int position = 12;
richedit1.Select( position, 0 );
richedit1.ScrollToCaret(); // if you want the position to be shown

It’s that simple.

         private void productNumber_KeyPress(object sender, KeyPressEventArgs e)
        {
            char c = e.KeyChar;
            // make it uppercase only
            if (c >= 'a' && c <= 'z')
            {
                int digit = (int)c;
                digit = digit - 'a' + 'A';
                e.KeyChar = Convert.ToChar(digit);
            }
        }

When the event handler is called it gives you a chance to edit the hit character. Just by changing e.KeyChar you change the actual input character. This is a nifty trick to have under your belt.

The techinque basically turns of drawing and events to the object on the win32 level underneath .Net.  This is very handy and it worked very very well.  Here is the code.

        using System.Runtime.InteropServices;
        private const int WM_SETREDRAW      = 0x000B;
        private const int WM_USER           = 0x400;
        private const int EM_GETEVENTMASK   = (WM_USER + 59);
        private const int EM_SETEVENTMASK   = (WM_USER + 69);

        [DllImport("user32", CharSet = CharSet.Auto)]
        private extern static IntPtr SendMessage(IntPtr hWnd, int msg, int wParam, IntPtr lParam);

        IntPtr eventMask = IntPtr.Zero;

        public void StopDrawing()
        {
            if (drawStopCount == 0)
            {
                // Stop redrawing:
                SendMessage(this.Handle, WM_SETREDRAW, 0, IntPtr.Zero);
                // Stop sending of events:
                eventMask = SendMessage(this.Handle, EM_GETEVENTMASK, 0, IntPtr.Zero);
            }
            drawStopCount++;
        }

        public void StartDrawing()
        {
            drawStopCount--;
            if (drawStopCount == 0)
            {
                // turn on events
                SendMessage(this.Handle, EM_SETEVENTMASK, 0, eventMask);

                // turn on redrawing
                SendMessage(this.Handle, WM_SETREDRAW, 1, IntPtr.Zero);

                Invalidate();
                Refresh();
            }
        }

// prepare to draw text

StringFormat sf = new StringFormat();

sf.Alignment = StringAlignment.Center;

sf.LineAlignment = StringAlignment.Center;// draw the text to a path

System.Drawing.Drawing2D.GraphicsPath path = new System.Drawing.Drawing2D.GraphicsPath();

path.AddString(text, Font.FontFamily, 0, 14.0f, fillRect, sf);

// fill in the outline

g.FillPath(Brushes.White, path);

// draw the outline

g.DrawPath(new Pen(Color.Black,2.0f) , path);

The first step is to add using System.Runtime.InteropServices; to you module. Then add the stubs for the libtiff functions as follows:

    static class TiffHandler
    {
        [DllImport("libtiff3.dll")]
        private static extern int TIFFOpen(String image_path, String opts);
        [DllImport("libtiff3.dll")]
        private static extern void TIFFClose(int handle);
        [DllImport("libtiff3.dll")]
        private static extern void TIFFGetField(int handle, uint property, ref UInt32 value );
        [DllImport("libtiff3.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
        private static extern int TIFFSetField(int handle, uint property, uint value);
        [DllImport("libtiff3.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
        private static extern int TIFFSetField(int handle, uint property, string value);
        [DllImport("libtiff3.dll")]
        private unsafe static extern int TIFFReadRGBAImage(int handle, UInt32 width, UInt32 height, byte *raster, int Unkown);
        [DllImport("libtiff3.dll")]
        private unsafe static extern int TIFFReadEncodedStrip(int handle, int strip, byte* buf, int size);
        [DllImport("libtiff3.dll")]
        private unsafe static extern byte* _TIFFmalloc(UInt32 size);
        [DllImport("libtiff3.dll")]
        private unsafe static extern void _TIFFfree(byte* pointer);
        [DllImport("libtiff3.dll")]
        private unsafe static extern void TIFFWriteEncodedStrip(int handle, int offset, byte* buffer, int size);
        [DllImport("libtiff3.dll")]
        private static extern uint TIFFScanlineSize(int handle);
        [DllImport("libtiff3.dll")]
        private static extern int TIFFDefaultStripSize(int handle, int size);
        [DllImport("libtiff3.dll")]
        private unsafe static extern int TIFFWriteScanline(int handle, byte* buffer, int row, int sample);
        [DllImport("libtiff3.dll")]
        private unsafe static extern int TIFFReadScanline(int handle, byte* data, int row, int sample);

