This article was previously published under Q149276
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SUMMARY
The Windows API provides the ability to add, modify, and remove icons from
the System Tray, or Taskbar Notification Area, available in the Windows 95, Windows 98, Windows Me, Windows NT 4.0, and Windows 2000 shell. This
functionality can be provided using only the Shell_NotifyIcon function that
is exported by Shell32.dll. This API function also provides the ability to
specify a text string for the ToolTip that is displayed when a user pauses
with the mouse pointer over the icon. The step-by-step example in this
article creates a Visual Basic program which demonstrates how to use this
API function.
The ability to take some action if the icon in the Taskbar Notification Area is clicked depends on a callback function. Because Visual Basic 4.0 does not support callback functions directly, there is no way to show a form or execute some code using solely Visual Basic 4.0. This functionality was added in Visual Basic 5.0 (and later) with the addition of the AddressOf operator. A number of options are available to Visual Basic 4.0 developers that can provide callback functionality, including the Message Blaster OCX, the OCX mentioned in the Microsoft Systems Journal article noted in the "References" section of this article, or the Callback OLE server that is detailed in Bruce McKinney's book, Hardcore Visual Basic. For more information on any of these options, see the "References" section. Because these products do not include Visual Basic, Microsoft Product Support Services does not support their use.
Change the form's icon property to the icon that should be shown in the Taskbar Notification Area.
3.
Draw three CommandButtons onto the form.
4.
Select Module from the Insert menu to add a single code module to the
project.
5.
Add the following code, consisting of function, type, and constant
declarations, to Module1:
Type NOTIFYICONDATA
cbSize As Long
hWnd As Long
uID As Long
uFlags As Long
uCallbackMessage As Long
hIcon As Long
szTip As String * 64
End Type
Global Const NIM_ADD = 0
Global Const NIM_MODIFY = 1
Global Const NIM_DELETE = 2
Global Const NIF_MESSAGE = 1
Global Const NIF_ICON = 2
Global Const NIF_TIP = 4
Declare Function Shell_NotifyIconA Lib "SHELL32" _
(ByVal dwMessage As Long, lpData As NOTIFYICONDATA) As Integer
6.
The following code is a function that takes the parameters that need to
be set for the NOTIFYICONDATA type and returns a variable of this type.
Add to Form1:
Private Function setNOTIFYICONDATA(hWnd As Long, ID As Long, _
Flags As Long, CallbackMessage As Long, Icon As Long, _
Tip As String) As NOTIFYICONDATA
Dim nidTemp As NOTIFYICONDATA
nidTemp.cbSize = Len(nidTemp)
nidTemp.hWnd = hWnd
nidTemp.uID = ID
nidTemp.uFlags = Flags
nidTemp.uCallbackMessage = CallbackMessage
nidTemp.hIcon = Icon
nidTemp.szTip = Tip & Chr$(0)
setNOTIFYICONDATA = nidTemp
End Function
7.
The three procedures in this block of code call the function created in step 5 to add, modify, and remove Taskbar Notification Area icons. Add this code to Form1 also:
Private Sub Command1_Click()
'Add an icon. This procedure uses the icon specified in
'the Icon property of Form1. This can be modified as desired.
Dim i As Integer
Dim s As String
Dim nid As NOTIFYICONDATA
s = InputBox("Enter string:")
nid = setNOTIFYICONDATA(hWnd:=Form1.hWnd, _
ID:=vbNull, _
Flags:=NIF_MESSAGE Or NIF_ICON _
Or NIF_TIP, _
CallbackMessage:=vbNull, _
Icon:=Form1.Icon, _
Tip:=s)
i = Shell_NotifyIconA(NIM_ADD, nid)
End Sub
Private Sub Command2_Click()
'Modify an existing icon. This procedure uses the icon
'specified in the Icon property of Form1. This can be modified
'as desired.
Dim i As Integer
Dim s As String
Dim nid As NOTIFYICONDATA
s = InputBox("Enter string:")
nid = setNOTIFYICONDATA(hWnd:=Form1.hWnd, _
ID:=vbNull, _
Flags:=NIF_MESSAGE Or NIF_ICON _
Or NIF_TIP, _
CallbackMessage:=vbNull, _
Icon:=Form1.Icon, _
Tip:=s)
i = Shell_NotifyIconA(NIM_MODIFY, nid)
End Sub
Private Sub Command3_Click()
'Delete an existing icon.
Dim i As Integer
Dim nid As NOTIFYICONDATA
nid = setNOTIFYICONDATA(hWnd:=Form1.hWnd, _
ID:=vbNull, _
Flags:=NIF_MESSAGE Or NIF_ICON _
Or NIF_TIP, _
CallbackMessage:=vbNull, _
Icon:=Form1.Icon, _
Tip:="")
i = Shell_NotifyIconA(NIM_DELETE, nid)
End Sub
8.
Press the F5 key or select Start from the Run menu to run the
application. Click the first button and enter a text string to add an
icon. Click the second button to modify an existing icon, and the third
to delete the icon.
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