Defining the Sample Class, the Main Function, and the Constructor

Maps > Map Projections > Adding Graphic Objects on Top of an Imported Map > Defining the Sample Class, the Main Function, and the Constructor

The Class

The sample is implemented as a class, SimpleMapViewer, that will load the map and create the cities.

It contains the following fields:

private:

IlvGadgetContainer* _container;

IlvSCManagerRectangle* _managerRectangle;

IlvMapInfo* _mapInfo;

IlvTextField* _statusBar;

Where _container is the top window of this application. _managerRectangle combines an IlvManager and an IlvView. _mapinfo field is an IlvMapInfo instance that stores the informations to convert coordinates from cartographic coordinate system to the manager coordinate system. As map information is saved along with .ilv files, this field is initialized when our map file is loaded so that we can use it to place cities on the map and display the geographic coordinates corresponding to the position of the mouse pointer on the map. These geographic coordinates are stored in an IlvTextField that acts as a status bar.

The Main Function

The main function initialize the IlvDisplay, creates an instance of our SimpleMapViewer class, then goes into the main loop of Rogue Wave Views.

int main(int, char**)

{

IlvDisplay* display = new IlvDisplay("Map Viewer");

if (display->isBad()) {

IlvPrint("Cannot create the display");

return 1;

}

SimpleMapViewer* viewer = new SimpleMapViewer(display,

"../data/usa.ilv");

IlvMainLoop();

return 0;

}

The Constructor

The constructor of SimpleMapViewer performs two actions: it creates the interface components of our class, then loads the map data.

SimpleMapViewer::SimpleMapViewer(IlvDisplay* display,

const char* fileName)

:_managerRectangle(0),

_statusBar(0),

_container(0),

_mapInfo(0)

{

createGUI(display);

loadMap(fileName);

}

The createGUI method creates an instance of IlvGadgetContainer that is the top view of our application, then call the methods to create the manager rectangle containing the map and to create the tool bar:

void

SimpleMapViewer::createGUI(IlvDisplay* display)

{

_container = new IlvGadgetContainer(display,

“SimpleMapViewer",

"Integrating projections and graphics",

IlvRect(50, 50, 450, 450),

IlFalse);

_container->setDestroyCallback(_exit, this);

createManagerRectangle(_container);

createStatusBar(_container);

}

The createManagerRectangle method creates the manager to store the map, and initialize the view:

void

SimpleMapViewer::createManagerRectangle(IlvGadgetContainer* container)

{

_managerRectangle = new IlvSCManagerRectangle(container->getDisplay(),

IlvRect(0, 0, 450, 435));

container->addObject(_managerRectangle);

// Attachments.

container->getHolder()->attach(_managerRectangle, IlvHorizontal);

container->getHolder()->attach(_managerRectangle, IlvVertical);

IlvManager* manager = _managerRectangle->getManager();

IlvView* view = _managerRectangle->getView();

manager->setKeepingAspectRatio(view, IlTrue);

manager->setDoubleBuffering(view, IlTrue);

}

Then the createStatusBar method creates and attach the IlvTextField, used as a status bar:

void

SimpleMapViewer::createStatusBar(IlvGadgetContainer* container)

{

_statusBar = new IlvTextField(container->getDisplay(),

"",

IlvRect(0, 435, 450, 15));

container->addObject(_statusBar, IlTrue);

_statusBar->setEditable(IlFalse);

// Attachments.

container->getHolder()->attach(_statusBar, IlvHorizontal);

container->getHolder()->attach(_statusBar, IlvVertical, 1, 0, 0);

}

When the graphic interface is ready, we can load the map.

void

SimpleMapViewer::loadMap(const char* fileName)

{

IlvManager* manager = _managerRectangle->getManager();

IlvView* view = _managerRectangle->getView();

manager->read(fileName);

_mapInfo = IlvMapInfo::Get(manager);

if (_mapInfo) {

view->setInputCallback(_showMousePosition, this);

addCities();

}

manager->fitTransformerToContents(view, IlTrue);

}

After the map has been loaded, we store the map info that was stored in the .ilv file in our _mapinfo field, install an input callback to show mouse position, then add the cities.

Version 6.1