Trackbar and SetGadgetState

dmoc · Post by **dmoc** » Sat May 06, 2006 8:25 am

I have a trackbar that is used as an indicator, ie, changed using SetGadgetState(). What EventType/#WM_???? tells me it has changed? I want to update a text control when the bars value changes, possibly from several places so I want to capture an event. Another situation is where a trackbar is used for both input and output (at different times).

srod · Post by **srod** » Sat May 06, 2006 11:01 am

In a window callback, use #WM_HSCROLL and check the lParam for the handle of the control etc.

This event doesn't seem to fire within a normal PB event loop for these controls as PB swallows the message.

josku_x · Post by **josku_x** » Sat May 06, 2006 11:03 am

Now I understand why my attemps don't work.

I hoped to help dmoc, but thanks to you srod now one more thing is clear here.

dmoc · Post by **dmoc** » Sat May 06, 2006 11:22 am

Thanks for the reply srod but the callback is not getting #WM_HSCROLL or #WM_VSCROLL (it's a vertical trackbar) messages when SetGadgetState() is called even though the trkbar is visibly changing.

PS: This is PB v4b11 if it makes any difference

srod · Post by **srod** » Sat May 06, 2006 11:27 am

Sorry, I didn't read the bit about SetGadgetState(). Back in a mo...

The following works here ok. Also on PB 4 -b11.

Code: Select all

REMOVED

srod · Post by **srod** » Sat May 06, 2006 11:39 am

dmoc, it's true the #TBM_SETPOS message doesn't seem to fire off any messages (at least at first glance). I guess the thing is, why would you need to intercept a message when your code is actually changing the track position anyhow? Surely you can set the contents of the text gadget at the same time?

I'll keep looking however.

netmaestro · Post by **netmaestro** » Sat May 06, 2006 11:43 am

This works here:

Code: Select all

Procedure Callback(hwnd, message, wparam, lparam)
  If message = #WM_VSCROLL
    If wparam & $FFFFFFFF = #SB_ENDSCROLL
      Debug "Changed!"   
    EndIf
  EndIf
  ProcedureReturn #PB_ProcessPureBasicEvents
EndProcedure

OpenWindow(0,0,0,640,480,"VistaClock dll Test",#PB_Window_ScreenCentered|#PB_Window_SystemMenu) 
CreateGadgetList(WindowID(0)) 
TrackBarGadget(0,200,50,20,200,64,320,#PB_TrackBar_Vertical) 

SetWindowCallback(@callback())

Repeat 
  EventID=WaitWindowEvent()
 
Until EventID=#PB_Event_CloseWindow

srod · Post by **srod** » Sat May 06, 2006 11:49 am

netmaestro, he wants to intercept changes to the trackbar position instigated not by the user, but by use of the SetGadgetState() function.

netmaestro · Post by **netmaestro** » Sat May 06, 2006 11:53 am

Why does that need trapped when the program already knows it just set the gadget state? And anyways, you can always put GetGadgetState in the loop and store its values.

srod · Post by **srod** » Sat May 06, 2006 11:55 am

My thoughts exactly.

netmaestro · Post by **netmaestro** » Sat May 06, 2006 11:57 am

Well, you may look like a mule...

srod · Post by **srod** » Sat May 06, 2006 12:02 pm

There's no may about it!

srod · Post by **srod** » Sat May 06, 2006 12:06 pm

dmoc, one completely unsubtle approach is to subclass the TrackBar and intercept it's #WM_PAINT event.

Code: Select all

Global oldproc

Procedure MyWindowCallback(WindowID, Message, wParam, lParam)
    Select Message
      Case #WM_PAINT
      Debug 1
    EndSelect
    ProcedureReturn CallWindowProc_(oldproc, WindowID, Message, wParam, lParam) 
  EndProcedure



If OpenWindow(0, 0, 0, 320, 200, "TrackBarGadget", #PB_Window_SystemMenu | #PB_Window_ScreenCentered) And CreateGadgetList(WindowID(0))
    TextGadget    (3, 10,  40, 250, 20,"TrackBar Standard", #PB_Text_Center)
    TrackBarGadget(0, 10,  60, 250, 20, 0, 10000)
    ButtonGadget(1,10,10,100,20,"Click!")
    oldproc=SetWindowLong_(GadgetID(0), #GWL_WNDPROC, @MyWindowCallback()) 
    SetGadgetState(0, 5000)
    Repeat
      ev=WaitWindowEvent()
      Select ev
        Case #PB_Event_Gadget
          Select EventGadget()
            Case 1
              SetGadgetState(0, 6000)
          EndSelect
      EndSelect
    Until ev = #PB_Event_CloseWindow
  EndIf

It aint pretty though!

dmoc · Post by **dmoc** » Sat May 06, 2006 12:09 pm

My friends, the path you suggest is the path to madness

I speak now of only one control and one dependent control. But a time may come when there are many controls each of which beget yet more controls. And so a multitude of controls and message thus go forth and hence forth chaos shall rule the world.

You see now how important it is that we find an answer and save the world?

srod · Post by **srod** » Sat May 06, 2006 12:16 pm

The following avoids subclassing and only fires for the the specified trackbar.

However, I've no idea what message corresponds to 312!!!

Code: Select all

Procedure MyWindowCallback(WindowID, Message, wParam, lParam)
    Result = #PB_ProcessPureBasicEvents
    Select Message
      Case 312
        If lparam=GadgetID(0)
          Debug "Trackbar changed!"
        EndIf
    EndSelect
    ProcedureReturn Result
  EndProcedure



If OpenWindow(0, 0, 0, 320, 200, "TrackBarGadget", #PB_Window_SystemMenu | #PB_Window_ScreenCentered) And CreateGadgetList(WindowID(0))
    TextGadget    (3, 10,  40, 250, 20,"TrackBar Standard", #PB_Text_Center)
    TrackBarGadget(0, 10,  60, 250, 20, 0, 10000)
    ButtonGadget(1,10,10,100,20,"Click!")
    SetWindowCallback(@MyWindowCallback(),0)
    ;SetGadgetState(0, 5000)
    Repeat
      ev=WaitWindowEvent()
      Select ev
        Case #PB_Event_Gadget
          Select EventGadget()
            Case 1
              SetGadgetState(0, 6000)
          EndSelect
      EndSelect
    Until ev = #PB_Event_CloseWindow
  EndIf