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Posted 12 Nov 2008


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Extended NumericUpDown Control

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23 Sep 2020CPOL5 min read
An extended NumericUpDown control with better focus and mouse wheel management.

Image 1


If you have ever written a data-entry application, there's a big chance you used the NumericUpDown control. This control is great to provide a field to enter numeric values, with advanced features like up-down buttons and accelerating auto-repeat.

The other side of the coin is that NumericUpDown is not really mouse-aware. I experienced some bugs and bad behaviors:

  • I need to select all the text when it gets focus (see below), but it misses some of the TextBox properties, like SelectedText, SelectionStart, SelectionLength (an AutoSelect property will be useful).
  • Some of the standard events are not working properly (see below): MouseEnter, MouseLeave.
  • Rotating the mouse wheel when the control is focused causes its value to change. A property to change this behavior, like InterceptArrowsKeys for up/down keys, will be useful.

That's why I decided to subclass it, fixing these points and adding missing features and properties.

Missing TextBox Properties

I needed some missing TextBox properties when I was asked to select all the text in the control when it gets the focus.

Yes, NumericUpDown exposes a Select(int Start, int Length) method you can call to select all text. At first try, I attached to the GotFocus event to call Select(0, x) but, hey, wait a moment... what should I use for x? It seems that any value is accepted, even if greater than the text length. OK, let's say x=100 and proceed. This works well with the keyboard focus keys (like TAB), but it's completely useless with the mouse: a mouse click raises the GotFocus event (where I select all the text), but as soon as you release the button, a zero-selection is done, leaving the control with no selection. OK, I thought, let's add a SelectAll on the MouseUp event too, but this way, the user cannot perform a partial selection anymore; each time the mouse button is released, all the text is selected. I need to know if a partial selection exists; in a TextBox, I can test it with SelectionLength > 0, so I need to access the underlying TextBox control.

Now comes the tricky part: NumericUpDown is a composite control, a TextBox and a button box. Looking inside it through the Reflector, we can find the internal field which holds the textbox part:

Friend upDownEdit As UpDownEdit  ' UpDownEdit inherits from TextBox

We'll obtain a reference to this field using the underlying Controls() collection. Note that we should add some safety checks because future .NET Framework implementations could change things.

''' <summary>
''' object creator
''' </summary>
Public Sub New()
    ' get a reference to the underlying UpDownButtons field
    ' Underlying private type is System.Windows.Forms.UpDownBase+UpDownButtons
    _upDownButtons = MyBase.Controls(0)
    If _upDownButtons Is Nothing _
           OrElse _upDownButtons.GetType().FullName <> _
           "System.Windows.Forms.UpDownBase+UpDownButtons" Then
        Throw New ArgumentNullException(Me.GetType.FullName & _
        ": Can't a reference to internal UpDown buttons field.")
    End If
    ' Get a reference to the underlying TextBox field.
    ' Underlying private type is System.Windows.Forms.UpDownBase+UpDownButtons
    _textbox = TryCast(MyBase.Controls(1), TextBox)
    If _textbox Is Nothing _
           OrElse _textbox.GetType().FullName <> _
           "System.Windows.Forms.UpDownBase+UpDownEdit" Then
        Throw New ArgumentNullException(Me.GetType.FullName & _
        ": Can't get a reference to internal TextBox field.")
    End If
End Sub 

Now that we have the underlying TextBox, it is possible to export some missing properties:

Public Property SelectionStart() As Integer
        Return _textbox.SelectionStart
    End Get
    Set(ByVal value As Integer)
        _textbox.SelectionStart = value
    End Set
End Property

And finally, we can have a perfectly working mouse management:

' MouseUp will kill the SelectAll made on GotFocus.
' Will restore it, but only if user have not made
' a partial text selection.
Protected Overrides Sub OnMouseUp(ByVal mevent As MouseEventArgs)
    If _autoSelect AndAlso _textbox.SelectionLength = 0 Then
    End If
End Sub

Mouse Events Not Raised Properly

The original MouseEnter and MouseLeave events are raised in couples: a MouseEnter immediately followed by a MouseLeave. Maybe that's why, to discourage their use, they are marked with a <Browsable(False)> attribute. Since I need the MouseEnter event to update my StatusBar caption, I investigated a little on this "bug".

