Question

I’m creating a custom ToolTip that will bold the first line of text if the text is multi-line. I’m also using the VisualStyleRenderer to draw the tool tip correctly with styles. However, when I draw the text (even with TextFormatFlags.VerticalCenter set), it draws at the top of the box. I was going to just bump the bounding box down 2 pixels (which fixed it on Windows 7) but I wasn’t 100% sure how portable that would be to another OS. Does anyone know how to draw the text vertically centered correctly?

EDIT: To make this clear, I know this code doesn’t bold the first line. I’m trying to first replicate a standard tooltip, and then afterwards do the bolding.

public class BoldedFirstLineToolTip : ToolTip
{
    public BoldedFirstLineToolTip()
    {
        this.OwnerDraw = true;
        this.Draw += new DrawToolTipEventHandler(OnDraw);
    }

    private void OnDraw(object sender, DrawToolTipEventArgs e)
    {
        // Try to draw using the visual style renderer.
        if (VisualStyleRenderer.IsElementDefined(VisualStyleElement.ToolTip.Standard.Normal))
        {
            var renderer = new VisualStyleRenderer(VisualStyleElement.ToolTip.Standard.Normal);
            renderer.DrawBackground(e.Graphics, e.Bounds);

            var b = e.Bounds;
            // b.Y + 2 // This works when using e.Graphics.DrawString.
            renderer.DrawText(e.Graphics, b, e.ToolTipText, false /*drawDisabled*/, 
                TextFormatFlags.HorizontalCenter | TextFormatFlags.VerticalCenter);
        }
        else
        {
            // Fall back to non-visual style drawing.
            e.DrawBackground();
            e.DrawBorder();
            e.DrawText();
        }
    }   
}

Answer 1

I’ve decided to just use padding fixes. I’ve provided my full solution below. I tested on both XP and Windows 7.

public class BoldedFirstLineToolTip : ToolTip
{
    public BoldedFirstLineToolTip()
    {
        this.OwnerDraw = true;
        this.Draw += new DrawToolTipEventHandler(OnDraw);
    }

    private void OnDraw(object sender, DrawToolTipEventArgs e)
    {
        // Try to draw using the visual style renderer.
        if (VisualStyleRenderer.IsSupported && VisualStyleRenderer.IsElementDefined(VisualStyleElement.ToolTip.Standard.Normal))
        {
            var bounds = e.Bounds;
            var renderer = new VisualStyleRenderer(VisualStyleElement.ToolTip.Standard.Normal);
            renderer.DrawBackground(e.Graphics, bounds);

            var color = renderer.GetColor(ColorProperty.TextColor);

            var text = e.ToolTipText;

            using (var textBrush = new SolidBrush(renderer.GetColor(ColorProperty.TextColor)))
            using (var font = e.Font)
            {
                // Fix the positioning of the bounds for the text rectangle.
                var rendererBounds = new Rectangle(e.Bounds.X + 6, e.Bounds.Y + 2, e.Bounds.Width - 6 * 2, e.Bounds.Height - 2 * 2);

                if (!text.Contains('\n'))
                {
                    renderer.DrawText(e.Graphics, rendererBounds, text);
                }
                else
                {
                    var lines = text.Split('\n').Select(l => l.Trim());
                    var first = lines.First();
                    var otherLines = Environment.NewLine + String.Join(Environment.NewLine, lines.Skip(1).ToArray());

                    // Draw the first line.
                    using (var boldFont = new Font(font, FontStyle.Bold))
                    {
                        e.Graphics.DrawString(first, boldFont, textBrush, rendererBounds.X - 1, rendererBounds.Y - 1);
                    }

                    renderer.DrawText(e.Graphics, rendererBounds, otherLines, false /*drawDisabled*/, TextFormatFlags.Left);
                }

            }
        }
        else
        {
            // Fall back to non-visual style drawing.
            e.DrawBackground();
            e.DrawBorder();
            using (var sf = new StringFormat())
            {
                sf.LineAlignment = StringAlignment.Center;
                e.Graphics.DrawString(e.ToolTipText, SystemFonts.DialogFont, Brushes.Black, e.Bounds, sf);
            }
        }
    }
}