We help IT Professionals succeed at work.

TScreen.ScreenDragOver ?

zhuhail
zhuhail asked
on
Medium Priority
213 Views
Last Modified: 2010-04-06
Want to do something during draging but don't want to put the code into the OnDragOver events of all the controls (too many) in a form and the form itself.

Can you find or make an event or similar:
  TScreen.ScreenDragOver (....X, Y: Integer..)
so that one may
1. do something based on the coordinates of the cursor in anywhere of the form during the draging;
2. stop doing that when this draging finished.
Comment
Watch Question

Author

Commented:
Edited text of question

Author

Commented:
Edited text of question
Commented:
You can create one OnDragOver proc, assign it to all the components of the form, and make the processing based
on source component, or call  GetCursorPos and use X,Y coordinates.

General idea is that you can assign ONE event proc to multiple events.

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts

Author

Commented:
Hi again,

I just think what you suggested was sharing one event by all
the controls in the form. That will be fine.

However, in my case there are many controls ....I don't want
to connect all the controls to the event by hand in design
time: I may miss one or two controls and, especially, when
add a new control later I may forget to do this:-)

Is this possible to put the OnDragOver event into a new
component and all the controls in the form and the form
itself can be automatically connected with it as long as
the new component is put to the form in design time?  

Cheers.

Author

Commented:
sure, no problem. just do something like this :


  for I:= 0 to Form1.ControlCount -1 do
     Form1.Controls[I].OnDragOver := TForm1.FormDragOver;

Commented:
Hi,

That is great.

I have tried put your code into the OnCreate event of the
form, but got error message:
   Undeclared identifier: 'OnDragOver'
Anything wrong I did?

Cheers.

Author

Commented:
sorry, my mistake. OnDragOver is declared protected in TControl,
so you can not change it.
if you know the type of components in advance, you can do something like this:
for I:= 0 to Form1.ControlCount -1 do
   if (Controls[I] is TEdit) then
      (Controls[I] as TEdit).OnDragOver := FormDragOver;

if not, you can select "view as text" and paste 'OnDragOver  = FormDragOver' in each component (easier the selecting in object inspector).

Commented:
Create a component

TControlHack = class(TControl)
public
  property OnDragOver;
end;


Then use zodiks solution, but change it to

TControlHack(Form1.Controls[I]).OnDragOver := TForm1.FormDragOver

This should work.

Regards,

Erik.
Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

OR

Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.