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Custom WaterMark TextBox for Windows Forms - VB.Net

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This article explains how to create and use a custom WaterMark textbox class.  The custom WaterMark textbox class allows you to set the WaterMark Background Color and WaterMark text at design time.  

IMAGE OF WATERMARKS

Form with textboxes and watermarks
STEPS

1. Create VB class


Create a new VB class in your solution and name it WaterMarkTextBox.vb

2. Copy VB code to new class


Copy the code from the snippet below to your new class
Option Strict On
Imports System
Imports System.Windows.Forms
Imports System.Drawing
Public Class WaterMarkTextBox
    Inherits TextBox
 
    Private oldFont As Font = Nothing
    Private waterMarkTextEnabled As Boolean = False
 
#Region "Attributes"
    Private _waterMarkColor As Color = Drawing.Color.Gray
 
    Public Property WaterMarkColor() As Color
        Get
            Return _waterMarkColor
        End Get
        Set(ByVal value As Color)
            _waterMarkColor = value
            Me.Invalidate()
        End Set
    End Property
 
    Private _waterMarkText As String = "Water Mark"
 
    Public Property WaterMarkText() As String
        Get
            Return _waterMarkText
        End Get
        Set(ByVal value As String)
            _waterMarkText = value
            Me.Invalidate()
        End Set
    End Property
#End Region
 
    ' Default constructor
    Public Sub New()
        JoinEvents(True)
    End Sub
 
    Private Sub JoinEvents(ByVal join As Boolean)
        If join Then
            AddHandler (TextChanged), AddressOf WaterMark_Toggle
            AddHandler (LostFocus), AddressOf WaterMark_Toggle
            AddHandler (FontChanged), AddressOf WaterMark_FontChanged
            'No one of the above events will start immeddiatlly 
            'TextBox control still in constructing, so,
            'Font object (for example) couldn't be catched from within WaterMark_Toggle
            'So, call WaterMark_Toggel through OnCreateControl after TextBox is totally created
            'No doupt, it will be only one time call
 
            'Old solution uses Timer.Tick event to check Create property
        End If
    End Sub
 
    Private Sub WaterMark_Toggle(ByVal sender As Object, ByVal args As EventArgs)
        If Me.Text.Length <= 0 Then
            EnableWaterMark()
        Else
            DisableWaterMark()
        End If
    End Sub
 
    Private Sub WaterMark_FontChanged(ByVal sender As Object, ByVal args As EventArgs)
        If waterMarkTextEnabled Then
            oldFont = New Font(Font.FontFamily, Font.Size, Font.Style, Font.Unit)
            Refresh()
        End If
    End Sub
 
    Private Sub EnableWaterMark()
        'Save current font until returning the UserPaint style to false (NOTE: It is a try and error advice)
        oldFont = New Font(Font.FontFamily, Font.Size, Font.Style, Font.Unit)
 
        'Enable OnPaint Event Handler
        Me.SetStyle(ControlStyles.UserPaint, True)
        Me.waterMarkTextEnabled = True
 
        'Trigger OnPaint immediatly
        Refresh()
 
    End Sub
 
    Private Sub DisableWaterMark()
        'Disbale OnPaint event handler
        Me.waterMarkTextEnabled = False
        Me.SetStyle(ControlStyles.UserPaint, False)
 
        'Return oldFont if existed
        If Not oldFont Is Nothing Then
            Me.Font = New Font(Font.FontFamily, Font.Size, Font.Style, Font.Unit)
        End If
    End Sub
 
    ' Override OnCreateControl 
    Protected Overrides Sub OnCreateControl()
        MyBase.OnCreateControl()
        WaterMark_Toggle(Nothing, Nothing)
    End Sub
 
    ' Override OnPaint
    Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
        ' Use the same font that was defined in base class
        Dim drawFont As Font = New Font(Font.FontFamily, Font.Size, Font.Style, Font.Unit)
        ' Create new brush with gray color or 
        Dim drawBrush As SolidBrush = New SolidBrush(Me.WaterMarkColor) 'use WaterMarkColor
        ' Draw Test or WaterMark
        e.Graphics.DrawString(IIf(waterMarkTextEnabled, WaterMarkText, Text).ToString(), drawFont, drawBrush, New Point(0, 0))
        MyBase.OnPaint(e)
    End Sub
 
End Class

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3. Compile application to use new WaterMarkTextBox control


Compile the application.  You should now see a "<Your Project Name> Components" section on your toolbox with a tool called WaterMarkTextBox

4. Use the new WaterMarkTextBox control


Drag the new control from your toolbox onto your form and you can set the properties in the properties window (WaterMarkColor, WaterMarkText)

3
Author:Rhino1272
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