As said above, NumericUpDown is a composite control (red rectangle in the following picture) containing a TextBox (left green rectangle) and some other controls:

Image 2

The "control" area is the one between the red and the green rectangles; when you fly over it with the mouse, you'll receive the MouseEnter event while between the red and the green, then MouseLeave when inside the green rectangle. The same happens when you leave.

The better way to raise these events, now that we can access the underlying TextBox, is to re-raise the MouseEnter and MouseLeave events as raised from the TextBox itself; this is what NumericUpDownEx does.

MouseWheel Management

NumericUpDown's management of the mouse wheel is, sometimes, really annoying. Suppose you have an application which displays some kind of chart, with a topmost dialog (toolbox) to let the user change some parameters of the graph. In this dialog, the only controls which can keep the focus are NumericUpDown ones:

Image 3

After your user puts the focus inside one of them, the mouse wheel is captured by the NumericUpDown. When the user wheels to, say, scroll the graph, the effect is that the focused field value is changed; this behavior is really annoying.

A fix could be to kill the WM_MOUSEWHEEL message for the control, but this will kill even "legal" wheelings.

The NumericUpDown has a property which allows WM_MOUSEWHEEL messages to pass only if the mouse pointer is over the control, making sure that the user is wheeling to change the control value.

This is done by keeping track of the mouse state in the MouseEnter-MouseLeave events, then killing WM_MOUSEWHEEL messages accordingly.

Image 4

How to Use the Control

Simply include NumericUpDownEx.vb in your project and use the control like you'll do with the standard NumericUpDown. If you have a C# project, you could reference the CoolSoft.NumericUpDownEx.dll assembly or, better, try to convert the code to C# (it should not be so difficult). I could provide a C# version upon request.


v1.6 (06/Jan/2016)

  • Added "Never" value to ShowUpDownButtonsMode enum to always hide UpDown spinner control

v1.5 (28/Mar/2014)

  • Removed reflection code, now underlying controls are retrieved with managed code only (thanks to JWhattam for this suggestion)

v1.4 (17/Dec/2012)

  • New option to show up/down buttons when the control has focus (regardless of mouseover), thanks to Fred Kreppert for his suggestion

v1.3 (15/Mar/2010)

  • Added new WrapValue property: when set, if Maximum is reached during an increment, Value will restart from Minimum (and vice versa)
    (feature suggested by YosiHakel here)
  • Cleaned up the C# version

v1.2 (10/Feb/2010)

  • Added two new events BeforeValueDecrement and BeforeValueIncrement, as suggested by andrea@gmi. This will allow to give different increment/decrement depending on the current control value
  • Added a C# version of the control to the ZIP


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Claudio Nicora
Technical Lead CoolSoft
Italy Italy
I started programming in the early 1984, when I was 12, using each and every version of VB, from QuickBasic (1985) to VB.NET 11.0, but also C#, C++, PHP, JavaScript, Fortran, Pascal, Modula2, together with a lot of frameworks like Symfony, jQuery, Drupal.

My most popular project is VirtualMIDISynth, a software MIDI synthesizer (using .sf2 soundfont files) implemented as a virtual device driver. It works on all modern Windows OS from XP to 8, both 32 and 64 bit.

Another project of mine is DeCodEx (DEsigner CODe EXtractor), a free tool to split VisualStudio 2003 forms and controls source code into the new 2005/2008 partial classes format (*.vb and *.Designer.vb, or *.cs and *.Designer.cs).

I like writing tools to make my seveloper and SysAdmin life easier.

