OpenEuphoria

RE: Syncronising Lists

• Posted by Derek Parnell <ddparnell at bigpond.com> Apr 24, 2002
• 355 views

pg_russell at lineone.net wrote:
> Hi,
> 
> Oops! Included a fix for when the user drags the mouse in a list window 
> (and tidied up a bit).
> 
> Phil Russell
> 
> include Win32Lib.ew
> without warning
> 
> integer oldwndproc, void
> 
> -- Window Test
> global constant Test = create( Window, "List Sync", 0, Default, Default,
> 333, 230, 0 )
> global constant List1 = create( List, "List1", Test, 8, 12, 92, 172, 0 )
> global constant List2 = create( List, "List2", Test, 116, 12, 92, 172,0
> )
> global constant List3 = create( List, "List3", Test, 222, 12, 92, 172, 0
> )
> 
> for n = 1 to 10 do
> addItem(List1, "item " & sprint(n) & " list1")
> addItem(List2, "item " & sprint(n) & " list2")
> addItem(List3, "item " & sprint(n) & " list3")
> end for
> 
> function Test_WndProc( atom hWnd, atom iMsg, atom wParam, atom lParam )
> 
> integer pos, ret
> 
> -- allow list box to process the message
> ret = w32Func( xCallWindowProc, { oldwndproc, hWnd, iMsg, wParam, lParam 
> 
> } )
> 
> -- intercept clicks and keypresses in the list boxes
> if iMsg = WM_LBUTTONDOWN
> or iMsg = WM_KEYDOWN
> or iMsg = WM_LBUTTONUP
> -- user drags the mouse in the list box
> or (iMsg = WM_MOUSEMOVE and and_bits(wParam, MK_LBUTTON))
> then
> 
>      -- get the resulting list box selection
>      pos = w32Func( xSendMessage, {hWnd, LB_GETCURSEL, 0, 0 } )
> 
>      -- if valid then update the other list boxes
> 	if pos >= 0 then
> 		if hWnd != getHandle(List1) then
> 			setIndex(List1, pos+1)
> 		end if
> 		if hWnd != getHandle(List2) then
> 			setIndex(List2, pos+1)
> 		end if
> 		if hWnd != getHandle(List3) then
> 			setIndex(List3, pos+1)
> 		end if
> 	end if
> end if
> 
> -- return value from default list box procedure
> return ret
> 
> end function
> 
> -- Subclass the list boxes
> oldwndproc = w32Func( xSetWindowLong, { getHandle(List1), GWL_WndProc,
> call_back(routine_id("Test_WndProc")) } )
> void = w32Func( xSetWindowLong, { getHandle(List2), GWL_WndProc,
> call_back(routine_id("Test_WndProc")) } )
> void = w32Func( xSetWindowLong, { getHandle(List3), GWL_WndProc,
> call_back(routine_id("Test_WndProc")) } )
> 
> setIndex(List1, 1)
> setIndex(List2, 1)
> setIndex(List3, 1)
> 
> -- Display window
> WinMain( Test, Normal )
> 
> 
It turns out that the issue is not whether or not the control is 
subclassed, because Win32lib already subclasses the controls, but when 
control is given to the user-written event handlers relative to the 
control handling the event. 

Currently, user-written handler code that is triggered by a Window 
message, is called *before* the control's own code gets the message. 
Thus for a List control, our onChange event gets called before the List 
updates its display.

What might be nice is if win32lib has a new event type "AfterEvent" that 
is called after the control has finished processing the Windows message, 
but before the next message is recieved. This would be similar to the 
current "Event" event type, which is called before any processing of the 
Windows message is done (even by Win32lib).

If there are no objections, I'll add it to the library (should take 
about 15 mins to do). 

P.S. I'll be back home on the weekend and will be able to issue the next 
release of the library with all the great feedback, including bug fixes, 
I've had. Thanks for all your support, people.

---------
Derek.