How to draw image to screen directly

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09 Sep
2009

Article Review by deepikagohil (20090909)

AS we all know that in a gaming application the spped of drawing on the screen is very important. The article described here deals with the same and facilitates us to draw an image on screen with more speed in Symbian OS. The article has presented the code for the same with the details of libraries and header files to be included.

The developers who are more interested in developing gaming application will find it very useful.

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The speed of image drawing is very important in game development, but the Symbian OS window frame does not offer full support for games. We need to access the screen buffer directly to provide fluent animation.

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Article

Created: Maxying (23 Mar 2007)

Last edited: hamishwillee (08 May 2013)

Library Needed:

LIBRARY  ws32.lib //RWsSession, CWsScreenDevice, RWindowGroup, CDirectScreenAccess
LIBRARY  bitgdi.lib  //CFbsBitGc

Display.h

#include <w32std.h> //RWsSession, CWsScreenDevice, RWindowGroup, CDirectScreenAccess
#include <bitstd.h>  //CFbsBitGc
 
 
class CDisplay : public MDirectScreenAccess
{
public:
	static CDisplay*NewL( RWsSession& pClient, CWsScreenDevice& pScreenDevice, RWindow& pWindow );
	static CDisplay*NewLC( RWsSession& pClient, CWsScreenDevice& pScreenDevice, RWindow& pWindow );
	~CDisplay();
 
	inline CWsScreenDevice& GetScreenDevice()
	{
		return m_pScreenDevice;
	}
 
	inline RWindow& GetWindow()
	{
		return m_pWindow;
	}
 
	inline CFbsBitGc* GetScreenGc()
	{
		return m_pGc;
	}
 
	void Start();
	void Stop();
	void Update();
 
private:
	CDisplay( RWsSession& pClient, CWsScreenDevice& pScreenDevice, RWindow& pWindow );
	void ConstructL();
	void Restart( RDirectScreenAccess::TTerminationReasons aReason );
	void AbortNow( RDirectScreenAccess::TTerminationReasons aReason );
 
private:
	CWsScreenDevice&	m_pScreenDevice;
	RWsSession&		m_pClient;
	RWindow&		m_pWindow;
 
	CDirectScreenAccess*	m_pDirectScreenAccess;
	RRegion*		m_pRegion;
	CFbsBitGc*		m_pGc;
 
	TBool			m_bDrawing;
};

Display.cpp

#include "Display.h"
 
 
CDisplay* CDisplay::NewL( RWsSession& pClient, CWsScreenDevice& pScreenDevice, RWindow& pWindow )
{
	CDisplay* self = NewLC( pClient, pScreenDevice, pWindow );
	CleanupStack::Pop( self );
	return self;
}
 
CDisplay* CDisplay::NewLC( RWsSession& pClient, CWsScreenDevice& pScreenDevice, RWindow& pWindow )
{
	CDisplay* self = new ( ELeave ) CDisplay( pClient, pScreenDevice, pWindow );
	CleanupStack::PushL( self );
	self->ConstructL();
	return self;
}
 
CDisplay::CDisplay( RWsSession& pClient, CWsScreenDevice& pScreenDevice, RWindow& pWindow ) :
m_pClient( pClient ),
m_pScreenDevice( pScreenDevice ),
m_pWindow( pWindow )
{
	m_pDirectScreenAccess = NULL;
	m_pRegion = NULL;
	m_pGc = NULL;
 
	m_bDrawing = EFalse;
}
 
CDisplay::~CDisplay()
{
	delete m_pDirectScreenAccess;
}
 
void CDisplay::ConstructL()
{
	m_pDirectScreenAccess = CDirectScreenAccess::NewL( m_pClient, m_pScreenDevice, m_pWindow, *this );
}
 
void CDisplay::Start()
{
	if( !m_bDrawing )
	{
		TRAPD( dsaErr, m_pDirectScreenAccess->StartL() );
		if( dsaErr == KErrNone )
		{
			m_pGc = m_pDirectScreenAccess->Gc();
			m_pRegion = m_pDirectScreenAccess->DrawingRegion();
			m_pGc->SetClippingRegion( m_pRegion );
			m_bDrawing = ETrue;
		}
	}
}
 
void CDisplay::Stop()
{
	if( m_bDrawing )
	{
		m_bDrawing = EFalse;
	}
}
 
void CDisplay::Update()
{
	m_pDirectScreenAccess->ScreenDevice()->Update();
}
 
void CDisplay::Restart( RDirectScreenAccess::TTerminationReasons /*aReason*/ )
{
	Start();
}
 
void CDisplay::AbortNow( RDirectScreenAccess::TTerminationReasons /*aReason*/ )
{
	m_pDirectScreenAccess->Cancel();
	m_bDrawing = EFalse;
}