GUICtrlCreateList scrolled to bottom by default

[GPinzone]

I have a list (GUICtrlCreateList) tall enough to display 7 items. A scrollbar appears when the list had more than 7 items, which is the desired behavior. However, if the list is showing the last 7 items, not the first 7. In other words, the scrollbar is scrolled to the end by default instead of the top of the list. Is there any way to change this behavior?

Here's what I have:

Local $List_Queue = GUICtrlCreateList("", 2, 60, 400, 100, BitOR($LBS_MULTIPLESEL,$WS_HSCROLL,$WS_VSCROLL,$WS_BORDER))
GUICtrlSetLimit(-1, 200) ; to limit horizontal scrolling

[Melba23]

GPinzone,

When I create a list it is the top 7 items that are displayed:

#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <Constants.au3>
#include <ListBoxConstants.au3>

$hGUI = GUICreate("Test", 500, 500)

Local $cList = GUICtrlCreateList("", 2, 60, 400, 100, BitOR($LBS_MULTIPLESEL,$WS_HSCROLL,$WS_VSCROLL,$WS_BORDER))
GUICtrlSetLimit(-1, 200) ; to limit horizontal scrolling

GUISetState()

For $i = 1 To 20
    GUICtrlSetData($cList, "Item " & $i)
    Sleep(100)
Next

While 1
    Switch GUIGetMsg()
        Case $GUI_EVENT_CLOSE
            Exit
    EndSwitch
WEnd

Can you post a reproducer that results in you keeping the bottom 7 in view? :waco:

M23

[GPinzone]

I Think I know what's causing the issue for me now that I look at your code. I'm also using _GUICtrlListBox_SetSel to pre select the items as I add them to the list. I modified your example to include _GUICtrlListBox_SetSel and it exhibits the same behavior. 

#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <Constants.au3>
#include <ListBoxConstants.au3>
#include <GuiListBox.au3>

$hGUI = GUICreate("Test", 500, 500)

Local $cList = GUICtrlCreateList("", 2, 60, 400, 100, BitOR($LBS_MULTIPLESEL, $WS_HSCROLL, $WS_VSCROLL, $WS_BORDER))
GUICtrlSetLimit(-1, 200) ; to limit horizontal scrolling GUISetState()

For $i = 1 To 20
    GUICtrlSetData($cList, "Item " & $i)
    _GUICtrlListBox_SetSel($cList, $i-1)
Next

GUISetState(@SW_SHOW)

While 1
    Switch GUIGetMsg()
        Case $GUI_EVENT_CLOSE
            Exit
    EndSwitch
WEnd

I suppose a "solution" would be to do the loop twice something like:

For $i = 1 To 20
    GUICtrlSetData($cList, "Item " & $i)
Next

For $i = 20 To 1 Step -1
    _GUICtrlListBox_SetSel($cList, $i-1)
Next

to do the _GUICtrlListBox_SetSel stuff in reverse order, but that's not very elegant.

[Melba23]

GPinzone,

Then I suggest you tell the listbox to scroll to the top once you have filled it:

#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <Constants.au3>
#include <ListBoxConstants.au3>
#include <GuiListBox.au3>

$hGUI = GUICreate("Test", 500, 500)

Local $cList = GUICtrlCreateList("", 2, 60, 400, 100, BitOR($LBS_MULTIPLESEL, $WS_HSCROLL, $WS_VSCROLL, $WS_BORDER))
GUICtrlSetLimit(-1, 200) ; to limit horizontal scrolling GUISetState()

For $i = 1 To 20
    GUICtrlSetData($cList, "Item " & $i)
    _GUICtrlListBox_SetSel($cList, $i-1)
Next

GUICtrlSendMsg($cList, $LB_SETTOPINDEX, 0, 0) ; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

GUISetState(@SW_SHOW)

While 1
    Switch GUIGetMsg()
        Case $GUI_EVENT_CLOSE
            Exit
    EndSwitch
WEnd

That seems to work.

M23

[GPinzone]

Yeah, that'll do it. Thanks!

[Melba23]

GPinzone,

Glad I could help.

M23

[TheSaint]

Why are you selecting each one as you add it?

I would (and do) just select the one I want, after the List has been fully populated, which is usually the first entry, by using

_GUICtrlListBox_SetSel($cList, 0)

which is outside the Loop, like Melba23's alternative method.

P.S. That will scroll it into view if it's not.

Edited August 26, 2013 by TheSaint

[GPinzone]

Knight:

   It's a CD/DVD duplicator queue, and I want all of the items on the list to be processed by default. That's why I want them all to be selected by default. If any of the discs are to be omitted, the person would click on the corresponding entry, which would toggle it off.

EDIT: After digging into _GUICtrlListBox_SetSel, I could have just used:

GUICtrlSendMsg(-1, $LB_SETSEL, True, $i)

instead of _GUICtrlListBox_SetSel. I still have to re-adjust the list position.
 

