WM_RBUTTONDOWN message

Posted when the user presses the right mouse button while the cursor is in the client area of a window. If the mouse is not captured, the message is posted to the window beneath the cursor. Otherwise, the message is posted to the window that has captured the mouse.

A window receives this message through its WindowProc function.

#define WM_RBUTTONDOWN                  0x0204

Parameters

wParam

Indicates whether various virtual keys are down. This parameter can be one or more of the following values.

Value Meaning
MK_CONTROL
0x0008
The CTRL key is down.
MK_LBUTTON
0x0001
The left mouse button is down.
MK_MBUTTON
0x0010
The middle mouse button is down.
MK_RBUTTON
0x0002
The right mouse button is down.
MK_SHIFT
0x0004
The SHIFT key is down.
MK_XBUTTON1
0x0020
The first X button is down.
MK_XBUTTON2
0x0040
The second X button is down.

lParam

The low-order word specifies the x-coordinate of the cursor. The coordinate is relative to the upper-left corner of the client area.

The high-order word specifies the y-coordinate of the cursor. The coordinate is relative to the upper-left corner of the client area.

Return value

If an application processes this message, it should return zero.

Remarks

Use the following code to obtain the horizontal and vertical position:

xPos = GET_X_LPARAM(lParam); 
yPos = GET_Y_LPARAM(lParam); 

As noted above, the x-coordinate is in the low-order short of the return value; the y-coordinate is in the high-order short (both represent signed values because they can take negative values on systems with multiple monitors). If the return value is assigned to a variable, you can use the MAKEPOINTS macro to obtain a POINTS structure from the return value. You can also use the GET_X_LPARAM or GET_Y_LPARAM macro to extract the x- or y-coordinate.

[!Important]
Do not use the LOWORD or HIWORD macros to extract the x- and y- coordinates of the cursor position because these macros return incorrect results on systems with multiple monitors. Systems with multiple monitors can have negative x- and y- coordinates, and LOWORD and HIWORD treat the coordinates as unsigned quantities.

To detect that the ALT key was pressed, check whether GetKeyState with VK_MENU < 0. Note, this must not be GetAsyncKeyState.

Requirements

Minimum supported client
Windows 2000 Professional [desktop apps only]
Minimum supported server
Windows 2000 Server [desktop apps only]
Header
Winuser.h (include Windowsx.h)

See also

Reference

GET_X_LPARAM

GET_Y_LPARAM

GetCapture

GetKeyState

SetCapture

WM_RBUTTONDBLCLK

WM_RBUTTONUP

Conceptual

Mouse Input

Other Resources

MAKEPOINTS

POINTS