You can find them here:

Comments and Discussions

SuggestionMore enhancements ... Pin
geth447-Nov-18 7:38
Membergeth447-Nov-18 7:38 
BugMore enhancements (bug correction) ... Pin
geth449-Nov-18 0:15
Membergeth449-Nov-18 0:15 
Found a small bug: if Value is null and control enabled or disabled, text is show again, so added this code to correct it.

protected override void OnEnabledChanged(EventArgs e)
    if (this.Nullable && IsNull)
        _textbox.Text = "";

GeneralRe: More enhancements ... Pin
Fred Kreppert12-Dec-18 8:16
MemberFred Kreppert12-Dec-18 8:16 
Bugmouse event control not correct. Pin
Dong Fei4-Jan-18 16:26
MemberDong Fei4-Jan-18 16:26 
Questionbutton width Pin
Konstantin Samsonov22-Jan-17 0:51
MemberKonstantin Samsonov22-Jan-17 0:51 
QuestionReally nice control Pin
us471114-Jan-16 7:35
Memberus471114-Jan-16 7:35 
AnswerRe: Really nice control Pin
Claudio Nicora14-Jan-16 10:19
MemberClaudio Nicora14-Jan-16 10:19 
QuestionPermanently Hide The Spinner? Pin
MJ_Karas6-Jan-16 4:39
MemberMJ_Karas6-Jan-16 4:39 
AnswerRe: Permanently Hide The Spinner? Pin
Claudio Nicora6-Jan-16 10:19
MemberClaudio Nicora6-Jan-16 10:19 
GeneralRe: Permanently Hide The Spinner? Pin
MJ_Karas6-Jan-16 17:43
MemberMJ_Karas6-Jan-16 17:43 
GeneralRe: Permanently Hide The Spinner? Pin
Claudio Nicora7-Jan-16 3:02
MemberClaudio Nicora7-Jan-16 3:02 
QuestionDecimal places hide when the up down arrows hide... Also, tab doesnt cause validation (standard nud issue) Pin
DDnDD25-Aug-15 7:13
MemberDDnDD25-Aug-15 7:13 
AnswerRe: Decimal places hide when the up down arrows hide... Also, tab doesnt cause validation (standard nud issue) Pin
Claudio Nicora25-Aug-15 22:31
MemberClaudio Nicora25-Aug-15 22:31 
QuestionNumericUpDOwn control in c# Pin
Member 939044415-May-15 0:32
MemberMember 939044415-May-15 0:32 
AnswerRe: NumericUpDOwn control in c# Pin
Claudio Nicora15-May-15 1:31
MemberClaudio Nicora15-May-15 1:31 
GeneralRe: NumericUpDOwn control in c# Pin
Member 939044415-May-15 2:44
MemberMember 939044415-May-15 2:44 
SuggestionEasier way to access contained controls Pin
JWhattam25-Mar-14 17:45
MemberJWhattam25-Mar-14 17:45 
GeneralRe: Easier way to access contained controls Pin
Claudio Nicora27-Mar-14 23:21
MemberClaudio Nicora27-Mar-14 23:21 
GeneralRe: Easier way to access contained controls Pin
Claudio Nicora25-Aug-15 22:25
MemberClaudio Nicora25-Aug-15 22:25 
Questionx86 to x64 produces designer errors? Pin
codetowns23-Jun-13 0:36
Membercodetowns23-Jun-13 0:36 
AnswerRe: x86 to x64 produces designer errors? Pin
Claudio Nicora23-Jun-13 20:55
MemberClaudio Nicora23-Jun-13 20:55 
GeneralRe: x86 to x64 produces designer errors? Pin
codetowns23-Jun-13 21:24
Membercodetowns23-Jun-13 21:24 
GeneralMouse wheel usage Pin
cvogt6145720-Mar-13 3:35
Membercvogt6145720-Mar-13 3:35 
SuggestionAddtional feature - display updown buttons with focus Pin
Fred Kreppert15-Dec-12 8:14
MemberFred Kreppert15-Dec-12 8:14 
GeneralRe: Addtional feature - display updown buttons with focus Pin
Claudio Nicora17-Dec-12 1:33
MemberClaudio Nicora17-Dec-12 1:33 

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