesignerTaskMenuExtension</a> is useful for custom widgets. It provides an extension that allows you to add custom menu entries to <i>Qt Designer</i>'s task menu.</p> <p>The <a href="designer-taskmenuextension.html">Task Menu Extension</a> example illustrates how to use this class.</p> </td></tr> <tr valign="top" class="even"><td ><img src="images/designer-manual-containerextension.png" alt="" /></td><td ><b><a href="qdesignercontainerextension.html">QDesignerContainerExtension</a></b><p><a href="qdesignercontainerextension.html">QDesignerContainerExtension</a> is necessary when implementing a custom multi-page container. It provides an extension that allows you to add and delete pages for a multi-page container plugin in <i>Qt Designer</i>.</p> <p>The <a href="designer-containerextension.html">Container Extension</a> example further explains how to use this class.</p> <p><b>Note:</b> It is not possible to add custom per-page properties for some widgets (e.g., <a href="qtabwidget.html">QTabWidget</a>) due to the way they are implemented.</p> </td></tr> </table> <table class="generic"> <tr valign="top" class="odd"><td ><img src="images/designer-manual-membersheetextension.png" alt="" /></td><td ><b><a href="qdesignermembersheetextension.html">QDesignerMemberSheetExtension</a></b><p>The <a href="qdesignermembersheetextension.html">QDesignerMemberSheetExtension</a> class allows you to manipulate a widget's member functions displayed when connecting signals and slots.</p> </td></tr> <tr valign="top" class="even"><td ><img src="images/designer-manual-propertysheetextension.png" alt="" /></td><td ><b><a href="qdesignerpropertysheetextension.html">QDesignerPropertySheetExtension</a>, <a href="qdesignerdynamicpropertysheetextension.html">QDesignerDynamicPropertySheetExtension</a></b><p>These extension classes allow you to control how a widget's properties are displayed in <i>Qt Designer</i>'s property editor.</p> </td></tr> </table> <p><i>Qt Designer</i> uses the <a href="qdesignerpropertysheetextension.html">QDesignerPropertySheetExtension</a> and the <a href="qdesignermembersheetextension.html">QDesignerMemberSheetExtension</a> classes to feed its property and signal and slot editors. Whenever a widget is selected in its workspace, <i>Qt Designer</i> will query for the widget's property sheet extension; likewise, whenever a connection between two widgets is requested, <i>Qt Designer</i> will query for the widgets' member sheet extensions.</p> <p><b>Warning:</b> All widgets have default property and member sheets. If you implement custom property sheet or member sheet extensions, your custom extensions will override the default sheets.</p> <a name="creating-an-extension"></a> <h2>Creating an Extension</h2> <p>To create an extension you must inherit both <a href="qobject.html">QObject</a> and the appropriate base class, and reimplement its functions. Since we are implementing an interface, we must ensure that it is made known to the meta object system using the <a href="qobject.html#Q_INTERFACES">Q_INTERFACES</a>() macro in the extension class's definition. For example:</p> <pre class="cpp"> <span class="keyword">class</span> MyExtension: <span class="keyword">public</span> <span class="type"><a href="qobject.html">QObject</a></span><span class="operator">,</span> <span class="keyword">public</span> QdesignerContainerExtension { Q_OBJECT Q_INTERFACE(<span class="type"><a href="qdesignercontainerextension.html">QDesignerContainerExtension</a></span>) <span class="operator">.</span><span class="operator">.</span><span class="operator">.</span> }</pre> <p>This enables <i>Qt Designer</i> to use the <a href="qobject.html#qobject_cast">qobject_cast</a>() function to query for supported interfaces using a <a href="qobject.html">QObject</a> pointer only.</p> <a name="exposing-an-extension-to-qt-designer"></a> <h2>Exposing an Extension to Qt Designer</h2> <p>In <i>Qt Designer</i> the extensions are not created until they are required. For this reason, when implementing extensions, you must subclass <a href="qextensionfactory.html">QExtensionFactory</a> to create a class that is able to make instances of your extensions. Also, you must register your factory with <i>Qt Designer</i>'s extension manager; the extension manager handles the construction of extensions.</p> <p>When an extension is requested, <i>Qt Designer</i>'s extension manager will run through its registered factories calling <a href="qextensionfactory.html#createExtension">QExtensionFactory::createExtension</a>() for each of them until it finds one that is able to create the requested extension for the selected widget. This factory will then make an instance of the extension.</p> <p class="centerAlign"><img src="images/qtdesignerextensions.png" alt="" /></p><a name="creating-an-extension-factory"></a> <h3>Creating an Extension Factory</h3> <p>The <a href="qextensionfactory.html">QExtensionFactory</a> class provides a standard extension factory, but it can also be used as an interface for custom extension factories.</p> <p>The purpose is to reimplement the <a href="qextensionfactory.html#createExtension">QExtensionFactory::createExtension</a>() function, making it able to create your extension, such as a <a href="designer-containerextension.html">MultiPageWidget</a> container extension.</p> <p>You can either create a new <a href="qextensionfactory.html">QExtensionFactory</a> and reimplement the <a href="qextensionfactory.html#createExtension">QExtensionFactory::createExtension</a>() function:</p> <pre class="cpp"> <span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>ANewExtensionFactory<span class="operator">::</span>createExtension(<span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>object<span class="operator">,</span> <span class="keyword">const</span> <span class="type"><a href="qstring.html">QString</a></span> <span class="operator">&</span>iid<span class="operator">,</span> <span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>parent) <span class="keyword">const</span> { <span class="keyword">if</span> (iid <span class="operator">!