问题
TL;DR: Did GetWindowText win32 api change behavior on windows 10?
I have some code that loops through all windows on the desktop to find a window where the title contains some text.
When this code hits a window named "" with class "URL Moniker Notification Window" it hangs on GetWindowText.
GetWindowText is trying to send a message, my guess is WM_GETTEXT.
This window is part of the exe "SearchUI.exe", the process is suspended and can't process messages.
When reading: https://blogs.msdn.microsoft.com/oldnewthing/20030821-00/?p=42833/ according to rule 2, this should not happen.
This code has been working fine for years. (win 7, 8, 8.1)
So did GetWindowText change behavior in Windows 10?
Update: The code in question.
public static int HwndGet(string partialTitle, string klassenavn)
{
partialTitle = partialTitle ?? "";
var cTitleTemp = new StringBuilder(255);
var hWndTemp = FindWindowEx((IntPtr)0, (IntPtr)0, null, null);
var nypartialTitle = partialTitle.ToUpper();
while (hWndTemp != (IntPtr)0)
{
GetWindowText(hWndTemp, cTitleTemp, cTitleTemp.Capacity);
string sTitleTemp = cTitleTemp.ToString();
sTitleTemp = sTitleTemp.ToUpper();
if (sTitleTemp.StartsWith(nypartialTitle, StringComparison.CurrentCultureIgnoreCase))
{
var className = new StringBuilder(255);
GetClassName(hWndTemp, className, 255);
//sTitleTemp: " + sTitleTemp + " ClassName: " + ClassName);
if (className.ToString().StartsWith(klassenavn, StringComparison.CurrentCultureIgnoreCase))
{
return (int)hWndTemp;
}
}
hWndTemp = GetWindow(hWndTemp, GwHwndnext);
}
return 0; // does not find the window
}
Stack trace:
回答1:
The code you are using isn't "safe". There is no guarantee that the order of the windows won't change between calls to FindWindowsEx
and GetWindow(GwHwndnext)
. For this reason there is another API, EnumWindows
, that is "safe". You could try with it.
Here there is a sample program (based on the one found here).
public static class WndSearcher
{
public static IntPtr SearchForWindow(string wndclass, string title)
{
var sd = new SearchData { Wndclass = wndclass, Title = title };
EnumWindows(sd.EnumWindowsProc, IntPtr.Zero);
return sd.hWndFound;
}
private class SearchData
{
// You can put any dicks or Doms in here...
public string Wndclass;
public string Title;
public IntPtr hWndFound;
public bool EnumWindowsProc(IntPtr hWnd, IntPtr lParam)
{
// Check classname and title
var sb = new StringBuilder(1024);
int res = GetClassName(hWnd, sb, sb.Capacity);
if (res == 0)
{
throw new Win32Exception();
}
if (sb.ToString().StartsWith(Wndclass, StringComparison.CurrentCultureIgnoreCase))
{
sb.Clear();
res = GetWindowText(hWnd, sb, sb.Capacity);
if (res == 0)
{
int error = Marshal.GetLastWin32Error();
if (error != 0)
{
throw new Win32Exception(error);
}
}
if (sb.ToString().StartsWith(Title, StringComparison.CurrentCultureIgnoreCase))
{
hWndFound = hWnd;
// Found the wnd, halt enumeration
return false;
}
}
return true;
}
}
[return: MarshalAs(UnmanagedType.Bool)]
private delegate bool EnumWindowsProc(IntPtr hWnd, IntPtr lParam);
[DllImport("user32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
private static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount);
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
private static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int nMaxCount);
}
and then use it like
IntPtr ptr = WndSearcher.SearchForWindow("classname", "windowname");
来源:https://stackoverflow.com/questions/35893314/getwindowtext-hangs-on-windows-10