C / C++ / MFC

23-Feb-02 10:41

Hi I'm new to this forum, but I think it's pretty cool. I had a question about CPoint object. I need to be able to randomly generate an array of them. Which I got that far, but my problem was when the user entered a point, and I was supposed to tell the program to find the closest point in the array. Do any of you know how to do that? I tried using like the '<' compare operator but the CPoint class doesn't have that operator. Don't worry I'm not trying to get free homework (I'm using Introduction to MFC with Visual C++ to learn MFC) or anything I just don't understand and I would like to understand it. Thanks in advance for your help.

-CDudd

Christian Graus23-Feb-02 10:43

Christian Graus

23-Feb-02 10:43

You need to use < on the members of CPoint, which are x and y.

And I'd answer this question if it *was* homework, because you're trying to do something, not just asking for a complete solution on a plate.

Christian

The tragedy of cyberspace - that so much can travel so far, and yet mean so little.

CDuddley23-Feb-02 10:49

23-Feb-02 10:49

I have tried that. I'm not really sure where to go from there. Another hint please? I'm not trying to do 'anything' I'm just trying to learn. Thanks for the quick post.

-CDudd

Peter Godec23-Feb-02 11:58

Peter Godec

23-Feb-02 11:58

CDuddley wrote:
to find the closest point

If i understand correctly, you need to define a measure of distance between CPoints to do that. Most probably that would be euclidean distance , i.e.

d = sqrt((x1 - x2)^2 + (y1 - y2)^2)

So define a function that calculates the euclidean distance between two CPoints, maybe something like this:

#include <math.h> // or <cmath> and std:: if your compiler/library isn't broken

double distance(const CPoint& p1, const CPoint& p2)
{
	return sqrt((p1.x - p2.x)*(p1.x - p2.x) + (p1.y - p2.y)*(p1.y - p2.y));
}

a nicer variant (performance?) of this would be

double distance(const CPoint& p1, const CPoint& p2)
{
	CSize diff = p1 - p2;
	return sqrt(diff.x * diff.x + diff.y * diff.y);
}

(of course, for your purpose, you don't need to calculate the sqrt, but now i'm blabbering)

Now all you's gotta do is iterate over the array of CPoints, calculating the distance between your given test point and each point in the array and keeping track of the array index of the point that is the closest to the test point (now read this paragraph again).

that-exercise-is-left-to-the-OP-ly y'rs --pg Smile | :)

CDuddley23-Feb-02 12:16

23-Feb-02 12:16

Thanks a bunch for the post. I was having trouble with the fact that if a random point was greater than the given point the point would be negative when I took the difference. I forgot all about the euclidian distance formula thanks a ton! I'll try to get the test program working now!

Thanks again,
CDudd

CDuddley23-Feb-02 13:23

23-Feb-02 13:23

You're awesome I got the exercise working without a hitch! Thanks a ton man.

-CDudd

Common Dialog Boxes

gordingin23-Feb-02 10:13

gordingin

23-Feb-02 10:13

I need to figure out via a hwnd if the hwnd I have is a common dialog box. Is there a style, class, etc associated with common dialog boxes? I am only interested in the open and close dialog boxes. What is the best way to do this?

Thanks
Ralph Krausse

Re: Common Dialog Boxes

Paul M Watt23-Feb-02 10:22

Paul M Watt

23-Feb-02 10:22

Using Spy++, it appears to me that there is no special class given to the Open and Save Dialog boxes, they are declared as the regular #32770 class, which is the identifier for the dialog class.

There may be some other trick that you can employ, like test the title or something, but this will not be guaranteed to work, especially if you are testing in someone elses application.

Group policies

Brian van der Beek23-Feb-02 10:00

Brian van der Beek

23-Feb-02 10:00

Does any one know a good article (preferably with source) about creating and reading group policies ?

Downcasting CButton...??

alex.barylski23-Feb-02 9:22

Re: Downcasting CButton...??

23-Feb-02 9:22

Joaquín and Christian...my appologies for asking a rtti question again, but I still don't have quite enough experience with it to fully understand whats going on despite numerous teaching attempts from both of you. Smile | :)

Anyways.

I have an dynamic array of CWnd's which I would like to be able to act, look and feel like CButton, CEdit, CComboBox etc...

//Create array of controls 
m_pControls = new CWnd[m_nControls];
		
//Downcast to derived class
dynamic_cast< CButton >(m_pControls[0]).Create(this, CRect(0,0,100, 20));

Someone wanna show how I do this properly..?

