I want to detect all the top-level windows in order to send messages to it's Descendants.
How can I do that?
The following code seems to not be detecting Qt top level window, I don't know why.
static BOOL CALLBACK EnumWindowsProc(_In_ HWND hwnd, _In_ LPARAM lParam) {
WORD far wndProcessID;
WORD currentProcessID = GetCurrentProcessId();
std::vector<HWND> *topWindowList = (std::vector<HWND> *)lParam;
if (topWindowList != NULL &&
GetWindowThreadProcessId(hwnd, NULL) == currentProcessID) {
printf("Found a top level window");
fflush(stdout);
topWindowList->push_back(hwnd);
}
return TRUE;
}
void enumAllDesktopChildWindow() {
std::vector<HWND> topWindowList;
EnumChildWindows(GetDesktopWindow(), EnumWindowsProc, LPARAM(&topWindowList));
}
First, the GetWindowThreadProcessId API returns a Thread ID (TID) not a Process ID (PID)
Second, if you want to enumerate all top-level Windows, you should use EnumWindows, not EnumChildWindows. If you want to use EnumChildWindows, pass NULL as the first parameter.
Related
How to get main window handle from process id?
I want to bring this window to the front.
It works well in "Process Explorer".
I checked how .NET determines the main window.
My finding showed that it also uses EnumWindows().
This code should do it similarly to the .NET way:
struct handle_data {
unsigned long process_id;
HWND window_handle;
};
HWND find_main_window(unsigned long process_id)
{
handle_data data;
data.process_id = process_id;
data.window_handle = 0;
EnumWindows(enum_windows_callback, (LPARAM)&data);
return data.window_handle;
}
BOOL CALLBACK enum_windows_callback(HWND handle, LPARAM lParam)
{
handle_data& data = *(handle_data*)lParam;
unsigned long process_id = 0;
GetWindowThreadProcessId(handle, &process_id);
if (data.process_id != process_id || !is_main_window(handle))
return TRUE;
data.window_handle = handle;
return FALSE;
}
BOOL is_main_window(HWND handle)
{
return GetWindow(handle, GW_OWNER) == (HWND)0 && IsWindowVisible(handle);
}
I don't believe Windows (as opposed to .NET) provides a direct way to get that.
The only way I know of is to enumerate all the top level windows with EnumWindows() and then find what process each belongs to GetWindowThreadProcessID(). This sounds indirect and inefficient, but it's not as bad as you might expect -- in a typical case, you might have a dozen top level windows to walk through...
There's the possibility of a mis-understanding here. The WinForms framework in .Net automatically designates the first window created (e.g., Application.Run(new SomeForm())) as the MainWindow. The win32 API, however, doesn't recognize the idea of a "main window" per process. The message loop is entirely capable of handling as many "main" windows as system and process resources will let you create. So, your process doesn't have a "main window". The best you can do in the general case is use EnumWindows() to get all the non-child windows active on a given process and try to use some heuristics to figure out which one is the one you want. Luckily, most processes are only likely to have a single "main" window running most of the time, so you should get good results in most cases.
This is my solution using pure Win32/C++ based on the top answer. The idea is to wrap everything required into one function without the need for external callback functions or structures:
#include <utility>
HWND FindTopWindow(DWORD pid)
{
std::pair<HWND, DWORD> params = { 0, pid };
// Enumerate the windows using a lambda to process each window
BOOL bResult = EnumWindows([](HWND hwnd, LPARAM lParam) -> BOOL
{
auto pParams = (std::pair<HWND, DWORD>*)(lParam);
DWORD processId;
if (GetWindowThreadProcessId(hwnd, &processId) && processId == pParams->second)
{
// Stop enumerating
SetLastError(-1);
pParams->first = hwnd;
return FALSE;
}
// Continue enumerating
return TRUE;
}, (LPARAM)¶ms);
if (!bResult && GetLastError() == -1 && params.first)
{
return params.first;
}
return 0;
}
Though it may be unrelated to your question, take a look at GetGUIThreadInfo Function.
As an extension to Hiale's solution, you could provide a different or modified version that supports processes that have multiple main windows.
