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Position Log Playback

In this guide you will learn how to play back a previously recorded position log, using DataSource on an interactive map, displayed using MapView, with frame per second (FPS) counter.

GPS Log Data Source

QML data source playback example

First, get an API key token, see the Getting Started guide.

Qt should be installed to continue.

The Maps SDK for Qt should be installed, see the Setup Maps SDK for Qt guide.


PositionLogPlayback demonstrates how easy it is to use MapView to display an interactive map and play back a position log using DataSource.

How it works

In Qt, go to the File menu and select Open File or Project…

then browse to the PositionLogPlayback example folder and open

You may want to have a look at Setting your API Key to see how to open and configure a project and set your API Key.

In main.qml, in the Component.onCompleted: block, the datasource is set by specifying the filename of a previously recorded [GPS] position log:

ServicesManager.dataSource.playbackFile = Qt.resolvedUrl("");

Also the content type that will be downloaded upon demand is specified:

let updater = ServicesManager.contentUpdater(ContentItem.Type.RoadMap);

The MapView displaying the interactive map also has 2 buttons, the one on the bottom left of the viewport to start/stop the position datasource playback, and the one on the bottom right to start/resume following position.

Panning the map during simulation/playback will stop follow position, and the button needs to be clicked again to resume following position.

 1MapView {
 2    id: mapView
 3    anchors.fill: parent
 4    viewAngle: 25
 5    zoomLevel: 69
 6    viewPerspective: MapView.ViewPerspective.View3D
 7    buildingsVisibility: MapView.BuildingsVisibility.Show3D
 8    detailsQualityLevel: MapView.DetailsQualityLevel.Medium
 9    gestures: MapView.Gesture.Pan | MapView.Gesture.PanEnableVelocity
10    | MapView.Gesture.Pinch | MapView.Gesture.Rotate | MapView.Gesture.Tilt
11    Text {
12        anchors.right: parent.right
14        text: fpsCounter.fps
15    }
16    Button {
17        anchors.left: parent.left
18        anchors.bottom: parent.bottom
19        text: ServicesManager.dataSource.type === DataSource.Type.Live
20        ? "Position Log playback" : "Live position"
21        onClicked: ServicesManager.dataSource.type = ServicesManager.dataSource.type
22        === DataSource.Type.Live ? DataSource.Type.Playback : DataSource.Type.Live;
23    }
24    Button {
25        anchors.left: parent.left
27        //enabled: ServicesManager.dataSource.type === DataSource.Type.Live
28        text: ? "Stop recording" : "Start recording"
29        onClicked: = !;
30    }
31    Button {
32        anchors.right: parent.right
33        anchors.bottom: parent.bottom
34        text: qsTr("Follow position")
35        enabled: !mapView.followingPosition
36        onClicked: mapView.followingPosition = true
37    }

Follow position means that the camera flies to the position of the green arrow and then follows the simulated position arrow. This is necessary, as the arrow is likely to be located elsewhere on the map, not at the current location of the camera.


The green position arrow plays back the previously recorded positions on the map, from the data source specified above.

QML Examples

Maps SDK for Qt Examples can be downloaded or cloned with Git