Get a a process window handle by click in C#

Question

At the moment, I can get a list of running processes with a main window using System.Diagnostics.Process.GetProcesses() and executing a simple LINQ query.

Then, I can import user32.dll and the SetWindowPos function and I manipulate other processes' window parameters.

Ok, it works. Now I'd like to select a window of a process, let's say calc.exe, by clicking it. In other words, I'd like to obtain a Process object (and then the MainWindowHandle) with a hook that catches the process name when I click on its window.

How can I achieve this?

Mike Kwan · Accepted Answer · 2012-04-25 16:32:06Z

5

I don't know how this is done in C#, but you have also tagged this question WinAPI so I can help there. In WinAPI, it can be done like so:

#include <stdio.h>
#include <Windows.h>
#include <Psapi.h>
#pragma comment(lib, "Psapi.lib")

int main(void)
{
  /* Hacky loop for proof of concept */
  while(TRUE) {
    Sleep(100);

    if(GetAsyncKeyState(VK_F12)) {
      break;
    }

    if(GetAsyncKeyState(VK_LBUTTON)) {
      HWND  hwndPt;
      POINT pt;

      if(!GetCursorPos(&pt)) {
        wprintf(L"GetCursorPos failed with %d\n", GetLastError());
        break;
      }

      if((hwndPt = WindowFromPoint(pt)) != NULL) {
        DWORD  dwPID;
        HANDLE hProcess;

        GetWindowThreadProcessId(hwndPt, &dwPID);

        hProcess = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, FALSE, dwPID);

        if(hProcess == NULL) {
          wprintf(L"OpenProcess failed with error: %d\n", GetLastError());
        } else {
          wchar_t lpFileName[MAX_PATH];
          DWORD   dwSize = _countof(lpFileName);

          QueryFullProcessImageName(hProcess, 0, lpFileName, &dwSize);
          wprintf(L"%s\n", lpFileName);

          CloseHandle(hProcess);
        }
      }
    }
  }

  return EXIT_SUCCESS;
}

Example result:

result

In this case, I am simply polling to get the mouse click. A more proper way would be to use some sort of windows hook.

edited Apr 25, 2012 at 16:32

answered Apr 25, 2012 at 15:23

Mike Kwan

24.5k12 gold badges65 silver badges98 bronze badges

Sign up to request clarification or add additional context in comments.

11 Comments

Martin Liversage Over a year ago

You probably need to capture the mouse to be able to receive the click on another window.

Mike Kwan Over a year ago

@MartinLiversage: GetAsyncKeyState can be used for that.

daliz Over a year ago

I'm having some problems getting the cursor position. I'm calling GetCursorPos but I get the X coordinate as something like 6,47208716579385E-312 and the Y coordinate as 0. What's going on?

Martin Liversage Over a year ago

@MikeKwan: But if I move the mouse pointer to another window and click on it my application looses focus and doesn't get the mouse click event. That is, unless I have captured the mouse.

Mike Kwan Over a year ago

@MartinLiversage: You don't need to capture the mouse for GetAsyncKeyState as far as I'm aware.

|

Chibueze Opata · Accepted Answer · 2012-04-25 20:07:15Z

1

As Mike Kwan said, you'll be better of writing a hook though both approaches have their own drawbacks, but bjarneds already did a good work on this. Have a look @ DotNET Object Spy. It's written in C# and will serve for your needs and more.

You should also note that using hooks are becoming redundant by the day. Depending on what you want to do, other winapis like GetForegroundWindow might serve better.

answered Apr 25, 2012 at 20:07

Chibueze Opata

10.1k8 gold badges47 silver badges71 bronze badges

Collectives™ on Stack Overflow

Get a a process window handle by click in C#

2 Answers 2

11 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

11 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related