ddbouncingball_engine.cpp

symbian平台下的一个游戏源代码

// DDBouncingBall_Engine.cpp
// ---------------------------
//
// Copyright (c) 2002 Symbian Ltd.  All rights reserved.
//

////////////////////////////////////////////////////////////////////
//
//	Engine takes ownership of bitmaps passed in during construction 
//  and therefore must be responsible for deletion.
//
////////////////////////////////////////////////////////////////////

#include "DDBouncingBall_Engine.h"

const TInt KGenerationInterval = 10;
const TInt KCBAOffset = 45;
_LIT(KDDBouncingBallApp, "DDBouncingBall");


CDDBouncingBallEngine::CDDBouncingBallEngine(RWsSession& aClient, CWsScreenDevice& aScreenDevice, RWindow& aWindow,
								   CFbsBitmap* aBitmap, CFbsBitmap* aBitmapMask, TInt aXVelocity, TInt aYVelocity)
: CTimer(CActive::EPriorityStandard),
	iClient(aClient),
	iScreenDevice(aScreenDevice),
	iWindow(aWindow),
	iBallImage(aBitmap),			// Takes ownership of bitmap		
	iBallImageMask(aBitmapMask),	// Takes ownership of bitmap
	iXVelocity(aXVelocity),
	iYVelocity(aYVelocity)
	{
	}

CDDBouncingBallEngine::~CDDBouncingBallEngine()
	{
	Cancel();
	delete iDirectScreenAccess;
	delete iBallImage;
	delete iBallImageMask;
	}

void CDDBouncingBallEngine::ConstructL()
	{
	iBouncing = EFalse;
	CTimer::ConstructL();
	// Create the DSA object
	iDirectScreenAccess = CDirectScreenAccess::NewL(iClient, iScreenDevice, iWindow, *this);
	CActiveScheduler::Add(this);
	}

// Start Bouncing
void CDDBouncingBallEngine::StartBouncingL()
	{
	if (iBouncing)
		User::Panic(KDDBouncingBallApp, EDDBouncingAlreadyStarted);
		
	iBouncing = ETrue;

	// Initialise DSA
	iDirectScreenAccess->StartL();

	// Get graphics context for it
	iGc = iDirectScreenAccess->Gc();

	// Get region that DSA can draw in
	iRegion = iDirectScreenAccess->DrawingRegion();

	// Set the display to clip to this region
	iGc->SetClippingRegion(iRegion); 

	After(TTimeIntervalMicroSeconds32(KGenerationInterval));
	}

// Stop Bouncing
void CDDBouncingBallEngine::StopBouncing()
	{
	if (!iBouncing)
		User::Panic(KDDBouncingBallApp, EDDBouncingAlreadyStopped);
	
	// Cancel timer and display
	Cancel();
	iBouncing = EFalse;
	}
	
// Implement MDirectScreenAccess
void CDDBouncingBallEngine::Restart(RDirectScreenAccess::TTerminationReasons /*aReason*/)
	{
	// Restart display
	// Note that this will result in the clipping region being updated
	// so that menus, overlaying dialogs, etc. will not be drawn over
	StartBouncingL();
	}

void CDDBouncingBallEngine::AbortNow(RDirectScreenAccess::TTerminationReasons /*aReason*/)
	{
	// Cancel timer and display
	Cancel();
	iBouncing = EFalse;
	}


void CDDBouncingBallEngine::RunL()
	{
	// Force screen update: this required for WINS, but may
	// not be for all hardware
	iDirectScreenAccess->ScreenDevice()->Update();

	TRect sourceRect(iPosition,iBallImage->SizeInPixels());
	iGc->Clear(sourceRect);
	
	// Update the balls position
	MoveBall();
	
	// and draw ball
	iGc->BitBlt(iPosition, iBallImage);

	iClient.Flush();

	// Renew request
	After(TTimeIntervalMicroSeconds32(KGenerationInterval));

	}

void CDDBouncingBallEngine::DoCancel()
	{
	// Cancel timer
	CTimer::DoCancel();

	// Cancel DSA
	iDirectScreenAccess->Cancel();
	}

void CDDBouncingBallEngine::MoveBall()
	{
	// Move Ball
	iPosition += TPoint(iXVelocity, iYVelocity);

	// Check for Boundary collision
	TRect bounds = iRegion->BoundingRect();

	// Has it gone outside the left right edge
	if ((iPosition.iX + iBallImage->SizeInPixels().iWidth > bounds.iBr.iX) || (iPosition.iX < bounds.iTl.iX))
		iXVelocity = -iXVelocity;

	// or top and bottom edge ?
	if ((iPosition.iY + iBallImage->SizeInPixels().iHeight > (bounds.iBr.iY - KCBAOffset)) || (iPosition.iY < 0))
		iYVelocity = -iYVelocity;

	}