The MOUSEINPUT structure contains information about a simulated mouse event.

Syntax

typedef struct tagMOUSEINPUT {
    LONG dx;
    LONG dy;
    DWORD mouseData;
    DWORD dwFlags;
    DWORD time;
    ULONG_PTR dwExtraInfo;
} MOUSEINPUT, *PMOUSEINPUT;

Members

dx

Specifies the absolute position of the mouse, or the amount of motion since the last mouse event was generated, depending on the value of the dwFlags member. Absolute data is specified as the x coordinate of the mouse; relative data is specified as the number of pixels moved.

dy

Specifies the absolute position of the mouse, or the amount of motion since the last mouse event was generated, depending on the value of the dwFlags member. Absolute data is specified as the y coordinate of the mouse; relative data is specified as the number of pixels moved.

mouseData

If dwFlags contains MOUSEEVENTF_WHEEL, then mouseData specifies the amount of wheel movement. A positive value indicates that the wheel was rotated forward, away from the user; a negative value indicates that the wheel was rotated backward, toward the user. One wheel click is defined as WHEEL_DELTA, which is 120.

Windows Vista: If dwFlags contains MOUSEEVENTF_HWHEEL, then dwData specifies the amount of wheel movement. A positive value indicates that the wheel was rotated to the right; a negative value indicates that the wheel was rotated to the left. One wheel click is defined as WHEEL_DELTA, which is 120.

Windows 2000/XP: IfdwFlags does not contain MOUSEEVENTF_WHEEL, MOUSEEVENTF_XDOWN, or MOUSEEVENTF_XUP, then mouseData should be zero.

If dwFlags contains MOUSEEVENTF_XDOWN or MOUSEEVENTF_XUP, then mouseData specifies which X buttons were pressed or released. This value may be any combination of the following flags.

XBUTTON1

Set if the first X button is pressed or released.

XBUTTON2

Set if the second X button is pressed or released.

dwFlags

A set of bit flags that specify various aspects of mouse motion and button clicks. The bits in this member can be any reasonable combination of the following values.

The bit flags that specify mouse button status are set to indicate changes in status, not ongoing conditions. For example, if the left mouse button is pressed and held down, MOUSEEVENTF_LEFTDOWN is set when the left button is first pressed, but not for subsequent motions. Similarly, MOUSEEVENTF_LEFTUP is set only when the button is first released.

You cannot specify both the MOUSEEVENTF_WHEEL flag and either MOUSEEVENTF_XDOWN or MOUSEEVENTF_XUP flags simultaneously in the dwFlags parameter, because they both require use of the mouseData field.

MOUSEEVENTF_ABSOLUTE

Specifies that the dx and dy members contain normalized absolute coordinates. If the flag is not set, dxand dy contain relative data (the change in position since the last reported position). This flag can be set, or not set, regardless of what kind of mouse or other pointing device, if any, is connected to the system. For further information about relative mouse motion, see the following Remarks section.

MOUSEEVENTF_MOVE

Specifies that movement occurred.

MOUSEEVENTF_MOVE_NOCOALESCE

Windows Vista: Specifies that WM_MOUSEMOVE messages will not be coalesced. The default behavior is to coalesce WM_MOUSEMOVE messages.

MOUSEEVENTF_LEFTDOWN

Specifies that the left button was pressed.

MOUSEEVENTF_LEFTUP

Specifies that the left button was released.

MOUSEEVENTF_RIGHTDOWN

Specifies that the right button was pressed.

MOUSEEVENTF_RIGHTUP

Specifies that the right button was released.

MOUSEEVENTF_MIDDLEDOWN

Specifies that the middle button was pressed.

MOUSEEVENTF_MIDDLEUP

Specifies that the middle button was released.

MOUSEEVENTF_VIRTUALDESK

Windows 2000/XP: Maps coordinates to the entire desktop. Must be used with MOUSEEVENTF_ABSOLUTE.

MOUSEEVENTF_WHEEL

Windows NT/2000/XP: Specifies that the wheel was moved, if the mouse has a wheel. The amount of movement is specified in mouseData.

MOUSEEVENTF_HWHEEL

Windows Vista: Specifies that the wheel was moved horizontally, if the mouse has a wheel. The amount of movement is specified in mouseData.

MOUSEEVENTF_XDOWN

Windows 2000/XP: Specifies that an X button was pressed.

MOUSEEVENTF_XUP

Windows 2000/XP: Specifies that an X button was released.

time

Time stamp for the event, in milliseconds. If this parameter is 0, the system will provide its own time stamp.

dwExtraInfo

Specifies an additional value associated with the mouse event. An application calls GetMessageExtraInfo to obtain this extra information.

Remarks

If the mouse has moved, indicated by MOUSEEVENTF_MOVE, dxand dy specify information about that movement. The information is specified as absolute or relative integer values.

If MOUSEEVENTF_ABSOLUTE value is specified, dx and dy contain normalized absolute coordinates between 0 and 65,535. The event procedure maps these coordinates onto the display surface. Coordinate (0,0) maps onto the upper-left corner of the display surface; coordinate (65535,65535) maps onto the lower-right corner. In a multimonitor system, the coordinates map to the primary monitor.

Windows 2000/XP: If MOUSEEVENTF_VIRTUALDESK is specified, the coordinates map to the entire virtual desktop.

If the MOUSEEVENTF_ABSOLUTE value is not specified, dxand dy specify movement relative to the previous mouse event (the last reported position). Positive values mean the mouse moved right (or down); negative values mean the mouse moved left (or up).

Relative mouse motion is subject to the effects of the mouse speed and the two-mouse threshold values. A user sets these three values with the Pointer Speed slider of the Control Panel's Mouse Properties sheet. You can obtain and set these values using the SystemParametersInfo function.

The system applies two tests to the specified relative mouse movement. If the specified distance along either the x or y axis is greater than the first mouse threshold value, and the mouse speed is not zero, the system doubles the distance. If the specified distance along either the x or y axis is greater than the second mouse threshold value, and the mouse speed is equal to two, the system doubles the distance that resulted from applying the first threshold test. It is thus possible for the system to multiply specified relative mouse movement along the x or y axis by up to four times.

Structure Information

Header	Declared in Winuser.h, include Windows.h
Minimum operating systems	Windows 98, Windows NT 4.0 Service Pack 3

See Also

Keyboard Input, GetMessageExtraInfo, INPUT, SendInput, SystemParametersInfo