WM_LBUTTONDBLCLK message

Posted when the user double-clicks the left 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_LBUTTONDBLCLK                0x0203

wParam

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

Expand table

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 XBUTTON1 is down.
MK_XBUTTON2 0x0040	The XBUTTON2 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.

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

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.

Only windows that have the CS_DBLCLKS style can receive WM_LBUTTONDBLCLK messages, which the system generates whenever the user presses, releases, and again presses the left mouse button within the system's double-click time limit. Double-clicking the left mouse button actually generates a sequence of four messages: WM_LBUTTONDOWN, WM_LBUTTONUP, WM_LBUTTONDBLCLK, and WM_LBUTTONUP.

Reference

GET_X_LPARAM

GET_Y_LPARAM

GetCapture

GetDoubleClickTime

SetCapture

SetDoubleClickTime

WM_LBUTTONDOWN

WM_LBUTTONUP

Conceptual

Mouse Input

Other Resources

MAKEPOINTS

POINTS