ComboBox: Autocomplete returns wrong Itemindex when Autodropdown=True

[CM630]

I have a form containing a combobox and a label and
the following code:


procedure TForm1.FormCreate(Sender: TObject);
  var
  i:integer;
  iname: integer=0;
begin
  ComboBox1.Clear;
  for i:=0 to 50 do
  begin
    iname:=iname+ 1+ trunc(Random* ;
    ComboBox1.Items.Add(IntToStr(iname) + '(' + IntToStr(i) + ')');
  end; //for
  ComboBox1.ItemIndex:=0;


  ComboBox1.AutoComplete:=True;
  ComboBox1.AutoCompleteText:=[cbactEnabled,cbactSearchAscending];
  ComboBox1.AutoDropDown:=True;
end;


procedure TForm1.ComboBox1EditingDone(Sender: TObject);
begin
  Label1.Caption:=IntToStr(ComboBox1.ItemIndex);
end;




When I execute the code, I start typing in the combobox for example 145.
If there is a value „145(35)‟ in the combobox I expect that when I hit Enter I will get Label1 showing „35‟, because the itemindex of entry „145(35)‟ is 35.
And that is what I get if ComboBox1.AutoDropDown:=False;
But when ComboBox1.AutoDropDown:=True; instead of 145, I get for example 0, because the first entry in the combo, starting with 1 has ItemIndex=0. 


Or if there is a value „217(43)‟ in the combobox I expect that when I hit enter I will get Label1 showing „43‟. But it shows something like „2‟, because the first entry starting with „2‟ is „2‟ or „25‟ or something like this.
Again, if ComboBox1.AutoDropDown:=False; I get 43 (as expected), since the ItemIndex of entry „217(43)‟ is 43.


Is this some bug in Lazarus, and if not, is there a way to overcome this behaviour?

[Handoko]

I cannot test your issue. Because running your code I got another issue. For example, there is an item '10(1)' in the the combo box. When I type the first character '1', the dropdown opened automatically. But then I can't type anything, except press esc or up/down arrow.

if I remove this line:
ComboBox1.AutoDropDown:=True;
then I can type freely. But I get one another issue. If I type the complete text, I always got result := -1. I have to type less than the whole text and let the system autocompletes the text, then I can get the correct result.

Tested on Lazarus 1.6.4 Gtk2 Linux64.

[Thaddy]

Don't feel offended but there is *a lot* wrong with your code:

    iname:=iname+ 1+ trunc(Random *  8 ) ;

Why call trunc on an integer multiplication?
Why not simply:

Code: Pascal  [Select][+][-]

1.   iname := iname+Random(8)+1;{Range of Random(8) is 0..7 and is an integer range}

Your bugs are caused by you: real programmers count from zero, so e.g. the 35th item has index 34... not 35...
Same here: Are you really sure you want 51 items, instead of 50? So for i := 0 to 49... instead of 51 items, because that is what for i := 0 to 50 means...... 
Unless you really mean 51....Which for some reason I don't believe.....

What you do is writing compilable, syntactically correct nonsense. {$RANGECHECKS ON} may help you solve half of it... The other half is learning to count from zero.
Some more e.g:

Again, if ComboBox1.AutoDropDown:=False; I get 43 (as expected), since the ItemIndex of entry „217(43)‟ is 43.

no it's not! it is 42
You defined (xx) as iname, remember? And that is itemindex + 1! See your  random code....

[CM630]

I cannot test your issue. Because running your code I got another issue. For example, there is an item '10(1)' in the the combo box. When I type the first character '1', the dropdown opened automatically. But then I can't type anything, except press esc or up/down arrow.
...
Tested on Lazarus 1.6.4 Gtk2 Linux64.

Thanks for the feedback. Possibly behaviour in GTK is different.
In Win7 I can write anything.
But, if you type 1, you could possibly type „11‟ or „12‟ or „13‟, because there will be entries in the list 11x, 12y (one-hundred and *teen; one-hundred twenty-something...)? I suppose you can see the existing values by scrolling down.

If behaviour of Combobox is system specific, I should use something else.
Any recommendation for a replacement component is welcome.

@Thaddy, I saw nothing in your post, related with my issue.
Anyway „random‟ without a parameter is extended. And about the second issue: 0 to 50, etc... I still do not see a mistake in my code, but I would not bother if I had.

Edit: For the time being I have solved the issue this way, which seems to work fine:

Code: [Select]

//Searches if the text of the combobox corresponds to an item from the Items property.
//Returns -1 if the item is not found.
function CboFindIndex (var ComboBox:TComboBox; CaseSensitive: Boolean= False): integer;
var
  i: integer;
  text: String;
begin
  Result:=-1;
  if ComboBox.Items.Count>0 then
  begin
    text:= ComboBox.Text;
    for i:=0 to ComboBox.Items.Count-1 do
      if StringCompare(text,ComboBox.Items,CaseSensitive)=0 then
      begin
        Result:=i;
        break;
      end; //if found
  end; //if
end;

function StringCompare(S1, S2: String; CaseSensitive: Boolean= false): integer;
begin
  if CaseSensitive=True
    then Result:=UTF8CompareStr(s1,s2)
    else Result:=UTF8CompareText(s1,s2);
end;


procedure TForm1.ComboBox1EditingDone(Sender: TObject);
begin
  Label1.Caption:=IntToStr(ComboBox1.ItemIndex);
end;

procedure TForm1.ComboBox1EditingDone(Sender: TObject);
var
  ItemIndex: integer;
begin
  ItemIndex:=CboFindIndex (ComboBox1);
  if ItemIndex>-1 then
  begin
    ComboBox1.ItemIndex:=ItemIndex;
    Label1.Caption:=ComboBox1.Items[ItemIndex];
End;


[Pascal]

Your sample works as expected with laz trunk and fpc trunk on windows 10 64bit.

[ASerge]

Is this some bug in Lazarus, and if not, is there a way to overcome this behaviour?

Confirm bug.
A simpler example:

Code: Pascal  [Select][+][-]

1. procedure TForm1.ComboBox1EditingDone(Sender: TObject);
2. begin
3.   Label1.Caption:=IntToStr(ComboBox1.ItemIndex);
4. end;
5.  
6. procedure TForm1.FormCreate(Sender: TObject);
7. begin
8.   ComboBox1.AutoDropDown := True;
9.   ComboBox1.AutoComplete := True;
10.   ComboBox1.Items.Append('1 - 0');
11.   ComboBox1.Items.Append('11 - 1');
12. end;

When typing "11" and "Enter", "0" is displayed, but if line 8 is commented out, it shows "1", as expected.

[CM630]

Thanks for the feedback, I will try to report it in the bucktracker in a couple of weeks.

[Michl]

Fixed in Lazarus trunk revision 55704 and merge requested for upcomming Lazarus 1.8.