利用 AttachThreadInput 和 WM_INPUTLANGCHANGEREQUEST 消息改变其它进程的输入状态

https://blog.csdn.net/kaizi318/article/details/7766283?utm_medium=distribute.pc_relevant_bbs_down.none-task-blog-baidujs-1.nonecase&depth_1-utm_source=distribute.pc_relevant_bbs_down.none-task-blog-baidujs-1.nonecase 

 https://stackoverflow.com/questions/24319987/delphi-simulate-key-press-for-automation 

https://www.it1352.com/2041624.html

c# AttachThreadInput  WM_INPUTLANGCHANGEREQUEST

HWND hWnd = GetForegroundWindow();
ASSERT(IsWindow(hWnd))

// Get Target Thread ID and Attach Thread Input
DWORD ProcID;
DWORD ThreadID = GetWindowThreadProcessId(hWnd, &ProcID);
AttachThreadInput(GetCurrentThreadId(), ThreadID, TRUE);

// Get Target Window
HWND hWndFocus = GetFocus();

// Post Input Messages 
ASSERT(IsWindow(hWndFocus));

// Change Input Language
PostMessage(hWndFocus, WM_INPUTLANGCHANGEREQUEST, (WPARAM)TRUE, (LPARAM)g_hklRPC);   // Use Language ID 0x0804(Chinese PRC)

// Detach Thread Input
AttachThreadInput(GetCurrentThreadId(), ThreadID, FALSE);