I need to automate a third party program, and the only course of action is to simulate a click on some buttons.
I do this by finding the HWND handle of the button with EnumChildWindows. When I've found the "window" (the button), I try to send BM_CLICK to it with SendMessageW. This works, my tests show that the button indeed think it was clicked.
The problem arise in my error handling. There is no feedback given by the BM_CLICK message, so I don't really know if it has been clicked. I thought I should be diligent and check for any error codes though with Marshal.GetLastWin32Error.
This returns ERROR_PROC_NOT_FOUND, which is not really what I would expect from a successful message handling.
I import SendMessageW as follows:
[DllImport("User32.dll",
CharSet = CharSet.Unicode,
CallingConvention = CallingConvention.Winapi,
SetLastError = true)]
public static extern IntPtr SendMessageW(
HandleRef hWnd,
UInt32 Msg,
UIntPtr wParam,
IntPtr lParam);
The code doing the call is:
User32.SendMessageW(
buttonHandle,
(uint)ButtonControlMessages.BM_CLICK, // value of BM_CLICK = 0x00F5.
UIntPtr.Zero,
IntPtr.Zero);
int error = Marshal.GetLastWin32Error();
if (error != ErrorCodes.ERROR_SUCCESS) // love the name of this error code.
throw new Win32Exception(error);
My tests are just using a simple Windows Forms with a button control attached. Thus, I can procure the handle through button.Handle. It gets clicked; could it be that this error is completely unrelated?
It sure would be nice to get rid of it though, I'd like some way to be sure that the call to SendMessageW at least didn't fail.
I'm on Windows 7 x86-32 with .NET 4.
The calling convention should be Stdcall, but since that is the default you can just drop it.
I think your SendMessage P/Invoke looks a bit odd but that's probably not the cause of the issue. In any case I would do it like this:
[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);
I think what's happening here is that SendMessage() is working but isn't assigning the last error. The only thing that the documentation for SendMessage() mentions about errors is:
When a message is blocked by UIPI the last error, retrieved with GetLastError, is set to 5 (access denied).
The return value for SendMessage() is dependent on the message sent. In the case of BM_CLICK there is apparently no message sent. In other words you simply do not get any feedback.
Related
I want to close window with some name (any application, for example, calculator and etc.). How to do it in C#? Import WinAPI functions?
Yes, you should import the Windows API functions: FindWindow(), SendMessage(); and WM_CLOSE constant.
Native definitions of the Windows API functions:
[DllImport("user32.dll", SetLastError = true)]
static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
/// <summary>
/// Find window by Caption only. Note you must pass IntPtr.Zero as the first parameter.
/// </summary>
[DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)]
static extern IntPtr FindWindowByCaption(IntPtr ZeroOnly, string lpWindowName);
[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);
const UInt32 WM_CLOSE = 0x0010;
Client code:
IntPtr windowPtr = FindWindowByCaption(IntPtr.Zero, "Untitled - Notepad");
if (windowPtr == IntPtr.Zero)
{
Console.WriteLine("Window not found");
return;
}
SendMessage(windowPtr, WM_CLOSE, IntPtr.Zero, IntPtr.Zero);
You're trying to close windows belonging to other processes. That isn't something you can assume will go reliably. For one thing, YOU don't own those windows so YOU don't really have any automatic entitlement to go and mess with the other processes' windows.
As the other answer suggests, you can try sending a WM_CLOSE to the window but it comes with the caveat that the other process isn't really entitled to honour it. The response to WM_CLOSE can be anything to acceptance and a clean shutdown to outright rejection. In the latter case, you've really got no option. It's not your process. In between, as you've seen, there could be any sort of intermediate windows, dialog boxes, etc, that you'd have to contend with.
So what are you trying to achieve here? Why are you trying to close windows belonging to other processes? It might help to clarify what the aim is.
I'm currently using SendKeys.SendWait(text); in C#
but SendKeys sending the key global and I have to activate my application and then send it. And another problem is when I type something in my keyboard (in another app) and the SendKeys function activates (in my app) mistakes happen.
So how can I send a message to my application regardless what application is active and what I type in my keyboard?
SendMessage() does what you want. You'll need to use it like:
[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);
const UInt32 WM_CHAR = 0x0102;
const int VK_Q = 0x51; // taken from http://msdn.microsoft.com/en-us/library/dd375731(v=vs.85).aspx
SendMessage(handleToTheInputForm, WM_CHAR, VK_Q, 1);
You will need to get a handle on the other application's window so that you can bring it to focus and reliably send your keystrokes to it,
Have a look at this tutorial
http://www.codeproject.com/KB/cs/SendKeys.aspx
According to my research, when I run C# executable which opens WinForm, within .NET, they don't offer the function to access those WinForm object from separate c# process (separate file I mean) but win32 API does.
