NavSlight

This page introduces a simple Qt-program called NavSlight that with some further development could be used for navigation. The "Slight"-part in the name refers to not only to the size of the program but also to stage of development. The idea is to have a navigator-type application that can display the map in the current location and the aerial or satellite photograph at that same location. Here are some screen shots of the desktop version of the program in the map and satellite image view. The user can drag the map-images around to see also the areas surrounding the current location.

Note
Changing between these views happens by pressing the "Flip"-button at the top of the view. The map is rotated based on the baring between the current and previous location. As you can see the UI is not that complicated and needs a lot of improvement.

The "Update Pos"-button is used to get the images for the new location. In other words the navigator does not follow the location changes constantly. When the "Options"-button is pressed the program gives the user a option to select the source for the map imagery. At this stage of development only service available is Google.

The program has also been tested on mobile-phone simulator in which case the bare bone UI makes little bit more sense. Here is a screen shot of the program running in Nokia-simulator showing the map at the default GPS-location.

Details of implementation and current status

The program, just like this web page, is very much work in progress. For example, errors in the image download are not handled very well. The main user interface was implemented with QML which made possible the fluid animation changes between different views. Obtaining position information is done in C++ using Qt Mobility - classes. The images are provided to the QML using a implementation of the QDeclarativeImageProvider-class. In practice this means that in the QML side I can just write something like

Image {
source:"image://google/62,13,17,mobile"
}

to show the map image at the location (62,13) at zoom level 17. Same thing for the satellite image would be

Image {
source:"image://google/62,13,17,satellite"
}

Naturally this makes updating the QML properties from C++ much easier. The real benefit is that the actual source of the information is hidden. Same UI could easily, with some programming skills, be used to obtain data from other web sources or e.g. from the georeferenced aerial photographs in the file system. If one is interested only in the webview based implementation then the easiest way to do it was explained in class .

The current version: not even alpha

To download the tar+gzip version follow this link .

Helpful links

Discussion on the QDeclarativeImageProvider-class can be found in. this blog

The lecture notes in the Qt-course are also helpful and they can be found under . Mobile Linux Development with QT