Author: Mike Shkolnik
Have a bad performance with standard TTreeView/TListView? Read this tip and
implement the hints...
If you uses the TTreeView and/or TListView from Win32 page of default component
palette, then you must know that if you have the large amount nodes, you have a
very bad performance...
Of course, at same moment you'll try to find a some other third-party component
that allow to work with your very large data but I want to give you the few hints
which allows to increase a performance without any third-party components. Only
using of optimized code.
if you need add a lot of nodes in same time (for example, after button click to
load the 10000 nodes in tree from some source) then you must call:
2 3 yourTreeView.Items.EndUpdate;
This constuction will disable a repainting when you append the nodes - it's save a
lot of time!
if you uses the some navigation by nodes, you must use the GetFirst and GetNext
methods instead Items[i] using!
4 var5 node: TTreeNode;
6 begin7 node := yourTreeView.Items.GetFirstNode;
8 repeat9 node := Result.GetNext;
10 until node = nil;
It's save a lot of time too! The GetFirstNode/GetNext is faster than standard
12 for i := 0 to yourTreeView.Items.Count - 1 do13 begin14 node := yourTreeView.Items[i];
Also, when adding lots of items, you could do
16 17 MyObj.AllocBy := 10000;
This will cause fewer allocations as it allocates more items each time.
For example, in own warehouse system I have a treeview with 5000 nodes which I load
from Oracle resultset. After applying of these tips, the time of execution of
procedure with append was decreased from 4-5 minutes to 15-20
seconds! Trust me :-)
I don't sure but I think that it's a bad work of Borland when team developed the
envelope for Win's treeview/listview. But maybe I'm wrong.
PS: of course, if you have a very-very large data with few billions of nodes or
after applying of tips above all the same you have a bad performance, you must use
the virtual mode of control or really select the other third-party
control. But I suggest to change the your interface logic - to navigate thru few billions of nodes in same time is very hard task for user! Not only for you :-)