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Graphics/Discussion/Photon microGUI/Determining PtList Selection/List of Posts
Forum Topic - Determining PtList Selection: (6 Items)
   
Update
Kendall Russell
05/25/2011 1:37 PM
post86139
Determining PtList Selection   
I am attempting to determine which item is selected in a PtList control.

I am currently using this code:
-----------------------------------
unsigned short* pnSelPos = 0;
short*                pnItem    = 0;

PtGetResource(ABW_ListBarcodes, Pt_ARG_SELECTION_INDEXES, &pnSelPos, &pnItem);
-----------------------------------

Pt_ARG_SELECTION_MODE is set to: Pt_SINGLE_MODE

It seems that *pnSelPos identifies the currently selected item.  However, when nothing is selected *pnSelPos can still 
have a value.

Can someone explain to me what *pnSelPos and *pnItem represent in this context and if there is another way to retrieve 
which item is currently selected if any?

Thank you,
Kendall
Thomas Haupt
05/25/2011 2:00 PM
post86141
AW: Determining PtList Selection   
Hi,

I think *pnItem should be the number of currently selected item.

Cheers,
Thomas

----- Originalnachricht -----
Von: Kendall Russell [mailto:community-noreply@qnx.com]
Gesendet: Wednesday, May 25, 2011 01:37 PM
An: photon-graphics <post86139@community.qnx.com>
Betreff: Determining PtList Selection

I am attempting to determine which item is selected in a PtList control.

I am currently using this code:
-----------------------------------
unsigned short* pnSelPos = 0;
short*                pnItem    = 0;

PtGetResource(ABW_ListBarcodes, Pt_ARG_SELECTION_INDEXES, &pnSelPos, &pnItem);
-----------------------------------

Pt_ARG_SELECTION_MODE is set to: Pt_SINGLE_MODE

It seems that *pnSelPos identifies the currently selected item.  However, when nothing is selected *pnSelPos can still 
have a value.

Can someone explain to me what *pnSelPos and *pnItem represent in this context and if there is another way to retrieve 
which item is currently selected if any?

Thank you,
Kendall





_______________________________________________

Photon microGUI
http://community.qnx.com/sf/go/post86139
Kendall Russell
05/25/2011 3:28 PM
post86145
Re: AW: Determining PtList Selection   
Well, here are a few scenarios that I ran and the values for those variables:

Scenario 1: PtList Widget is empty

pnSelPos == 0
*pnSelPos == 0
pnItem == has an address
*pnItem == 0

Scenario 2: PtList Widget has 4 items with the 3rd item highlighted.

*pnSelPos == 3
*pnItem == 1

Scenario 3: PtList Widget has 5 items with nothing highlighted 

*pnSelPos == 61692
*pnItem == 0


So, if the PtList widget has items and one is highlighted, then it appears that *pnSelPos is correct.  If the PtList 
Widget is empty, the return seems correct to me.  The only thing that doesn't seem correct is if the PtList Widget has 
contents, but nothing is selected.  (Scenario 3)


> Hi,
> 
> I think *pnItem should be the number of currently selected item.
> 
> Cheers,
> Thomas
> _______________________________________________
> 
> Photon microGUI
> http://community.qnx.com/sf/go/post86139
Wojtek Lerch
05/25/2011 3:38 PM
post86146
Re: AW: Determining PtList Selection   
It's an array resource.  pnItem points to the length and pnSelPos to the array elements, if any.  When *pnItem is zero, 
that means that the array has zero elements and you're not supposed to even look at *pnSelPos (a.k.a. pnSelPos[0]) 
because it's outside of the array.
Kendall Russell
05/26/2011 1:59 PM
post86169
Re: AW: Determining PtList Selection   
> It's an array resource.  pnItem points to the length and pnSelPos to the array
>  elements, if any.  When *pnItem is zero, that means that the array has zero 
> elements and you're not supposed to even look at *pnSelPos (a.k.a. pnSelPos[0]
> ) because it's outside of the array.


So, is there a better or easier way to determine which item in a PtList widget is selected?
Wojtek Lerch
05/26/2011 2:05 PM
post86171
Re: AW: Determining PtList Selection   
> So, is there a better or easier way to determine which item in a PtList widget
>  is selected?

I can't think of anything better or easier than

  PtGetResource(ABW_ListBarcodes, Pt_ARG_SELECTION_INDEXES, &pArr, &pLen);
  if ( *pLen == 0 ) {
    printf( "Nothing is selected\n" );
  } else {
    printf( "Item #%d is selected\n", pArr[0] );
  }

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