Balloon Help as a non-modal replacement for MessageBox()

// ******************************************************************************
// BalloonHelp.cpp : header file
// Copyright 2001-2002, Joshua Heyer
//  You are free to use this code for whatever you want, provided you
// give credit where credit is due.  (I seem to get a lot of questions
// about that statement...  All i mean is, don't copy huge bits of code
// and then claim you wrote it.  You don't have to put my name in an about
// box or anything.  Though i'm not going to stop you if that's really what
// you want :~) )
//  I'm providing this code in the hope that it is useful to someone, as i have
// gotten much use out of other peoples code over the years.
//  If you see value in it, make some improvements, etc., i would appreciate it 
// if you sent me some feedback.
//
// ******************************************************************************
// 5/30/02 - Release #2: i begin versioning
//
// I suppose i should have kept a progress log for this.
// But i didn't, so you'll just have to assume it was mostly right to begin with.
// And i'll further confuse this by versioning it R2, even though it's the 
// fourth release (?) (i haven't been keeping track, heheh).
// I will, however, thank several people who have shown me better ways to do
// things, and thus improved the class greatly.
//
// Thanks to:
// Jan van den Baard for showing me the right way to use AnimateWindow(),
//    and for demonstrating how WM_NCHITTEST can be used to provide hot tracking.
//    Check out his ClassLib library on CP!
// Maximilian H�nel for his WTL port, and for demonstrating therein a
//    nicer way to handle message hooks.
// Mustafa Demirhan for the original idea and code for using keyboard hooks.
// All the other people who have provided suggestions, feeback, and code on the
// CP forums.  This class would not be half as useful as it is without you all.
//
// ******************************************************************************

#ifndef _BALLOON_HELP_H_INCLUDED_
#define _BALLOON_HELP_H_INCLUDED_

// This was introduced to me by Maximilian H�nel in his WTL port.  Cool, eh?
////////////////////////////////////////////////////////////////////////////////
// The class _ThunkImpl is a renamed version of Andrew Nosenko CAuxThunk implementation.
// Thanks Andrew, it's a fantastic class!
//
// Copyright (c) 1997-2001 by Andrew Nosenko <andien@nozillium.com>,
// (c) 1997-1998 by Computer Multimedia System, Inc.,
// (c) 1998-2001 by Mead & Co Limited
//
// http://www.nozillium.com/atlaux/
// Version: 1.10.0021
//
#ifndef _M_IX86
	#pragma message("_ThunkImpl/ is implemented for X86 only!")
#endif

#pragma pack(push, 1)

template <class T>
class _ThunkImpl
{
private:

	BYTE	m_mov;			// mov ecx, %pThis
	DWORD	m_this; 		//
	BYTE	m_jmp;			// jmp func
	DWORD	m_relproc;		// relative jmp

protected:
	
	typedef void (T::*TMFP)();
	void InitThunk(TMFP method, const T* pThis)
	{
		union { DWORD func; TMFP method; } addr;
		addr.method = (TMFP)method;
		m_mov  = 0xB9;
		m_this = (DWORD)pThis;
		m_jmp  = 0xE9;
		m_relproc = addr.func - (DWORD)(this+1);

		::FlushInstructionCache(GetCurrentProcess(), this, sizeof(*this));
	}
	FARPROC GetThunk() const 
   {
		_ASSERTE(m_mov == 0xB9);
		return (FARPROC)this; 
   }
};
#pragma pack(pop) // _ThunkImpl


// we need these three dummy classes so we can 
// derive more than once from _ThunkImpl
template <class T>
class BHMouseHookThunk: public _ThunkImpl<T> {};

template <class T>
class BHKeybHookThunk: public _ThunkImpl<T> {};

template <class T>
class BHCallWndRetHookThunk: public _ThunkImpl<T> {};

class CBalloonHelp : public CWnd,
                     public BHKeybHookThunk<CBalloonHelp>,
                     public BHMouseHookThunk<CBalloonHelp>,
                     public BHCallWndRetHookThunk<CBalloonHelp>
{
public:
	CBalloonHelp();
	virtual ~CBalloonHelp();

