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Resizing Controls at run time

, 30 Nov 2000
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A method to allow the user to visually resize and position any control at run time.

Sample Image - resize_at_runtime.gif

Introduction

Suppose you wanted to give the user the ability to modify the size and position on a certain control? This example shows how to implement resizing controls on a dialog box as it is done when drawing controls on a dialog template or using Visual Basic at design time.

In order to accomplish this, we can use the class CRectTracker to manage all the drawing and resizing of a rectangular frame which also has (optional) 6 resize handlers (as in the image above). First thing to do is to invoke a CRectTracker and specify given coordinates:

LPRECT rect = new RECT;
CWnd* wnd = (CWnd*)(GetDlgItem(IDC_EDIT1));
wnd->GetWindowRect(rect);
ScreenToClient(rect);
m_tracker = new CRectTracker(rect,CRectTracker::dottedLine  | 
                CRectTracker::resizeOutside | 
                CRectTracker::hatchedBorder );
m_tracker->Draw(pDC);

There are two events that are needed to be taken care of:

  1. SetCursor
    if (pWnd == this && m_tracker->SetCursor(this, nHitTest))
        return TRUE;

    This is done in order to draw the correct mouse cursors when floating the mouse pointer over the rectangle.

  2. OnLButtonDown
    m_tracker->Track(this, point, TRUE);
    Invalidate(FALSE);
    CDC* pDC = GetDC();
    m_tracker->Draw(pDC);

    This will take care of the drawing of the rectangle with resizing it.

Once you have finished, all you have to do is draw the control with the new rectangle coordinates:

LPRECT rect = new RECT;
CWnd* wnd = (CWnd*)(GetDlgItem(IDC_EDIT1));
rect = LPRECT(m_tracker->m_rect); 
wnd->MoveWindow(rect,TRUE) ;

That's it!

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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About the Author

Amit Nabarro

United States United States
No Biography provided

Comments and Discussions

 
Questiontracker is coveraged by the sibling object Pinmemberhandsome0314-Jun-12 18:56 

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