Qt Sensors - Explorer QML Example

Demonstrates how to read the meta-data of available sensors.

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.

Sensor Explorer QML Import

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.

Sensor Explorer QML Application

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 特性:


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

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