- Handle v4.22
- Introduction
- Installation
- Usage
- Handle Output
- More Information
- GetWindow function (winuser.h)
- Syntax
- Parameters
- Return value
- Remarks
- C++: Best way to get Window Handle of the only window from a process by process id, process handle and title name [duplicate]
- 1 Answer 1
- Get Window instance from Window Handle
- 2 Answers 2
Handle v4.22
By Mark Russinovich
Published: June 14, 2019
Download Handle (887 KB)
Introduction
Ever wondered which program has a particular file or directory open? Now you can find out. Handle is a utility that displays information about open handles for any process in the system. You can use it to see the programs that have a file open, or to see the object types and names of all the handles of a program.
You can also get a GUI-based version of this program, Process Explorer, here at Sysinternals.
Installation
You run Handle by typing «handle». You must have administrative privilege to run Handle.
Usage
Handle is targeted at searching for open file references, so if you do not specify any command-line parameters it will list the values of all the handles in the system that refer to open files and the names of the files. It also takes several parameters that modify this behavior.
usage: handle [[-a] [-u] | [-c [-l] [-y]] | [-s]] [-p
| Parameter | Description |
|---|---|
| -a | Dump information about all types of handles, not just those that refer to files. Other types include ports, Registry keys, synchronization primitives, threads, and processes. |
| -c | Closes the specified handle (interpreted as a hexadecimal number). You must specify the process by its PID. WARNING: Closing handles can cause application or system instability. |
| -l | Dump the sizes of pagefile-backed sections. |
| -y | Don’t prompt for close handle confirmation. |
| -s | Print count of each type of handle open. |
| -u | Show the owning user name when searching for handles. |
| -p | Instead of examining all the handles in the system, this parameter narrows Handle’s scan to those processes that begin with the name process. Thus: handle -p exp would dump the open files for all processes that start with «exp», which would include Explorer. |
| name | This parameter is present so that you can direct Handle to search for references to an object with a particular name. For example, if you wanted to know which process (if any) has «c:\windows\system32» open you could type: handle windows\system The name match is case-insensitive and the fragment specified can be anywhere in the paths you are interested in. |
Handle Output
When not in search mode (enabled by specifying a name fragment as a parameter), Handle divides its output into sections for each process it is printing handle information for. Dashed lines are used as a separator, immediately below which you will see the process name and its process id (PID). Beneath the process name are listed handle values (in hexadecimal), the type of object the handle is associated with, and the name of the object if it has one.
When in search mode, Handle prints the process names and id’s are listed on the left side and the names of the objects that had a match are on the right.
More Information
You can find more information on the Object Manager in Windows Internals, 4th Edition or by browsing the Object Manager name-space with WinObj.
Download Handle (887 KB)
GetWindow function (winuser.h)
Retrieves a handle to a window that has the specified relationship (Z-Order or owner) to the specified window.
Syntax
Parameters
A handle to a window. The window handle retrieved is relative to this window, based on the value of the uCmd parameter.
The relationship between the specified window and the window whose handle is to be retrieved. This parameter can be one of the following values.
