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Revision as of 10:24, 22 April 2008 by Forum Nokia KB (Talk | contribs)

Archived:Displaying sensor data on Symbian

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ID   Creation date April 17, 2008
Platform S60 3rd Edition, MR Tested on devices Nokia N95 8GB
Category Symbian C++ Subcategory Hardware, Sensor


Keywords (APIs, classes, methods, functions): MRRSensorDataListener, TRRSensorInfo, TRRSensorEvent, CFont, CWindowGc, MRRSensorDataListener::HandleDataEventL(), CGraphicsDevice::GetNearestFontInTwips(), CWindowGc::SetBrushColor(), CWindowGc::UseFont(), CWindowGc::DrawText()

Overview

This code snippet demonstrates how to display on the screen the data produced by the accelerometer and rotation sensors of the device.

Registering listeners for the sensors is not covered in this snippet. For that, you may want to see CS000888 - Listening for accelerometer sensor data events and Listening for rotation sensor data events.

Note: In order to use the code, you need to install the sensor plugin for your SDK.

This snippet can be self-signed.

MMP file

The following libraries are required:

LIBRARY  RRSensorApi.lib
LIBRARY gdi.lib

Header file

#include <coecntrl.h>   // CCoeControl
#include <gdi.h> // CFont
#include <RRSensorApi.h>
// Accelerometer sensor UID
const TInt KAccelerometerSensorUID = 0x10273024;
// Rotation sensor UID
const TInt KRotationSensorUID = 0x303E;
class CMyControl : public CCoeControl, public MRRSensorDataListener
{
// ...
 
private: // Functions from base classes
/**
* From CCoeControl.
* Draws this control to the screen.
* @param aRect the rectangle of this view that needs updating
*/

void Draw(const TRect& aRect) const;
 
/**
* From MRRSensorDataListener.
* Callback function for receiving sensor data events.
*
* @param aSensor identifies the sensor that created the event.
* @param aEvent contains data about created event.
*/

void HandleDataEventL(TRRSensorInfo aSensor, TRRSensorEvent aEvent);
 
private: // Data
CRRSensorApi* iAccelerometerSensor;
TInt iAccSensorDataX;
TInt iAccSensorDataY;
TInt iAccSensorDataZ;
CRRSensorApi* iRotationSensor;
TInt iRotSensorDataX;
TInt iRotSensorDataY;
TInt iRotSensorDataZ;
CFont* iFont;
}

Source file

#include <EIKENV.H> // CEikonEnv
#include <gdi.h> // TFontSpec, CGraphicsDevice
#include <RRSensorApi.h>
void CMyControl::ConstructL(const TRect& aRect)
{
// ...
 
// Reset sensor data
iAccSensorDataX = 0;
iAccSensorDataY = 0;
iAccSensorDataZ = 0;
iRotSensorDataX = 0;
iRotSensorDataY = 0;
iRotSensorDataZ = 0;
 
// Initialize the font used in drawing onto the screen
_LIT(KFontName, "Arial");
const TInt KFontSize = 120;
TFontSpec fontSpec(KFontName, KFontSize);
CGraphicsDevice* screenDevice = CEikonEnv::Static()->ScreenDevice();
screenDevice->GetNearestFontInTwips(iFont, fontSpec);
 
// ...
}
/**
* Draws the display.
*/

void CMyControl::Draw(const TRect& /*aRect*/) const
{
// Get the standard graphics context
CWindowGc& gc = SystemGc();
 
// Get the control's extent
TRect drawRect(Rect());
 
// Clear the screen with white color
gc.SetBrushColor(KRgbWhite);
gc.Clear(drawRect);
 
// Set the font
gc.UseFont(iFont);
// The text is drawn in black
gc.SetBrushColor(KRgbBlack);
 
TBuf<255> buffer;
 
// Draw accelerometer sensor data
_LIT(KAccTxt, "Accel. sensor: X: %d, Y: %d, Z: %d");
buffer.Format(KAccTxt, iAccSensorDataX, iAccSensorDataY, iAccSensorDataZ);
gc.DrawText(buffer, TPoint(0, 20));
 
// Draw rotation sensor data
_LIT(KRotTxt, "Rotation sensor: X: %d, Y: %d, Z: %d");
buffer.Format(KRotTxt, iRotSensorDataX, iRotSensorDataY, iRotSensorDataZ);
gc.DrawText(buffer, TPoint(0, 40));
}
/**
* Gets called whenever a data event occurs.
*/

void CMyControl::HandleDataEventL(TRRSensorInfo aSensor, TRRSensorEvent aEvent)
{
// A data event occurred. Store new values from the sensor in question.
switch (aSensor.iSensorId)
{
case KAccelerometerSensorUID:
{
iAccSensorDataX = aEvent.iSensorData1;
iAccSensorDataY = aEvent.iSensorData2;
iAccSensorDataZ = aEvent.iSensorData3;
}
break;
case KRotationSensorUID:
{
iRotSensorDataX = aEvent.iSensorData1;
iRotSensorDataY = aEvent.iSensorData2;
iRotSensorDataZ = aEvent.iSensorData3;
}
default:
break;
}
// Update the display
DrawNow();
}

Postconditions

Data received from accelerometer and rotation sensors is constantly drawn onto the screen.

See also

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