Floating icon above desktop

Question

I'm writing a C# application and I want it to have a floating icon over the desktop (like the Facebook messenger in mobile).

I've been searching the internet but couldn't find anything useful. Any articles? Ideas?

Answer 1

You need to create a form without title bar and border and use an image as background of your form. Also make area around the image, transparent. Then make the form movable.

• Set the form FormBorderStyle to None
• Set the form TopMost to true
• You can also set ShowInTaskbar to false.
• Set an image as BackgroundImage and set BackgroundImageLayout to Center
• Set a suitable BackColor for form, for example if your BackGroundImage has Magenta color around, set the BackColor of form to Magenta.
• Set the TransparencyKey of form to the color you choose for BackColor

This way you will have a shaped form, for example a circle form (if your background image was circle shape).

Then to make the form move by dragging with left mouse button, write this code:

public const int WM_NCLBUTTONDOWN = 0xA1;
public const int HT_CAPTION = 0x2;

[DllImportAttribute("user32.dll")]
public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);
[DllImportAttribute("user32.dll")]
public static extern bool ReleaseCapture();

protected override void OnMouseDown(MouseEventArgs e)
{
    base.OnMouseDown(e);
    if (e.Button == MouseButtons.Left)
    {
        ReleaseCapture();
        SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
    }
}

And don't forget to add using System.Runtime.InteropServices;

Here is the image used:

And as you see in the result below, now we have a floating icon above other windows:

To have a high quality Icon with more smooth edges take a look at this post:

• C# Windows Form Transparent Background Image