Question

I am making very simple test app, just to see how drag & drop works.

Basically I have two stringgrids, source & destination, and want to drag one cell from the source’s select row to the destination, creating a new row for it as I drop it.

In order to keep things as simple as possible, I am using drag mode = automatic, so as not to have to code manual drag mode handlers.

WIth just a few lines of code I can drag & drop, BUT only from the first row of the source. When I try to click on different row, to use that as the source, the OnClick event handler doesn’t even fire.

Short question … can I do what I want (both drag & drop and cange the source row) when using drag mode = automatic, or not?

The drop handler looks like this …

DestinationStringGrid.RowCount := DestinationStringGrid.RowCount + 1;
DestinationStringGrid.Cells[0, DestinationStringGrid.RowCount - 1] :=
    SourceStringGrid.Cells[0, SourceStringGrid.Row];

so, obviously, I want to be able to change SourceStringGrid.Row when I click on SourceStringGrid

Please let me know if teh question is not clear. Thanks in advance for your help

Answer 1

You can use the OnStartDrag event to determine the mouse position where the drag started:

procedure TForm1.StringGrid1StartDrag(Sender: TObject;
  var DragObject: TDragObject);
var
  Pt: TPoint;
  C, R: Integer;
begin
  Pt := StringGrid1.ScreenToClient(Mouse.CursorPos);
  StringGrid1.MouseToCell(Pt.X, Pt.Y, C, R);
  if (R > 0) and (R < StringGrid1.RowCount) then
    StringGrid1.Row := R;
end;