【转】VB 技巧一

改变 ListIndex而不发生 Click 事件

    在修改 Combo 或 Listview 的ListIndex 时， 会发生 Click 事件， 下面的函数可以阻止该事件。
    声明：
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
Const CB_GETCURSEL = &H147
Const CB_SETCURSEL = &H14E
Const LB_SETCURSEL = &H186
Const LB_GETCURSEL = &H188
    函数：
Public Function SetListIndex(lst As Control, _
ByVal NewIndex As Long) As Long
　
If TypeOf lst Is ListBox Then
Call SendMessage(lst.hWnd, _
LB_SETCURSEL, NewIndex, 0&)
SetListIndex = SendMessage(lst.hWnd, _
LB_GETCURSEL, NewIndex, 0&)
ElseIf TypeOf lst Is ComboBox Then
Call SendMessage(lst.hWnd, _
CB_SETCURSEL, NewIndex, 0&)
SetListIndex = SendMessage(lst.hWnd, _
CB_GETCURSEL, NewIndex, 0&)
End If
End Function

调整 Combo 下拉部分的宽度

    声明：
Private Declare Function SendMessage Lib _
"USER32" Alias "SendMessageA" _
(ByVal hwnd As Long, ByVal Msg As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long
Private Const CB_GETDROPPEDWIDTH = &H15F
Private Const CB_SETDROPPEDWIDTH = &H160
Private Const CB_ERR = -1
    函数：
' 取得 Combo 下拉的宽度
' 可以利用该函数比例放大或缩小宽度
Public Function GetDropdownWidth(cboHwnd As Long) As Long
Dim lRetVal As Long
lRetVal = SendMessage(cboHwnd, CB_GETDROPPEDWIDTH, 0, 0)
If lRetVal <> CB_ERR Then
GetDropdownWidth = lRetVal
'单位为 pixels
Else
GetDropdownWidth = 0
End If
End Function
'设置 Combo 下拉的宽度
'单位为 pixels
Public Function SetDropdownWidth(cboHwnd As _
Long, NewWidthPixel As Long) As Boolean
Dim lRetVal As Long
lRetVal = SendMessage(cboHwnd, _
CB_SETDROPPEDWIDTH, NewWidthPixel, 0)
If lRetVal <> CB_ERR Then
SetDropdownWidth = True
Else
SetDropdownWidth = False
End If
End Function

Combo的自动查询技术

Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Public Const CB_FINDSTRING = &H14C
Private Sub Combo1_Change()
Dim iStart As Integer
Dim sString As String
Static iLeftOff As Integer
iStart = 1
iStart = Combo1.SelStart
If iLeftOff <> 0 Then
Combo1.SelStart = iLeftOff
iStart = iLeftOff
End If
sString = CStr(Left(Combo1.Text, iStart))
Combo1.ListIndex = SendMessage(Combo1.hwnd, _
B_FINDSTRING, -1, ByVal CStr(Left( _
ombo1.Text, iStart)))
　
If Combo1.ListIndex = -1 Then
iLeftOff = Len(sString)
combo1.Text = sString
End If
Combo1.SelStart = iStart
iLeftOff = 0
End Sub
    静态变量 iLeftOff 指定了字符长度。

自动选择 Text 的内容

    在使用 VFP 的应用进行录入时，每进入一个录入框，就自动选择该框中的所有内容。利用以下的代码，也可实现类似的功能。
Private Sub MyTextBox_GotFocus()
AutoSelect MyTextBox
End Sub
　
Sub AutoSelect(SelObject As Control)
SelObject.SelStart = 0
If TypeOf SelObject Is MaskEdBox Then
SelObject.SelLength = Len(SelObject.FormattedText)
Else
If TypeOf SelObject Is TextBox Then
SelObject.SelLength = Len(SelObject.Text)
End If
End If
End Sub