WM HITTEST

This message is sent to determine which window is associated with an input from the pointing device.

Syntax

param1
    POINTS    ptspointerpos;  /* Pointer position. */

param2
    ULONG     ulReserved;   /* Reserved value, should be 0. */

Parameters

ptspointerpos (POINTS) - Input

Pointer position. The pointer position is in window coordinates relative to the bottom-left corner of the window.

ulReserved (ULONG) - Input

Reserved value, should be 0.

Returns

ulresult (ULONG) - returns

Hit-test indicator. The application may return one of these values:

HT_NORMAL

The message should be processed as normal. A WM_MOUSEMOVE, WM_BUTTON2DOWN, or WM_BUTTON1DOWN message is posted to the window.

HT_TRANSPARENT

The part of the window underneath the pointer is transparent; hit-testing should continue on windows underneath this window, as if the window did not exist.

HT_DISCARD

The message should be discarded; no message is posted to the application.

HT_ERROR

As HT_DISCARD, except that if the message is a button-down message, an alarm sounds and the window concerned is brought to the foreground.

Remarks

This message occurs when an application requests a message by issuing a WinPeekMsg or a WinGetMsg function.

If the message that is to be retrieved represents a pointer related event, this message is sent to a window to determine whether the message is in fact destined for that window.

This message is only sent if the window class has the CS_HITTEST style set.

Note

The handling of this message determines whether a disabled window can process pointing device events.

Default Processing

The default window procedure takes no action on this message, other than to set ulresult to HT_ERROR if the window is disabled, or to HT_NORMAL otherwise.