TListBox, TListView how to use Sort(Compare) ?

[Serge_G 87]

Hi,

I found a way to sort my lists using Sort an OnCompare event but I don't figure out a functional way to use Sort(Compare) method (Rio 10.3.3)

Any clues ?

Thanks

[Remy Lebeau 1392]

Can you be more specific?  What exactly is not working for you?  Please show the code you are having trouble with.

[Vandrovnik 214]

You mean something like this?

type tSledovaniVykonuSeznamVysledku=class(tObjectList<tSledovaniVykonuVysledky>)
...  
 var Cmp: IComparer<tSledovaniVykonuVysledky>;
 begin
 Cmp:=tDelegatedComparer<tSledovaniVykonuVysledky>.Create(
  function(const Left, Right: tSledovaniVykonuVysledky): Integer
   begin
   result:=CompareStr(Left.Nazev, Right.Nazev);
  end);
 Sort(Cmp);

 

[Remy Lebeau 1392]

1 hour ago, Vandrovnik said:

You mean something like this?

What does that code have to do with TListBox/TListView?  Their Sort() methods are quite different than TObjectList's Sort() method.

 

Edited April 28, 2020 by Remy Lebeau

[Vandrovnik 214]

4 minutes ago, Remy Lebeau said:

What does that code have to do with TListBox/TListView?  Their Sort() methods are quite different than TObjectList's Sort() method.

 

Sorry, I did not read carrefully the title.

[Serge_G 87]

Sorry, not being specific. Late I found, really by chance, why the code I used

procedure TForm110.btnDetailClick(Sender: TObject);
// numeric sort on detail 
var Compare : TFMXObjectSortCompare;
begin
Tri:=btnDetail.Tag;
if btnDetail.Tag=1 then btnDetail.Tag:=0
                   else btnDetail.Tag:=1;
ListBox1.Sorted:=False;
Compare:=function(item1, item2: TFmxObject): Integer
  var n1,n2 : Single;
  begin
    n1:=StrToFloatDef(TListBoxItem(item1).ItemData.Detail,0);
    n2:=StrToFloatDef(TListBoxItem(item2).ItemData.Detail,0);
    if n2=n1 then result:=0
    else begin
      if n2>n1 then Result := 1
               else Result := -1;
    end;
    if tri=0 then result:=result*-1;
  end;
ListBox1.Sort(Compare);
// here 
end;

seems to be useless.

Just resizing the form (to take a picture)  'refreshed' the aligned list. Before solving, I used a BeginUpdate/EndUpdate sequence with no effect ! So that was why I don't understood the usage of list.sort(compare) was not 'working'. A self.width:=self.width+1; self.width:=self.width; confirmed that but was not the solution. 

Finally, digging in the source code, I found the solution

ListBox1.RealignContent;

Just after the sort did it. 

Joined, comparative runtime screens (first alpha sort on text using sorted:=true, second numeric sort on detail using sort(compare) twice to have DESC order)