Mobile Software: Windows Phone- Sensors and Services (5)

Hello

Accelerometer

Accelerometer measures acceleration.
It measures acceleration in three axis X,Y,Z as follows :

This coordinate system remains fixed relative to the phone regardless of orientation change.
In this position the accelerometer reading is (0,-1,0) . -1 means g in -Y direction
If you rotate above emulator 90 degrees counterclockwise you will get (-1,0,0)

simple accelerometer sample code :
AccelerometerSample.zip

Adding acc_CurrentValueChanged handler and starting the accelerometer obect - acc

Defining the handler

Writing to text block from non UI thread :
The problem is that access to a UI object such as TextBlock can be done only from the main thread (thread safety). However, we can not be sure that the handler will be executed on the main thread context, so we first check this by calling CheckAccess if it is true then access to this UI object can be done. If CheckAccess is false then you must use the Dispatcher.BeginInvoke to queue executing the handler on the main thread.

Note that BeginInvoke is used with Action as argument type. Action encapsulate a method which return nothing and has no arguments.

Remarks

Note that Accelerometer reside in Microsoft.Devices.Sensors and you might need to add a reference.
Altough this is the default note that WMAppManifest must have the following :

otherwise the accelometer will not function!

Run the application , invoke the accelerometer via the emulator and the same values X,Y,Z which appears on the emulator will appear also on the application TextBlock

Note that as the emulator start the acceleration is 0,-1,0 , why ?

Geographic Location

Geographic location is supported in Windows Phone 7 using A-GPS.

Core class for Location - GeoCoordinateWatcher

sample code :
The sample register a handler for event name PositionChanged for GeoCoordinatorWatcher object. The handler write the longitude and latitude via GeoCoordinate argument into a textblock after the watcher is started.

Latitude

Angular distance from the equator
An angle between 0 - 90 degrees.
North pole latitude is 90 while south pole is -90

Longitude

An angle between 180 to -180

A graphical representation of longitude and latitude

A perspective view of the Earth showing how latitude (φ) and longitude (λ) are defined on a spherical model. The graticule spacing is 10 degrees.

Source sample
Location.zip

MainPage.xaml.cs

Run the application and verify that latitude and longitude are the same in the emulator and application

Map Service
Location is possible as was shown in terms of latitude\longitude ,but most people prefer location in terms of map.
Microsoft supports Map Control.

Before using map service you will need to do the following once :

Sample code using map control
MapService.zip

The sample contains map control and four buttons : Zoom In, Zoom Out, Road Mode , Aerial Mode

Add namespace Microsoft.Phone.Controls.Maps to MainPage.xaml.cs
Drag and drop map control from the toolbox