Next we add the constants. I’m not going to add them all there are thousands of them but here is an example of the ones that are used in writting a tiff. If you want more look in the libtiff header files. It seems like it’s in tiff.h

        const uint TIFFTAG_IMAGEWIDTH = 256;	/* image width in pixels */
        const uint TIFFTAG_IMAGELENGTH	= 257;	/* image height in pixels */
        const uint TIFFTAG_BITSPERSAMPLE = 258;	/* bits per channel (sample) */
        const uint TIFFTAG_SAMPLESPERPIXEL = 277;	/* samples per pixel */
        const uint TIFFTAG_COMPRESSION	= 259;	/* data compression technique */
        const uint COMPRESSION_DEFLATE	= 32946;	/* Deflate compression */
        const uint PHOTOMETRIC_RGB = 2;	/* RGB color model */
        const uint TIFFTAG_PLANARCONFIG = 284;	/* storage organization */
        const uint PLANARCONFIG_CONTIG	= 1;	/* single image plane */

And then the code to write out the image to a file:

        public static unsafe void SaveTiff(string fileName, ImageArray array)
        {
            int tif = TIFFOpen(fileName, "w");
            int Samples = 3;

            TIFFSetField(tif, TIFFTAG_IMAGEWIDTH, (uint)array.Width);
            TIFFSetField(tif, TIFFTAG_IMAGELENGTH, (uint)array.Height);
            TIFFSetField(tif, TIFFTAG_COMPRESSION, COMPRESSION_DEFLATE);
            TIFFSetField(tif, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
            TIFFSetField(tif, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_RGB);
            TIFFSetField(tif, TIFFTAG_BITSPERSAMPLE, 16);
            TIFFSetField(tif, TIFFTAG_SAMPLESPERPIXEL, (uint)Samples);
            TIFFSetField(tif, TIFFTAG_ARTIST, "Bee Eee Inventions, LLC");

            int cnt = array.Width * array.Height;
            int size = (cnt * Samples * sizeof(ushort));
            ushort* buffer;

            buffer = (ushort*)_TIFFmalloc((uint)size);

            // We set the strip size of the file to be size of one row of pixels
            //int RowSize = TIFFDefaultStripSize(tif, array.Width*3);

            // copy data into buffer
            int i,pos,ptr=0;
            for (i = 0, pos = 0; i < cnt; i++, pos += Samples, ptr++)
            {
                buffer[pos] =  (ushort)(array.Data[ptr].r);
                buffer[pos + 1] = (ushort)(array.Data[ptr].g);
                buffer[pos + 2] = (ushort)(array.Data[ptr].b);
            }

            // Write the information to the file
            TIFFWriteEncodedStrip(tif, 0, (byte *)buffer, size);

            TIFFClose(tif);

            _TIFFfree((byte *)buffer);
        }

Enjoy. Next article I’ll show you how to read some tiff files. Opening all tiff files could be difficult. :)

The magic function is Graphics.MeasureString. This functions returns the calculated size of the string that is being drawn.

// measure the string
StringFormat sf = new StringFormat();
sf.Alignment = StringAlignment.Near;
sf.LineAlignment = StringAlignment.Near;
SizeF boundry = g.MeasureString(ToString(), font);

// draw the string
Rectangle textRect = new Rectangle(10, 10, (int)(boundry.Width + 2), (int)(boundry.Height + 2));
g.FillRectangle(Brushes.Black, textRect);
g.DrawRectangle(Pens.White, textRect);
g.DrawString(ToString(), font, Brushes.Yellow, textRect.X, textRect.Y, sf);

Adjusting brightness is just preforming a translate on the color data, and contrast is preforming a scale on the color. Gamma is a whole different form of transform, but it’s included in ImageAttributes which accepts the ColorMatrix.

