can't I set transparency of a window by its handle in c#?
-
13-09-2019 - |
Question
i am trying to set transparency of all windows. I have following code.
public partial class Form1 : Form
{
[DllImport("user32.dll")]
static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);
[DllImport("user32.dll")]
static extern int GetWindowLong(IntPtr hWnd, int nIndex);
[DllImport("user32.dll")]
static extern bool SetLayeredWindowAttributes(IntPtr hwnd, uint crKey, byte bAlpha, uint dwFlags);
public const int GWL_EXSTYLE = -20;
public const int WS_EX_LAYERED = 0x80000;
public const int LWA_ALPHA = 0x2;
public Form1()
{
InitializeComponent();
this.Load += new EventHandler(Form1_Load);
}
private void Form1_Load(object sender, EventArgs e)
{
Process[] processlist = Process.GetProcesses();
foreach (Process theprocess in processlist)
{
SetWindowLong(theprocess.Handle, GWL_EXSTYLE,
GetWindowLong(theprocess.Handle, GWL_EXSTYLE) ^ WS_EX_LAYERED);
SetLayeredWindowAttributes(theprocess.Handle, 0, 128, LWA_ALPHA);
}
}
}
nothing happens when I execute the code.
What is wrong??
Solution
SetWindowLong
takes a window handle (hWnd), but you're passing it a process handle instead.
Change all instances of
theprocess.Handle
to
theProcess.MainWindowHandle
After changing that, it worked on the Windows XP machine I tested it on. Now I'm gonna have to modify the code to get the windows back to normal ;) Luckily, the Visual Studio 2010 window was unaffected.
OTHER TIPS
This part of your code: ^ WS_EX_LAYERED
flips the WS_EX_LAYERED bit,
I think you want: | WS_EX_LAYERED
Have you tried setting the Opacity?
this.Opacity = 0.50;
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