a.cs

internal class CheckBoxEx : CheckBox
{
  private const float factor  = 0.6f;
  private const int  check    = 2;

  public Color DisableFore = SystemColors.GrayText;
  
  protected override void OnPaint( PaintEventArgs pevent )
  {
    base.OnPaint( pevent );

    // To clear the background, it is necessary to use a non-transparent color and
    // this type of controls usually are, so fetch the first parent's that is not
    var backColor = BackColor;

    while( backColor.A == 0 )
    {
      if( Parent == null )
      {
        break;
      }

      backColor = Parent.BackColor;
    }

    if( backColor.A == 0 )
    {
      // The back color is still transparent, so max the alpha component
      backColor = Color.FromArgb( 255, backColor.R, backColor.G, backColor.B );
    }

    pevent.Graphics.Clear( backColor );

    // Calculate the size of the box by using a large default character (since there could be no text
    // in the control) and neither that ClientRectangle or pevent.ClipRectangle might have a valid value
    var height     = TextRenderer.MeasureText( pevent.Graphics, "X", Font ).Height;
    var boxSide    = (int)( height * factor );
    var boxFrame   = new Rectangle( 0, ( height - boxSide ) / 2, boxSide, boxSide );
    var textFrame  = new Rectangle( boxFrame.Right + 2, 0, ClientRectangle.Width - boxFrame.Right - 2, height );

    if( Text.Length == 0 )
    {
      // The box cannot be aligned with non-existing text
      boxFrame.Y = 0;
    }

    // Draw box
    using var backBrush = new SolidBrush( BackColor );
    using var foreBrush = new SolidBrush( ForeColor );
    using var forePen   = new Pen( ForeColor );

    if( Enabled == false )
    {
      forePen.Color = foreBrush.Color = DisableFore;
    }
  
    pevent.Graphics.FillRectangle( backBrush, boxFrame );
    pevent.Graphics.DrawRectangle( forePen, boxFrame );

    if( Checked == true )
    {
      boxFrame.Offset( check, check );
      boxFrame.Width  -= check + 1;
      boxFrame.Height -= check + 1;
      pevent.Graphics.FillRectangle( foreBrush, boxFrame );
    }

    // Draw text
    if( Text.Length != 0 )
    {
      using var sf = new StringFormat
          {
            Alignment     = StringAlignment.Near,
            LineAlignment = StringAlignment.Center
          };

      pevent.Graphics.SmoothingMode = SmoothingMode.HighQuality;

      TextRenderer.DrawText( pevent.Graphics,
                             Text,
                             Font,
                             textFrame,
                             foreBrush.Color,
                             TextFormatFlags.Top | TextFormatFlags.Left );

      pevent.Graphics.SmoothingMode = SmoothingMode.None;

      if( Focused == true )
      {
        textFrame.Inflate( -1, 0 );

        ControlPaint.DrawFocusRectangle( pevent.Graphics, textFrame, foreBrush.Color, backBrush.Color );
      }
    }

    pevent.Dispose();
  }
}


internal class RadioButtonEx : RadioButton
{
  private const float factor  = 0.6f;
  private const int  check    = 3;

  public Color DisableFore = SystemColors.GrayText;

  protected override void OnPaint( PaintEventArgs pevent )
  {
    base.OnPaint( pevent );

    // To clear the background, it is necessary to use a non-transparent color and
    // this type of controls usually are, so fetch the first parent's that is not
    var backColor = BackColor;

    while( backColor.A == 0 )
    {
      if( Parent == null )
      {
        break;
      }

      backColor = Parent.BackColor;
    }

    if( backColor.A == 0 )
    {
      // The back color is still transparent, so max the alpha component
      backColor = Color.FromArgb( 255, backColor.R, backColor.G, backColor.B );
    }

    pevent.Graphics.Clear( backColor );

    // Calculate the size of the box by using a large default character (since there could be no text
    // in the control) and neither that ClientRectangle or pevent.ClipRectangle might have a valid value
    var height     = TextRenderer.MeasureText( pevent.Graphics, "X", Font ).Height;
    var boxSide    = (int)( height * factor );
    var boxFrame   = new Rectangle( 0, ( height - boxSide ) / 2, boxSide, boxSide );
    var textFrame  = new Rectangle( boxFrame.Right + 2, 0, ClientRectangle.Width - boxFrame.Right - 2, height );

    if( Text.Length == 0 )
    {
      // The box cannot be aligned with non-existing text
      boxFrame.Y = 0;
    }

    // Draw box
    pevent.Graphics.SmoothingMode = SmoothingMode.HighQuality;

    using var backBrush = new SolidBrush( BackColor );
    using var foreBrush = new SolidBrush( ForeColor );
    using var forePen   = new Pen( ForeColor );

    if( Enabled == false )
    {
      forePen.Color = foreBrush.Color = DisableFore;
    }

    pevent.Graphics.FillEllipse( backBrush, boxFrame );
    pevent.Graphics.DrawEllipse( forePen, boxFrame );

    if( Checked == true )
    {
      boxFrame.Offset( check, check );
      boxFrame.Width  -= check * 2;
      boxFrame.Height -= check * 2;
      pevent.Graphics.FillEllipse( foreBrush, boxFrame );
    }

    // Draw text
    if( Text.Length != 0 )
    {
      using var sf = new StringFormat
          {
            Alignment     = StringAlignment.Near,
            LineAlignment = StringAlignment.Center
          };

      TextRenderer.DrawText( pevent.Graphics,
                             Text,
                             Font,
                             textFrame,
                             foreBrush.Color,
                             TextFormatFlags.Top | TextFormatFlags.Left );

      pevent.Graphics.SmoothingMode = SmoothingMode.None;

      if( Focused == true )
      {
        textFrame.Inflate( -1, 0 );

        ControlPaint.DrawFocusRectangle( pevent.Graphics, textFrame, foreBrush.Color, backBrush.Color );
      }
    }

    pevent.Dispose();
  }
}