Then I came across 3 functions from API.
FindWindow();
GetWindowLong();
CallWindowProc()
I need to call it from top down to the bottom but then I got stuck by CallWIndowProc() because
I can't figure what I should pass for last 3 arguments.
private static extern UIntPtr CallWindowProc(IntPtr a, IntPtr b, uint c, IntPtr d, IntPtr e);
c, d and e
According to the doc, it should be some sort of "message" which is int. But where can I get such value???
http://msdn.microsoft.com/en-us/library/ms633571(v=vs.85).aspx
Code:
[DllImportAttribute("User32.dll")]
private static extern IntPtr FindWindow(String ClassName, String WindowName);
[DllImportAttribute("User32.dll")]
private static extern long GetWindowLong(IntPtr a, int b);
[DllImportAttribute("User32.dll")]
private static extern UIntPtr CallWindowProc(IntPtr a, IntPtr b, uint c, IntPtr d, IntPtr e);
[STAThread]
static void Main(string[] args)
{
IntPtr lResult;
uint lMsg = 0;
IntPtr HWND = FindWindow("WindowsFormsApplication1.Form1", "Form1");
int GWL_WNDPROC = -4;
long WNDPROC = GetWindowLong(HWND, GWL_WNDPROC);
lResult = CallWindowProc(WNDPROC, HWND, lMsg, 0, 0);
}
Clarification
OK.. I should have made it clear.. my goal is to run following chunk of code against the WebForm being executed. (I'ts WatiN)
var t = new Thread(() =>
{
Settings.AutoStartDialogWatcher = false;
var ie = new IE(form1.webBrowser1.ActiveXInstance);
ie.GoTo("http://www.google.com");
ie.TextField(Find.ByClass("lst")).TypeText("this is awesome!!");
ie.Button(Find.ByName("btnG")).Click();
});
t.SetApartmentState(ApartmentState.STA);
t.Start();
What message you are trying to send to callWinProc?
Arguments are
nProc is a value returned previously by SubClassWindow() (Source Window).
hWnd is the handle to the window that was subclassed (target window).
nMsg is the message (one of the WM_* values defined in WINDOWS.CH, basically kind of event or message like click is one message). For complete system messages see http://msdn.microsoft.com/en-us/library/ms644927(v=vs.85).aspx#system_defined
wParam depends on nMsg. For click, it takes left or right click
lParam depends on nMsg. for click it takes the location as lparam
you can see wparam and lparam defination for each message.
It looks like you're trying to call the window proc of a window from a different thread/process. I'm assuming this because you're using FindWindow, and I can't see where you created the window. If that is what you are doing, CallWindowProc won't work because you cannot call a window proc from a thread other than the one that created the window. What you need is SendMessage, which accepts the same last four parameters (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) - to interpret them you need to know what message you're sending.
I recommand to use the parameter names from the native methode just for clearness. You can get those pinvoke signatures from pinvoke.net so you don't have to do it on your own all the time. These messages are definded in header files and documented in the msdn. Its quiete hard to use the right message in the correct manner if you're new to win32 and/or C#.
If you want to intercept the windows messages of your form you need a windows message hook, but this doesn't work in .Net. You can also read this article which cover this topic.
Maybe you should try to find a complete different solution for your problem. Other IPC methodes etc.
EDIT: The CLR type of your form (WindowsFormsApplication1.Form1) is not the class name you have to put in FindWindow, FindWindow is an unmanaged api and isn't aware of the CLR typesystem. Try out Spy++ to investigate some windows on your PC.
I wanna send key stroke to a program even if it is running in background. But I can do this only for NOTEPAD like this,
[DllImport("user32.dll")]
protected static extern byte VkKeyScan(char ch);
[DllImport("user32.dll", SetLastError = true)]
protected static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);
[DllImport("User32.Dll", EntryPoint = "PostMessageA")]
protected static extern bool PostMessage(IntPtr hWnd, uint msg, int wParam, int lParam);
char Key = // key value to send
IntPtr hWnd = FindWindowEx(_handle, IntPtr.Zero, "edit", null); // _handle is the windows handle of the program (here its notepad)
PostMessage(hWnd, WM_KEYDOWN, VkKeyScan(Key), 0);
But for all other applications I can't send keystrokes if its in background. Since I don't know the lpszClass of that program (I think this is the userControl name of the typing area in that program. For NotePad it is "edit". I found this surfing internet).
