Title: Optimization of work with standard TTreeView/TListView components
Question: Have a bad performance with standard TTreeView/TListView? Read this tip and implement the hints...
Answer:
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.
Tip1:
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:
yourTreeView.Items.BeginUpdate;
yourTreeView.Items.EndUpdate;
This constuction will disable a repainting when you append the nodes - it's
save a lot of time!
Tip2:
if you uses the some navigation by nodes, you must use the GetFirst and
GetNext methods instead Items[i] using!
For example,
var
node: TTreeNode;
begin
node := yourTreeView.Items.GetFirstNode;
repeat
node := Result.GetNext;
until node = nil;
end;
It's save a lot of time too! The GetFirstNode/GetNext is faster than
standard
for i := 0 to yourTreeView.Items.Count-1 do
begin
node := yourTreeView.Items[i];
end;
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 inteface logic - to navigate thru
few billions of nodes in same time is very hard task for user! Not only for
you:-)
With best regards, Mike Shkolnik.
E-Mail: mshkolnik@scalabium.com
mshkolnik@yahoo.com
WEB: http://www.scalabium.com
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