<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- qqmlconnections.cpp --> <title>Connections QML Type | Qt QML 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="qtqml-index.html">Qt QML</a></td><td ><a href="qtqml-qmlmodule.html">QML Types</a></td><td >Connections QML Type</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="#properties">Properties</a></li> <li class="level1"><a href="#details">Detailed Description</a></li> </ul> </div> <div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">Connections QML Type</h1> <span class="subtitle"></span> <!-- $$$Connections-brief --> <p>Describes generalized connections to signals <a href="#details">More...</a></p> <!-- @@@Connections --> <div class="table"><table class="alignedsummary"> <tr><td class="memItemLeft rightAlign topAlign"> Import Statement:</td><td class="memItemRight bottomAlign"> import QtQml 2.2</td></tr></table></div><ul> <li><a href="qml-qtqml-connections-members.html">List of all members, including inherited members</a></li> </ul> <a name="properties"></a> <h2 id="properties">Properties</h2> <ul> <li class="fn"><b><b><a href="qml-qtqml-connections.html#enabled-prop">enabled</a></b></b> : bool</li> <li class="fn"><b><b><a href="qml-qtqml-connections.html#ignoreUnknownSignals-prop">ignoreUnknownSignals</a></b></b> : bool</li> <li class="fn"><b><b><a href="qml-qtqml-connections.html#target-prop">target</a></b></b> : Object</li> </ul> <!-- $$$Connections-description --> <a name="details"></a> <h2 id="details">Detailed Description</h2> <p>A Connections object creates a connection to a QML signal.</p> <p>When connecting to signals in QML, the usual way is to create an "on<Signal>" handler that reacts when a signal is received, like this:</p> <pre class="qml"> <span class="type">MouseArea</span> { <span class="name">onClicked</span>: { <span class="name">foo</span>(<span class="name">parameters</span>) } } </pre> <p>However, it is not possible to connect to a signal in this way in some cases, such as when:</p> <ul> <li>Multiple connections to the same signal are required</li> <li>Creating connections outside the scope of the signal sender</li> <li>Connecting to targets not defined in QML</li> </ul> <p>When any of these are needed, the Connections type can be used instead.</p> <p>For example, the above code can be changed to use a Connections object, like this:</p> <pre class="qml"> <span class="type">MouseArea</span> { <span class="type"><a href="qml-qtqml-connections.html">Connections</a></span> { <span class="name">onClicked</span>: <span class="name">foo</span>(<span class="name">parameters</span>) } } </pre> <p>More generally, the Connections object can be a child of some object other than the sender of the signal:</p> <pre class="qml"> <span class="type">MouseArea</span> { <span class="name">id</span>: <span class="name">area</span> } <span class="comment">// ...</span> </pre> <pre class="qml"> <span class="type"><a href="qml-qtqml-connections.html">Connections</a></span> { <span class="name">target</span>: <span class="name">area</span> <span class="name">onClicked</span>: <span class="name">foo</span>(<span class="name">parameters</span>) } </pre> <p><b>See also </b><a href="qtqml-index.html">Qt QML</a>.</p> <!-- @@@Connections --> <h2>Property Documentation</h2> <!-- $$$enabled --> <div class="qmlitem"><div class="qmlproto"> <div class="table"><table class="qmlname"> <tr valign="top" class="odd" id="enabled-prop"> <td class="tblQmlPropNode"><p> <a name="enabled-prop"></a><span class="name">enabled</span> : <span class="type">bool</span></p></td></tr> </table></div> </div><div class="qmldoc"><p>This property holds whether the item accepts change events.</p> <p>By default, this property is <code>true</code>.</p> <p>This QML property was introduced in Qt 5.7.</p> </div></div><!-- @@@enabled --> <br/> <!-- $$$ignoreUnknownSignals --> <div class="qmlitem"><div class="qmlproto"> <div class="table"><table class="qmlname"> <tr valign="top" class="odd" id="ignoreUnknownSignals-prop"> <td class="tblQmlPropNode"><p> <a name="ignoreUnknownSignals-prop"></a><span class="name">ignoreUnknownSignals</span> : <span class="type">bool</span></p></td></tr> </table></div> </div><div class="qmldoc"><p>Normally, a connection to a non-existent signal produces runtime errors.</p> <p>If this property is set to <code>true</code>, such errors are ignored. This is useful if you intend to connect to different types of objects, handling a different set of signals for each object.</p> </div></div><!-- @@@ignoreUnknownSignals --> <br/> <!-- $$$target --> <div class="qmlitem"><div class="qmlproto"> <div class="table"><table class="qmlname"> <tr valign="top" class="odd" id="target-prop"> <td class="tblQmlPropNode"><p> <a name="target-prop"></a><span class="name">target</span> : <span class="type">Object</span></p></td></tr> </table></div> </div><div class="qmldoc"><p>This property holds the object that sends the signal.</p> <p>If this property is not set, the <code>target</code> defaults to the parent of the Connection.</p> <p>If set to null, no connection is made and any signal handlers are ignored until the target is not null.</p> </div></div><!-- @@@target --> <br/> </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>