Automating mouse actions
by Richard Russell, October 2008
You may on occasion want to automate mouse actions, such as simulating the effect of the user clicking a button or rotating the wheel. One use for such a facility could, for example, be in a training or tutorial situation where you wish to illustrate how to use the mouse to achieve a particular result.
Windows provides the means to do that by means of the SendInput API (Windows 98 and later only). The following code has the same effect as the user double-clicking the left mouse button:
_INPUT_MOUSE = 0
_MOUSEEVENTF_LEFTDOWN = 2
_MOUSEEVENTF_LEFTUP = 4
DIM Input{type%, Mouse{dx%, dy%, mouseData%, dwFlags%, time%, dwExtraInfo%}}
Input.type% = _INPUT_MOUSE
Input.Mouse.dwFlags% = _MOUSEEVENTF_LEFTDOWN
SYS "SendInput", 1, Input{}, DIM(Input{})
Input.Mouse.dwFlags% = _MOUSEEVENTF_LEFTUP
SYS "SendInput", 1, Input{}, DIM(Input{})
Input.Mouse.dwFlags% = _MOUSEEVENTF_LEFTDOWN
SYS "SendInput", 1, Input{}, DIM(Input{})
Input.Mouse.dwFlags% = _MOUSEEVENTF_LEFTUP
SYS "SendInput", 1, Input{}, DIM(Input{})
Other constants that you may need are as follows:
_MOUSEEVENTF_RIGHTDOWN = &8
_MOUSEEVENTF_RIGHTUP = &10
_MOUSEEVENTF_MIDDLEDOWN = &20
_MOUSEEVENTF_MIDDLEUP = &40
_MOUSEEVENTF_WHEEL = &800
In the case of wheel movements the mouseData% member of the structure must be loaded with a positive value for rotations away from the user, and a negative value for rotations towards the user. A value of 120 corresponds to one 'click':
_INPUT_MOUSE = 0
_MOUSEEVENTF_WHEEL = &800
DIM Input{type%, Mouse{dx%, dy%, mouseData%, dwFlags%, time%, dwExtraInfo%}}
Input.type% = _INPUT_MOUSE
Input.Mouse.dwFlags% = _MOUSEEVENTF_WHEEL
Input.Mouse.mouseData% = 120
SYS "SendInput", 1, Input{}, DIM(Input{})
The SendInput API provides many other facilities, such as simulating keyboard input (you can use it as an alternative to the method described at Faking keyboard input). For full details see the relevant Microsoft documentation.