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Breadcrumbs go here --> <li><a href="all-examples.html">Examples</a></li> <li>Event Transitions 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"> <h1 class="title">Event Transitions Example</h1> <span class="subtitle"></span> <!-- $$$statemachine/eventtransitions-description --> <div class="descr"> <a name="details"></a> <p>Files:</p> <ul> <li><a href="statemachine-eventtransitions-main-cpp.html">statemachine/eventtransitions/main.cpp</a></li> <li><a href="statemachine-eventtransitions-eventtransitions-pro.html">statemachine/eventtransitions/eventtransitions.pro</a></li> </ul> <p>The Event Transitions example shows how to use event transitions, a feature of <a href="statemachine-api.html">The State Machine Framework</a>.<pre class="cpp"> <span class="keyword">class</span> Window : <span class="keyword">public</span> <span class="type"><a href="qwidget.html">QWidget</a></span> { <span class="keyword">public</span>: Window(<span class="type"><a href="qwidget.html">QWidget</a></span> <span class="operator">*</span>parent <span class="operator">=</span> <span class="number">0</span>) : <span class="type"><a href="qwidget.html">QWidget</a></span>(parent) { <span class="type"><a href="qpushbutton.html">QPushButton</a></span> <span class="operator">*</span>button <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qpushbutton.html">QPushButton</a></span>(<span class="keyword">this</span>); button<span class="operator">-</span><span class="operator">></span>setSizePolicy(<span class="type"><a href="qsizepolicy.html">QSizePolicy</a></span><span class="operator">::</span>Expanding<span class="operator">,</span> <span class="type"><a href="qsizepolicy.html">QSizePolicy</a></span><span class="operator">::</span>Expanding); <span class="type"><a href="qvboxlayout.html">QVBoxLayout</a></span> <span class="operator">*</span>layout <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qvboxlayout.html">QVBoxLayout</a></span>; layout<span class="operator">-</span><span class="operator">></span>addWidget(button); layout<span class="operator">-</span><span class="operator">></span>setContentsMargins(<span class="number">80</span><span class="operator">,</span> <span class="number">80</span><span class="operator">,</span> <span class="number">80</span><span class="operator">,</span> <span class="number">80</span>); setLayout(layout);</pre> <p>The <tt>Window</tt> class's constructors begins by creating a button.</p> <pre class="cpp"> <span class="type"><a href="qstatemachine.html">QStateMachine</a></span> <span class="operator">*</span>machine <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qstatemachine.html">QStateMachine</a></span>(<span class="keyword">this</span>); <span class="type"><a href="qstate.html">QState</a></span> <span class="operator">*</span>s1 <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qstate.html">QState</a></span>(); s1<span class="operator">-</span><span class="operator">></span>assignProperty(button<span class="operator">,</span> <span class="string">"text"</span><span class="operator">,</span> <span class="string">"Outside"</span>); <span class="type"><a href="qstate.html">QState</a></span> <span class="operator">*</span>s2 <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qstate.html">QState</a></span>(); s2<span class="operator">-</span><span class="operator">></span>assignProperty(button<span class="operator">,</span> <span class="string">"text"</span><span class="operator">,</span> <span class="string">"Inside"</span>);</pre> <p>Two states, <tt>s1</tt> and <tt>s2</tt>, are created; upon entry they will assign "Outside" and "Inside" to the button's text, respectively.</p> <pre class="cpp"> <span class="type"><a href="qeventtransition.html">QEventTransition</a></span> <span class="operator">*</span>enterTransition <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qeventtransition.html">QEventTransition</a></span>(button<span class="operator">,</span> <span class="type"><a href="qevent.html">QEvent</a></span><span class="operator">::</span>Enter); enterTransition<span class="operator">-</span><span class="operator">></span>setTargetState(s2); s1<span class="operator">-</span><span class="operator">></span>addTransition(enterTransition);</pre> <p>When the button receives an event of type <a href="qevent.html#Type-enum">QEvent::Enter</a> and the state machine is in state <tt>s1</tt>, the machine will transition to state <tt>s2</tt>.