   // options
   static const unsigned int unCLOSE_ON_LBUTTON_UP;   // closes window on WM_LBUTTON_UP
   static const unsigned int unCLOSE_ON_MBUTTON_UP;   // closes window on WM_MBUTTON_UP
   static const unsigned int unCLOSE_ON_RBUTTON_UP;   // closes window on WM_RBUTTON_UP
   static const unsigned int unCLOSE_ON_LBUTTON_DOWN; // closes window on WM_LBUTTON_DOWN
   static const unsigned int unCLOSE_ON_MBUTTON_DOWN; // closes window on WM_MBUTTON_DOWN
   static const unsigned int unCLOSE_ON_RBUTTON_DOWN; // closes window on WM_RBUTTON_DOWN
   static const unsigned int unCLOSE_ON_MOUSE_MOVE;   // closes window when user moves mouse past threshhold
   static const unsigned int unCLOSE_ON_KEYPRESS;     // closes window on the next keypress message sent to this thread.    (!!! probably not thread safe !!!)
   static const unsigned int unDELETE_THIS_ON_CLOSE;  // deletes object when window is closed.  Used by LaunchBalloon(), use with care
   static const unsigned int unSHOW_CLOSE_BUTTON;     // shows close button in upper right
   static const unsigned int unSHOW_INNER_SHADOW;     // draw inner shadow in balloon
   static const unsigned int unSHOW_TOPMOST;          // place balloon above all other windows
   static const unsigned int unDISABLE_FADEIN;        // disable the fade-in effect (overrides system and user settings)
   static const unsigned int unDISABLE_FADEOUT;       // disable the fade-out effect (overrides system and user settings)
   static const unsigned int unDISABLE_FADE;          // disable the fade-in/fade-out effects (overrides system and user settings)

   BOOL Create(const CString& strTitle,         // title of balloon
               const CString& strContent,       // content of balloon
               const CPoint& ptAnchor,          // anchor (tail position) of balloon
               unsigned int unOptions,          // options (see above)
               CWnd* pParentWnd = NULL,         // parent window (NULL == MFC main window)
               const CString strURL = "",       // URL to open (ShellExecute()) when clicked
               unsigned int unTimeout = 0,      // delay before closing automatically (milliseconds)
               HICON hIcon = NULL);             // icon to display

   // Show a help balloon on screen.
   static void LaunchBalloon(const CString& strTitle, const CString& strContent, 
               const CPoint& ptAnchor, 
               LPCTSTR szIcon = IDI_EXCLAMATION,
               unsigned int unOptions = unSHOW_CLOSE_BUTTON,
               CWnd* pParentWnd = NULL, 
               const CString strURL = "",
               unsigned int unTimeout = 10000);

   // Sets the font used for drawing the balloon title.  Deleted by balloon, do not use CFont* after passing to this function.
   void SetTitleFont(CFont* pFont);
   // Sets the font used for drawing the balloon content.  Deleted by balloon, do not use CFont* after passing to this function.
   void SetContentFont(CFont* pFont);
   // Sets the icon displayed in the top left of the balloon (pass NULL to hide icon)
   void SetIcon(HICON hIcon);
   // Sets the icon displayed in the top left of the balloon (pass NULL hBitmap to hide icon)
   void SetIcon(HBITMAP hBitmap, COLORREF crMask);
   // Sets the icon displayed in the top left of the balloon
   void SetIcon(HBITMAP hBitmap, HBITMAP hMask);
   // Set icon displayed in the top left of the balloon to image # nIconIndex from pImageList
   void SetIcon(CImageList* pImageList, int nIconIndex);
   // Sets the URL to be opened when balloon is clicked.  Pass "" to disable.
   void SetURL(const CString& strURL);
   // Sets the number of milliseconds the balloon can remain open.  Set to 0 to disable timeout.
   void SetTimeout(unsigned int unTimeout);
   // Sets the distance the mouse must move before the balloon closes when the unCLOSE_ON_MOUSE_MOVE option is set.
   void SetMouseMoveTolerance(int nTolerance);
   // Sets the point to which the balloon is "anchored"
   void SetAnchorPoint(CPoint ptAnchor, CWnd* pWndAnchor = NULL);
   // Sets the title of the balloon
   void SetTitle(const CString& strTitle);
   // Sets the content of the balloon (plain text only)
   void SetContent(const CString& strContent);
   // Sets the forground (text and border) color of the balloon
   void SetForegroundColor(COLORREF crForeground);
   // Sets the background color of the balloon
   void SetBackgroundColor(COLORREF crBackground);
protected:
   // layout constants
   static const int nTIP_TAIL;
   static const int nTIP_MARGIN;

   // calculate anchor position (adjust for client coordinates if used)
   CPoint GetAnchorPoint();

   // determine bounds of screen anchor is on (Multi-Monitor compatibility)
   void GetAnchorScreenBounds(CRect& rect);

   // determine section of the screen balloon is on
   enum BALLOON_QUADRANT { BQ_TOPRIGHT, BQ_TOPLEFT, BQ_BOTTOMRIGHT, BQ_BOTTOMLEFT };
   BALLOON_QUADRANT GetBalloonQuadrant();

