by Jon B. Mooty (4 Submissions)
Category: Miscellaneous
Compatability: Visual Basic 3.0
Difficulty: Advanced
Date Added: Wed 3rd February 2021
Rating: 
(2 Votes)
As you move your mouse pointer over top of a listbox this code will return the index and select the item underneath it.
API DeclarationsPrivate Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Const LB_GETITEMRECT = &H198
Private Type RECT
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type
'You will also need a ListBox named List1
VBcoders
Private Sub Form_Load()
Dim i As Integer
' populate the listbox with the
' indexes for each entry
For i = 0 To 50
List1.AddItem i, i
Next i
End Sub
Private Sub List1_MouseMove(Button As Integer, Shift As Integer, x As Single, y As Single)
Dim iSelected As Integer
' retrieve the index the mouse
' pointer is over (-1 represents
' mouse is over nothing)
iSelected = GetListItemFromPt(List1, x, y)
' select the item the mouse
' is currently over
If Not iSelected = -1 Then
List1.ListIndex = iSelected
End If
End Sub
Public Function GetListItemFromPt(plist As ListBox, x As Single, y As Single) As Integer
Dim bFound As Boolean
Dim rCur As RECT
Dim iIndex As Integer
Dim iPixX As Integer, iPixY As Integer
' convert the coordinates to
' pixels (remove the next two
' lines if you will be passing
' the coordinates in pixels)
iPixX = Me.ScaleX(x, vbTwips, vbPixels)
iPixY = Me.ScaleY(y, vbTwips, vbPixels)
For iIndex = 0 To plist.ListCount - 1
' get the coordinates for each
' item in the listbox in its current
' state, if Top is less than 0 or Bottom
'
' is greater than the height of the
' listbox then the item is currently off
' screen
SendMessage plist.hwnd, LB_GETITEMRECT, iIndex, rCur
' if passed corrdinates are within
' the bounds of the current item than
' exit the loop and return the index
If iPixY >= rCur.Top And iPixY <= rCur.Bottom Then
bFound = True
Exit For
End If
Next iIndex
If bFound Then
GetListItemFromPt = iIndex
Else
GetListItemFromPt = -1
End If
End Function