Thanx

"An expert is someone who has made all the mistakes in his or her field" - Niels Bohr

Joaquín M López Muñoz23-Feb-02 9:40

Joaquín M López Muñoz

23-Feb-02 9:40

Well, I think you have some misunderstandings about what kind of things one is supposed to do with dynamic_cast.
First of all, dynamic_cast only works for pointers or references. Your last sentence cannot work because you are tyring to use it to cast to CButton instead of CButton *. There are a lot of other reasons why it won't work, however.
Suppose you have a inheritance hierarchy like this

   A
   |
-------
|  |  |
B  C  D

Now you're given a pointer to A and you want to know whether the object pointed to is really a B:

A * pA;
... //set pA somehow
B * pB=dynamic_cast<B *>(pA);

At this point, if pA was actually pointing to a B (which is legitimate, as B derives from A), pB will be non-null. Otherwise, pB is null, menaing that pA points to a C, a D or something else. In this way, dynamic_cast lets you peep into the actual nature of an object referred to from its base class. What dynamic_cast does not do is create objects of derived classes on demand, as your code seems to assume. Hope this helped clariy things a bit more.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: Downcasting CButton...??

alex.barylski23-Feb-02 10:06

Re: change coordination rule

23-Feb-02 10:06

Ummm...sorta...RTTI is proving to be the most difficult thing for me to understand fully. I'll probably have to hit the books again for a while.

I did however find another way around my problem, which actually is easier and less overhead. I hate it when I do that, try to solve a simple problem with a difficult solution. One day i'll learn.

Thanx again

"An expert is someone who has made all the mistakes in his or her field" - Niels Bohr

change coordination rule

Mazdak23-Feb-02 8:40

Mazdak

23-Feb-02 8:40

The coordination in client rect is like this:
------------->+
|
|
|
|
|
|
|+
(I mean Y increase when it goes down)

Is there any way to change this rule and it increaze when it goes up?

Mazy

"So,so you think you can tell,
Heaven from Hell,
Blue skies from pain,...
How I wish,how I wish you were here."
Wish You Were Here-Pink Floyd-1975

Simon Walton23-Feb-02 9:02

Simon Walton

23-Feb-02 9:02

Pass a negative y value into SetWindowExt().

Simon
There's one for you, nineteen for me
Sonork ID 100.10024

Pbs with Internet Explorer Rebars in MFC

23-Feb-02 8:35

I have created a Multiple Documents MFC project, using Internet Explorer Rebars for my toolbars instead of normal MFC toolbar.

When I put a control in my IDR_MAINFRAME dialog (the dialog bar), the control remains disabled even if I associated it with a member function for the message BN_CLICKED.

How can I do to enable my control?

Re: Pbs with Internet Explorer Rebars in MFC

Shog⁹23-Feb-02 13:47

Shog⁹

23-Feb-02 13:47

Put in an ON_UPDATE_COMMAND_UI() handler for it.
Make sure the ON_UPDATE_COMMAND_UI() handler gets called - it must be in the toolbar OWNER window class.

Good Luck!

farewell goodnight last one out turn out the lights

Smashing Pumpkins, Tales of a Scorched Earth

Splitter window...???

alex.barylski23-Feb-02 6:43

23-Feb-02 6:43

How would I go about creating a triple pane setup using splitters...?

Would I create a split window normally, then in the OnCreateClient of one of the child splits repeat the process...?

Cheers!

"An expert is someone who has made all the mistakes in his or her field" - Niels Bohr

Mazdak23-Feb-02 7:31

Mazdak

23-Feb-02 7:31

I think there is one in CP,Did you search ?

Mazy

"So,so you think you can tell,
Heaven from Hell,
Blue skies from pain,...
How I wish,how I wish you were here."
Wish You Were Here-Pink Floyd-1975

alex.barylski23-Feb-02 8:29

23-Feb-02 8:29

I'm aware of the triple pane CSplitterWndEx 'T' control, but it's not what I need unfortunately.

Thanx anyways!

Cheers

"An expert is someone who has made all the mistakes in his or her field" - Niels Bohr

Simon Walton23-Feb-02 9:04

Simon Walton

23-Feb-02 9:04

The CSplitterWndEx class can create virtually any splitter layout you wish. Want do you want done differently?

Simon
There's one for you, nineteen for me
Sonork ID 100.10024

alex.barylski23-Feb-02 9:09

23-Feb-02 9:09

I've used that class before, it's a great time saver!

But it's to much extra overhead and i'm curious as to what the best approach would be, without a third party class.

Cheers!

"An expert is someone who has made all the mistakes in his or her field" - Niels Bohr

Nish Nishant23-Feb-02 16:07

Nish Nishant

23-Feb-02 16:07

You can split the main frame into two views. Then split the right split into two views to get an OE like 3-pane view.

I used to do it slightly different for some time.
I used to split the main frame into two. The left split is a view and the right split is another frame window. This frame window, I again split into two

The difference is that now the splitters are distinct. Means there are two splitters. There is a slight difference in look and feel. Also in resizing.

Regards
Nish

My most recent CP article :-

A newbie's elementary guide to spawning processes

www.busterboy.org

alex.barylski23-Feb-02 18:51