77.txt

介绍VB里的各种控件的使用方法,窗口控制,图像编程以及OCX等内容,还提供了一个API集供参考.

将长ListBox项显示为ToolTip
Showing long ListBox entries as a ToolTip
By Matt Vandenbush, [e-mail] 
Sometimes the data you want to display in a list is too long for the size of ListBox you can use. When this happens, you can use some simple code to display the ListBox entries as ToolTips when the mouse passes over the ListBox. 

First, start a new VB project and add a ListBox to the default form. Then declare the SendMessage API call and the constant (LB_ITEMFROMPOINT) needed for the operation: 

Option Explicit 

注释：Declare the API function call.
Private Declare Function SendMessage _
Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Long, _
lParam As Any) As Long
注释： Add API constant
Private Const LB_ITEMFROMPOINT = &H1A9 

Next, add some code to the form load event to fill the ListBox with data: 

Private Sub Form_Load()
注释：
注释： load some items in the list box
With List1
.AddItem "Michael Clifford Amundsen"
.AddItem "Walter P.K. Smithworthy, III"
.AddItem "Alicia May Sue McPherson-Pennington"
End With
注释：
End Sub 

Finally, in the MouseMove event of the ListBox, put the following code: 

Private Sub List1_MouseMove(Button As Integer, Shift As Integer, _
X As Single, Y As Single)
注释：
注释： present related tip message
注释：
Dim lXPoint As Long
Dim lYPoint As Long
Dim lIndex As Long
注释：
If Button = 0 Then 注释： if no button was pressed
  lXPoint = CLng(X / Screen.TwipsPerPixelX)
  lYPoint = CLng(Y / Screen.TwipsPerPixelY)
  注释：
  With List1
    注释： get selected item from list
    lIndex = SendMessage(.hwnd, _
    LB_ITEMFROMPOINT, _
    0, _
    ByVal ((lYPoint * 65536) + lXPoint))
    注释： show tip or clear last one
    If (lIndex >= 0) And (lIndex <= .ListCount) Then
      .ToolTipText = .List(lIndex)
    Else
      .ToolTipText = ""
    End If
  End With 注释：(List1)
End If 注释：(button=0)
注释：
End Sub