For all other applications what I'm doing is, get the application to foreground, then send the key, then again get my program foreground. I need my program to be run as foreground always.
[DllImport("USER32.DLL")]
public static extern bool SetForegroundWindow(IntPtr hWnd);
SetForegroundWindow(_handle); // _handle is the windows handle of the program
System.Threading.Thread.Sleep(50); // Waiting few milliseconds till application coming to foreground.
wsh.SendKeys(Key.ToString(), ref wait); // wsh is WshShellClass wsh= new WshShellClass();
SetForegroundWindow(_mainHandle); // _mainHandle is the windows handle of my application
But this way is not working. some keys getting missed and the program foreground->background->foregound->background...... like its dancing...
How to send keys to other applications if its running in background.
or are there any way/source to find the lpszClass of a program ?
Sorry if I have missed any required information. this is a large application. I have posted only required parts here. If someone needs any additional information, pls ask.
I think you'll need to have the background program install a low-level keyboard hook via the win32 function SetWindowsHookEx().
Here's the MSDN documentation for SetWindowsHookEX()
http://msdn.microsoft.com/en-us/library/ms644990(v=vs.85).aspx
And here's the KB article on how to do it from C#
http://support.microsoft.com/kb/318804
This article goes into some detail, too: http://www.codeguru.com/columns/vb/article.php/c4829
I expect your app will get caught by various spyware/anti-virus software as a keyboard logger, though.
Good luck.
You may be able to figure out the lpszClass of the program using an inspection tool such as WinSpy++. It gives you a crosshair that you can drag and position over the desired control. This was able to easily provide me with the "edit" class name for notepad.
If things aren't working, click the "More>>" button in the lower right of WinSpy++, then click the "Locate" button to view the control hierarchy; you may need to post the WM_KEYDOWN message to one of the parent or child controls instead.
I am working with an application in C# that need to send a message to a C++ application.
I imported
[DllImport("user32.dll")]
public static extern IntPtr SendMessage(
int hWnd, // handle to destination window
uint Msg, // message
IntPtr wParam, // first message parameter
IntPtr lParam // second message parameter
);
but now, my problem is that I need to passe string to wParam and lParam. I tried unsafe code, but it seems string just doesnt work like the rest of variables. How can I achieve that? Thanks.
The declaration is wrong, the wParam and lParam arguments are IntPtr, not long.
There is a complication because you are trying to send strings. What matters if the target window is Unicode enabled or not. There are two versions of SendMessage, SendMessageA() and SendMessageW(). The former needs to be used if the program is dated and uses 8-bit character strings rather than UTF-16 encoded strings.
You can find out by using Spy++. Use the finder tool to select the window of the application. In the General property tab, you'll see "Window proc". It will say (Unicode) if the window is Unicode enabled. If you don't see it then the strings have to be translated to 8-bit characters.
To generate the string pointers you need to pass, you can use Marshal.StringToHGlobalAnsi or StringToHGlobalUni (respectively 8-bit and Unicode). You can however play a trick to let the P/Invoke marshaller translate the string for you. Saves you the hassle of having to free the strings after the call. For the Ansi version, you can declare the API function like this:
[DllImport("user32.dll", CharSet = CharSet.Ansi, EntryPoint = "SendMessageA", ExactSpelling = true)]
private static extern IntPtr SendMessageStrings(IntPtr hWnd, int msg, string wParam, string lParam);
And the Unicode version like this:
[DllImport("user32.dll", CharSet = CharSet.Unicode, EntryPoint = "SendMessageW", ExactSpelling = true)]
private static extern IntPtr SendMessageStrings(IntPtr hWnd, int msg, string wParam, string lParam);
One final note: this will not work as-is if the window belongs to another application, you'll crash it. The pointer values you pass are only valid in your own process, not in the C++ process. To work around that, you have to allocate memory in the target process so that the pointer is valid. That requires OpenProcess to get a handle to the process, VirtualAllocEx() to allocate memory in the target process, big enough to store the string, WriteProcessMemory to write the string. Now you can call SendMessage(), use a version that is declared with IntPtr for the wParam and lParam arguments, pass the value you got from VirtualAllocEx. Next use VirtualFreeEx() to release the memory and CloseHandle to clean up. Or keep the memory around for the next time if you do this often.
Quite a lot of P/Invoke to get wrong there. Not to mention security issues, WriteProcessMemory requires admin privileges, UAC elevation is required.
Passing the address of the string would involve unsafe code,
since Win32 API calls expect addresses (in a C/C++ native envrion). What windows message are you sending that requires a string in wParam or lParam?
We ended up using "WmCpyDta_d.dll" to deal with all that.