First, amend the structure to allow storing of multiple handles:
struct handle_data {
unsigned long process_id;
std::vector<HWND> handles;
};
Second, amend the callback function:
BOOL CALLBACK enum_windows_callback(HWND handle, LPARAM lParam)
{
handle_data& data = *(handle_data*)lParam;
unsigned long process_id = 0;
GetWindowThreadProcessId(handle, &process_id);
if (data.process_id != process_id || !is_main_window(handle)) {
return TRUE;
}
// change these 2 lines to allow storing of handle and loop again
data.handles.push_back(handle);
return TRUE;
}
Finally, amend the returns on the main function:
std::vector<HWD> find_main_window(unsigned long process_id)
{
handle_data data;
data.process_id = process_id;
EnumWindows(enum_windows_callback, (LPARAM)&data);
return data.handles;
}
Just to make sure you are not confusing the tid (thread id) and the pid (process id):
DWORD pid;
DWORD tid = GetWindowThreadProcessId( this->m_hWnd, &pid);
I have a dll that gets called by a process and now I would like to implement an input check in the dll to react on certain inputs that occur in the application.
SetWindowsHookEx() with a KeyboardProc function seemed like a possible solution so I implemented it.
This is roughly how the code in the dll looks like:
static HHOOK hhk = NULL;
LRESULT CALLBACK keyboardProc(int code, WPARAM wParam, LPARAM lParam)
{
if(code == HC_ACTION && ((DWORD)lParam & 0x80000000) == 0) // if there is an incoming action and a key was pressed
{
switch(wParam)
{
case VK_SPACE:
printf("Space was pressed\n");
break;
}
}
return CallNextHookEx(hhk, code, wParam, lParam);
}
BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
if(ul_reason_for_call == DLL_PROCESS_ATTACH)
{
if(AllocConsole()){
freopen("CONOUT$", "w", stdout); // redirect output to console for debugging
}
printf("Dll loaded, lastError = %i\n", GetLastError());
printf("lastError = %i\n", GetLastError());
// sidenote: for some reason the first GetLastError() returns 0 while the second one returns 6 (invalid handle)
hhk = SetWindowsHookEx(WH_KEYBOARD, keyboardProc, hModule, GetCurrentThreadId());
}
else if (ul_reason_for_call == DLL_PROCESS_DETACH)
{
printf("\nCleaning up...");
FreeConsole();
UnhookWindowsHookEx(hhk);
}
return TRUE;
}
However nothing happens (or gets printed) in the Console window when I press any key. It doesn't even seem like the keyboardProc function is accessed at any time.
It does work though when I pass NULL instead of GetCurrentThreadId() to SetWindowsHookEx().
But this causes the hook to work globally meaning that whenever I press a key in another application, a Console window pops up (because the dll gets called again) and he checks for key inputs there.
Obviously this is not desired and I would like to make this work with only the process that originally called the dll.
I already checked if GetCurrentThreadId() returns a valid ID and it seems to be indeed the main thread ID of the process that initially called the dll (checked with Process Explorer).
So now my question is what could be the problem and more importantly, what can I do to make it working?
[DllImport("user32.dll", SetLastError = true)]
static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);
uint process_id;
uint thread_id = GetWindowThreadProcessId(windowHandle, out process_id);
hhook = SetWindowsHookEx(WH_KEYBOARD, a_KeyboardProc, hInstance, 0);
I have used the code above to get the main thread_ID for a certain process. The good part is, the SetWindowsHookEx function gives a logical output. Unfortunately, the bad part is, if a key is pressed in the thread that has been hooked, the thread stops working.
In specific, the idHook parameter of SetWindowsHoookEx function was set to 2 (instead of 13) in my case for non-low-level keyboard events. It seems, at least to me, that LL corresponds to low-level, where keyboardProc should come with a WH_KEYBOARD instead of WH_KEYBOARD_LL.
I am not sure at this point how my response would be related to your question. Hopefully, we get what we need through discussion.
I've been reading posts all over and trying different approaches, but I can't make this work.
