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Posted 30 Nov 2000

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


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));
m_tracker = new CRectTracker(rect,CRectTracker::dottedLine  | 
                CRectTracker::resizeOutside | 
                CRectTracker::hatchedBorder );

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);
    CDC* pDC = GetDC();

    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!


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

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Comments and Discussions

GeneralCursor goes away when linked with Static Library Pin
cdsmith29-Apr-03 6:34
membercdsmith29-Apr-03 6:34 
GeneralRe: Cursor goes away when linked with Static Library Pin
lesnikowski9-Jan-04 2:20
memberlesnikowski9-Jan-04 2:20 
GeneralRe: Cursor goes away when linked with Static Library Pin
tohichoi19-Sep-05 20:57
membertohichoi19-Sep-05 20:57 
GeneralRe: Cursor goes away when linked with Static Library Pin
M A V11-Jul-08 6:56
memberM A V11-Jul-08 6:56 
See this article[^]

When an application is linked to MFC by using the static library, the MFC resources are compiled into the executable of an application. The executable of the application will include the Afxres.rc file. To check this, click Resource Includes on the View menu. The Afxres.rc file has the resources that CRectTracker uses in the MFC source code.

These resources are only included when _AFX_NO_TRACKER_RESOURCES is not defined. The BLOCKS32 project has _AFX_NO_TRACKER_RESOURCES defined. Therefore, it does not put the resources that CRectTracker requires in the executable image of the application. Therefore, none of the cursors that are used by CRectTracker will show up when you build the sample by using MFC statically.

1. On the View menu, click Resource Includes.
2. Delete the following line:

AnswerRe: Cursor goes away when linked with Static Library Pin
Anthony Dunk1-Jul-09 19:34
memberAnthony Dunk1-Jul-09 19:34 

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