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// **************************************************************************
// * This file is part of the FreeFileSync project. It is distributed under *
// * GNU General Public License: http://www.gnu.org/licenses/gpl.html *
// * Copyright (C) Zenju (zenju AT gmx DOT de) - All Rights Reserved *
// **************************************************************************
//redirect mouse wheel events directly to window under cursor rather than window having input focus
//implementing new Windows Vista UI guidelines: http://msdn.microsoft.com/en-us/library/bb545459.aspx#wheel
//this is confirmed to be required for at least Windows 2000 to Windows 8
//on Ubuntu Linux, this is already the default behavior
//Usage: just include this file into a Windows project
#include <cassert>
#include "win.h" //includes "windows.h"
#include <Windowsx.h> //WM_MOUSEWHEEL
namespace
{
LRESULT CALLBACK mouseInputHook(int nCode, WPARAM wParam, LPARAM lParam)
{
//"if nCode is less than zero, the hook procedure must pass the message to the CallNextHookEx function
//without further processing and should return the value returned by CallNextHookEx"
if (nCode == HC_ACTION) //the only valid value for this hook type
{
MSG& msgInfo = *reinterpret_cast<MSG*>(lParam);
if (msgInfo.message == WM_MOUSEWHEEL ||
msgInfo.message == WM_MOUSEHWHEEL)
{
POINT pt = {};
pt.x = GET_X_LPARAM(msgInfo.lParam); //yes, there's also msgInfo.pt, but let's not take chances
pt.y = GET_Y_LPARAM(msgInfo.lParam); //
//visible child window directly under cursor; attention: not necessarily from our process!
if (HWND hWin = ::WindowFromPoint(pt)) //http://blogs.msdn.com/b/oldnewthing/archive/2010/12/30/10110077.aspx
if (msgInfo.hwnd != hWin && ::GetCapture() == nullptr)
{
DWORD winProcessId = 0;
::GetWindowThreadProcessId( //no-fail!
hWin, //_In_ HWND hWnd,
&winProcessId); //_Out_opt_ LPDWORD lpdwProcessId
if (winProcessId == ::GetCurrentProcessId()) //no-fail!
msgInfo.hwnd = hWin; //it would be a bug to set handle from another process here
}
}
}
return ::CallNextHookEx(nullptr, nCode, wParam, lParam);
}
struct InstallMouseHook
{
InstallMouseHook()
{
hHook = ::SetWindowsHookEx(WH_GETMESSAGE, //__in int idHook,
mouseInputHook, //__in HOOKPROC lpfn,
nullptr, //__in HINSTANCE hMod,
::GetCurrentThreadId()); //__in DWORD dwThreadId
assert(hHook);
}
~InstallMouseHook()
{
if (hHook)
::UnhookWindowsHookEx(hHook);
}
private:
HHOOK hHook;
} dummy;
}
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