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27
28/*!
29    \example planespotter
30    \title Plane Spotter (QML)
31    \ingroup qtlocation-examples
32
33    \brief The \c {Plane Spotter} example demonstrates the tight integration of
34    location and positioning data types into QML.
35
36    \image planespotter.png
37
38    The \c {Plane Spotter} example demonstrates how to integrate location and positioning
39    related C++ data types into QML and vice versa. This is useful when it is desirable to
40    run CPU intensive position calculations in native environments
41    but the results are supposed to be displayed using QML.
42
43    The example shows a map of Europe and airplanes on two routes across Europe.
44    The first airplane commutes between Oslo and Berlin and the second airplane
45    commutes between London and Berlin. The position tracking of each airplane
46    is implemented in C++. The Oslo-Berlin plane is piloted in QML and the London-Berlin
47    plane is commanded by a C++ pilot.
48
49    \include examples-run.qdocinc
50
51    \section1 Overview
52
53
54    This example makes use of the \l Q_GADGET feature as part of its position controller
55    implementation. It permits \l {Cpp_value_integration_positioning}{direct integration}
56    of non-QObject based C++ value types into QML.
57
58    The main purpose of the \c PlaneController class is to track the current
59    coordinates of the plane at a given time. It exposes the position
60    via its position property.
61
62    \snippet planespotter/main.cpp PlaneController1
63    \snippet planespotter/main.cpp PlaneController2
64
65    The example's \c main() function is responsible for the binding of the
66    \c PlaneController class instances into the QML context:
67
68    \snippet planespotter/main.cpp PlaneControllerMain
69
70    Similar to QObject derived classes, \l QGeoCoordinate can be integrated without
71    an additional QML wrapper.
72
73    \section1 Steering the Planes
74
75    As mentioned above, the primary purpose of \c PlaneController class is to track the current
76    positions of the two planes (Oslo-Berlin and London-Berlin) and advertise them as a property
77    to the QML layer. Its secondary purpose is to set and progress a plane along a given
78    flight path. In a sense it can act as a pilot. This is very much like
79    \l CoordinateAnimation which can animate the transition from one geo coordinate to another.
80    This example demonstrates how the \c {PlaneController}'s position property is modified
81    by C++ code using the PlaneController's own piloting abilities and by QML code using
82    \l CoordinateAnimation as pilot. The Oslo-Berlin plane is animated using QML code
83    and the London-Berlin plane is animated using C++ code.
84
85    No matter which pilot is used, the results to the pilot's
86    actions are visible in C++ and QML and thus the example demonstrates unhindered and direct
87    exchange of position data through the C++/QML boundary.
88
89    The visual representation of each \c Plane is done using
90    the \l MapQuickItem type which permits the embedding of arbitrary QtQuick items
91    into a map:
92
93    \snippet planespotter/Plane.qml PlaneMapQuick1
94    \snippet planespotter/Plane.qml PlaneMapQuick2
95
96    \section2 The C++ Pilot
97
98    The C++ plane is steered by C++. The \c from and \c to property of the controller
99    class set the origin and destination which the pilot uses to calculate the
100    bearing for the plane:
101
102    \snippet planespotter/main.cpp C++Pilot1
103
104    The pilot employs a \l QBasicTimer and \l {QTimerEvent}{QTimerEvents} to
105    constantly update the position. During each timer iteration
106    \c PlaneController::updatePosition() is called and a new position calculated.
107
108    \snippet planespotter/main.cpp C++Pilot3
109
110    Once the new position is calculated, \c setPosition() is called and
111    the subsequent change notification of the property pushes the new position
112    to the QML layer.
113
114    The C++ plane is started by clicking on the plane:
115
116    \snippet planespotter/planespotter.qml CppPlane1
117    \snippet planespotter/planespotter.qml CppPlane2
118
119    \l {azimuthTo}() calculates the bearing in degrees from one coordinate to another.
120    Note that the above code utilizes a QML animation to tie the rotation
121    and the position change into a single animation flow:
122
123    \snippet planespotter/planespotter.qml CppPlane3
124
125    First, \l NumberAnimation rotates the plane into the correct direction
126    and once that is done the \c startFlight() function takes care of
127    starting the plane's position change.
128
129    \snippet planespotter/main.cpp C++Pilot2
130
131    \section2 The QML Pilot
132
133    The \l CoordinateAnimation type is used to control the flight from Oslo
134    to Berlin and vice versa. It replaces the above \l ScriptAction.
135
136    \snippet planespotter/planespotter.qml QmlPlane1
137
138    The \l MouseArea of the QML plane implements the logic for the course setting
139    and starts the animation when required.
140
141    \snippet planespotter/planespotter.qml QmlPlane2
142
143*/
144