I want to be able to track the last window before the user clicks on my application. This way I can bring it to the front and send a copy command to retrieve whatever the user has selected.
I thought about using hooks to receive notifications of activated windows, but it is not working as expected. I'm using HSHELL_WINDOWACTIVATED global hook to keep track of the current and last active window, but I always get both handles to be the same, pointing to my application.
The code looks like:
#pragma data_seg("ASEG")
HWND lastWindow = 0;
HWND currentWindow = 0;
#pragma data_seg()
#pragma comment(linker, "/section:ASEG,RWS")
HINSTANCE dllHandle;
BOOL APIENTRY DllMain(
HINSTANCE hinstDLL,
DWORD fdwReason,
PVOID lpReserved )
{
switch( fdwReason )
{
case DLL_PROCESS_ATTACH:
dllHandle = hinstDLL;
return TRUE;
break;
}
}
LRESULT CALLBACK ShellHookProc(int nCode, WPARAM wParam, LPARAM lParam)
{
if (nCode > 0)
{
switch (nCode)
{
case HSHELL_WINDOWACTIVATED: lastWindow = currentWindow;
currentWindow = (HWND)wParam;
break;
}
}
return ::CallNextHookEx(NULL, nCode,wParam,lParam);
}
extern "C" {
__declspec(dllexport) void Init()
{
SetWindowsHookEx(WH_SHELL, ShellHookProc, dllHandle, 0);
}
}
Later on I would use the lastWindow to bring that window to the front and send a Ctrl+C command.
If you call GetWindowTextA(..) for each handle, the first time you activate a different window and go back to the application, lastWindow retrieves blank and currentWindow my application name. Any consecutive activations retrieve always the name of my application for both lastWindow and currentWindow.
I don't quite understand why this is happening. Any ideas?
Thanks!
I think you can use SetWinEventHook. This hook should allow you to capture the EVENT_SYSTEM_FOREGROUND message so that each time a window is brought to the foreground, you can capture the window handle. Then when your app window is activated, just look at the last value you captured.
See this: https://stackoverflow.com/a/4407715/1502289
Also, in your own code, you could simply do a comparison to see if the window handle is the handle to your own window. If not, save the handle.
Example:
...
case HSHELL_WINDOWACTIVATED:
if (lastWindow != [your own window's handle])
{
lastWindow = (HWND)wParam;
}
break;
...
in my application i have timer, in TimerProc i want to get handles of all windows(main and child) of the another application that has focus. I have no idea how to do that because i don't understand functions like GetNextWindow or GetParent and Z-oder of windows and i can't find anywhere very detailed explanation of how this functions works(i dont understand explanation on msdn). Please can you give me some advice or block of code which do that? Many thanks for answer.
Use GetForegroundWindow() function - it returns the HWND of the window the user currently is working with.
Then having this handle you can retrieve childs in such a way:
HWND a_hWnd = (HWND)hParent;
HWND a_FirstChild = NULL;
a_FirstChild = ::GetWindow(a_hWnd, GW_CHILD);
if (a_FirstChild != NULL)
{
HWND a_NextChild = NULL;
do
{
a_NextChild = ::GetWindow(a_FirstChild, GW_HWNDNEXT);
if (a_NextChild != NULL)
{
a_FirstChild = a_NextChild;
}
}
while (a_NextChild != NULL);
}
GetForeGroundWindow to get the current foreground window/dialog
GetParent until you get NULL (that gets you to the top level window)**
EnumChildWindows to get to all the dependent windows
** Note that an application can have more than one top level window, though this isn't usual.
Code:
void Ccpp_testDlg::DoWalk ()
{
HWND hCurrent;
HWND hNew;
hCurrent = ::GetForegroundWindow ();
hNew = hCurrent;
while (hNew != NULL)
{
hNew = ::GetParent (hCurrent);
if (hNew != NULL)
{
hCurrent = hNew;
}
}
EnumChildWindows (hCurrent, EnumProc, 0);
}
BOOL CALLBACK EnumProc (HWND hwnd,LPARAM lParam)
{
TCHAR szText [MAX_PATH];
GetWindowText (hwnd, szText, sizeof(szText));
// do something with text
return TRUE;
}
How to get main window handle from process id?
