Re: SetCursor weirdness

domehead100 wrote:
> When reviewing the code, I discovered that the class was declared
> like this:
>
> template<class TValidator = CNoSWSValidate>
> class CSelectWindowStaticT : public CWindowImpl<CStatic>
> {
> ...
> }
>
> Note that it is not ": public
> CWindowImpl<CSelectWindowStaticT<TValidator>, CStatic>", it's just ":
> public CWindowImpl<CStatic>"
>
> Yet, all of my message handlers in CSelectWindowStaticT ARE being
> called (OnMouseMove, OnLButtonDown, etc.).
>
> Why?  The message map should be calling ProcessWindowMessage for the
> first template argument to CWindowImpl

No. The message map _is_ ProcessWindowMessage - check out what 
BEGIN_MSG_MAP macro actually expands to. ProcessWindowMessage is a 
virtual function, so a call goes to the most-derived class.

CWindowImpl uses its first parameter only to call GetWndClassInfo, 
GetWndStyle, GetWndExStyle and GetWndCaption. I imagine you don't 
override any of these.

> Oddity #2
> One of the things the OnLButtonDown handler does is call SetCursor()
> to set the cursor (mouse pointer) to the crosshairs.  Then it calls
> SetCapture() to track the mouse movement.  As it turns out, the class
> works perfectly when it's ": public CWindowImpl<CStatic>"; e.g., when
> I click on the control the crosshairs seem to move off of the static
> as I move the mouse.
>
> When I derive it correctly, however, then when I click the left mouse
> button the cursor remains the standard arrow and does not change to
> the crosshairs.

In the first case you call ::SetCursor from Win32 API. In the second, 
you call CStatic::SetCursor from WTL's atlctrls.h, which translates to 
SendMessage(STM_SETIMAGE) and doesn't actually affect mouse cursor in 
any way.

Igor Tandetnik 





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