 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
.NET Forum / .NET Framework / .NET SDK / February 2005EnumWindows & returning data
Hi; When calling EnumWindows from C#, how do I get data back? The C++ way is to pass in a pointer as the second parameter and in the EnumProc cast the lParam to the appropiate pointer and set it. But C# won't let you do that.  Signaturethanks - dave Pass a delegate with the correct signature as first argument to the EnumWindows API. public delegate bool CallBack(IntPtr hwnd, int lParam); [DllImport("user32"), SuppressUnmanagedCodeSecurityAttribute] public static extern int EnumWindows(CallBack x, int y); ... // Call Win32 API passing a callback delegate (function pointer) EnumWindows(new CallBack(Report), 0); ... // This is the function that gets called by the API static void Report(IntPtr hwnd, int lParam) { ... } Willy. > Hi; > [quoted text clipped - 3 lines] > lParam > to the appropiate pointer and set it. But C# won't let you do that. Right, but how do I get data back from CallBack to the method that calls EnumWindows()? thanks - dave > Pass a delegate with the correct signature as first argument to the > EnumWindows API. [quoted text clipped - 23 lines] > > lParam > > to the appropiate pointer and set it. But C# won't let you do that. That data is the IntPtr hwnd, or what did you expect?. static void Report(IntPtr hwnd, int lParam) { Console.WriteLine(hwnd); } Willy. > Right, but how do I get data back from CallBack to the method that calls > EnumWindows()? [quoted text clipped - 29 lines] >> > lParam >> > to the appropiate pointer and set it. But C# won't let you do that. Right - I have the hwnd in Report. I am looking for a specific window so for each hwnd I do a GetWindowText() and when it has some specific text in the caption, I have found my window. So Report() returns false because I have found the window I need. How do I get that hwnd value back up to the method that called EnumWindows()? thanks - dave > That data is the IntPtr hwnd, or what did you expect?. > [quoted text clipped - 39 lines] > >> > lParam > >> > to the appropiate pointer and set it. But C# won't let you do that. Hi I think you may try define a class member variable to pass the value back to the method call the enumwindows. Best regards, Perter Huang Microsoft Online Partner Support SignatureGet Secure! - www.microsoft.com/security This posting is provided "AS IS" with no warranties, and confers no rights. Hi; I tried that but you pass an int and C# won't let you cast an object to an int. Any other approaches? thanks - dave > Hi > [quoted text clipped - 8 lines] > Get Secure! - www.microsoft.com/security > This posting is provided "AS IS" with no warranties, and confers no rights. Hi I think we can cast the object to int as below which is known as unbox. object o = 10; int i = (int)o; int j = Convert.ToInt32(o); Console.Write(i); Console.Write(j); Type Fundamentals http://msdn.microsoft.com/msdnmag/issues/1200/dotnet/ Best regards, Perter Huang Microsoft Online Partner Support SignatureGet Secure! - www.microsoft.com/security This posting is provided "AS IS" with no warranties, and confers no rights. Hi; Please read the sample code I created. The problem is getting the hwnd from the EnumProc back up to the method that calls EnumWindows. I don't see how to do that. ??? - thanks - dave > Hi > [quoted text clipped - 15 lines] > Get Secure! - www.microsoft.com/security > This posting is provided "AS IS" with no warranties, and confers no rights. Hi I think use the member variable to do the job as below, if I have any misunderstanding, please feel free to post here. int tmpWindowHandle=0; public static int GetParentWindow(Application app) { // Setting caption in Word - but Word then adds more to this text string saveCaption = app.Caption; app.Caption = CAPTION; CallBack myCallBack = new CallBack(Report); EnumWindows(myCallBack, 0); // I need hwnd from below here!!!!! //We can get the hwnd based on tmpWindowHandle app.Caption = saveCaption; return hwnd; //we can change to return tmpWindowHandle; } private static bool Report(int hwnd, int lParam) { string lpText = new string((char) 0, 100); GetWindowText(new IntPtr(hwnd), lpText, lpText.Length); if (lpText.IndexOf(CAPTION) == -1) return true; // how do I get hwnd returned to GetParentWindow method???? tmpWindowHandle =hwnd ;//found the windows handle and assign to the temp variable return false; } Best regards, Perter Huang Microsoft Online Partner Support SignatureGet Secure! - www.microsoft.com/security This posting is provided "AS IS" with no warranties, and confers no rights. Hi; Yes, that's what I am doing right now. But it means the code is not thread safe. It should be ok for my situation but it is not a good way to write code like this. And the usual use of the lParam in C++ was to pass a pointer in - but you can't do that with C#. Is there any way around using the static variable to pass the hwnd back? thanks - dave > Hi > [quoted text clipped - 38 lines] > Get Secure! - www.microsoft.com/security > This posting is provided "AS IS" with no warranties, and confers no rights. Hi If you want to make it thread safe we can use the synchronized method to guarantee it.e.g. the Mutex class. Also in C# we can pass a IntPtr byref so that it will be passed by address. [DllImport("user32")] public static extern int EnumWindows(CallBack x, ref IntPtr y); public delegate bool CallBack(IntPtr hwnd, ref IntPtr lParam); private void button1_Click(object sender, System.EventArgs e) { CallBack myCallBack = new CallBack(Report); IntPtr lp = this.Handle; EnumWindows(myCallBack, ref lp); Debug.WriteLine("button1_Click: "+lp.ToInt32().ToString("X")); } public static bool Report(IntPtr hwnd,ref IntPtr lParam) { string str = "Window handle is :" +hwnd.ToInt32().ToString("X"); Debug.WriteLine(str); if (hwnd == lParam) { Debug.WriteLine("Matched!"+"hwnd:" +hwnd.ToInt32().ToString("X")+"lParam:"+lParam.ToInt32().ToString("X")); lParam = new IntPtr(0x1234);//return return false; } return true; } Best regards, Perter Huang Microsoft Online Partner Support SignatureGet Secure! - www.microsoft.com/security This posting is provided "AS IS" with no warranties, and confers no rights. The ref IntPtr worked great - THANK YOU. > Hi > [quoted text clipped - 34 lines] > Get Secure! - www.microsoft.com/security > This posting is provided "AS IS" with no warranties, and confers no rights. I guess my question wasn't very clear. Here's some sample code: private const string CAPTION = "F076B0EA-FEE3-40E0-A576-4E68D13FAC75"; public static int GetParentWindow(Application app) { // Setting caption in Word - but Word then adds more to this text string saveCaption = app.Caption; app.Caption = CAPTION; CallBack myCallBack = new CallBack(Report); EnumWindows(myCallBack, 0); // I need hwnd from below here!!!!! app.Caption = saveCaption; return hwnd; } private static bool Report(int hwnd, int lParam) { string lpText = new string((char) 0, 100); GetWindowText(new IntPtr(hwnd), lpText, lpText.Length); if (lpText.IndexOf(CAPTION) == -1) return true; // how do I get hwnd returned to GetParentWindow method???? return false; } > Hi; > > When calling EnumWindows from C#, how do I get data back? The C++ way is to > pass in a pointer as the second parameter and in the EnumProc cast the lParam > to the appropiate pointer and set it. But C# won't let you do that. > I guess my question wasn't very clear. Here's some sample code: > [quoted text clipped - 30 lines] >>pass in a pointer as the second parameter and in the EnumProc cast the lParam >>to the appropiate pointer and set it. But C# won't let you do that. Why dont you use FindWindow straightaway? Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.