Using GDI+, what's the easiest approach to align text (drawn in several different fonts) along a common baseline?

Question

My problem:

I'm currently working on a custom user control which displays pieces of text (each with a potentially different font) on one line. I'd like to align all those bits of text exactly along a common baseline. For example:

  Hello,    I am    George.  
------------------------------   <- all text aligns to a common baseline
    ^         ^        ^
    |         |        |
 Courier    Arial    Times       <- font used for a particular bit of text
  20pt      40pt     30pt

Because I haven't found any GDI+ functionality to do this directly, I came up with my own method (outlined below). However:

I wonder if there really isn't an easier way to get this done?

My current approach:

1) Gather a list of all System.Drawing.Fonts that will be used for drawing text.

2) For each Font, find the vertical position of the baseline in pixels, using the following code:

// variables used in code sample (already set)
Graphics G;
Font font;
...

// compute ratio in order to convert from font design units to pixels:
var designUnitsPerPixel = font.GetHeight(G) / 
                          font.FontFamily.GetLineSpacing(font.Style);

// get the cell ascent (baseline) position in design units:
var cellAscentInDesignUnits = font.FontFamily.GetCellAscent(font.Style);

// finally, convert the baseline position to pixels:
var baseLineInPixels = cellAscentInDesignUnits * designUnitsPerPixel;

3) For all Fonts used, determine the maximum baseLineInPixels value as computed above and store this value to maxBaseLineInPixels.

4) Draw each bit of text in the following manner:

// variables used in code sample (already set):
Graphics G;
Font font;
string text;
...

// find out how much space is needed for drawing the text
var measureF = G.MeasureString(text, font);

// determine location where text will be drawn:
var layoutRectF = new RectangleF(new PointF(0f, 0f), measureF);
layoutRectF.Y += maxBaseLineInPixels - baseLineInPixels;
// ^ the latter value 'baseLineInPixels' is specific to the font used

// draw text at specified location
G.DrawString(text, font, Brushed.Black, layoutRectF);

Am I missing something, or is there really no easier way?

Glean

Thanks for your feedback. I'm relieved to hear (well... :) that drawing text with GDI+ actually is that complicated and that I'm not just imagining this. I've since decided to drop this issue and go onward to WPF (where GDI+ no longer matters and things will hopefully be a little easier). – Glean

Answer 1

I thinks this way is work , please you try.

List<RectangleF> rects = new List<RectangleF>();

private void Form1_Paint(object sender, PaintEventArgs e)
{
    ////////////////////Not Set baseLine
    //baseline
    e.Graphics.DrawLine(Pens.Red , new Point(100,200),new Point(800,200));

    //words
    Point point = new Point(100,100);
    e.Graphics.DrawString("hello world", new Font("Times", 30), Brushes.Black, point);
    RectangleF rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Times", 30)));
    e.Graphics.DrawRectangle(Pens.Green,rectangleF.X ,rectangleF.Y , rectangleF.Width , rectangleF.Height);
    rects.Add(rectangleF);

    point = new Point(400, 100);
    e.Graphics.DrawString("hello world", new Font("Arial", 40), Brushes.Black, point);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Arial", 40)));
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

    point = new Point(800, 100);
    e.Graphics.DrawString("hello world", new Font("Courier", 20), Brushes.Black, point);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Courier", 20)));
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

    ///////////////////SetBaseLine/////////////////////////////
    var maxHeight = GetMaxHeight();
    ///////////////////

    //baseLine
    e.Graphics.DrawLine(Pens.Pink, new Point(100, (int) (400 + maxHeight / 2)), new Point(800, (int) (400 + maxHeight / 2)));

    StringFormat stringFormat = new StringFormat();
    stringFormat.LineAlignment = StringAlignment.Center;

    //words
    point = new Point(100, 400);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Times", 30)));
    e.Graphics.DrawString("hello world", new Font("Times", 30), Brushes.Black, new RectangleF(rectangleF.X ,rectangleF.Y , rectangleF.Width , maxHeight) , stringFormat);
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

    point = new Point(400, 400);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Arial", 40)));
    e.Graphics.DrawString("hello world", new Font("Arial", 40), Brushes.Black, new RectangleF(rectangleF.X, rectangleF.Y, rectangleF.Width, maxHeight), stringFormat);
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

    point = new Point(800, 400);
    rectangleF = new RectangleF(point, e.Graphics.MeasureString("hello world", new Font("Courier", 20)));
    e.Graphics.DrawString("hello world", new Font("Courier", 20), Brushes.Black, new RectangleF(rectangleF.X, rectangleF.Y, rectangleF.Width, maxHeight), stringFormat);
    e.Graphics.DrawRectangle(Pens.Green, rectangleF.X, rectangleF.Y, rectangleF.Width, rectangleF.Height);
    rects.Add(rectangleF);

}

private float GetMaxHeight()
{
    float temp = 0;
    foreach (RectangleF rectangleF in rects)
        if (rectangleF.Height > temp)
            temp = rectangleF.Height;

    return temp;
}

Kei

Thanks for posting. However, this solution is unfortunately not helpful... sorry. This is for two reasons: 1. I've long since given up on this (see the original posting date) and decided to switch to WPF instead. 2. I suspect that there's some good approaches in your code (MeasureString, GetMaxHeight); unfortunately, most of the remaining code suggests something else, namely that you're working purely with pre-calculated fixed coordinates and drawing text twice (which seems unnecessary). Nevertheless, thanks for taking the time to answer. – Glean

Answer 2

I've been researching the same thing for the last few days, and I finally found an answer on this blog page. This code (at the bottom of the article) worked really well for me and hopefully helps anyone else struggling with this problem:

private void DrawOnBaseline(string s, Graphics g, Font f, Brush b, Point pos)
    {
      float baselineOffset=f.SizeInPoints/f.FontFamily.GetEmHeight(f.Style)*f.FontFamily.GetCellAscent(f.Style);
      float baselineOffsetPixels = g.DpiY/72f*baselineOffset;

      g.DrawString(s,f,b,new Point(pos.X,pos.Y-(int)(baselineOffsetPixels+0.5f)),StringFormat.GenericTypographic);
    }

Feeney