threads.cpp

Introduces synchronization concepts and practices in multithreaded applications

#include "StdAfx.h"
#include "Threads.h"


extern CEvent g_eventEnd;

UINT ThreadDraw(PVOID pParam)
{
	static int snCount = 0;
	snCount ++;
	TRACE(TEXT("- ThreadDraw %d: started...\n"), snCount);

	THREADINFO *pInfo = reinterpret_cast<THREADINFO *> (pParam);

	CWnd *pWnd = CWnd::FromHandle(pInfo->hWnd);

	CClientDC dc(pWnd);
	
	int x = pInfo->point.x;
	int y = pInfo->point.y;

	srand((UINT)time(NULL));
	CRect rectEllipse(x - 25, y - 25, x + 25, y + 25);

	CSize sizeOffset(1, 1);

	CBrush brush(RGB(rand()% 256, rand()% 256, rand()% 256));
	CBrush *pOld = dc.SelectObject(&brush);
	while (WAIT_TIMEOUT == ::WaitForSingleObject(g_eventEnd, 0))
	{
		CRect rectClient;
		pWnd->GetClientRect(rectClient);

		if (rectEllipse.left < rectClient.left || rectEllipse.right > rectClient.right)
			sizeOffset.cx *= -1;

		if (rectEllipse.top < rectClient.top || rectEllipse.bottom > rectClient.bottom)
			sizeOffset.cy *= -1;

		dc.FillRect(rectEllipse, CBrush::FromHandle((HBRUSH)GetStockObject(WHITE_BRUSH)));

		rectEllipse.OffsetRect(sizeOffset);
		
		dc.Ellipse(rectEllipse);
		Sleep(25);
	}

	dc.SelectObject(pOld);	

	delete pInfo;

	TRACE(TEXT("- ThreadDraw %d: exiting.\n"), snCount --);
	return 0;
}