?
Solved

Manipulating event sequencing

Posted on 2002-04-14
7
Medium Priority
?
212 Views
Last Modified: 2010-04-04
My application maintains a tree full of nodes and a property sheet window (PS for brevity) that shows an appropriate editor for the object at which Node.Data points.

The TreeView Change event calls an Edit(Node) method on the PS form, which in turn loads the correct editor and gives it a reference to the object on which it should operate.

Each edit widget in a PS editor uses its Enter and Exit events to manage updates.

The problem occurs when the user edits a property and then clicks a different node in the tree without first moving focus off the edit widget.

The tree's change event fires BEFORE the edit widget's exit event. This sets a different object reference in the editor, so when the Exit event occurs the changes are written to the wrong object.

I have tried to no avail Application.ProcessMessages and Application.HandleMessage in the start of the tree's Change event handler.

Eventually [sic] I gave the PS form a FinaliseEditing method that calls the exit method explicitly and then sets a flag to prevent it from running again when the even is processed naturally.

This works, but, well, YUCK!

Any suggestions, people?
0
Comment
Question by:wamoz
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
7 Comments
 
LVL 1

Expert Comment

by:MBo
ID: 6941080
I checked this problem with exit code in OnDeactivate of PSForm. All works fine.
0
 
LVL 10

Accepted Solution

by:
Jacco earned 800 total points
ID: 6941170
This is also not very beatiful but it worked for me:

procedure TForm1.TreeView1Change(Sender: TObject; Node: TTreeNode);
begin
  TreeView1.SetFocus;
  // .. rest of the code
end;

Regards Jacco
0
 
LVL 1

Author Comment

by:wamoz
ID: 6941210
MBo, there's some more pertinent info that I forgot to mention last time. The PS can be docked, and when it is docked, you don't get FormDeactivate events.
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 27

Expert Comment

by:kretzschmar
ID: 6941257
add a condition-flag (boolean or integer)

just check set this on your editing

in your onchange-event check the flag,
if allowed, then do there your code,
otherwise not

or remove the event by assigning nil there,
and after your work reassign your event-procedure

meikl ;-)
0
 
LVL 12

Expert Comment

by:Lee_Nover
ID: 6941515
how about 'Apply' and 'Cancel' buttons ? :)
you update all the data with the apply button
still the simplest solution would be as jacco suggested
eg OnMouseDown of the listview do Windows.SetFocus(ListView.Handle);
that should trigger the active controls exit event
0
 
LVL 1

Expert Comment

by:MBo
ID: 6941828
Have you tried OnChanging treeview event?
0
 
LVL 1

Expert Comment

by:pnh73
ID: 9003214
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

Accept answer from Jacco

Please leave any comments here within the next seven days.
 
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
 
Paul (pnh73)
EE Cleanup Volunteer
0

Featured Post

On Demand Webinar: Networking for the Cloud Era

Ready to improve network connectivity? Watch this webinar to learn how SD-WANs and a one-click instant connect tool can boost provisions, deployment, and management of your cloud connection.

Question has a verified solution.

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

This article explains how to create forms/units independent of other forms/units object names in a delphi project. Have you ever created a form for user input in a Delphi project and then had the need to have that same form in a other Delphi proj…
Hello everybody This Article will show you how to validate number with TEdit control, What's the TEdit control? TEdit is a standard Windows edit control on a form, it allows to user to write, read and copy/paste single line of text. Usua…
Michael from AdRem Software outlines event notifications and Automatic Corrective Actions in network monitoring. Automatic Corrective Actions are scripts, which can automatically run upon discovery of a certain undesirable condition in your network.…
In this video, Percona Solution Engineer Dimitri Vanoverbeke discusses why you want to use at least three nodes in a database cluster. To discuss how Percona Consulting can help with your design and architecture needs for your database and infras…
Suggested Courses

752 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