How to use LoadImage

[karmeye]

I'm trying to load an icon to set in the Windows taskbar, using this code:

public static void LoadIcon(Window window, string iconName)
{
	string iconPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, iconName);

	if (!File.Exists(iconPath))
		return;

	var hwnd = new HWND(GetWindowHandle(window));

	using var hIcon = PInvoke.LoadImage(null, iconPath, GDI_IMAGE_TYPE.IMAGE_ICON, 128, 128, IMAGE_FLAGS.LR_LOADFROMFILE);

	var handle = hIcon.DangerousGetHandle();
	if (handle != 0)
	{
		PInvoke.SendMessage(hwnd, PInvoke.WM_SETICON, new WPARAM(PInvoke.ICON_BIG), new LPARAM(handle));
	}

	//PInvoke.DestroyIcon(handle);
}

• Whether I call SendMessage or not, I get SEHException.
• If I do not dispose (with using) I eventually get a exception with message: "External component has thrown an exception."
• Is it related to SEHException when disposing SafeHandle obtained from LoadImage #715 ?

Is there any workaround?

Thanks

[AArnott]

I wonder if you're expected to keep the icon valid for the life of it being displayed on the taskbar, rather than disposing of it. I also see you calling DangerousGetHandle without calling DangerousAddRef, which may be a problem for non-deterministic disposal by the runtime.
Your pointing out #715 is apt. You should probably avoid the SafeHandle overload altogether.

[karmeye]

Say I needed to keep it retain for the lifetime of the application, how would I correctly get the handle of the icon and then, how would I dispose it when the application exits?

[AArnott]

If you avoid the SafeHandle overload altogether, there won't be a SafeHandle to worry about releasing or finalizing. The native HANDLE you get back would typically need to be released when you're done with it, but if you want it for the lifetime of your application, you don't ever have to release it because closing the process has the OS implicitly release it. So you can call the LoadImage overload that returns a HANDLE and then just drop the result (after using it in SendMessage).