Q198880: FIX: Cannot Simultaneously Set DTPicker’s MinDate And MaxDate
Article: Q198880
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:6.0
Operating System(s):
Keyword(s): kbservicepack kbAPI kbCtrl kbGrpDSUser kbVBp kbVBp600bug kbGrpDSVB kbVS600sp2 kbVS600SP
Last Modified: 11-JAN-2001
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The information in this article applies to:
- Microsoft Visual Basic Learning Edition for Windows, version 6.0
- Microsoft Visual Basic Professional Edition for Windows, version 6.0
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0
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SYMPTOMS
========
When you programmatically set the DateTimePicker's MinDate property, any current
setting for the MaxDate property is lost. Conversely, setting the MaxDate
property causes a loss of the MinDate's setting.
CAUSE
=====
When an attempt is made to set either the MinDate or MaxDate properties, a
SendMessage API call is made to send the "DTM_SETRANGE" message to the control
to inform it of the new date range settings. This message can be used to set the
date range in one of three ways:
- Establish a minimum date with no maximum date.
- Establish a maximum date with no minimum date.
- Establish both a minimum and maximum date.
The MinDate and MaxDate properties that are exposed to the Visual Basic
programmer correspond directly to the first two methods. The DateTimePicker
control does not offer any property that directly corresponds to the third
method, thus leaving no way to set both a MinDate and a MaxDate at the same time
through the control's object model.
This problem does not affect setting the MinDate and MaxDate properties at design
time.
RESOLUTION
==========
Because there is no exposed property or method for setting MinDate and MaxDate
at the same time, a direct call to the SendMessage API must be made to manually
send the "DTM_SETRANGE" message with the appropriate information.
The parameters for this message consist of setting wParam to represent the
part(s) of the date range you are setting; "GDTR_MIN" for the minimum date,
"GDTR_MAX" for the maximum date, or the combination of both constants for
setting the minimum and maximum dates at the same time. The lParam must be set
to point to a two element array of SYSTEMTIME structures. The first element is
for specifying the minimum date information and the second element is for the
maximum date information.
STATUS
======
Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.
This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information
about Visual Studio service packs, please see the following articles in the
Microsoft Knowledge Base:
Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why
Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed
MORE INFORMATION
================
Steps to Reproduce Behavior
---------------------------
1. Create a new Standard EXE project. Form1 is created by default.
2. From the Project menu, choose References, select "Microsoft Windows Common
Controls - 2 6.0", and then click OK.
3. Add a DTPicker control to Form1.
4. Add five command buttons to Form1.
5. Paste the following code into Form1's Code window:
Option Explicit
Private Sub Command1_Click()
' Set DTPicker MinDate through normal means.
Me.DTPicker1.MinDate = "1/10/99"
End Sub
Private Sub Command2_Click()
'Set DTPicker MaxDate through normal means.
Me.DTPicker1.MaxDate = "1/17/99"
End Sub
Private Sub Command3_Click()
Dim TimeArray(1) As SYSTEMTIME
Dim result As Long
' Define first element of SYSTEMTIME Array to be minimum date.
TimeArray(0).wDay = 10
TimeArray(0).wMonth = 1
TimeArray(0).wYear = 1999
' Call API to send message to control to set MinDate.
result = SendMessage(Me.DTPicker1.hwnd, DTM_SETRANGE, _
GDTR_MIN, TimeArray(0))
End Sub
Private Sub Command4_Click()
Dim TimeArray(1) As SYSTEMTIME
Dim result As Long
' Define second element of SYSTEMTIME Array to be maximum date.
TimeArray(1).wDay = 17
TimeArray(1).wMonth = 1
TimeArray(1).wYear = 1999
' Call API to send message to control to set MaxDate.
result = SendMessage(Me.DTPicker1.hwnd, DTM_SETRANGE, _
GDTR_MAX, TimeArray(0))
End Sub
Private Sub Command5_Click()
Dim TimeArray(1) As SYSTEMTIME
Dim result As Long
' Define first element of SYSTEMTIME Array to be minimum date.
TimeArray(0).wDay = 10
TimeArray(0).wMonth = 1
TimeArray(0).wYear = 1999
' Define second element of SYSTEMTIME Array to be maximum date.
TimeArray(1).wDay = 17
TimeArray(1).wMonth = 1
TimeArray(1).wYear = 1999
' Call API to send message to control to set MinDate and MaxDate.
result = SendMessage(Me.DTPicker1.hwnd, DTM_SETRANGE, _
GDTR_MIN + GDTR_MAX, TimeArray(0))
End Sub
Private Sub Form_Load()
Me.Command1.Caption = "Set DTPicker MinDate Normally"
Me.Command2.Caption = "Set DTPicker MaxDate Normally"
Me.Command3.Caption = "Set DTPicker MinDate Via API"
Me.Command4.Caption = "Set DTPicker MaxDate Via API"
Me.Command5.Caption = "Set DTPicker Min and MaxDate Via API"
End Sub
6. From the Project menu, choose Add Module and add a standard Module to the
project.
7. Paste the following code into the module:
Option Explicit
Public Type SYSTEMTIME
wYear As Integer
wMonth As Integer
wDayOfWeek As Integer
wDay As Integer
wHour As Integer
wMinute As Integer
wSecond As Integer
wMilliseconds As Integer
End Type
Public 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 DTM_SETRANGE = &H1004&
Public Const GDTR_MIN = 1
Public Const GDTR_MAX = 2
8. Save and run the sample.
9. Try each button (based on their captions) and attempt to select a date
outside the specified range.
When setting a minimum date, the command buttons use the date "1/10/99" and
"1/17/99" is used when setting a maximum date.
The first two command buttons allow you to set either the MinDate or MaxDate but
not both concurrently. The third and fourth buttons perform the same as the
first two but they demonstrate how to set the MinDate or MaxDate using the API
instead of the properties. The last command button demonstrates using the API to
set both the MinDate and MaxDate at the same time.
Additional query words: Minimum Maximum Range kbcode
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Keywords : kbservicepack kbAPI kbCtrl kbGrpDSUser kbVBp kbVBp600bug kbGrpDSVB kbVS600sp2 kbVS600SP1 kbVS600sp3fix
Technology : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVBA600 kbVB600
Version : WINDOWS:6.0
Issue type : kbbug
Solution Type : kbfix
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