| Value | Meaning |
|---|---|
| GW_CHILD 5 | The retrieved handle identifies the child window at the top of the Z order, if the specified window is a parent window; otherwise, the retrieved handle is NULL. The function examines only child windows of the specified window. It does not examine descendant windows. |
| GW_ENABLEDPOPUP 6 | The retrieved handle identifies the enabled popup window owned by the specified window (the search uses the first such window found using GW_HWNDNEXT); otherwise, if there are no enabled popup windows, the retrieved handle is that of the specified window. |
| GW_HWNDFIRST 0 | The retrieved handle identifies the window of the same type that is highest in the Z order. If the specified window is a topmost window, the handle identifies a topmost window. If the specified window is a top-level window, the handle identifies a top-level window. If the specified window is a child window, the handle identifies a sibling window. |
| GW_HWNDLAST 1 | The retrieved handle identifies the window of the same type that is lowest in the Z order. If the specified window is a topmost window, the handle identifies a topmost window. If the specified window is a top-level window, the handle identifies a top-level window. If the specified window is a child window, the handle identifies a sibling window. |
| GW_HWNDNEXT 2 | The retrieved handle identifies the window below the specified window in the Z order. If the specified window is a topmost window, the handle identifies a topmost window. If the specified window is a top-level window, the handle identifies a top-level window. If the specified window is a child window, the handle identifies a sibling window. |
| GW_HWNDPREV 3 | The retrieved handle identifies the window above the specified window in the Z order. If the specified window is a topmost window, the handle identifies a topmost window. If the specified window is a top-level window, the handle identifies a top-level window. If the specified window is a child window, the handle identifies a sibling window. |
| GW_OWNER 4 | The retrieved handle identifies the specified window’s owner window, if any. For more information, see Owned Windows. |
Return value
If the function succeeds, the return value is a window handle. If no window exists with the specified relationship to the specified window, the return value is NULL. To get extended error information, call GetLastError.
Remarks
The EnumChildWindows function is more reliable than calling GetWindow in a loop. An application that calls GetWindow to perform this task risks being caught in an infinite loop or referencing a handle to a window that has been destroyed.
C++: Best way to get Window Handle of the only window from a process by process id, process handle and title name [duplicate]
I’m looking for the best way to get a Window Handle in the following situation:
I have the process id and process handle, I know the window titlename and I know that the process has only one window.
So how would I do it? FindWindow ? EnumWIndows ?
1 Answer 1
Using FindWindow requires that you either know the window class or the window title. Both of these are not necessarily unique. Since you alread have the process handle (and its ID) you can implement a robust solution using EnumWindows .
First, declare a structure used for communication. It passes a process ID to the enumeration procedure and returns the window handle back.
Next, we need a callback procedure that retrieves the process ID ( GetWindowThreadProcessId ) for any given window and compares it to the one we are looking for:
What’s left is the public interface. It populates the structure used for communication with the process ID, triggers the enumeration of top-level windows, and returns the window handle. The calls to SetLastError and GetLastError are required, since EnumWindows returns FALSE for both error and success in this case:
This will retrieve the first top-level window that matches a given process ID. Since the requirements state that there will only ever be a single window for the given process, the first one that matches is the correct window.
If additional restrictions exist, EnumProc can be expanded to include those. I have marked the spot in the implementation above, where additional filters can be applied.
Get Window instance from Window Handle
I am able get a Window handle from running applications using the following code.
But I want to get the Window instance from this handler. Is it possible?
Any quick idea please?
2 Answers 2
Try the following:
Update:
But this will work only inside the same AppDomain, because otherwise it would mean that you could share an object across different AppDomains and even processes, which is obviously impossible.
In a WPF application (or WinForms) there are two ‘objects’ (that is blocks of memory containing information) to a ‘window’:
- The system window object.
- The managed objects that ‘wraps’ the system object.
Access to the system window object is provided through the window handle (typeof HWND in unmanaged code, IntPtr in managed code). Given a window handle, which you already obtained, you can manipulate that window using the Window API methods. You can use p/invoke for this.
Access to the managed object, which resides in the heap of the process (or AppDomain in the case of a managed process) is forbidden. This memory is ‘protected’ from other processes(1).
The only way that objects can be shared between processes (or AppDomains) is through marshalling which is a cooperative effort on the part of both processes. This applies even to many of the Win32 API methods when accessing a window in another process. Not all access is possible without custom marshalling.
Note that unlike WinForms, WPF does not (normally) use system windows for controls. If your aim is to manipulate the visual tree in another WPF process/domain, you’re simply out of luck unless that process provides some sort of Automation interface.
(1) While it is possible to read the raw memory of another process, objects on a managed heap are moving targets. One could never even find them, even if you could somehow suspend the garbage collecting thread of that process.
