Library tutorials & articles
Subclassing
- Introduction
- Catching those messages!
- Using messages - MAXMIN INFO
- Using messages - MENU STATUS
- Other Messages
- Using SSubTmr
Using messages - MENU STATUS
Another example is giving status messages when the mouse cursor is over a menu item. This time, windows sends a WM_MENUSELECT message. Make sure your Form is named Form1 and you have a label called lblSel before starting.
'// extra constants and windows api
Public Const MF_BYCOMMAND = &H0&
Public Const MF_BYPOSITION = &H400&
Public Const MF_POPUP = &H10&
Public Const WM_MENUSELECT = &H11F
Declare Function GetMenuString Lib "user32" Alias "GetMenuStringA"
(ByVal hMenu As Long, ByVal wIDItem As Long, ByVal lpString As String, ByVal nMaxCount As
Long, ByVal wFlag As Long) As Long
Public Function WindowProc(ByVal hWnd As Long, ByVal iMsg As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long
'// ----WARNING----
'// do not attempt to debug this procedure!!
'// ----WARNING----
'// this is our implementation of the message handling routine
'// determine which message was recieved
Select Case iMsg
Case WM_MENUSELECT
'// This occurs when the menu is being closed
If lParam = 0 Then Exit Function
'// variables
Dim MenuItemStr As String * 128
Dim MenuHandle As Integer
'// Get the low word from wParam: this contains
the command ID or position of the menu entry
MenuHandle = GetLowWord(wParam)
'//If the highlighted menu is the top of a poup
menu, pass menu item by position
If (GetHighWord(wParam) And
MF_POPUP) =
MF_POPUP Then
'//Get the caption of
the menu item
If
GetMenuString(lParam, MenuHandle, MenuItemStr, 127, MF_BYPOSITION) = 0 Then Exit Function
Else '// Otherwise pass it by command ID
'//Get the caption of
the menu item
If
GetMenuString(lParam, MenuHandle, MenuItemStr, 127, MF_BYCOMMAND) = 0 Then Exit Function
End If
'// return item to label to remove any nulls
Form1.lblSelItem = MenuItemStr
'// display a message in a label
Select Case Form1.lblSelItem
Case "Item 1"
Form1.lblSelItem =
"Adds a Font"
Case Else
Form1.lblSelItem
= "Item Unknown: " & Form1.lblSelItem
End Select
Case Else
'// pass all messages on to VB and then return
the value to windows
WindowProc =
CallWindowProc(procOld, hWnd, iMsg, wParam, lParam)
End Select
End Function
Public Function GetLowWord(Word As Long)
GetLowWord = CInt("&H" & Right$(Hex$(Word), 4))
End Function
Public Function GetHighWord(Word As Long)
GetHighWord = CInt("&H" &
Left$(Hex$(Word), 4))
End Function
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Pretty hacky functions... Try these:
GetLowWord = Word Mod 65536
End Function
Public Function GetHighWord(Word As Long)
GetHighWord = (Word \ 65536) Mod 65536
End Function
Those will chop off the 1st/2nd and 3rd/4th bytes respectively using pure math. Much faster and more universal.
Hummmm..... This code looks surprisingly like the code in the GETMINMAXINFO example at http://www.mvps.org/vbvision/ Right down to the exact same comments! Coincidence? You be the judge!
http://www.vbaccelerator.com/home/VB/Code/Libraries/Subclassing/SSubTimer/article.asp
the link Download the SSubTmr project code (no DLL) (9kb) not working.
This thread is for discussions of Subclassing.