Note: This OnKeyPress event handler does not deal with the case when the user types the Delete key. That case must be caught in the OnKeyDown event handler instead.
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procedure TForm1.ComboBox1KeyPress(Sender: TObject; var Key: Char) ;
var
Found: boolean;
j,SelSt: Integer;
TmpStr: string;
begin
{ first, process the keystroke to obtain the current string }
{ This code requires all items in list to be uppercase}
if Key in ['a'..'z'] then Dec(Key,32) ; {Force Uppercase only!}
with (Sender as TComboBox) do
begin
SelSt := SelStart;
if (Key = Chr(vk_Back)) and (SelLength <> 0) then
TmpStr := Copy(Text,1,SelStart)+Copy(Text,SelLength+SelStart+1,255)
else if Key = Chr(vk_Back) then {SelLength = 0}
TmpStr := Copy(Text,1,SelStart-1)+Copy(Text,SelStart+1,255)
else {Key in ['A'..'Z', etc]}
TmpStr := Copy(Text,1,SelStart)+Key+Copy(Text,SelLength+SelStart+1,255) ;
if TmpStr = '' then Exit;
{ update SelSt to the current insertion point }
if (Key = Chr(vk_Back)) and (SelSt > 0) then Dec(SelSt)
else if Key <> Chr(vk_Back) then Inc(SelSt) ;
Key := #0; { indicate that key was handled }
if SelSt = 0 then
begin
Text:= '';
Exit;
end;
{Now that TmpStr is the currently typed
string, see if we can locate a match }
Found := False;
for j := 1 to Items.Count do
if Copy(Items[j-1],1,Length(TmpStr)) = TmpStr then
begin
Text := Items[j-1]; { update to the match that was found }
ItemIndex := j-1;
Found := True;
Break;
end;
if Found then { select the untyped end of the string }
begin
SelStart := SelSt;
SelLength := Length(Text)-SelSt;
end
else Beep;
end;
end;
~~~~~~~~~~~~~~~~~~~~~~~~~
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