Resizing Controls at Runtime

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 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 shown in the image above). The first thing, you'll need 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)  ;

• 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.
• LButtonDown

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 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) ;

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