Attaching Elements to Borders

With the XConstraint-class you will be able to attach every border of any element to a border of
the parent dialog. This means, if you change the size of the dialog, the size or position (or both) of the
attached elements will also change. Normaly, every Element inside a dialog-window was attached to
the left, upper corner. If you resize the dialog, the elements stay at their place and nothing changes.
With this class, it’s possible to attach a button to the right corner of the dialog. When you now resize
the dialog, the button moves in the same way the dialog grows.

In this example, the “Test Object” was attached to the right and lower border of the dialog. If you
resize the dialog, the object moves, so that the distance to the right and to the lower border of the
dialog doesn’t change. The four icons in the edges of the dialog are attachted to the according
borders of the dialog.

What have you to do, to use this class?

The use the XConstraint-class is quite
simple. First you have to declare a XConstraint-object in the
headerfile of your dialog-class:

protected:
     XConstraint cs;

Second, add a message-handler to message the WM_SIZE-event (use class-wizzard):

.cpp:

/{{AFX_MSG_MAP(CConstraintDlg)
     ...
     ON_WM_SIZE()
     ...
     //}}AFX_MSG_MAP

.h

//{{AFX_MSG(CConstraintDlg)
     ...
     afx_msg void OnSize(UINT nType, int cx, int cy);
     ...
     //}}AFX_MSG

Third, set the attachments for every element in your dialog in the OnInitDialog()-Method:

cs.Set(this); // tell the class who is using it
     cs.Add(IDC_BUTTON1, CS_RIGHT, CS_RIGHT, CS_TOP, CS_TOP);
     cs.Add(IDC_BUTTON2, CS_LEFT, CS_RIGHT, CS_TOP, CS_BOTTOM);
     cs.Add(IDC_BUTTON3, CS_FIXWIDTH, CS_FIXWIDTH, CS_FIXHEIGHT,
     CS_FIXHEIGHT);

This means:

• Button1 moves to the right, when the dialog grows and it
  moves to the left if the dialog is shrinking
• Button2 grows in the same way the dialog grows
• Button3 doesn’t change it’s size, but moves accordingly
  to the size of the dialog. If button3 appears in the
  middle of the dialog, it will allway stay in the middle.

The syntax for the Add-command is:
Add(ID, leftAttachment, rightAttachment, topAttachment,
bottomAttachment).

The following attachments are possible:

Fourth and last step: Tell the OnSize()-Method to resize (or
move) the dialog-elements:

void CConstraintDlg::OnSize(UINT nType, int cx, int cy)
     {
     cs.Resize(cx, cy);
     }

That’s all. Now your dialog will move and resize your
elements.

If you’ve questions contact me at Joachim.Raidl@iname.com