Edited August 26, 2013 by GPinzone

[GPinzone]

BTW, Take a look at the _GUICtrlListBox_SetSel function:

expandcollapse popup

Func _GUICtrlListBox_SetSel($hWnd, $iIndex = -1, $fSelect = -1)
    If $Debug_LB Then __UDF_ValidateClassName($hWnd, $__LISTBOXCONSTANT_ClassNames)
    Local $i_ret = True
    If IsHWnd($hWnd) Then
        If $iIndex == -1 Then ; toggle all
            For $iIndex = 0 To _GUICtrlListBox_GetCount($hWnd) - 1
                $i_ret = _GUICtrlListBox_GetSel($hWnd, $iIndex)
                If ($i_ret == $LB_ERR) Then Return SetError($LB_ERR, $LB_ERR, False)
                If ($i_ret > 0) Then ;If Selected Then
                    $i_ret = _SendMessage($hWnd, $LB_SETSEL, False, $iIndex) <> -1
                Else
                    $i_ret = _SendMessage($hWnd, $LB_SETSEL, True, $iIndex) <> -1
                EndIf
                If ($i_ret == False) Then Return SetError($LB_ERR, $LB_ERR, False)
            Next
        ElseIf $fSelect == -1 Then ; toggle state of index
            If _GUICtrlListBox_GetSel($hWnd, $iIndex) Then ;If Selected Then
                Return _SendMessage($hWnd, $LB_SETSEL, False, $iIndex) <> -1
            Else
                Return _SendMessage($hWnd, $LB_SETSEL, True, $iIndex) <> -1
            EndIf
        Else ; set state according to flag
            Return _SendMessage($hWnd, $LB_SETSEL, $fSelect, $iIndex) <> -1
        EndIf
    Else
        If $iIndex == -1 Then ; toggle all
            For $iIndex = 0 To _GUICtrlListBox_GetCount($hWnd) - 1
                $i_ret = _GUICtrlListBox_GetSel($hWnd, $iIndex)
                If ($i_ret == $LB_ERR) Then Return SetError($LB_ERR, $LB_ERR, False)
                If ($i_ret > 0) Then ;If Selected Then
                    $i_ret = GUICtrlSendMsg($hWnd, $LB_SETSEL, False, $iIndex) <> -1
                Else
                    $i_ret = GUICtrlSendMsg($hWnd, $LB_SETSEL, True, $iIndex) <> -1
                EndIf
                If ($i_ret == False) Then Return SetError($LB_ERR, $LB_ERR, False)
            Next
        ElseIf $fSelect == -1 Then ; toggle state of index
            If _GUICtrlListBox_GetSel($hWnd, $iIndex) Then ;If Selected Then
                Return GUICtrlSendMsg($hWnd, $LB_SETSEL, False, $iIndex) <> -1
            Else
                Return GUICtrlSendMsg($hWnd, $LB_SETSEL, True, $iIndex) <> -1
            EndIf
        Else ; set state according to flag
            Return GUICtrlSendMsg($hWnd, $LB_SETSEL, $fSelect, $iIndex) <> -1
        EndIf
    EndIf
    Return $i_ret
EndFunc ;==>_GUICtrlListBox_SetSel

If the function is called without an index value (or given -1 as the index), it toggles all the entries and leaves the list at the bottom. Perhaps the loop counter should go from _GUICtrlListBox_GetCount($hWnd) - 1 to 0 instead? Or maybe the existing position is temporarily saved at the beginning of the function and then reset after it's run?

EDIT: Is it possible to use_GUIScrollBars_GetScrollPos to get the position on a list? I tried it just for fun, but it always returns -1.

Edited August 26, 2013 by GPinzone

[TheSaint]

Sorry, hadn't picked up on the Multiple selection angle.

By memory, another possible alternative way, and using Melba23's final scroll method, would be to do a count after the list is fully populated, and then a range selection.

Overall, I'd recommend following what Melba23 provided, I only interjected out of curiosity and to provide what I thought might be an alternative.

 

Not sure what you mean by getting position on list?

If you are just after a single selected item, then just get the selected Index for that.

[GPinzone]

Let's assume the listbox contains 100 items and the user has scrolled down some arbitrary distance from the top. The _GUICtrlListBox_SetSel command is issued to toggle one or more entries in the list, but this forces the list to scroll to the entry in being modified. If we want to preserve the scrollbar locations prior to executing _GUICtrlListBox_SetSel, how would we do that? I suggested using _GUIScrollBars_GetScrollPos to get the position before executing _GUICtrlListBox_SetSel, store it in a variable, execute _GUICtrlListBox_SetSel, then restore the scrolbar position after it's done. However, I'm not sure it possible to get or set a listbox's scrollbar position.

The second question would be whether or not the _GUICtrlListBox_SetSel function should be modified assuming preservation of scrollbar positions is possible.