So here’s the simple code:

            Bitmap origanalImage;
            Bitmap adjustedImage;
            double brightness = 1.0f; // no change in brightness
            double constrast = 2.0f; // twice the contrast
            double gamma = 1.0f; // no change in gamma

            float adjustedBrightness = brightness - 1.0f;
            // create matrix that will brighten and contrast the image
            float[][] ptsArray ={
                    new float[] {contrast, 0, 0, 0, 0}, // scale red
                    new float[] {0, contrast, 0, 0, 0}, // scale green
                    new float[] {0, 0, contrast, 0, 0}, // scale blue
                    new float[] {0, 0, 0, 1.0f, 0}, // don't scale alpha
                    new float[] {adjustedBrightness, adjustedBrightness, adjustedBrightness, 0, 1}};

            imageAttributes = new ImageAttributes();
            imageAttributes.ClearColorMatrix();
            imageAttributes.SetColorMatrix(new ColorMatrix(ptsArray), ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
            imageAttributes.SetGamma(gamma, ColorAdjustType.Bitmap);
            Graphics g = Graphics.FromImage(adjustedImage);
            g.DrawImage(originalImage, new Rectangle(0,0,adjustedImage.Width,adjustedImage.Height)
                ,0,0,bitImage.Width,bitImage.Height,
                GraphicsUnit.Pixel, imageAttributes);

So there it is. Simple enough isn’t it.

so again here’s how to enable double buffering on the form:

this.SetStyle(
          ControlStyles.AllPaintingInWmPaint |
          ControlStyles.UserPaint |
          ControlStyles.DoubleBuffer,true);

And then the override

protected override void OnPaintBackground(PaintEventArgs e)
{
}

However, in c# .Net there is a simple way to untangle the call stack of the message queue. Just use the BeginInvoke method. This unwinds the stack and uses a delegate to call your message reception handler from the control’s thread.

For instance:

delegate void PostOfficeMessageHandler( POMessage message );

public void SendMessage(Control Sender, POMessage Message)
{
    PostOfficeMessageHandler mh = recipients[Sender];
    Sender.BeginInvoke(mh, Message);
}

The advantages of this method of deliver are two fold. 1. The stack is unwound. 2. It makes message handler in the control’s threads solving some threading issues.

There are a couple of disadvantages. 1. Extra overhead. 2. If the message causes problems you may not know where it’s coming from!

Instead I had to create a global mouse hook so that no matter what control the mouse was over I could get a mouse event.

First was the code to import the hook function:

// create a mouse over eventstatic int WH_MOUSE_LL = 14;
[System.Runtime.InteropServices.DllImport("kernel32.dll")]
static extern IntPtr GetModuleHandle(string moduleName);

[System.Runtime.InteropServices.DllImport("user32.dll")]
static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hMod, uint dwThreadId);

[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern int UnhookWindowsHookEx(IntPtr hhook);

[System.Runtime.InteropServices.DllImport("user32.dll")]
static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, uint wParam, IntPtr lParam);
delegate IntPtr HookProc(int nCode, uint wParam, IntPtr lParam);

private HookProc hookProc;
private IntPtr hook;

Here is the event handler

IntPtr LowLevelMouseProc(int nCode, uint wParam, IntPtr lParam)
{
    // get the current mouse position
    Point p = Cursor.Position;

    // convert to client rectangle to screen position
    Rectangle r = RectangleToScreen(ClientRectangle);

    // check to see if mouse is within control bounds
    bool exp = (p.Y > r.Top && p.Y < r.Bottom && p.X > r.Left && p.X < r.Right);

    // adjust the expansion
    if (exp != Expanded)
         Expanded = exp;

    // Finished with this
    return CallNextHookEx(IntPtr.Zero, nCode, wParam, lParam);
}

Then the initialization code I put in the OnLoad event handler:

if (!DesignMode)
{
    hookProc = new HookProc(LowLevelMouseProc);
    hook = SetWindowsHookEx(WH_MOUSE_LL, hookProc, GetModuleHandle(null), 0);
}

And then code for closing in the OnHandleDestroyed event handler:

protected override void OnHandleDestroyed(EventArgs e)
{
        UnhookWindowsHookEx(hook);
        base.OnHandleDestroyed(e);
}

That should just about do it then. Now the UserControl can sense whether the mouse is overhead whether or not the mouse is over a child control.