Solved

Scroll in TreeView components

Posted on 2003-10-30
4
475 Views
Last Modified: 2010-04-05
I have a TreeView (in a Delphi 7 program) and one of the operations I want supported is to "Move" elements between nodes. The problem is that when I'm dragging an element and the target node is out of sight the view does not scroll down to show the other elements.

How can I add scroll up and down when the cursor gets out of the control's boundaries ?

Thanks in advance !


AJ
0
Comment
Question by:ajgonzalezm
4 Comments
 
LVL 5

Accepted Solution

by:
snehanshu earned 50 total points
ID: 9654776
Does this help?
(Changing Drag-Over event of the TreeView);

procedure TForm1.TreeView1DragOver(Sender, Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
begin
   // draggin over
  if (Sender is TForm) and (Source is TTreeView) then
    begin
    with Source as TTreeView do
        // check if we are in the hot zone (in this case only above or below)
      if (x > Left) and (x < Left + Width) and
         (y > Top - HOTZONE_WIDTH) and (y < Top + Height + HOTZONE_WIDTH)
        then begin
          Accept := true;  // we could set false here, too.
          if y < Top
            then Perform(WM_VSCROLL, SB_LINEUP, 0)
            else Perform(WM_VSCROLL, SB_LINEDOWN, 0);
          end
        else Accept := false;
    end
  else
    Accept := (Sender = Source);
end;

I picked this up from
http://www.experts-exchange.com/Programming/Programming_Languages/Delphi/Q_10125137.html?query=TreeView+Scroll&searchType=topic

HTH,
...Snehanshu
0
 
LVL 27

Assisted Solution

by:kretzschmar
kretzschmar earned 50 total points
ID: 9677227
well, another method

procedure TForm1.TreeView1DragOver(Sender, Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
var ANode : TTreeNode;
begin
  ANode := TreeView1.GetNodeAt(x,y);
  Accept := assigned(ANode); //just as sample
  //Scrolling needed ?
  if ((y < 9) or
     (y > TreeView1.Height - 9)) and
     (assigned(ANode)) then
    //ScrollUp ?
    if (y < 5) then
      ANode := ANode.getPrevSibling
    else
      ANode := ANode.getNextSibling;
  If assigned(ANode) then
    ANode.MakeVisible;
end;

meikl ;-)
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
indy tidtcpclient threading issue 8 63
PDF library for Delphi 2 105
Downloading email attachments 2 67
Open a URL with Internet Explorer in a new tab (not a new window) 1 72
In this tutorial I will show you how to use the Windows Speech API in Delphi. I will only cover basic functions such as text to speech and controlling the speed of the speech. SAPI Installation First you need to install the SAPI type library, th…
Introduction Raise your hands if you were as upset with FireMonkey as I was when I discovered that there was no TListview.  I use TListView in almost all of my applications I've written, and I was not going to compromise by resorting to TStringGrid…
This Micro Tutorial will teach you how to censor certain areas of your screen. The example in this video will show a little boy's face being blurred. This will be demonstrated using Adobe Premiere Pro CS6.
Video by: Mark
This lesson goes over how to construct ordered and unordered lists and how to create hyperlinks.

895 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

19 Experts available now in Live!

Get 1:1 Help Now