TaskbarNotifier, a skinnable MSN Messenger-like popup in C# and now in VB.NET too

void SetCloseBitmap(string strFilename, 
            Color transparencyColor, Point position)

Sets the 3-State close button bitmap, its transparency color and its coordinates.

Parameters

• strFilename: Path of the 3-state close button bitmap on the disk (width must be a multiple of 3)
• transparencyColor: Color of the bitmap which won't be visible
• position: Location of the close button on the popup

void SetCloseBitmap(Image image, Color transparencyColor, Point position)

Sets the 3-State close button bitmap, its transparency color and its coordinates.

Parameters

• image: Image/Bitmap object which represents the 3-state close button bitmap (width must be a multiple of 3)
• transparencyColor: Color of the bitmap which won't be visible
• position: Location of the close button on the popup

Properties

string TitleText (get/set)
string ContentText (get/set)
TaskbarStates TaskbarState (get)
Color NormalTitleColor (get/set)
Color HoverTitleColor (get/set)
Color NormalContentColor (get/set)
Color HoverContentColor (get/set)
Font NormalTitleFont (get/set)
Font HoverTitleFont (get/set)
Font NormalContentFont (get/set)
Font HoverContentFont (get/set)
Rectangle TitleRectangle (get/set) //must be defined before calling show())
Rectangle ContentRectangle (get/set) //must be defined before calling show())
bool TitleClickable (get/set) (default = false);
bool ContentClickable (get/set) (default = true);
bool CloseClickable (get/set) (default = true);
bool EnableSelectionRectangle (get/set) (default = true);

Events

event EventHandler CloseClick
event EventHandler TitleClick
event EventHandler ContentClick

Technical issues

The popup is skinned using a region generated dynamically from a bitmap and a transparency color:

protected Region BitmapToRegion(Bitmap bitmap, Color transparencyColor)
{
    if (bitmap == null)
        throw new ArgumentNullException("Bitmap", "Bitmap cannot be null!");

    int height = bitmap.Height;
    int width = bitmap.Width;

    GraphicsPath path = new GraphicsPath();

    for (int j=0; j<height; j++ )
        for (int i=0; i<width; i++)
        {
            if (bitmap.GetPixel(i, j) == transparencyColor)
                continue;

            int x0 = i;

            while ((i < width) && 
                    (bitmap.GetPixel(i, j) != transparencyColor))
                i++;

            path.AddRectangle(new Rectangle(x0, j, i-x0, 1));
        }

    Region region = new Region(path);
    path.Dispose();
    return region;
}

The refresh() of the popup is done using the double buffering technique to avoid flickering:

protected override void OnPaintBackground(PaintEventArgs pea)
{
    Graphics grfx = pea.Graphics;
    grfx.PageUnit = GraphicsUnit.Pixel;

    Graphics offScreenGraphics;
    Bitmap offscreenBitmap;

    offscreenBitmap = new Bitmap(BackgroundBitmap.Width, 
                                BackgroundBitmap.Height);
    offScreenGraphics = Graphics.FromImage(offscreenBitmap);

    if (BackgroundBitmap != null)
    {
        offScreenGraphics.DrawImage(BackgroundBitmap, 
            0, 0, BackgroundBitmap.Width, BackgroundBitmap.Height);
    }

    DrawCloseButton(offScreenGraphics);
    DrawText(offScreenGraphics);

    grfx.DrawImage(offscreenBitmap, 0, 0);
}

Bugs/Limitations

Since I wanted to keep only managed code, I used the Screen.GetWorkingArea(WorkAreaRectangle) function instead of using unmanaged code to get the taskbar position. As a result, I made the popup always appear at the bottom of WorkAreaRectangle whichever position the taskbar has.

I didn't find any C# managed equivalent to the Win32 function ShowWindow(SW_SHOWNOACTIVATE) to make the popup, not steal the focus of the active window.

Updates

• 01 April 2003: Small bug fix in the OnMouseUp handler.
• 11 January 2003: Patrick Vanden Driessche updated both the C# and VB.NET versions:
  • The popup now doesn't close automatically when the mouse is still over it
  • The popup is shown again when it was disappearing and the mouse comes over it
  • A few other bugs have been corrected.
• 10 January 2003: A port of TaskbarNotifier has been done by Patrick Vanden Driessche in VB.NET
• 05 December 2002: The popup is now shown using the Win32 function ShowWindow(SW_SHOWNOACTIVATE), to prevent the popup from stealing the focus.

Conclusion

I hope this code will be useful to you. If you have suggestions to enhance this class functionalities, please post a comment.