"Fixing down" a CButton or CEdit control.

Hello again,

I was wondering how I could "fix down" a CButton or CEdit control in a scrollable main window. The problem is that when such a window is scrolled, the CButton or CEdit control floats over to the next scrolled region. How can I stop this from happening?

Place the controls (buttons, edits, and so on) in a control bar (preferable a dialog bar).
See CDialogBar and CControlBar MFC classes.

Quote:

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Originally Posted by ovidiucucu

Place the controls (buttons, edits, and so on) in a control bar (preferable a dialog bar).
See CDialogBar and CControlBar MFC classes.

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Thank you so much for replying! I'm working on it and I will get back to you about it. I've sub-classed CControlBar and i'm transferring all the control related functions.

Thanks again.

I tried making a CControlBar derived class, but it signals this error:

Code:

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1>        'void CControlBar::OnUpdateCmdUI(CFrameWnd *,BOOL)' : is abstract
1>        c:\program files (x86)\microsoft visual studio 8\vc\atlmfc\include\afxext.h(167) : see declaration of 'CControlBar::OnUpdateCmdUI'

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What is an abstract class? Why is this happening?

Am abstract class is a class which contains just abstract/general stuff and has no sense to be instantiated.
In C++, a class is abstract if has at least one pure virtual function.

Imagine a class Shape:

Code:

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class Shape
{
protected:
  int pen_color;
public:
  void Draw();
};

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Can we implement Shape::Draw? What to draw? A rectangle, an ellipse, something else? I think, in Shape class we have no idea.

So, let's make Shape abstract:

Code:

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class Shape // abstract class
{
protected:
  int pen_color;
public:
  virtual void Draw() = 0; // pure virtual function
};

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To make a derived class "concrete" we have to override all the base pure virtual functions, in our case the function Shape::Draw.

Code:

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class Rectangle : public Shape
{
// ....
public:
  virtual void Draw()
  {
      // draw a rectangle here.
  }
};

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CControlBar is like Shape: an abstract class. It has no sense to create an object of CControlBar type, then the compiler doesn't let you to do silly things. ;).
Use one of its derived concrete classes CDialogBar, CToolBar and so on.
As I already said, for your purpose, CDialogBar is preferable.

Thanks very much for the explanation. I've now tried using the CDialogBar instead.

1.) Since I've chosen to use CDialogBar, do i still subclass it and create the controls as private?

2.) Further, how could I reposition the CDialopBar? It's create function does not accept any CRect parameter.

3.) The CDialogBar will be created dynamically in the program. The CEdit controls may be created anywhere in a table in the program. Is this possible?

Dialog Bars
How to initialize child controls in a derived CDialogBar