QtSensors Qt Sensors - Explorer QML Example

This example is divided into two parts:

  • A C++ plugin that provides QML alternatives for QSensorExplorer, QPropertyInfo and QSensorItem C++ classes.
  • A QML Application that uses the QML types to read the sensor meta-data and present it.

This example is built as an executable with C++ code that runs the QML, but it can also be launched directly using the qmlscene tool. You should build the top-level sensor_explorer project before trying to run this example or it will not be able to find its dependencies.

qmlscene -I . sensor_explorer.qml

Above, the -I . parameter adds the current directory as a module import path to locate the Explorer QML module.

The Sensor Explorer QML import defines the Explorer QML module, exporting QSensorExplorer, QPropertyInfo and QSensorItem C++ classes as QML types. The source code is available in the sensor_explorer/import subdirectory.

To write a QML application that will use the QML types exposed by the Explorer module, following steps are needed:

Import the Explorer 1.0 declarative plugin:

import Explorer 1.0

Create a SensorExplorer QML item:

SensorExplorer {
    id: explorer
}

You can retrieve a list of all available sensors using SensorExplorer.availableSensors:

model: explorer.availableSensors

The example uses the returned list as a model to populate a view of available sensors.

To retrieve the properties of a sensor, use SensorItem.properties:

propertyList.model = explorer.selectedSensorItem.properties

The property list is used as a model for another view that displays the property names and values.

It is possible to edit the values of certain sensor properties. Selecting a writable property value will open an editor. SensorExplorer QML type allows you to pass a new value for a sensor property value as follows:

explorer.selectedSensorItem.changePropertyValue(propertyList.selectedItem, loaderEditor.item.text);

Starting and stopping a sensor can be done by setting the SensorItem.start property:

if (text === "Start") {
    explorer.selectedSensorItem.start = true;
    text = "Stop";
}
else {
    explorer.selectedSensorItem.start = false;
    text = "Start";
}

Files:

  • sensor_explorer/Makefile.qml
  • sensor_explorer/sensor_explorer.qml
  • sensor_explorer/import/explorer.cpp
  • sensor_explorer/import/explorer.h
  • sensor_explorer/import/propertyinfo.cpp
  • sensor_explorer/import/propertyinfo.h
  • sensor_explorer/import/sensoritem.cpp
  • sensor_explorer/import/sensoritem.h
  • sensor_explorer/main.cpp
  • sensor_explorer/qml.pro
  • sensor_explorer/qml.qrc
  • sensor_explorer/sensor_explorer.pro
  • sensor_explorer/import/import.pro
  • sensor_explorer/import/qmldir