blob: 62c6dd3444059c4e13c7f52bc48aaca75920d638 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Free Documentation License Usage
** 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. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\example planespotter
\title Plane Spotter (QML)
\ingroup qtlocation-examples
\brief The \c {Plane Spotter} example demonstrates the tight integration of
location and positioning data types into QML
\image planespotter.png
The \c {Plane Spotter} example demonstrates how to integrate location and positioning
related C++ data types into QML and vice versa. This is useful when it is desirable to
run CPU intensive position calculations in native environments
but the results are supposed to be displayed using QML.
The example shows a map of Europe and airplanes on two routes across Europe.
The first airplane commutes between Oslo and Berlin and the second airplane
commutes between London and Berlin. The position tracking of each airplane
is implemented in C++. The Oslo-Berlin plane is piloted in QML and the London-Berlin
plane is commanded by a C++ pilot.
\include examples-run.qdocinc
\section1 Overview
This example makes use of the \l Q_GADGET feature as part of its position controller
implementation. It permits \l {Cpp_value_integration_positioning}{direct integration}
of non-QObject based C++ value types into QML.
The main purpose of the \c PlaneController class is to track the current
coordinates of the plane at a given time. It exposes the position
via its position property.
\snippet planespotter/main.cpp PlaneController1
\snippet planespotter/main.cpp PlaneController2
The example's \c main() function is responsible for the binding of the
\c PlaneController class instances into the QML context:
\snippet planespotter/main.cpp PlaneControllerMain
Similar to QObject derived classes, \l QGeoCoordinate can be integrated without
an additional QML wrapper.
\section1 Steering the Planes
As mentioned above, the primary purpose of \c PlaneController class is to track the current
positions of the two planes (Oslo-Berlin and London-Berlin) and advertise them as a property
to the QML layer. Its secondary purpose is to set and progress a plane along a given
flight path. In a sense it can act as a pilot. This is very much like
\l CoordinateAnimation which can animate the transition from one geo coordinate to another.
This example demonstrates how the \c {PlaneController}'s position property is modified
by C++ code using the PlaneController's own piloting abilities and by QML code using
\l CoordinateAnimation as pilot. The Oslo-Berlin plane is animated using QML code
and the London-Berlin plane is animated using C++ code.
No matter which pilot is used, the results to the pilot's
actions are visible in C++ and QML and thus the example demonstrates unhindered and direct
exchange of position data through the C++/QML boundary.
The visual representation of each \c Plane is done using
the \l MapQuickItem type which permits the embedding of arbitrary QtQuick items
into a map:
\snippet planespotter/Plane.qml PlaneMapQuick1
\snippet planespotter/Plane.qml PlaneMapQuick2
\section2 The C++ Pilot
The C++ plane is steered by C++. The \c from and \c to property of the controller
class set the origin and destination which the pilot uses to calculate the
bearing for the plane:
\snippet planespotter/main.cpp C++Pilot1
The pilot employs a \l QBasicTimer and \l {QTimerEvent}{QTimerEvents} to
constantly update the position. During each timer iteration
\c PlaneController::updatePosition() is called and a new position calculated.
\snippet planespotter/main.cpp C++Pilot3
Once the new position is calculated, \c setPosition() is called and
the subsequent change notification of the property pushes the new position
to the QML layer.
The C++ plane is started by clicking on the plane:
\snippet planespotter/planespotter.qml CppPlane1
\snippet planespotter/planespotter.qml CppPlane2
\l {azimuthTo}() calculates the bearing in degrees from one coordinate to another.
Note that the above code utilizes a QML animation to tie the rotation
and the position change into a single animation flow:
\snippet planespotter/planespotter.qml CppPlane3
First, \l NumberAnimation rotates the plane into the correct direction
and once that is done the \c startFlight() function takes care of
starting the plane's position change.
\snippet planespotter/main.cpp C++Pilot2
\section2 The QML Pilot
The \l CoordinateAnimation type is used to control the flight from Oslo
to Berlin and vice versa. It replaces the above \l ScriptAction.
\snippet planespotter/planespotter.qml QmlPlane1
The \l MouseArea of the QML plane implements the logic for the course setting
and starts the animation when required.
\snippet planespotter/planespotter.qml QmlPlane2
*/
|
