Juniper Systems LandMark Mobile - Manual (Page 68)

LandMark Mobile User’s Manual
Programming LandMark Mobile
LandMark Mobile is designed to be used as a GPS utility for
third party applications. This chapter explains details about how
LandMark Mobile and third party applications work together.
This chapter is intended to give programming tips on interfacing
with LandMark Mobile.
The Memory Exchange file is used to exchange information
between LandMark Mobile and a third party application
program. There are three methods to obtain information
from Memory Exchange. These methods are divided into two
categories: data pushed by LandMark Mobile (real time), or data
pulled from LandMark Mobile by a third party application. The
following is a list and description of each category.
Using the Memory Exchange Mechanism
The memory exchange module can be accessed by third party
applications by using the lmce.dll provided with the software
package. It supports C++ projects only.
Static link the library using the files lmce.h and lmce.lib in the
third party application project. This is the recommended method
of using the DLL module.
The alternative method is to dynamically link to the library at
run time. If you are planning on using this method, please make
sure to use LoadLibrary at the beginning of application installation
and free it when the application closes. This methodology is
needed because the module contains state variables that should
only be initialized once.
The DLL can be used by one third party application at a time.
Internal GPS — Pulled Data
The third party application calls the following function when it
needs new GPS data. The function returns with the most current
GPS data LandMark Mobile has copied to shared memory, or
provides the information after a three second delay.
The internal GPS function provides GPS data in WGS84 datum,
decimal degrees, and altitude/elevation in meters. This is the
recommended internal format of most GPS receivers as the most
accurate GPS data.