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diff --git a/doc/src/qml/qmlevents.qdoc b/doc/src/qml/qmlevents.qdoc deleted file mode 100644 index 2567dddb2a..0000000000 --- a/doc/src/qml/qmlevents.qdoc +++ /dev/null @@ -1,130 +0,0 @@ -/**************************************************************************** -** -** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). -** Contact: http://www.qt-project.org/ -** -** This file is part of the documentation of the Qt Toolkit. -** -** $QT_BEGIN_LICENSE:FDL$ -** GNU Free Documentation License -** Alternatively, this file may be used under the terms of the GNU Free -** Documentation License version 1.3 as published by the Free Software -** Foundation and appearing in the file included in the packaging of -** this file. -** -** Other Usage -** Alternatively, this file may be used in accordance with the terms -** and conditions contained in a signed written agreement between you -** and Nokia. -** -** -** -** -** -** $QT_END_LICENSE$ -** -****************************************************************************/ - -/*! -\page qmlevents.html -\ingroup qml-features - -\title QML Signal and Handler Event System -\brief the event sytem in QML - -Application and user interface components communicate with each other. For -example, a button component needs to know that the user is clicking on it. -The button may change colors to indicate its state or perform some logic. As -well, application needs to know whether the user is clicking the button. The -application may need to relay this clicking event to other applications. - -QML has a signal and handler mechanism, where the \e signal is the event -and the component responds to the event through the \e handler. The signal -is emitted and the handler is invoked. Placing logic such as scripts or other -operations in the handler allows the component to respond to the event. - -\keyword qml-signals-and-handlers -\section1 Signals and Handlers - -Signals provide a way to notify other objects when an event has occurred. For -example, the MouseArea \c clicked signal notifies other objects that the mouse -has been clicked within the area. - -The syntax for defining a new signal is: - -\tt{signal <name>[([<type> <parameter name>[, ...]])]} - -Attempting to declare two signals or methods with the same name in the same type -block generates an error. However, a new signal may reuse the name of an existing signal on the type. (This should be done with caution, as the existing signal may be hidden and become inaccessible.) - -Here are various examples of signal declarations: -\snippet doc/src/snippets/qml/events.qml parent begin -\snippet doc/src/snippets/qml/events.qml signal declaration -\snippet doc/src/snippets/qml/events.qml parent end - -If the signal has no parameters, the "\c{()}" brackets are optional. If -parameters are used, the parameter types must be declared, as for the \c string -and \c variant arguments of the \c perform signal. - -Adding a signal to an item automatically adds a \e{signal handler} as well. The -signal hander is named \c on<SignalName>, with the first letter of the signal in -uppercase. The previous signals have the following signal handlers: -\snippet doc/src/snippets/qml/events.qml signal handler declaration - -Further, each QML properties have a \c{<property_name>Changed} signal and its -corresponding \c{on<property_name>Changed} signal handler. As a result, property -changes may notify other components for any changes. -\snippet doc/src/snippets/qml/events.qml automatic signals - -To emit a signal, invoke it as a method. The signal handler binding is similar -to a property binding and it is invoked when the signal is emitted. Use the -defined argument names to access the respective arguments. -\snippet doc/src/snippets/qml/events.qml signal emit -Note that the \c Component.onCompleted is an -\l{attached-signalhandlers}{attached signal handler}; it is invoked when the -\l Component initialization is complete. - -\keyword qml-connect-signals-to-method -\section2 Connecting Signals to Methods and Signals - -Signal objects have a \c connect() method to a connect a signal either to a -method or another signal. When a signal is connected to a method, the method is -automatically invoked whenever the signal is emitted. This mechanism enables a -signal to be received by a method instead of a -\l {Signal Handlers}{signal handler}. - -\snippet doc/src/snippets/qml/events.qml connect method -The \c {connect()} method is appropriate when connecting a JavaScript method to -a signal. - -There is a corresponding \c disconnect() method for removing connected -signals. - -\section3 Signal to Signal Connect - -By connecting signals to other signals, the \c connect() method can form different -signal chains. -\snippet doc/src/snippets/qml/events.qml forward signal - - -Whenever the \l MouseArea \c clicked signal is emitted, the \c send -signal will automatically be emitted as well. - -\code -output: - MouseArea clicked - Send clicked -\endcode - -\section1 Events from the Declarative Runtime - -There maybe cases where a signal comes from the \l{The QML Engine}{declarative -runtime}. For example, it is possible to receive events from \l{QML Plugins}{QML -plugins}. For more signal control, the \c connect() method and the \l -Connections element may connect a signal from the runtime to another signal or -method. - -For complete information on events from the runtime or creating signals from the -runtime, read the \l{The QML Engine} and the \l{Creating QML Types} articles. - -*/ |