Show Text on ProgressBar

Question

Hi,

To show different text strings on my ProgressBar at runtime, I have this code which prints a static text on ProgressBar, I need to add a Text property to the ProgressBar, any idea how to implement properly?

Here's the full ProgressBar class:

Public NotInheritable Class ProgressBarZ
    Inherits ProgressBar
    Public Sub New()
        MyBase.New()
        Style = ProgressBarStyle.Continuous
    End Sub
    Protected Overrides ReadOnly Property CreateParams As CreateParams
        Get
            Dim MyCP As CreateParams = MyBase.CreateParams
            MyCP.ExStyle = MyCP.ExStyle Or &H200000 ' or &H2000000 ??? For WndProc Text on Progress
            Return MyCP
        End Get
    End Property
    Protected Overrides Sub WndProc(ByRef m As Message)
        MyBase.WndProc(m)
        If m.Msg = &HF Then AdditionalPaint(m) 'WM_PAINT
    End Sub
    Public Sub AdditionalPaint(ByVal m As Message)
        'If DisplayType = TextDisplayType.None Then
        '    Return
        'End If
        Dim text As String = "Blah blah"
        Using g As Graphics = Graphics.FromHwnd(Handle)
            Dim rect As New Rectangle(0, 0, Width, Height)
            Dim format As New StringFormat(StringFormatFlags.NoWrap) With {
                .Alignment = StringAlignment.Center,
                .LineAlignment = StringAlignment.Center
            }
            Using textBrush As New SolidBrush(Color.Black)
                g.DrawString(text, Font, textBrush, rect, format)
            End Using
        End Using
    End Sub
End Class

Thanks in advance :)

Answer 1

1. Add a public Text property to hold the text value.
2. Invalidate the control when the text changes to force a redraw.
3. Use that property in the AdditionalPaint method instead of the static string "Blah blah".

Here's the modified class with the dynamic text capability:

Public NotInheritable Class ProgressBarZ
    Inherits ProgressBar

    Private _displayText As String = String.Empty

    Public Sub New()
        MyBase.New()
        Style = ProgressBarStyle.Continuous
        SetStyle(ControlStyles.UserPaint, True) ' Optional: to take full control over painting
    End Sub

    Protected Overrides ReadOnly Property CreateParams As CreateParams
        Get
            Dim MyCP As CreateParams = MyBase.CreateParams
            MyCP.ExStyle = MyCP.ExStyle Or &H200000 ' WS_EX_TRANSPARENT
            Return MyCP
        End Get
    End Property

    Protected Overrides Sub WndProc(ByRef m As Message)
        MyBase.WndProc(m)
        If m.Msg = &HF Then AdditionalPaint(m) ' WM_PAINT
    End Sub

    ''' <summary>
    ''' Property to get/set the display text.
    ''' </summary>
    Public Property DisplayText As String
        Get
            Return _displayText
        End Get
        Set(value As String)
            If _displayText <> value Then
                _displayText = value
                Invalidate() ' Force redraw to update the text
            End If
        End Set
    End Property

    ''' <summary>
    ''' Paints the text on top of the progress bar.
    ''' </summary>
    Public Sub AdditionalPaint(ByVal m As Message)
        If String.IsNullOrEmpty(_displayText) Then Return

        Using g As Graphics = Graphics.FromHwnd(Handle)
            Dim rect As New Rectangle(0, 0, Width, Height)
            Dim format As New StringFormat(StringFormatFlags.NoWrap) With {
                .Alignment = StringAlignment.Center,
                .LineAlignment = StringAlignment.Center
            }
            Using textBrush As New SolidBrush(ForeColor)
                g.DrawString(_displayText, Font, textBrush, rect, format)
            End Using
        End Using
    End Sub
End Class

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hth

Marcin