child cwnd detect other chlid cwnd --- magnetic cwnd?

I want to have 2 cbutton that if they are placed close to each other (say 30 pixels or so) they will attract eachother and stick together.

I have my own little hack of drag n' drop, and I can make the one cbutton link up with the second, if I know that it is close enough.

But, that is the problem I don't know what is the best way to tell if a cbutton is close to another cbutton.

I'd like the behavior to be in the MagButton class, not in my CDialog class.

the only solution I know how to work is by putting all my cbuttons that I will be using in a list, and then cycling through that list, looking at the RECTS to see where they are.

I don't like it because that code would have to go in the CDialog class.

I want code that could go in the MagButton class, ...

how can I tell from a child cwnd where other child cwnds are, and where they are.

that is my question

more details available if needed.

Thanks,

Bob
LVL 8
bebonhamAsked:
Who is Participating?
 
mblatCommented:
May be several ways....

One would be to have to overwrite PreSubclassWindow and do it there...

void CMagButton::PreSubclassWindow()
{
  m_buttonList.push_back(this);

  CButton::PreSubclassWindow();
}

just as a side note (and you may know it already - so no offence....)
if you declate you list static there will be only one copy of it.  That is all good, but if you have MORE THAN ONE dialog with CMagButtons it may represent some problem - you need to remember to clear that list when dialog is closed....

Or lets say there is one dialog brings up other dialogs, both having CMagButtons? THen what?  I don't know structure of your app - so take it for what it is - trying to think about you potencial problem - may be there is none....

By the way if something like this is the case you could use something like this:

class MyPair
{
 CDialog*    m_pParent;
 CMagButton* m_pButton;
};

std::vector<MyPair> m_buttonList;

void CMagButton::PreSubclasssWindow()
{
  MyPair  pair;
  pair.m_pParent = GetParent();
  pair.m_pButton = this;

  m_buttonList.push_back(MyPair);
}

and go from there....


Hope it helps....
0
 
mblatCommented:
Here is an idea:

class CMagButton
{
static std::list<CMagButton*> m_buttonList;
// so there is one and only one copy
};

void CMagButton::OnMove()
{
  // loop through you list here!!!!

   std::for_each(m_buttonList.begin(),.......);
}


Hope it helps....
0
 
bebonhamAuthor Commented:
yes, that appears to be part of the answer.
but can you suggest how do I get the data into the list inside the class?

it seems like I would have to pass it from the main dialog?

Bob
0
 
bebonhamAuthor Commented:
thanks a lot, very helpful!
0
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