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ScrollBarGadget Position
Posted: Thu Aug 07, 2003 12:30 am
by geoff
When a scroll bar is moved the new position can be obtained with GetGadgetState().
But this only seems to work when the scroll movement is complete and the left mouse button is released.
How can one get the scroll bar position continuously as it is moved?
This is needed to update a window content smoothly and continuously.
Is this already possible? If so, sorry for posting in the wish list.
Posted: Fri Aug 15, 2003 9:15 am
by freedimension
A little Example by Danilo (posted in the German Forum a while ago)
Code: Select all
Procedure RealTimeScrollEvent(GadgetID,Pos)
; Your stuff here, for each Scrollbar
Select GadgetID
Case GadgetID(1) ; Scrollbar 1
SetGadgetText(2,Str(Pos))
Case GadgetID(3) ; Scrollbar 2
SetGadgetText(4,Str(Pos))
EndSelect
EndProcedure
Procedure ScrollCallback(hWnd,Msg,wParam,lParam)
; dont change this procedure
Shared DK_OldScrollCallback
If ((Msg = #WM_HSCROLL) Or (Msg = #WM_VSCROLL)) And (wParam & $FFFF) = #SB_THUMBTRACK
RealTimeScrollEvent(lParam,(wParam >> 16) & $FFFF)
EndIf
If DK_OldScrollCallback
ProcedureReturn CallWindowProc_(DK_OldScrollCallback,hWnd,Msg,wParam,lParam)
Else
ProcedureReturn 0
EndIf
EndProcedure
Procedure SetScrollbarCallback(GadgetNr)
; dont change this procedure
Shared DK_OldScrollCallback
DK_OldScrollCallback = SetWindowLong_(GetParent_(GadgetID(GadgetNr)),#GWL_WNDPROC,@ScrollCallback())
EndProcedure
OpenWindow(0,200,200,200,200,#PB_Window_SystemMenu,"ScrollIt!")
CreateGadgetList(WindowID())
ScrollBarGadget(1,20,20,15,160,1,1000,100,#PB_ScrollBar_Vertical)
TextGadget(2,0,0,100,20,"1")
ScrollBarGadget(3,40,20,100,15,1,8000,1)
TextGadget(4,100,0,100,20,"1")
SetScrollbarCallback(1) ; Gadget 1, first Scrollbar
SetScrollbarCallback(3) ; Gadget 3, second Scrollbar
Repeat:Until WaitWindowEvent()=#PB_Event_CloseWindow
Posted: Tue Aug 26, 2003 6:59 pm
by geoff
Thanks freedimension.
Since I posted this I have found an easier way.
Just look for WM_COMMAND messages in your normal callback routine (ie $111) and use the normal GetGadgetState() to retrieve the slider position.
This solves the problem because the callback routine executes whenever you move the mouse in the slider but your normal control loop does not run until your finger is lifted from the mouse button.