Improvement to SpinEdit code

[GrahamNZ]

Sorry, I don't use Github much so don't know how to create a pull request. Here is an improvement to the value handling in Spin Edits:

procedure TfpgSpinEdit.EditExit(Sender: TObject);
begin
  if FEdit.Text = '' then
  begin
    if FMinValue>0 then
    begin
      FValue      := FMinValue;
      FEdit.Value := FValue;
    end else
    begin
      FValue      := 0;
      FEdit.Value := FValue;
    end;
  end
  else if StrToInt(FEdit.Text) > FMaxValue then
  begin
    FValue      := FMaxValue;
    FEdit.Value := FValue;
  end
  else if StrToInt(FEdit.Text) < FMinValue then
  begin
    FValue      := FMinValue;
    FEdit.Value := FValue;
  end else
    FValue      := FEdit.Value;
  EnableButtons;
end;

[graemeg]

Hi Graham,

Thank you very much for taking the time to look into this and share your improvement — no worries at all about the pull request, posting the code here works just fine.

You spotted two genuine problems: an empty edit could end up holding a value outside the MinValue/MaxValue range, and out-of-range input was silently discarded rather than being clamped to the nearest bound. Clamping is also what the Up/Down arrow keys already do, so your change makes the widget nicely consistent with itself.

I've committed a fix based on your idea, with a few extra refinements it enabled along the way:

• Negative-only ranges (e.g. -20 to -5) are now handled correctly when the edit is left empty.
• The same clamping now applies when pressing Enter, and to TfpgSpinEditFloat as well.
• A lone - character no longer raises an exception on focus loss.
• OnChange now fires when the committed value changes.

There's also a new set of unit tests covering all of these cases, so the behaviour is locked in going forward. The fix is on the develop branch — thanks again for the contribution!

Regards,
Graeme