C ++:按进程ID，进程句柄和标题名称从进程中获取唯一窗口的窗口句柄的最佳方法

问题描述

我正在寻找在以下情况下获取窗口句柄的最佳方法:
我有进程ID 和进程句柄，我知道窗口标题名称，而且我知道该进程只有一个窗口.

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.

那我该怎么办呢? FindWindow? EnumWIndows?

So how would I do it? FindWindow? EnumWIndows?

推荐答案

使用 FindWindow 要求您知道窗口类或窗口标题.两者不一定都是唯一的.由于您已经拥有流程句柄(及其ID)，因此可以使用 EnumWindows .

首先，声明用于通信的结构.它将进程ID传递给枚举过程，并返回窗口句柄.

First, declare a structure used for communication. It passes a process ID to the enumeration procedure and returns the window handle back.

// Structure used to communicate data from and to enumeration procedure
struct EnumData {
    DWORD dwProcessId;
    HWND hWnd;
};

接下来，我们需要一个回调过程来检索进程ID( GetWindowThreadProcessId )，然后将其与我们要查找的窗口进行比较:

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:

// Application-defined callback for EnumWindows
BOOL CALLBACK EnumProc( HWND hWnd, LPARAM lParam ) {
    // Retrieve storage location for communication data
    EnumData& ed = *(EnumData*)lParam;
    DWORD dwProcessId = 0x0;
    // Query process ID for hWnd
    GetWindowThreadProcessId( hWnd, &dwProcessId );
    // Apply filter - if you want to implement additional restrictions,
    // this is the place to do so.
    if ( ed.dwProcessId == dwProcessId ) {
        // Found a window matching the process ID
        ed.hWnd = hWnd;
        // Report success
        SetLastError( ERROR_SUCCESS );
        // Stop enumeration
        return FALSE;
    }
    // Continue enumeration
    return TRUE;
}

剩下的就是公共接口.它使用进程ID填充用于通信的结构，触发顶级窗口的枚举，并返回窗口句柄.对SetLastError 和在这种情况下，错误和成功都是如此:

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:

// Main entry
HWND FindWindowFromProcessId( DWORD dwProcessId ) {
    EnumData ed = { dwProcessId };
    if ( !EnumWindows( EnumProc, (LPARAM)&ed ) &&
         ( GetLastError() == ERROR_SUCCESS ) ) {
        return ed.hWnd;
    }
    return NULL;
}

// Helper method for convenience
HWND FindWindowFromProcess( HANDLE hProcess ) {
    return FindWindowFromProcessId( GetProcessId( hProcess ) );
}

这将检索与给定进程ID匹配的第一个顶级窗口.由于要求指出，给定进程将永远只有一个窗口，因此匹配的第一个窗口是正确的窗口.

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.

如果存在其他限制，可以将EnumProc扩展为包括这些限制.我已经在上面的实现中标记了地点，可以在其中应用其他过滤器.

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.

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