We have a treeview in a form which allows dragging of nodes around inside
the tree... (Iknow, I know, simple stuff, works fine)... However there is the
need for having the treeview autoscroll during the drag so that nodes
offscreen scroll into view.
I hacked together this OnDragOver routine to perform the scrolling (which works)
but since an OnDragOver event is fired on a mouse movement it scrolled only
1 node at a time. To replicate explorers constant scrolling I wanted to reenter
the OnDragOver while the mouse was in the scroll-zone. To do this I called
the tvDragOver recursively - this is not the correct method since it could
potentially fill the stack.
What IS the correct method to retrigger the OnDragOver event... A message?
if so which one... Can someone suggest a replacement for the line:
tvDragOver(Sender,Source,Pnt.X,Pnt.Y,State,Accept);
procedure TForm1.tvDragOver(Sender, Source: TObject; X, Y: Integer;
State: TDragState; var Accept: Boolean);
const
Boundry = 30;
var
N :TTreeNode;
Pnt :TPoint;
begin
if (Y<=Boundry) or ((TV.Height-Boundry)<=Y) then begin
Accept := False; {This will be replaced with the drop condition}
N := TV.GetNodeAt(X,Y);
if N<>nil then begin
if Y<=Boundry then N := N.GetPrevVisible
else N := N.GetNextVisible;
if N<>nil then begin
TV.Selected := N;
Pnt := Mouse.CursorPos;
Pnt := TV.ScreenToClient(Pnt);
{Bad line below, naughty line, this line needs a good spanking}
tvDragOver(Sender,Source,Pnt.X,Pnt.Y,State,Accept);
end;
end;
end;
Application.ProcessMessages;
end;
--
Aaron Scott-Boddendijk
Jump Productions
(07) 838-3371 Voice
(07) 838-3372 Fax
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