I want to bring this window to the front.
It works well in "Process Explorer".
I checked how .NET determines the main window.
My finding showed that it also uses EnumWindows().
This code should do it similarly to the .NET way:
struct handle_data {
unsigned long process_id;
HWND window_handle;
};
HWND find_main_window(unsigned long process_id)
{
handle_data data;
data.process_id = process_id;
data.window_handle = 0;
EnumWindows(enum_windows_callback, (LPARAM)&data);
return data.window_handle;
}
BOOL CALLBACK enum_windows_callback(HWND handle, LPARAM lParam)
{
handle_data& data = *(handle_data*)lParam;
unsigned long process_id = 0;
GetWindowThreadProcessId(handle, &process_id);
if (data.process_id != process_id || !is_main_window(handle))
return TRUE;
data.window_handle = handle;
return FALSE;
}
BOOL is_main_window(HWND handle)
{
return GetWindow(handle, GW_OWNER) == (HWND)0 && IsWindowVisible(handle);
}
I don't believe Windows (as opposed to .NET) provides a direct way to get that.
The only way I know of is to enumerate all the top level windows with EnumWindows() and then find what process each belongs to GetWindowThreadProcessID(). This sounds indirect and inefficient, but it's not as bad as you might expect -- in a typical case, you might have a dozen top level windows to walk through...
There's the possibility of a mis-understanding here. The WinForms framework in .Net automatically designates the first window created (e.g., Application.Run(new SomeForm())) as the MainWindow. The win32 API, however, doesn't recognize the idea of a "main window" per process. The message loop is entirely capable of handling as many "main" windows as system and process resources will let you create. So, your process doesn't have a "main window". The best you can do in the general case is use EnumWindows() to get all the non-child windows active on a given process and try to use some heuristics to figure out which one is the one you want. Luckily, most processes are only likely to have a single "main" window running most of the time, so you should get good results in most cases.
This is my solution using pure Win32/C++ based on the top answer. The idea is to wrap everything required into one function without the need for external callback functions or structures:
#include <utility>
HWND FindTopWindow(DWORD pid)
{
std::pair<HWND, DWORD> params = { 0, pid };
// Enumerate the windows using a lambda to process each window
BOOL bResult = EnumWindows([](HWND hwnd, LPARAM lParam) -> BOOL
{
auto pParams = (std::pair<HWND, DWORD>*)(lParam);
DWORD processId;
if (GetWindowThreadProcessId(hwnd, &processId) && processId == pParams->second)
{
// Stop enumerating
SetLastError(-1);
pParams->first = hwnd;
return FALSE;
}
// Continue enumerating
return TRUE;
}, (LPARAM)¶ms);
if (!bResult && GetLastError() == -1 && params.first)
{
return params.first;
}
return 0;
}
Though it may be unrelated to your question, take a look at GetGUIThreadInfo Function.
As an extension to Hiale's solution, you could provide a different or modified version that supports processes that have multiple main windows.
First, amend the structure to allow storing of multiple handles:
struct handle_data {
unsigned long process_id;
std::vector<HWND> handles;
};
Second, amend the callback function:
BOOL CALLBACK enum_windows_callback(HWND handle, LPARAM lParam)
{
handle_data& data = *(handle_data*)lParam;
unsigned long process_id = 0;
GetWindowThreadProcessId(handle, &process_id);
if (data.process_id != process_id || !is_main_window(handle)) {
return TRUE;
}
// change these 2 lines to allow storing of handle and loop again
data.handles.push_back(handle);
return TRUE;
}
Finally, amend the returns on the main function:
std::vector<HWD> find_main_window(unsigned long process_id)
{
handle_data data;
data.process_id = process_id;
EnumWindows(enum_windows_callback, (LPARAM)&data);
return data.handles;
}
Just to make sure you are not confusing the tid (thread id) and the pid (process id):
DWORD pid;
DWORD tid = GetWindowThreadProcessId( this->m_hWnd, &pid);