PDFsharp DrawString line height

Question

I am using PDFsharp (http://www.pdfsharp.net/) to draw a string to a PDF file. I want the text to be placed at position (0,0) but when it is rendered to the PDF, the X position is at 0, but the top of the text is offset down. I think this is due to the line height of the font because when I highlight the text I can see that the highlight extends beyond the top and bottom. How can I get PDFsharp to position the text without the padding at the top so the top of the text is sitting right on the edge of the label?

This is a snippet of the code that I am using for drawing the text:

XFont font = new XFont(text.Font, 
              XUnit.FromMillimeter(text.Height), XFontStyle.Regular);

gfx.DrawString(text.Content, font, textLayer,
                new XPoint(XUnit.FromMillimeter(0), XUnit.FromMillimeter(0)), 
                 XStringFormats.TopLeft);

Answer 1

The padding is part of the font. Some characters have diacritical marks - some even have two, one stacked on top of the other.

You can draw "u", "A", "Ä" or "Ǻ" - and they will all share the same base-line.

I don't know if you can query the height of the ascender from the font to have the top bar of the "T" at the 0 line.
In the worst case you can measure the "padding" in the resulting PDF file and use that as an offset to draw the string at a negative position.
However, if the text varies you may lose important diacritical marks.

Answer 2

This is what I ended up doing. Convert the string into a XGraphicsPath. Then use the GdiPath to get the min/max points on each side of the text. After I got those, I was able to figure out where the top of the highest letter was and subtract the difference from where the original position (with the padding) was supposed to be. Then I can draw the actual text offset by that value.

XGraphicsPath path = new XGraphicsPath();
    XFont font = new XFont(text.Font, XUnit.FromMillimeter(text.Height), XFontStyle.Regular);
    //path.AddString with my string details

    PointF[] points = path.Internals.GdiPath.PathPoints;

    foreach (PointF point in points)
    {
        //Get leftmost point x value
        if (minX == null || point.X < minX)
        {   
            minX = point.X;
        }

        //Get top most point y value
        if (minY == null || point.Y < minY)
        {
            minY = point.Y;
        }

        //Get top most point y value
        if (maxX == null || point.X > maxX)
        {
            maxX = point.X;
        }

        //Get bottom most point y value
        if (maxY == null || point.Y > maxY)
        {
            maxY = point.Y;
        }
    }