C# Signature:
[DllImport("user32.dll")]
static extern bool SetLayeredWindowAttributes(IntPtr hwnd, uint crKey,
byte bAlpha, uint dwFlags);
VB Signature:
Public Declare Auto Function SetLayeredWindowAttributes Lib "User32.Dll" _
(ByVal hWnd As IntPtr, ByVal crKey As Integer, ByVal Alpha As Byte, ByVal dwFlags As Integer) As Boolean
User-Defined Types:
None.
Notes:
This method may only be called on Windows 2000 and above.
Tips & Tricks:
Sample Code:
public const int GWL_EXSTYLE = -20;
public const int WS_EX_LAYERED = 0x80000;
public const int LWA_ALPHA = 0x2;
public const int LWA_COLORKEY = 0x1;
//set the window style to alpha appearance
private void button4_Click(object sender, EventArgs e)
{
SetWindowLong(Handle, GWL_EXSTYLE, GetWindowLong(Handle, GWL_EXSTYLE) ^ WS_EX_LAYERED);
SetLayeredWindowAttributes(Handle, 0, 128, LWA_ALPHA);
}
Alternative Managed API:
When setting Layered Window Attributes for window transparency, you can set the .Opacity property of your form instead.
