Declare Function Shell_NotifyIcon Lib "shell32.dll" Alias "Shell_NotifyIconA" (ByVal dwMessage As Long, pnid As NOTIFYICONDATA) As Long
Shell_NotifyIcon manipulates an icon located in the taskbar's status area, commonly referred to as the "system tray." This function adds a new icon, removes an existing icon, or changes an existing icon owned by the calling program. Programs typically use tray icons when they run in the background without a window; the icon gives the user a way to access the running program.
All of a tray icon's messages are sent to its owner window for processing. See the page for the NOTIFYICONDATA structure for more details on how this is done. The standard behavior of Shell_NotifyIcon used the following messages: WM_MOUSEMOVE, WM_LBUTTONDOWN, WM_LBUTTONUP, WM_RBUTTONDOWN, WM_RBUTTONUP, etc.
The function returns 0 if an error occured, or a non-zero value if successful.
Const NIM_ADD = &H0 Const NIM_DELETE = &H2 Const NIM_MODIFY = &H1 Const NIM_SETFOCUS = &H4 Const NIM_SETVERSION = &H8
Note: To use this example, you must first use the Menu Editor utility to create a small menu on Form1. Create a menu called mnuTrayIconPopup with its Visible check box cleared. Then, create two menu items under it: mnuAbout and mnuExit. You can give those items whatever captions you which; those are what will be displayed in the menu. If you do this properly, you will not see a menu bar in Form1 but the example code will function properly.
' This code is licensed according to the terms and conditions listed here. ' Place an icon in the system tray when window Form1 opens. When right- ' clicked, a small pop-up menu appears. The icon is deleted when Form1 closes. ' Notice how the window procedure for Form1 is extended in order to process the ' messages for the icon. Also, note the application-defined message used for tray ' icons. ' *** Place the following code in a module. *** ' Public variable definitions. Public pOldProc As Long ' pointer to Form1's previous window procedure Public Const PK_TRAYICON = &H401 ' program-defined message for tray icon action ' This function acts as the new window procedure for Form1. It handles the program- ' defined PK_TRAYICON message, used whenever a user event occurs with the ' tray icon. Public Function WindowProc(ByVal hWnd As Long, ByVal uMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long Select Case uMsg Case PK_TRAYICON ' If the user released the right mouse button over the icon, display the ' mnuTrayIconPopup menu at the mouse cursor's position. Make ' mnuAbout the default selection in the menu. If lParam = WM_RBUTTONUP Then Form1.PopupMenu mnuTrayIconPopup, , , , mnuAbout End If WindowProc = 1 ' this return value doesn't really matter Case Else ' Pass the message to the procedure Visual Basic provided. WindowProc = CallWindowProc(pOldProc, hWnd, Msg, wParam, lParam) End Select End Function ' *** Place the following code in Form1. *** ' This function creates the tray icon and hooks up the window procedure ' when Form1 first opens. Private Sub Form1_Open() Dim nid As NOTIFYICONDATA ' icon information Dim retval As Long ' return value ' Put the icon settings into the structure. With nid .cbSize = Len(nid) ' size of structure .hWnd = Form1.hWnd ' owner of the icon and processor of its messages .uID = 1 ' unique identifier for the window's tray icons .uFlags = NIF_ICON Or NIF_MESSAGE Or NIF_TIP ' provide icon, message, and tool tip text .uCallbackMessage = PK_TRAYICON ' message to use for icon events .hIcon = Form1.Icon ' handle to the icon to actually display in the tray .szTip = "Sample Tray Icon" & vbNullChar ' tool tip text for icon End With ' Add the icon to the system tray. retval = Shell_NotifyIcon(NIM_ADD, nid) ' Set the new window procedure for window Form1. pOldProc = SetWindowLong(Form1.hWnd, GWL_WNDPROC, AddressOf WindowProc) End Sub ' This function removes the tray icon and returns the old window procedure to use. Private Sub Form1_Unload(Cancel As Integer) Dim nid As NOTIFYICONDATA ' icon information Dim retval As Long ' return value ' Load the structure with just the identifying information. With nid .cbSize = Len(nid) ' size of structure .hWnd = Form1.hWnd ' handle of owning window .uId = 1 ' unique identifier End With ' Remove the icon from the system tray. retval = Shell_NotifyIcon(NIM_DELETE, nid) ' Make the old window procedure the current window procedure. retval = SetWindowLong(Form1.hWnd, GWL_WNDPROC, pOldProc) End Sub
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Last Modified: March 19, 2000
This page is copyright © 2000 Paul Kuliniewicz. Copyright Information Revised October 29, 2000
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