   // Draw the non-client area
   virtual void DrawNonClientArea(CDC* pDC);
   // Draw the client area
   virtual void DrawClientArea(CDC* pDC);
   // Calculate the dimensions and draw the balloon header
   virtual CSize DrawHeader(CDC* pDC, bool bDraw = TRUE);
   // Calculate the dimensions and draw the balloon contents
   virtual CSize DrawContent(CDC* pDC, int nTop, bool bDraw = TRUE);
   // Calculate the dimensions required to draw the balloon header
   CSize CalcHeaderSize(CDC* pDC) { return DrawHeader(pDC, FALSE); }
   // Calculate the dimensions required to draw the balloon content
   CSize CalcContentSize(CDC* pDC) { return DrawContent(pDC, 0, FALSE); }
   // Calculate the total size needed by the balloon window
	CSize CalcWindowSize();
   // Calculate the total size needed by the client area of the balloon window
	CSize CalcClientSize();
   // Size and position the balloon window on the screen.
	void PositionWindow();

   // Displays the balloon on the screen, performing fade-in if enabled.
   void ShowBalloon(void);
   // Removes the balloon from the screen, performing the fade-out if enabled
   void HideBalloon(void);

   // Returns the class ATOM for a BalloonHelp control.  Registers the class first, if necessary.
   static ATOM GetClassAtom();

   // message handlers
   afx_msg void OnShowWindow(BOOL bShow, UINT nStatus);
   afx_msg LRESULT OnPrint(WPARAM wParam, LPARAM lParam);
   afx_msg LRESULT OnPrintClient(WPARAM wParam, LPARAM lParam);
	afx_msg BOOL OnEraseBkgnd(CDC* pDC);
	afx_msg void OnPaint();
	afx_msg void OnNcPaint();
	afx_msg void OnLButtonDown(UINT, CPoint point);
	afx_msg void OnLButtonUp(UINT, CPoint point);
	afx_msg void OnNcCalcSize(BOOL bCalcValidRects, NCCALCSIZE_PARAMS FAR* lpncsp);
	afx_msg void OnTimer(UINT nIDEvent);
   afx_msg void OnMouseMove(UINT, CPoint point);
   afx_msg UINT OnNcHitTest(CPoint point);
   afx_msg void OnClose();
   afx_msg void OnDestroy();
   virtual void PostNcDestroy();

	DECLARE_MESSAGE_MAP()
private:
   // Keyboard hook
   void SetKeyboardHook();
   void RemoveKeyboardHook();
   // Mouse hook
   void SetMouseHook();
   void RemoveMouseHook();
   // Call Window Return hook
   void SetCallWndRetHook();
   void RemoveCallWndRetHook();

   // Keyboard hook callback
   LRESULT KeyboardHookProc( int code, WPARAM wParam, LPARAM lParam);
   // Mouse hook callback
	LRESULT MouseHookProc(int code, WPARAM wParam, LPARAM lParam);
   // Call Window Return hook callback (automatic following)
	LRESULT CallWndRetProc(int code, WPARAM wParam, LPARAM lParam);

   // animate window API, if available
   typedef BOOL (WINAPI* FN_ANIMATE_WINDOW)(HWND,DWORD,DWORD);
   FN_ANIMATE_WINDOW m_fnAnimateWindow;

   // hook handles, if set
   HHOOK          m_hKeyboardHook;
   HHOOK          m_hMouseHook;
   HHOOK          m_hCallWndRetHook;

   unsigned int   m_unOptions;
   unsigned int   m_unTimeout;      // max time to show, in milliseconds
   unsigned int   m_unTimerClose;   // ID of kill timer
   CString        m_strContent;     // text to show in content area
   CString        m_strURL;         // url to open, if clicked.
   HWND           m_hwndAnchor;     // window to anchor to (can be NULL)
   CPoint         m_ptAnchor;       // "anchor" (point of tail)
   CImageList     m_ilIcon;         // icon

   CFont*         m_pTitleFont;     // font to use for title
   CFont*         m_pContentFont;   // font to use for content
   
   COLORREF       m_crBackground;   // Background color for balloon   
   COLORREF       m_crForeground;   // Foreground color for balloon
   
   CRect          m_screenRect;     // bounds of screen anchor is on
   CRgn           m_rgnComplete;    // Clipping / Drawing region
   CPoint         m_ptMouseOrig;    // original mouse position; for hiding on mouse move
   UINT           m_uCloseState;    // current state of the close button
   int            m_nMouseMoveTolerance;  // distance mouse has to move before balloon will close.

   static ATOM    m_ClassAtom;      // class atom
};

#endif // _BALLOON_HELP_H_INCLUDED_