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Tutorial Series | Marble C++ Tutorial |
Previous | Tutorial 10 - Using the GeoPainter in order to paint GeoDataLineString objects |
What's Next | Tutorial 12 - Yet missing |
Further Reading | n/a |
We have seen in the previous tutorials how basic geometry can be painted using the GeoPainter, now let's see how we can make it hold information too!
GeoDataPlacemark is a class which implements the features of KML's Placemark. Basically, it represents an interest point (a simple point or a more complex geometry) on the map, which has some information attached.
In order to add a GeoDataPlacemark to our widget, we will use the GeoDataDocument class, which is a container for features (including placemarks) and styles. In order to make the document visible, we need to add it to Marble's TreeModel, as shown in the example below:
#include <QtGui/QApplication>
#include <QtGui/QTreeView>
#include <marble/MarbleWidget.h>
#include <marble/GeoDataDocument.h>
#include <marble/GeoDataPlacemark.h>
#include <marble/GeoDataTreeModel.h>
#include <marble/MarbleModel.h>
#include <cstdio>
using namespace Marble;
int main(int argc, char** argv) {
QApplication app(argc,argv);
// Create a Marble QWidget without a parent
MarbleWidget *mapWidget = new MarbleWidget();
// Load the OpenStreetMap map
mapWidget->setMapThemeId("earth/plain/plain.dgml");
GeoDataPlacemark *place = new GeoDataPlacemark( "Marble Virtual City" );
place->setCoordinate( 11.1, 48.41, 0.0, GeoDataCoordinates::Degree );
place->setPopulation( 1024 );
place->setCountryCode ( "Germany" );
GeoDataDocument *document = new GeoDataDocument;
document->append( place );
// Add the document to MarbleWidget's tree model
mapWidget->model()->treeModel()->addDocument( document );
mapWidget->show();
return app.exec();
}
Copy and paste the code above into a text editor. Then save it as my_marble.cpp and compile it by entering the following command on the command line:
g++ -I /usr/include/qt4/ -o my_marble my_marble.cpp -lmarblewidget -lQtGui -lQtCore
If things go fine, execute ./my_marble some-file.kml and you get a tree view of its structure similar to this screenshot (showing the structure of a route calculated with Marble):
Tip |
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Here's a little checklist to tackle some problems that might arise when compiling the code above:
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Note |
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If you provide maps in your application please check the Terms of Use of the map material. The map material that is shipped with Marble is licensed in the spirit of Free Software. This usually means at least that the authors should be credited and that the license is mentioned. E.g. for OpenStreetMap the license is CC-BY-SA. Other map data shipped with Marble is either public domain or licensed in the spirit of the BSD license. |