Issues with JvDBGrid: duplicate cell drawing on click...

[CDametto]

Hi everyone,
I am currently using JVCL version 3.50 with Delphi 12, and I have encountered the following issues with JvDBGrid:

1) JvDBGrid painting issue

When a TJvDBGrid is configured to display only a single column and the indicator is hidden (dgIndicator = False in Options), clicking on a cell causes it to be drawn twice if the column width exceeds the default value.

I have attached a sample project where you can reproduce the bug by clicking on the first grid.
TestJvDBGrid.zip

As a temporary workaround, I added the following fix at the very beginning of TJvDBGrid.DrawCell (around line 3563 in JvDBGrid.pas):

procedure TJvDBGrid.DrawCell(ACol, ARow: Longint; ARect: TRect; AState: TGridDrawState);
begin
  if not (gdFixed in AState) and (Columns.Count = 1) and not (dgIndicator in Options) then
    ARect := CellRect(ACol, ARow);
  ...

I haven't fully identified the root cause of why this happens; this is just a quick patch.

2) Missing separator line under titles

When using the standard Windows theme, the separator line between the column headers (titles) and the first row of data is no longer drawn.

3) Feature Request

Would it be possible to make the selected row in JvDBGrid look visually identical to the standard Delphi TDBGrid?

Thank you for your help and for your great work!

[CDametto]

Correction

I noticed that the problem occurs even when the horizontal scrollbar is visible; when you move it, all the data cells are drawn out of alignment.

To resolve this, I replaced the previous correction with these lines:

if (ColCount = 1) and not (gdFixed in AState) and (ARow >= TitleOffset) then
begin
  var lHOfs := ARect.Left - (inherited CellRect(ACol, ARow)).Left;
  if (lHOfs <= 0) and (lHOfs >= -ColWidths[ACol]) then
    FCellRectHOfs := lHOfs;

  ARect := CellRect(ACol, ARow);
end;

Where FCellRectHOfs: Integer; is declared in TJvDBGrid's private variables.

I also changed this function to:

function TJvDBGrid.CellRect(ACol, ARow: Longint): TRect;
begin
  Result := inherited CellRect(ACol, ARow);

  // PATCH: applies the delta calculated in DrawCell to compensate
  if (ColCount = 1) and (FCellRectHOfs <> 0) and (ARow >= TitleOffset) and not IsRectEmpty(Result) then
  begin
    Inc(Result.Left, FCellRectHOfs);
    Result.Right := Min(Result.Left + ColWidths[ACol], ClientWidth);
  end;
end;

Notes

• I haven't checked if InplaceEditor works yet.

Thank you for your time