 While
the standard VB5 text box offers more properties than its VB3 and VB4 counterparts, there remain some styles and messages that can only be
set via the API. Styles require changing the edit class default style using SetWindowLong, while the messages use the workhorse SendMessage
to add the functionality.
This code shows how to manipulate the styles to convert typed input
into upper or lower case, or to force the control to limit its input to numbers only. This last style is explicit .. numbers means
numbers .. so no decimal points or commas can be entered. The messages used in this demo set the control to read only (similar to the
now-available Locked property in VB5), perform an undo from code (you can testing if undoing is possible using the EM_CANUNDO message first),
and an odd one .. EM_SCROLLCARET. |
Option Explicit
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Copyright ©1996-2011 VBnet/Randy Birch, All Rights Reserved.
' Some pages may also contain other copyrights by the author.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Distribution: You can freely use this code in your own
' applications, but you may not reproduce
' or publish this code on any web site,
' online service, or distribute as source
' on any media without express permission.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Private Const GWL_STYLE As Long = (-16)
'edit styles used
Private Const ES_UPPERCASE As Long = &H8&
Private Const ES_LOWERCASE As Long = &H10&
Private Const ES_NUMBER As Long = &H2000
'edit messages used
Private Const EM_SETREADONLY As Long = &HCF
Private Const EM_UNDO As Long = &HC7
Private Const EM_SCROLLCARET As Long = &HB7
Private Const EM_SETSEL As Long = &HB1
Private Declare Function GetWindowLong Lib "user32" _
Alias "GetWindowLongA" _
(ByVal hwnd As Long, _
ByVal nIndex As Long) As Long
Private Declare Function SetWindowLong Lib "user32" _
Alias "SetWindowLongA" _
(ByVal hwnd As Long, _
ByVal nIndex As Long, _
ByVal dwNewLong As Long) As Long
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
Dim defstyle As Long
Private Sub Form_Load()
'store the default textbox style for
'use later in the option button routines
defstyle = GetWindowLong(Text1.hwnd, GWL_STYLE)
'force a form show so the SetFocus call
'in the option routine won't generate
'an error
Show
'check the first item
Option1(0).Value = True
End Sub
Private Sub Command2_Click()
Unload Me
End Sub
Private Sub Text1_GotFocus()
'uncomment this to have the textbox
'select all text on focus
'Call SendMessage(Text1.hwnd, EM_SETSEL, 0&, ByVal -1&)
End Sub
Private Sub Check1_Click()
'EM_SETREADONLY
'Prevents the user from typing or editing
'text in the edit control. Disables the
'cut and paste commands on the textbox
'context menu.
'if the check button is checked (value=1)
'then state is true, else state is false.
'Pass state as the wParam member of the
'message.
Dim state As Long
state = Check1.Value = 1
Call SendMessage(Text1.hwnd, EM_SETREADONLY, _
state, ByVal 0&)
Text1.SetFocus
End Sub
Private Sub Command1_Click(index As Integer)
Select Case index
Case 0 'EM_UNDO
'An application sends an EM_UNDO message to
'undo the last edit control operation.
'
'wParam and lParam are not used and must be 0.
Call SendMessage(Text1.hwnd, EM_UNDO, 0, ByVal 0)
Case 1: 'EM_SCROLLCARET
'An application sends an EM_SCROLLCARET
'message to scroll the caret into view
'in an edit control.
'
'To bring the caret into view, wParam and
'lParam which are reserved, must be 0.
Call SendMessage(Text1.hwnd, EM_SCROLLCARET, 0, ByVal 0)
End Select
Text1.SetFocus
End Sub
Private Sub Option1_Click(index As Integer)
'reset to the default style for the textbox
Call SetWindowLong(Text1.hwnd, GWL_STYLE, defstyle)
'apply the new style
Select Case index
Case 0: 'nothing to do .. it was done above
Case 1: 'ES_NUMBER
'Allows only digits to be entered
'into the edit control.
Call SetWindowLong(Text1.hwnd, GWL_STYLE, _
defstyle Or ES_NUMBER)
Case 2: 'ES_UPPERCASE
'Converts all characters to upper case
'as they are typed into the edit control.
'Does not affect existing text.
Call SetWindowLong(Text1.hwnd, GWL_STYLE, _
defstyle Or ES_UPPERCASE)
Case 3: 'ES_LOWERCASE
'Converts all characters to lower case
'as they are typed into the edit control.
'Does not affect existing text.
Call SetWindowLong(Text1.hwnd, GWL_STYLE, _
defstyle Or ES_LOWERCASE)
End Select
Text1.SetFocus
End Sub |
