From Geography to Cartography - Programming GPS and OpenStreetMap Applications with Java - page 58

tonic object to be placed in the framework. The fundamental object auto-
matically takes care of the communication and the programmer implements
behavior inside this development environment.
It is also important to understand that the framework and the basic com-
ponent can be developed highly independently of one other. The Swing
Framework provides a large number of components specializing the base
component in a hierarchical manner. The idea of the RealObject is to pro-
vide a base class for any real-world object with pre-implemented physical
attributes and automated positioning mechanisms.

If you are not familiar with the Swing Framework, you should study
the roaf.book.map.gui.SwingApplication.main method. This applica-
tion demonstrates how to create JComponent s and how to fit a variable
grid into a component.

The development of a map panel will be based on the JPanel extending
the JComponent . In the long term, a ROAF developer choosing to create a
trac application might prefer to use a predefined RealCar extending the
RealObject to focus on implementing a navigation system to steer the car.
By connecting the RealObject to a trac application, it can listen to the
trac to adjust the speed.

5.5 Creating a MapPanel

The remainder of this chapter will walk you through the development
of the roafx.gui.map package. In Section 5.8, a GPXviewer is rolled
out to demonstrate the usage of the mapping components with the
GPSunit. The GPXviewer resides in roaf.book.map.gui , and it is also
deployed as an executable jar file in the ../resources/deployed folder
together with instructions in the GPXviewer.txt file.
It is suggested to go through these instructional steps now.

The first step in creating a roafx.gui.map.MapPanel is to extend a Swing
component and add the vital information to the constructor:

public class MapPanel extends JPanel {
public MapPanel( Rectangle2D.Double gridArea )
{ this.gridArea = gridArea; }

:

The rectangle indicates the task to draw a Cartesian coordinate system
on the provided screen space. The parameter Rectangle2D in the construc-
tor defines the horizontal and vertical (from,to) pairs for the grid. The