TAwImageGrid - Program leaks memory if the last image is deleted - delphi

Question

Using: Delphi XE7 Update 1, TAwImageGrid, Windows 10 Professional running on Intel Core i7-2820QM.
This code loads images into the grid from a database:
var
s, w: String;
r: Integer;
ms: TMemoryStream;
bmp: TBitmap;
begin
r := uqProj_Search.RecordCount;
// Load images
for r := imgGrid.Count - 1 downto 0 do
imgGrid.Items.Images[r].Free;
imgGrid.Clear;
ms := TMemoryStream.Create;
try
while not(uqProj_Search.Eof) do
begin
r := uqProj_Search.FieldByName('row_id').AsInteger;
// :proj_id
uqImg_S.ParamByName('proj_id').AsInteger := r;
uqImg_S.Prepared := True;
uqImg_S.Open;
ms.Clear;
uqImg_Simg.SaveToStream(ms);
uqImg_S.Close;
ms.Position := 0;
bmp := TBitmap.Create;
try
bmp.LoadFromStream(ms);
imgGrid.Items.Add(IntToStr(r));
imgGrid.Items.Images[imgGrid.Count - 1] := TBitmap.Create;
imgGrid.Items.Images[imgGrid.Count - 1].Assign(bmp);
finally
bmp.Free;
end;
uqProj_Search.Next;
end;
finally
ms.Free;
end;
end;
I have this code in the KeyDown event (called when the Del key is pressed):
procedure TfmSrchRec.imgGridKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
var
x, p: Integer;
AFormat: Word;
AData: THandle;
APalette: HPalette;
begin
x := imgGrid.ItemIndex;
p := StrToInt(imgGrid.Items.Strings[x]);
if (x = -1) then
Exit;
if (UpCase(Char(Key)) = 'C') and (Shift = [ssCtrl]) then
begin
// Clipboard.Assign(imgGrid.Images[imgGrid.ItemIndex])
TBitmap(imgGrid.Images[x]).Dormant;
TBitmap(imgGrid.Images[x]).SaveToClipboardFormat(AFormat, AData, APalette);
Clipboard.SetAsHandle(AFormat, AData);
end
else if (Key = VK_DELETE) then
begin
imgGrid.Items.Images[x].Free;
imgGrid.Items.Delete(x);
end;
end;
Freeing up memory in the form's OnClose event:
procedure TfmSrchRec.FormClose(Sender: TObject; var Action: TCloseAction);
var
r: Integer;
begin
for r := imgGrid.Count - 1 downto 0 do
imgGrid.Items.Images[r].Free;
end;
Here's the problem:
After deleting an image from the grid, if that image was the last remaining image, then closing the program would produce this error message:
---------------------------
Unexpected Memory Leak
---------------------------
An unexpected memory leak has occurred. The unexpected small block leaks are:
61 - 68 bytes: Unknown x 1
---------------------------
OK
---------------------------
The error does not occur if there was a remaining image in the grid before the application was closed. I have ReportMemoryLeaksOnShutDown := True at project startup (in the DPR file).
I'm guessing that this error has to do with the component's code more than the way I am using it. I'm hoping that the TAwImageGrid component author NGLN could have a look at this question and provide the answer, but other Delphi gurus are also welcome.
Links:
TAwImageGrid component source official home page:
https://github.com/NGLN/AwImageGrid
StackOverflow Question that gives a good introduction to the component:
Looking for a custom image grid

Answer 1

I can reproduce your findings and consider it a bug.
When making the component, I copied the implementation of TStringList from D7, i.e. by using a pointer to a non-existing fix-sized array for the internal storage of the items. Strangely enough, I cannot find flaws in it, but D7's TStringList implementation does not produce this bug. I suppose it has something to do as explained here.
I see that the implementation of TStringList in XE2 is changed to the use of a dynamic array. When I change the component's code to that same design, the memory leak is gone. So I will change the open source code too, but for the time being you might do yourself.