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<td >Qt 5.12</td><td ><a href="qtquick-index.html">Qt Quick</a></td><td >Mouse Events</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qtquick-index.html">Qt 5.12.6 Reference Documentation</a></td>
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<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#mouse-types">Mouse Types</a></li>
<li class="level1"><a href="#mouse-event-handling">Mouse Event Handling</a></li>
<li class="level1"><a href="#defining-a-mouse-area">Defining a Mouse Area</a></li>
<li class="level1"><a href="#receiving-events">Receiving Events</a></li>
<li class="level1"><a href="#enabling-gestures">Enabling Gestures</a></li>
<li class="level1"><a href="#mouseevent-object">MouseEvent Object</a></li>
<li class="level2"><a href="#accepting-further-signals">Accepting Further Signals</a></li>
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<h1 class="title">Mouse Events</h1>
<span class="subtitle"></span>
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<div class="descr"> <a name="details"></a>
<p>A more modern way of handling events from all pointing devices, including mouse and touchscreen, is via <a href="qtquickhandlers-index.html">Input Handlers</a>. This page describes the original Qt Quick <a href="qml-qtquick-mousearea.html">MouseArea</a> type, which was initially designed to handle mouse input, and later began handling single-touch events (in the form of synthetic mouse events) in simple touch-oriented user interfaces.</p>
<a name="mouse-types"></a>
<h2 id="mouse-types">Mouse Types</h2>
<ul>
<li><a href="qml-qtquick-mousearea.html">MouseArea</a> type</li>
<li><a href="qml-qtquick-mouseevent.html">MouseEvent</a> object</li>
</ul>
<a name="mouse-event-handling"></a>
<h2 id="mouse-event-handling">Mouse Event Handling</h2>
<p>QML uses signals and handlers to deliver mouse interactions. Specifically, Qt Quick provides the <a href="qml-qtquick-mousearea.html">MouseArea</a> and <a href="qml-qtquick-mouseevent.html">MouseEvent</a> types that allow developers to define JavaScript callbacks (also called signal handlers), which accept mouse events within a defined area.</p>
<a name="defining-a-mouse-area"></a>
<h2 id="defining-a-mouse-area">Defining a Mouse Area</h2>
<p>The <a href="qml-qtquick-mousearea.html">MouseArea</a> type receives events within a defined area. One quick way to define this area is to anchor the <code>MouseArea</code> to its parent's area using the <code>anchors.fill</code> property. If the parent is a <a href="qml-qtquick-rectangle.html">Rectangle</a> (or any <a href="qml-qtquick-item.html">Item</a> component), then the <a href="qml-qtquick-mousearea.html">MouseArea</a> will fill the area defined by the parent's dimensions. Alternatively, an area smaller or larger than the parent is definable.</p>
<pre class="qml">
Rectangle {
id: button
width: 100; height: 100
MouseArea {
anchors.fill: parent
onClicked: console.log("button clicked")
}
MouseArea {
width:150; height: 75
onClicked: console.log("irregular area clicked")
}
}
</pre>
<a name="receiving-events"></a>
<h2 id="receiving-events">Receiving Events</h2>
<p>The <a href="qml-qtquick-mousearea.html">MouseArea</a> type emits signals in response to different mouse events. The <a href="qml-qtquick-mousearea.html">MouseArea</a> type documentation describes these gestures in greater detail:</p>
<ul>
<li>canceled</li>
<li>clicked</li>
<li>doubleClicked</li>
<li>entered</li>
<li>exited</li>
<li>positionChanged</li>
<li>pressAndHold</li>
<li>pressed</li>
<li>released</li>
</ul>
<p>These signals can have callbacks that are invoked when the signals are emitted.</p>
<pre class="qml">
MouseArea {
anchors.fill: parent
onClicked: console.log("area clicked")
onDoubleClicked: console.log("area double clicked")
onEntered: console.log("mouse entered the area")
onExited: console.log("mouse left the area")
}
</pre>
<a name="enabling-gestures"></a>
<h2 id="enabling-gestures">Enabling Gestures</h2>
<p>Some mouse gestures and button clicks need to be enabled before they send or receive events. Certain <a href="qml-qtquick-mousearea.html">MouseArea</a> and <a href="qml-qtquick-mouseevent.html">MouseEvent</a> properties enable these gestures.</p>
<p>To listen to (or explicitly ignore) a certain mouse button, set the appropriate mouse button to the <a href="qml-qtquick-mousearea.html#acceptedButtons-prop">acceptedButtons</a> property.</p>
<p>Naturally, the mouse events, such as button presses and mouse positions, are sent during a mouse click. For example, the <code>containsMouse</code> property will only retrieve its correct value during a mouse press. The <a href="qml-qtquick-mousearea.html#hoverEnabled-prop">hoverEnabled</a> will enable mouse events and positioning even when there are no mouse button presses. Setting the <code>hoverEnabled</code> property to <code>true</code>, in turn will enable the <code>entered</code>, <code>exited</code>, and <code>positionChanged</code> signal and their respective signal handlers.</p>
<pre class="qml">
MouseArea {
hoverEnabled: true
acceptedButtons: Qt.LeftButton | Qt.RightButton
onEntered: console.log("mouse entered the area")
onExited: console.log("mouse left the area")
}
</pre>
<p>Additionally, to disable the whole mouse area, set the <a href="qml-qtquick-mousearea.html">MouseArea</a> <code>enabled</code> property to <code>false</code>.</p>
<a name="mouseevent-object"></a>
<h2 id="mouseevent-object">MouseEvent Object</h2>
<p>Signals and their callbacks receive a <a href="qml-qtquick-mouseevent.html">MouseEvent</a> object as a parameter. The <code>mouse</code> object contains information about the mouse event. For example, the mouse button that started the event is queried through the <a href="qml-qtquick-mouseevent.html#button-prop">mouse.button</a> property.</p>
<p>The <code>MouseEvent</code> object can also ignore a mouse event using its <code>accepted</code> property.</p>
<a name="accepting-further-signals"></a>
<h3 id="accepting-further-signals">Accepting Further Signals</h3>
<p>Many of the signals are sent multiple times to reflect various mouse events such as double clicking. To facilitate the classification of mouse clicks, the <a href="qml-qtquick-mouseevent.html">MouseEvent</a> object has an <code>accepted</code> property to disable the event propagation.</p>
<p>To learn more about QML's event system, please read the signals and handlers, and event system document.</p>
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