WM_NCHITTEST
The
WM_NCHITTEST message is sent to a window when the cursor moves, or when a mouse
button is pressed or released. If the mouse is not captured, the message is
sent to the window beneath the cursor. Otherwise, the message is posted to the
window that has captured the mouse.
WM_NCHITTEST
xPos = LOWORD(lParam); // horizontal position of cursor
yPos = HIWORD(lParam); // vertical position of cursor
Parameters
xPos
Value of the
low-order word of lParam. Specifies the x-coordinate of the cursor. The
coordinate is relative to the upper-left corner of the screen.
yPos
Value of the
high-order word of lParam. Specifies the y-coordinate of the cursor. The
coordinate is relative to the upper-left corner of the screen.
Return Values
The return
value of the DefWindowProc
function is one of the following values, indicating the position of the cursor
hot spot:
|
Value |
Location
of hot spot |
|
HTBORDER |
In the
border of a window that does not have a sizing border |
|
HTBOTTOM |
In the
lower horizontal border of a window |
|
HTBOTTOMLEFT |
In the
lower-left corner of a window border |
|
HTBOTTOMRIGHT |
In the
lower-right corner of a window border |
|
HTCAPTION |
In a title
bar |
|
HTCLIENT |
In a client
area |
|
HTERROR |
On the
screen background or on a dividing line between windows (same as HTNOWHERE,
except that the DefWindowProc function produces a system beep to
indicate an error) |
|
HTGROWBOX |
In a size
box (same as HTSIZE) |
|
HTHSCROLL |
In a
horizontal scroll bar |
|
HTLEFT |
In the left
border of a window |
|
HTMENU |
In a menu |
|
HTNOWHERE |
On the
screen background or on a dividing line between windows |
|
HTREDUCE |
In a
Minimize button |
|
HTRIGHT |
In the
right border of a window |
|
HTSIZE |
In a size
box (same as HTGROWBOX) |
|
HTSYSMENU |
In a System
menu or in a Close button in a child window |
|
HTTOP |
In the
upper horizontal border of a window |
|
HTTOPLEFT |
In the
upper-left corner of a window border |
|
HTTOPRIGHT |
In the
upper right corner of a window border |
|
HTTRANSPARENT |
In a window
currently covered by another window |
|
HTVSCROLL |
In the
vertical scroll bar |
|
HTZOOM |
In a
Maximize button |
Remarks
An
application can use the MAKEPOINTS macro to convert the lParam
parameter to a POINTS structure.
See Also