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/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
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** information use the contact form at http://www.qt.io/contact-us.
**
** 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
** will be met: http://www.gnu.org/copyleft/fdl.html.
** $QT_END_LICENSE$
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****************************************************************************/
/*!
\example grue
\title Qt Sensors - Grue Sensor Example
\brief The Qt Sensors - Grue sensor example demonstrates all the steps from creating a new sensor to using it.
\ingroup qtsensors-examples
\image qtsensors-examples-grue.png
The Qt Sensors - Grue sensor example demonstrates all the steps from creating a new sensor to using it.
The sensor definition is placed in a library where client apps can access it. The actual implementation
lives in a plugin.
\list
\li \l{Grue Sensor Definition}
\li \l{Grue Sensor Implementation}
\endlist
The sensor can now be used by a C++ application, even if the application does not have access to the
definition.
\list
\li \l{Grue Sensor Console Application}
\endlist
To make the sensor available to a QML application an import must be created.
\list
\li \l{Grue Sensor QML Import}
\li \l{Grue Sensor QML Application}
\endlist
\section1 Grue Sensor Definition
The Grue sensor is defined in a library so that applications can use it.
The source code is available in the \c{grue/lib} subdirectory.
First up is the sensor type. This is the interface for sensors that report
on your likelihood of being eaten by a Grue. Such sensors are very important
to adventurers, particularly if they are going into dark places as this is
where Grues live.
The interface is a simple one. It provides only 1 piece of information, your
chance of being eaten. For the details on how this is property should be
interpreted please see the documentation in gruesensor.cpp.
This example was created using the make_sensor.pl script which can be found in
src/sensors. As such, it contains some generated code that defines the convenience
classes GrueFilter and GrueSensor.
\section1 Grue Sensor Implementation
The Grue sensor implementation lives in a plugin that is loaded by the Qt Sensors
library. The source code is available in the \c{grue/plugin} subdirectory.
The Grue sensor needs a backend before it can be used. The backend provided
is rather basic and it relies on some kind of light sensor to work but it
gets the job done. If new hardware that can detect the actual presence of Grues
becomes available a backend could be created that supports this hardware and
applications using the Grue sensor would be able to use it without any changes.
There are a few mandatory parts to a backend. They are the start and stop methods
and the setReading call. The start and stop methods are used to start and stop
any underlying hardware. In the case of this backend they start and stop a
light sensor. In the start method, the backend should be sure to call the
sensorStopped() or sensorBusy() methods if it cannot start.
\snippet grue/plugin/gruesensorimpl.cpp start
The setReading method is needed so that the sensors library knows where the
readings are coming from. This backend has a local copy of the reading so
it passes a pointer to the function.
\snippet grue/plugin/gruesensorimpl.cpp setReading
However it is also possible to pass null to the setReading method in which
case the sensors library will create an instance and return a pointer.
\code
// Create a reading instance for us to use
m_reading = setReading<GrueSensorReading>(0);
\endcode
The Grue sensor backend also supplies some metadata.
The backend checks 2 things, how dark it is and how long you have been in the dark.
It uses the readingChanged() signal to know when to check the light sensor's
value. Once it is dark, it uses a timer to increase your chance of being eaten.
The Grue sensor backend is delivered as a plugin. The plugin has a factory object
that registers the types available and does the actual instantiation of the backend.
\section1 Grue Sensor Console Application
The Grue sensor console application demonstrates use of the Grue sensor.
The source code is available in the \c{grue/console_app} subdirectory.
This is a simple commandline application. It demonstrates how to use the generic
access feature of Qt Sensors to avoid a link-time dependency on the Grue Sensor
library.
\section1 Grue Sensor QML Import
The Grue sensor QML import exports the GrueSensor class as a QML type.
The source code is available in the \c{grue/import} subdirectory.
This creates the \e {Grue 1.0} import.
\section1 Grue Sensor QML Application
The Grue sensor QML application demonstrates the use of GrueSensor QML type.
The application consists of a single QML file and an image. It is built as an
exucutable with C++ code that runs the QML, but it can also be launched directly
using the \c qmlscene tool.
You should build the top-level 'grue' project before trying to run
this example or it will not be able to find its dependencies.
\code
qmlscene -I . grue.qml
\endcode
Above, the \c{-I .} parameter adds the current directory as a module import
path to locate the Grue QML module.
*/
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