</p> <pre class="cpp"> <span class="type"><a href="qeventtransition.html">QEventTransition</a></span> <span class="operator">*</span>leaveTransition <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qeventtransition.html">QEventTransition</a></span>(button<span class="operator">,</span> <span class="type"><a href="qevent.html">QEvent</a></span><span class="operator">::</span>Leave); leaveTransition<span class="operator">-</span><span class="operator">></span>setTargetState(s1); s2<span class="operator">-</span><span class="operator">></span>addTransition(leaveTransition);</pre> <p>When the button receives an event of type <a href="qevent.html#Type-enum">QEvent::Leave</a> and the state machine is in state <tt>s2</tt>, the machine will transition back to state <tt>s1</tt>.</p> <pre class="cpp"> <span class="type"><a href="qstate.html">QState</a></span> <span class="operator">*</span>s3 <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qstate.html">QState</a></span>(); s3<span class="operator">-</span><span class="operator">></span>assignProperty(button<span class="operator">,</span> <span class="string">"text"</span><span class="operator">,</span> <span class="string">"Pressing..."</span>); <span class="type"><a href="qeventtransition.html">QEventTransition</a></span> <span class="operator">*</span>pressTransition <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qeventtransition.html">QEventTransition</a></span>(button<span class="operator">,</span> <span class="type"><a href="qevent.html">QEvent</a></span><span class="operator">::</span>MouseButtonPress); pressTransition<span class="operator">-</span><span class="operator">></span>setTargetState(s3); s2<span class="operator">-</span><span class="operator">></span>addTransition(pressTransition); <span class="type"><a href="qeventtransition.html">QEventTransition</a></span> <span class="operator">*</span>releaseTransition <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qeventtransition.html">QEventTransition</a></span>(button<span class="operator">,</span> <span class="type"><a href="qevent.html">QEvent</a></span><span class="operator">::</span>MouseButtonRelease); releaseTransition<span class="operator">-</span><span class="operator">></span>setTargetState(s2); s3<span class="operator">-</span><span class="operator">></span>addTransition(releaseTransition);</pre> <p>Next, the state <tt>s3</tt> is created. <tt>s3</tt> will be entered when the button receives an event of type <a href="qevent.html#Type-enum">QEvent::MouseButtonPress</a> and the state machine is in state <tt>s2</tt>. When the button receives an event of type <a href="qevent.html#Type-enum">QEvent::MouseButtonRelease</a> and the state machine is in state <tt>s3</tt>, the machine will transition back to state <tt>s2</tt>.</p> <pre class="cpp"> machine<span class="operator">-</span><span class="operator">></span>addState(s1); machine<span class="operator">-</span><span class="operator">></span>addState(s2); machine<span class="operator">-</span><span class="operator">></span>addState(s3); machine<span class="operator">-</span><span class="operator">></span>setInitialState(s1); machine<span class="operator">-</span><span class="operator">></span>start(); } };</pre> <p>Finally, the states are added to the machine as top-level states, the initial state is set to be <tt>s1</tt> ("Outside"), and the machine is started.</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><span class="operator">*</span>argv) { <span class="type"><a href="qapplication.html">QApplication</a></span> app(argc<span class="operator">,</span> argv); Window window; window<span class="operator">.</span>resize(<span class="number">300</span><span class="operator">,</span> <span class="number">300</span>); <span class="preprocessor">#if defined(Q_OS_SYMBIAN)</span> window<span class="operator">.</span>showMaximized(); <span class="preprocessor">#else</span> window<span class="operator">.</span>show(); <span class="preprocessor">#endif</span> <span class="keyword">return</span> app<span class="operator">.</span>exec(); }</pre> <p>The main() function constructs a Window object and shows it.</p> </div> <!-- @@@statemachine/eventtransitions --> </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. 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