C#

David935 wrote:

You had streamlined my example a bit

        // private float mmToInches = 1.0f / 25.4f;
// private float xMultiplyer = mmToInches * e.Graphics.DpiX;
// private float yMultiplyer = mmToInches * e.Graphics.DpiY;
// private Rectangle rect = new Rectangle(LabelElement.Left, LabelElement.Top, LabelElement.Width, LabelElement.Height);

//Draw(e.Graphics, rect, xMultiplyer, yMultiplyer, someRichText);

public static void Draw(Graphics graphics, RectangleF mm, float xScale, float yScale, string richText)
{
    float mmToTwips = (1f / 10f) * 567f; // 567 twips per cm, 1440 twips per inch 

    RichTextBox edit = new RichTextBox();
    edit.Rtf = richText;

    SafeNativeMethods.RECT twips;
    twips.Left = 0;
    twips.Top = 0;
    twips.Right = (int)(mm.Width * mmToTwips);
    twips.Bottom = (int)(mm.Height * mmToTwips);

    using (Bitmap drawArea = new Bitmap((int)(twips.Right), (int)(twips.Bottom)))
    {
        using (Graphics drawAreaGraphics = Graphics.FromImage(drawArea))
        {
            IntPtr hdc = drawAreaGraphics.GetHdc();

            SafeNativeMethods.FORMATRANGE fmtRange;
            fmtRange.chrg.cpMax = -1;           //Indicate character from to character to 
            fmtRange.chrg.cpMin = 0;
            fmtRange.hdc = hdc;                 //Use the same DC for measuring and rendering
            fmtRange.hdcTarget = hdc;           //Point at printer hDC
            fmtRange.rc = twips;                //Indicate the area on page to print
            fmtRange.rcPage = twips;            //Indicate size of page

            IntPtr wParam = IntPtr.Zero;
            wParam = new IntPtr(1);

            //Get the pointer to the FORMATRANGE structure in memory
            IntPtr lParam = IntPtr.Zero;
            lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(fmtRange));
            Marshal.StructureToPtr(fmtRange, lParam, false);

            SafeNativeMethods.SendMessage(edit.Handle, SafeNativeMethods.EM_FORMATRANGE, wParam, lParam);

            //Free the block of memory allocated
            Marshal.FreeCoTaskMem(lParam);

            //Release the device context handle obtained by a previous call
            drawAreaGraphics.ReleaseHdc(hdc);
        }
        graphics.DrawImage(drawArea, mm.Left * xScale, mm.Top * yScale);
    }
}

private string ScaleRtf(string text, double scale) {
	log(text);
	int lastPosition=-1;
	for (; ; ) {
		int i=text.IndexOf(@"\fs", lastPosition+1);
		if (i<0) break;
		lastPosition=i;
		log("Found fs at "+i);
		int fs=0;

		for (i+=3; ; i++) {
			char c=text[i];
			int j="0123456789".IndexOf(c);
			if (j<0) break;
			fs=10*fs+j;
		}
		int newFs=ScaleUp(fs, scale);
		text=text.Substring(0, lastPosition)+@"\fs"+newFs.ToString()+text.Substring(i);
		log(text);
	}
	return text;
}

private int ScaleUp(int fs, double scale) {
	return (int)(fs*scale+0.5);
}

private void log(string s) { }

using System;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        System.Timers.Timer timer;
        public Form1()
        {
            InitializeComponent();
            timer = new System.Timers.Timer();
            timer.Elapsed += new System.Timers.ElapsedEventHandler(timer_Elapsed);
            timer.Start();
        }

        void timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
        {
            /* System.InvalidOperationException "Cross-thread operation not valid..."
            will be thrown if you try to alter the property directly from a different thread */
            if (this.InvokeRequired)
            {
                BeginInvoke(new MethodInvoker(delegate() { UpdateText(sender, e); }));
            }
            else
            {
                UpdateText(sender, e);
            }
        }
        private void UpdateText(object sender, System.Timers.ElapsedEventArgs e)
        {
            Text = e.SignalTime.ToString();
        }
    }
}