GeoFlickr (QML)▲
This is a small example, illustrating one of the very core parts of the Qt Positioning API: the ability to retrieve and use the user's current geographic position.
Key QML types shown in this example:
Running the Example▲
To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.
Retrieving the Current Position▲
Retrieving the user's current position is achieved using the PositionSource type. In this example, we instantiate the PositionSource as part of the GeoTab component (the floating "window" describing current position and status).
PositionSource {
id: positionSource
// used with nmea plugin only
PluginParameter { name: "nmea.source"; value: "qrc:///flickrmobile/nmealog.txt" }
onPositionChanged: {
planet.source = "images/sun.png";
sourceText.text = ((name === "nmea") ? "(filesource): " : "Source: ") +
printableMethod(supportedPositioningMethods)
}
onSourceErrorChanged: {
if (sourceError == PositionSource.NoError)
return
console.log("Source error: " + printableError(sourceError))
activityText.fadeOut = true
if (supportedPositioningMethods === PositionSource.NoPositioningMethods) {
name = "nmea";
update();
}
}
}When the "Locate and update" button is pressed, we instruct the PositionSource to request a location update. If the update finishes with an error, we check if the default backend is capable of providing positioning data. If it's not, we switch to nmea backend with pre-recorded data, and request the location update again.
We cannot check the supportedPositioningMethods in advance, because on mobile platforms (Android and iOS) this method will return NoPositioningMethods before the permissions are granted. And the permissions request is first performed when location update is requested.
Button {
id: locateButton
text: "Locate & update"
onClicked: {
positionSource.update();
}
}To share the new position data with the rest of the application, we use properties that we have created on the GeoTab component:
property var coordinateUsing the Current Position▲
The longitude and latitude values retrieved here are eventually set in the properties on the RestModel component. The RestModel is an XmlListModel, which retrieves XML data from a URL and creates a data model by parsing it.
In this case, it retrieves data from the Flickr REST API online, based on our current position
XmlListModel {
property var coordinate
source: "https://api.flickr.com/services/rest/?" +
"min_taken_date=2000-01-01+0:00:00&" +
"extras=date_taken&" +
"method=flickr.photos.search&" +
"per_page=30&" +
"sort=date-taken-desc&" +
"api_key=e36784df8a03fea04c22ed93318b291c&" +
"lat=" + coordinate.latitude + "&lon=" + coordinate.longitude;
query: "/rsp/photos/photo"
XmlListModelRole { name: "title"; elementName: ""; attributeName: "title" }
XmlListModelRole { name: "datetaken"; elementName: ""; attributeName: "datetaken" }
XmlListModelRole { name: "farm"; elementName: ""; attributeName: "farm" }
XmlListModelRole { name: "server"; elementName: ""; attributeName: "server" }
XmlListModelRole { name: "id"; elementName: ""; attributeName: "id" }
XmlListModelRole { name: "secret"; elementName: ""; attributeName: "secret" }
}This model data is then shown in a variety of Qt Quick views to produce the example application.