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public static extern bool SetLayeredWindowAttributes(IntPtr hwnd, uint crKey, byte bAlpha, uint dwFlags);
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
public enum LayeredWindowFlags
LWA_ALPHA = 0x00000002,
LWA_COLORKEY = 0x00000001,
A layered window is created by specifying WS_EX_LAYERED when creating the window with the
CreateWindowEx function or by setting WS_EX_LAYERED via SetWindowLong after the window has been created.
Windows 8: The WS_EX_LAYERED style is supported for top-level windows and child windows. Previous Windows versions support WS_EX_LAYERED only for top-level windows.
Tips & Tricks:
C# 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:
If you just want to change the transparency of a Form you own, then use the Opacity property.
The SetLayeredWindowAttributes API
11/26/2021 2:16:59 AM - -188.8.131.52
Like CreateWindow, but creates the window with an extended window style.
12/23/2022 5:31:17 AM - 184.108.40.206
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