</span><span class="operator">=</span> Q_TYPEID(<span class="type"><a href="qdesignercontainerextension.html">QDesignerContainerExtension</a></span>)) <span class="keyword">return</span> <span class="number">0</span>; <span class="keyword">if</span> (MyCustomWidget <span class="operator">*</span>widget <span class="operator">=</span> qobject_cast<span class="operator"><</span>MyCustomWidget<span class="operator">*</span><span class="operator">></span> (object)) <span class="keyword">return</span> <span class="keyword">new</span> MyContainerExtension(widget<span class="operator">,</span> parent); <span class="keyword">return</span> <span class="number">0</span>; }</pre> <p>or you can use an existing factory, expanding the <a href="qextensionfactory.html#createExtension">QExtensionFactory::createExtension</a>() function to enable the factory to create your custom extension as well:</p> <pre class="cpp"> <span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>AGeneralExtensionFactory<span class="operator">::</span>createExtension(<span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>object<span class="operator">,</span> <span class="keyword">const</span> <span class="type"><a href="qstring.html">QString</a></span> <span class="operator">&</span>iid<span class="operator">,</span> <span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>parent) <span class="keyword">const</span> { MyCustomWidget <span class="operator">*</span>widget <span class="operator">=</span> qobject_cast<span class="operator"><</span>MyCustomWidget<span class="operator">*</span><span class="operator">></span>(object); <span class="keyword">if</span> (widget <span class="operator">&</span><span class="operator">&</span> (iid <span class="operator">=</span><span class="operator">=</span> Q_TYPEID(<span class="type"><a href="qdesignertaskmenuextension.html">QDesignerTaskMenuExtension</a></span>))) { <span class="keyword">return</span> <span class="keyword">new</span> MyTaskMenuExtension(widget<span class="operator">,</span> parent); } <span class="keyword">else</span> <span class="keyword">if</span> (widget <span class="operator">&</span><span class="operator">&</span> (iid <span class="operator">=</span><span class="operator">=</span> Q_TYPEID(<span class="type"><a href="qdesignercontainerextension.html">QDesignerContainerExtension</a></span>))) { <span class="keyword">return</span> <span class="keyword">new</span> MyContainerExtension(widget<span class="operator">,</span> parent); } <span class="keyword">else</span> { <span class="keyword">return</span> <span class="number">0</span>; } }</pre> <a name="accessing-qt-designer-s-extension-manager"></a> <h3>Accessing Qt Designer's Extension Manager</h3> <p>When implementing a custom widget plugin, you must subclass the <a href="qdesignercustomwidgetinterface.html">QDesignerCustomWidgetInterface</a> to expose your plugin to <i>Qt Designer</i>. This is covered in more detail in the <a href="designer-creating-custom-widgets.html">Creating Custom Widgets for Qt Designer</a> section. The registration of an extension factory is typically made in the <a href="qdesignercustomwidgetinterface.html#initialize">QDesignerCustomWidgetInterface::initialize</a>() function:</p> <pre class="cpp"> <span class="type">void</span> MyPlugin<span class="operator">::</span>initialize(<span class="type"><a href="qdesignerformeditorinterface.html">QDesignerFormEditorInterface</a></span> <span class="operator">*</span>formEditor) { <span class="keyword">if</span> (initialized) <span class="keyword">return</span>; <span class="type"><a href="qextensionmanager.html">QExtensionManager</a></span> <span class="operator">*</span>manager <span class="operator">=</span> formEditor<span class="operator">-</span><span class="operator">></span>extensionManager(); Q_ASSERT(manager <span class="operator">!</span><span class="operator">=</span> <span class="number">0</span>); manager<span class="operator">-</span><span class="operator">></span>registerExtensions(<span class="keyword">new</span> MyExtensionFactory(manager)<span class="operator">,</span> Q_TYPEID(<span class="type"><a href="qdesignertaskmenuextension.html">QDesignerTaskMenuExtension</a></span>)); initialized <span class="operator">=</span> <span class="keyword">true</span>; }</pre> <p>The <tt>formEditor</tt> parameter in the <a href="qdesignercustomwidgetinterface.html#initialize">QDesignerCustomWidgetInterface::initialize</a>() function is a pointer to <i>Qt Designer</i>'s current <a href="qdesignerformeditorinterface.html">QDesignerFormEditorInterface</a> object. You must use the <a href="qdesignerformeditorinterface.html#extensionManager">QDesignerFormEditorInterface::extensionManager</a>() function to retrieve an interface to <i>Qt Designer</i>'s extension manager. Then you use the <a href="qextensionmanager.html#registerExtensions">QExtensionManager::registerExtensions</a>() function to register your custom extension factory.</p> <a name="related-examples"></a> <h2>Related Examples</h2> <p>For more information on creating custom widget extensions in <i>Qt Designer</i>, refer to the <a href="designer-taskmenuextension.html">Task Menu Extension</a> and <a href="designer-containerextension.html">Container Extension</a> examples.</p> </div> <!-- @@@designer-creating-custom-widgets-extensions.html --> <p class="naviNextPrevious footerNavi"> <a class="prevPage" href="designer-creating-custom-widgets.html">Creating Custom Widgets for Qt Designer</a> <a class="nextPage" href="designer-ui-file-format.html">Qt Designer's UI File Format</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>