Change ToolTip font

Question

I need a tooltip with custom Font.

I have the following code, and this works... but the tooltip size does not fit the text.

Where is the error?

Public Class KeolisTooltip
  Inherits ToolTip

  Sub New()
    MyBase.New()
    Me.OwnerDraw = True
    AddHandler Me.Draw, AddressOf OnDraw
  End Sub

  Private _Font As Font
  Public Property Font() As Font
    Get
      Return _Font
    End Get
    Set(ByVal value As Font)
      _Font = value
    End Set
  End Property

  Public Sub New(ByVal Cont As System.ComponentModel.IContainer)
    MyBase.New(Cont)
    Me.OwnerDraw = True
    AddHandler Me.Draw, AddressOf OnDraw
  End Sub


  Private Sub OnDraw(ByVal sender As Object, ByVal e As DrawToolTipEventArgs)
    Dim newArgs As DrawToolTipEventArgs

    If _Font Is Nothing Then
      newArgs = e
    Else
      Dim newSize As Size = Size.Round(e.Graphics.MeasureString(e.ToolTipText, Me._Font))
      Dim newBounds As New Rectangle(e.Bounds.Location, newSize)

      newArgs = New DrawToolTipEventArgs( _
         e.Graphics, _
         e.AssociatedWindow, _
         e.AssociatedControl, _
         newBounds, _
         e.ToolTipText, _
         Me.BackColor, _
         Me.ForeColor, _
         Me._Font)
    End If

    newArgs.DrawBackground()
    newArgs.DrawBorder()
    newArgs.DrawText()
  End Sub

End Class

Answer 1

Size.Round (from the MSDN page)

Converts the specified SizeF structure to a Size structure by rounding the values of the SizeF structure to the nearest integer values.

(my emphasis).

Therefore, if

e.Graphics.MeasureString(e.ToolTipText, Me._Font)

produces values of 23.4 and 42.1 (say) then they will be rounded to 23 and 42 respectively so your tooltip will be slightly too small.

Answer 2

Could you try to add the resizing logic on the OnResize event in addition to the OnDraw event? I think you will get the correct values on that event. Just try and let know if it works.