/**********************************************************************************************
	
	MFC screen dim test
		:: oystein			:: November 2010
		
	Creates a simple window - click it to toggle whether a translucent black "dimmer" window 
	is shown. The dimmer-window covers the entire screen, but the taskbar ("superbar" in 
	Windows 7) will jump on top of it if clicked - it seems. Simple suggestions to fix that
	are welcome.
	
	Should work on Windows 2000 and	later. 

	Disclaimer: This is my first MFC program ever, so if anything seems wrong, it probably is.
	I have previously only coded with pure Win32 API, and hacked this together using online
	tutorials. Code provided "as-is" with no guarantees - I can not be held responsible for 
	anything bad that happens if you run this program.

***********************************************************************************************/

#include "stdafx.h"

#undef WINVER
#define WINVER 0x500 // Windows 2000 & above, because of layered windows


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
//
//						 Black window used to dim everything else 
//
class CDimWnd : public CFrameWnd
{               
public: 
	CDimWnd()
	{
		// Get screen res into rect
		RECT rc;
		GetDesktopWindow()->GetWindowRect(&rc);

		CreateEx(WS_EX_LAYERED |		// Layered window for translucency
				 WS_EX_TRANSPARENT |	// Click through
				 WS_EX_TOPMOST |		// Always on top
				 WS_EX_TOOLWINDOW,		// Do not appear in taskbar & similar
				 NULL, TEXT(""), 
				 WS_POPUP,				// No frame/borders - though there is 
										// still some border left - we'll remove 
										// it with regions

				 0, 0, rc.right + 10, rc.bottom + 10, // Make the window 10px larger 
													  // than screen resolution in both 
													  // directions - it is still positioned 
													  // at 0,0
				 NULL, NULL);
		
		// Grab a part of the window the size of the desktop - but 5px into it  
		// Because the window is larger than the desktop res, the borders are removed 
		CRgn rgn;                         
		rgn.CreateRectRgn(rc.left + 5, rc.top + 5, rc.right + 5, rc.bottom + 5);
		SetWindowRgn((HRGN)rgn, FALSE);
		rgn.Detach();                               
		
		// We have to reposition window - (0,0) of window has not changed
		SetWindowPos(NULL, -5, -5, 0, 0, SWP_NOSIZE | SWP_NOZORDER);		

		// This is where we set the opacity of the window: 0-255
		SetLayeredWindowAttributes(RGB(0,0,0), 150, LWA_ALPHA);						
	}
	void Close()
	{
		CFrameWnd::OnClose();
	}
	BOOL CDimWnd::OnEraseBkgnd(CDC* pDC); // Set BKG color
	DECLARE_MESSAGE_MAP()
};

BOOL CDimWnd::OnEraseBkgnd(CDC* pDC)
{
    // Set brush to desired background color
    CBrush backBrush(RGB(0, 0, 0));

    // Save old brush
    CBrush* pOldBrush = pDC->SelectObject(&backBrush);

    CRect rect;
    pDC->GetClipBox(&rect);     // Erase the area needed

    pDC->PatBlt(rect.left, rect.top, rect.Width(), rect.Height(), PATCOPY);
    pDC->SelectObject(pOldBrush);	
    return TRUE;
}

BEGIN_MESSAGE_MAP(CDimWnd, CFrameWnd)
	ON_WM_ERASEBKGND()
END_MESSAGE_MAP()

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


// Global variable - is screen dimmed?
bool g_bIsDimmed = false;


// The main window
class CMainWnd : public CFrameWnd
{     
	// Contains a CDimWnd - I'm not sure if this is the "MFC way" of doing things
	CDimWnd dimmer; 
	
public: 
	CMainWnd()
	{
		Create(NULL, TEXT("Screen dimmer - Press left mouse button on window to toggle"), 
			WS_OVERLAPPEDWINDOW, CRect(50, 50, 400, 250));
	}
	// Left mouse button toggles dimming
	afx_msg void OnLButtonDown(UINT Flags, CPoint Point)
	{
		if(!g_bIsDimmed)
		{
			dimmer.ShowWindow(SW_SHOW);
			dimmer.BringWindowToTop();			
			g_bIsDimmed = true;
		}
		else
		{			
			dimmer.ShowWindow(SW_HIDE);		
			g_bIsDimmed = false;
		}
	}
	DECLARE_MESSAGE_MAP()
};

BEGIN_MESSAGE_MAP(CMainWnd, CFrameWnd)
	ON_WM_LBUTTONDOWN()
END_MESSAGE_MAP()


// The app
class CApp : public CWinApp
{
public:         
	virtual BOOL InitInstance();
};

BOOL CApp::InitInstance()
{               
	m_pMainWnd = new CMainWnd();              
	m_pMainWnd->ShowWindow(m_nCmdShow);           
	m_pMainWnd->UpdateWindow();        
	return TRUE;
}

CApp HelloApp;