Outlook like notification window using ATL






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Create an Outlook like notification window using ATL.
Introduction
When using Microsoft® Outlook®, we come across the mail notification window, which appears slowly and starts disappearing. It displays a summary of a mail, including the sender's name etc. This articles describes how to build that kind of a window using ATL.
Background
I recently came across an article by Nick Wälti. But did not find any C++ code for achieving the same. So I tried to achieve something similar using ATL.
Using the code
There are three classes:
CATLNotifyDialog
represents the main UI.CNotifyWnd
represents the notification window.CBmpButton
represents the bitmap button class, used as the 'Close' button.
typedef CWinTraits <WS_CLIPCHILDREN | WS_POPUP |WS_VISIBLE ,0 > CNotificationWinTraits; class CNotifyWnd : public CWindowImpl<CNotifyWnd,CWindow,CNotificationWinTraits> { . . CBmpButton* m_pButton;//owner drawn button class public: //constructor DECLARE_WND_CLASS("CNotifyWnd") BEGIN_MSG_MAP(CNotifier) MESSAGE_HANDLER(WM_CREATE, OnCreate) . . . //reflect notifications to child REFLECT_NOTIFICATIONS() END_MSG_MAP() void CreateNotifyWindow(); private: LRESULT ChangeOpacity(BYTE iFactor); //message handler functions };
The macro REFLECT_NOTIFICATIONS
is declared to send messages to child windows. In this case, the button window is the child. In the OnCreate
function, modify the extended style of the window by adding WS_EX_LAYERED
. More information on Layered Windows can found in the MSDN.
if ( ModifyStyleEx(0,WS_EX_LAYERED )) { //successfully modified style to make window as layered window //now use timer SetTimer(TIMER_ID ,30); m_bTimerActive=TRUE; }
The ChangeOpacity
function of this class will bring a translucent effect to the window.
LRESULT CNotifyWnd::ChangeOpacity(BYTE iFactor) { //define function pointer typedef DWORD (WINAPI *pSetLayeredWindowAttributes)(HWND, DWORD, BYTE, DWORD); pSetLayeredWindowAttributes SetLayeredWindowAttributes; HMODULE hDLL = LoadLibrary ("user32"); if (hDLL ) { SetLayeredWindowAttributes = (pSetLayeredWindowAttributes) GetProcAddress(hDLL,"SetLayeredWindowAttributes"); ATLASSERT(SetLayeredWindowAttributes );//using WIN2k or onward ? BOOL bRes=SetLayeredWindowAttributes(m_hWnd,RGB(255,255,255), iFactor, LWA_COLORKEY | LWA_ALPHA); FreeLibrary(hDLL); } else { //not able to load library ATLASSERT(0); } return 0; }
The class CBmpButton
is a button class. It uses three bitmaps to represent its states, i.e., normal, mouse move, and pressed. I could not get better bitmaps for this application, but a more artistic person can really make it beautiful.
class CBmpButton :public CWindowImpl<CBmpButton> { UINT m_BitmapId[3];//represents three states of button UINT m_nCurrentBmp; public: DECLARE_WND_SUPERCLASS( _T("BitmapButton"), _T("Button") ) BEGIN_MSG_MAP(CBmpButton) //message handlers . . . MESSAGE_HANDLER(OCM_DRAWITEM, OnDrawItem) DEFAULT_REFLECTION_HANDLER()//this will handle messages refected by parent END_MSG_MAP() private: //message handlers };
Here is an important function of the above class:
LRESULT CBmpButton::OnCreate(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled) { //make button owner drawn ModifyStyle(0,BS_OWNERDRAW); return 1; }
Functions like CBmpButton::OnLButtonDown
, CBmpButton::OnLButtonUP
, CBmpButton::OnMouseLeave
, and CBmpButton::OnMouseLeave
will set m_nCurrentBmp
with the appropriate bitmap.
//using this will enable WM_MOUSELEAVE notification TrackMouseEvent(&stMouseEvent);
The code assumes that the taskbar is always at the bottom (does not consider other cases).
Points of Interest
It does not use MFC (that's lighter!).
History
- v1.0 - 11 Aug 2006.