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/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
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**
** GNU Free Documentation License Usage
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** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
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****************************************************************************/
/*!
\example weatherinfo
\title Weather Info (C++/QML)
\brief The Weather Info example shows how to use the user's current position
to retrieve local content from a web service in a C++ plugin for QML.
\ingroup qtpositioning-examples
Key \l{Qt Positioning} classes used in this example:
\list
\li \l{QGeoPositionInfo}
\li \l{QGeoPositionInfoSource}
\endlist
\image ../images/example-weatherinfo.png
\include examples-run.qdocinc
The example uses weather data provided by \l http://www.openweathermap.org.
The key part of this example is the application's data model, contained
in the WeatherData and AppModel classes. WeatherData represents the weather
information taken from the HTTP service. It is a simple data class, but we
give it Q_PROPERTies to expose it nicely to QML, later.
\snippet weatherinfo/appmodel.h 0
\snippet weatherinfo/appmodel.h 1
AppModel models the state of the entire application. At startup, we
get the platform's default position source using
QGeoPositionInfo::createDefaultSource()
\snippet weatherinfo/appmodel.cpp 0
\snippet weatherinfo/appmodel.cpp 1
If no default source is available, we take a static position and fetch
weather for that. If, however, we do have a position source, we connect
its positionUpdated() signal to a slot on the AppModel and call
startUpdates(), which begins regular updates of device position.
When a position update is received, we use the longitude and latitude
of the returned coordinate to retrieve the current "city" name for use
in the weather lookup.
\snippet weatherinfo/appmodel.cpp 2
To inform the UI about this process, the cityChanged() signal is emitted
when a new city is used, and the weatherChanged() signal whenever a
weather update occurs.
\snippet weatherinfo/appmodel.h 2
\snippet weatherinfo/appmodel.h 3
\snippet weatherinfo/appmodel.h 4
We use a QQmlListProperty for the weather forecast information,
which contains the next 4 days of forecast weather. This makes it
easy to access from QML.
To expose these to the QML UI layer, we use the qmlRegisterType()
function. We call this once for each type we wish to register, before
loading the actual QML file.
\snippet weatherinfo/main.cpp 0
\snippet weatherinfo/main.cpp 1
Finally, in the actual QML, we instantiate the AppModel.
\snippet weatherinfo/weatherinfo.qml 0
\snippet weatherinfo/weatherinfo.qml 1
\snippet weatherinfo/weatherinfo.qml 2
Once instantiated like this, we can use its properties elsewhere in the
QML document:
\snippet weatherinfo/weatherinfo.qml 3
\snippet weatherinfo/weatherinfo.qml 4
\section1 Files and Attributions
The example bundles the following images from Third-Party sources:
\table
\row
\li \l{weatherinfo-tango-icons}{Tango Icons}
\li Public Domain
\row
\li \l{weatherinfo-tango-weather-pack}{Tango Weather Icon Pack by Darkobra}
\li Public Domain
\endtable
*/
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