Send "button pressed" message to UnityWndClass - c++

Question

I have 3D game and i need to press buttons in this game from another application. Spy++ says that window of the game is UnityWndClass. When i pressing buttons in game, window recives only mouse messages like WM_SETCURSOR, WM_LBUTTONDOWN etc, but when i try to send WM_LBUTTONDOWN and WM_LBUTTONUP with coordinates of the button from another window nothing happend. Why? Any ideas how to press buttons?

Answer 1

WM_SETCURSOR is for changing the cursor image of your own window. WM_LBUTTONDOWN and WM_LBUTTONUP are notification messages sent after mouse click. WM_LBUTTONXXX messages are probably not handled by the main Window procedure.
To fake mouse input, you can use mouse_event or SendInput. For example, this moves cursor to x=10 / y=10 and and clicks left mouse.
int x = 10 * 65536 / GetSystemMetrics(SM_CXSCREEN);
int y = 10 * 65536 / GetSystemMetrics(SM_CYSCREEN);
mouse_event(MOUSEEVENTF_ABSOLUTE | MOUSEEVENTF_MOVE, x, y, 0, 0);
mouse_event(MOUSEEVENTF_LEFTDOWN, 0, 0, 0, 0);
mouse_event(MOUSEEVENTF_LEFTUP, 0, 0, 0, 0);
Or use SendInput for multiple calls (see comments)
INPUT input[3];
for (int i = 0; i < 3; i++)
{
memset(&input[i], 0, sizeof(INPUT));
input[i].type = INPUT_MOUSE;
}
input[0].mi.dx = x;
input[0].mi.dy = y;
input[0].mi.dwFlags = MOUSEEVENTF_ABSOLUTE | MOUSEEVENTF_MOVE;
input[1].mi.dwFlags = MOUSEEVENTF_LEFTDOWN;
input[2].mi.dwFlags = MOUSEEVENTF_LEFTUP;
SendInput(3, input, sizeof(INPUT));
Window should be at least visible and preferably be active. You can use SetForegroundWindow. See this example to make sure window is visible and active.
Other alternatives:
Use Spy++ to get information about the button which you want to press.
For example, if this was Windows Calculator, you can spy on calculator's buttons, it shows calculator button 2 has ID set to 0x84. You can send WM_COMMAND with WPARAM set to 0x84 to simulate button press.
HWND hwnd = FindWindow(0, L"Calculator");
if (IsWindow(hwnd))
{
//this should put "234" in to calculator's edit box
SendMessage(hwnd, WM_COMMAND, 0x84, 0);
SendMessage(hwnd, WM_COMMAND, 0x85, 0);
SendMessage(hwnd, WM_COMMAND, 0x86, 0);
}