Click here to Skip to main content
Click here to Skip to main content

Saving a windows size position and state in MFC

, 30 May 2001
Rate this:
Please Sign up or sign in to vote.
Saving the size and positions of windows so that they can be restored next time the app loads up


When building a UI application, one feature which I always include is saving the size and positions of my windows so that they can be restored next time the app loads up. Each time I make a new application, I always try a new method of doing this. Finally I've come up with what I think is the simplest and best solution to save and restore windows sizes and positions.


The trick lies behind the GetWindowPlacement/SetWindowPlacement functions. The GetWindowPlacement function is part of the Windows API and it basically retrieves the show state and the restored, minimized, and maximized positions a window and stores it into a WINDOWPLACEMENT structure. This structure can then be passed to the SetWindowPlacement function to restore the window to its old state.

Saving the window placement

Saving the WINDOWPLACEMENT structure is fairly simple and can be done from anywhere in your program. Since I use MFC for my UI applications I found that the best place to save the window's size and position is in the DestroyWindow virtual function, since it is called every time the window closes, for every type of window:

BOOL CMainFrame::DestroyWindow() 
    AfxGetApp()->WriteProfileBinary("MainFrame", "WP", (LPBYTE)&wp, sizeof(wp));

    return CMDIFrameWnd::DestroyWindow();

The WriteProfileBinary() is part of the MFC class CWinApp which simply dumps the WINDOWPLACEMENT structure into the registry as a REG_BINARY value called "WP" in a key called MainFrame. A good idea, especially for child windows of the CMainFrame class, is to replace the hard-coded MainFrame with the caption of the frame.

Restoring the window placement

Next, we need to restore the window. The SetWindowPlacement function will only work after the window has been created, so the best place to call it is when the window is about to be shown for the first time. To my knowledge there is no single windows message or over-ridable virtual function to serve this purpose. However it is possible to handle the WM_SHOWWINDOW message and call SetWindowPlacement from there. Ideally it will be as simple as this:

void CMainFrame::OnShowWindow(BOOL bShow, UINT nStatus) 
    CMDIFrameWnd::OnShowWindow(bShow, nStatus);

    if(bShow && !IsWindowVisible())
        UINT nl;

        if(AfxGetApp()->GetProfileBinary("MainFrame", "WP", (LPBYTE*)&lwp, &nl))
            delete [] lwp;

The formal parameter bShow is true when the window is about to be shown, and false when it is about to be hidden. With the if() statement we are ensuring that we will reposition the window only when the window is hidden and about to be shown. There are two problems here:

  1. If your application hides the window and shows it during program execution, it will be displayed at the saved coordinates each time.
  2. SetWindowPlacement causes a WM_SHOWWINDOW to be fired.

A simple workaround fixes the problem:

void CMainFrame::OnShowWindow(BOOL bShow, UINT nStatus) 
    CMDIFrameWnd::OnShowWindow(bShow, nStatus);

    static bool bOnce = true;

    if(bShow && !IsWindowVisible()
        && bOnce)
        bOnce = false;

        UINT nl;

        if(AfxGetApp()->GetProfileBinary("MainFrame", "WP", (LPBYTE*)&lwp, &nl))
            delete [] lwp;

A static variable inside a function is only initialized once. Since the if() statement now requires bOnce to be true in order to execute the block, we are assured that the code will be only executed once; the first time the window is shown. Instead of having bOnce as a static it could obviously also be a member variable. In fact, if you create two instances of the same class, bOnce will only be true once, which means that you'll have to create it as a member variable. Happy Coding!


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.

A list of licenses authors might use can be found here


About the Author

[James Pullicino]
Web Developer
United Kingdom United Kingdom
We need to develop some good software for the brain.

Comments and Discussions

SuggestionBetter Solution for OnShowWindow PinmemberMember 871346010-Apr-13 1:47 
GeneralMy vote of 4 Pinmemberddas-edEn12-Feb-12 22:07 
GeneralTitle bar not painted - solved PinmemberMember 380048931-Jul-08 3:57 
GeneralRe: Title bar not painted - solved Pinmembershamada19-Nov-08 1:26 
GeneralRe: Title bar not painted - solved PinmemberArmand Molinski18-May-11 9:30 
GeneralModeless dialogs PinmemberJase Jennings13-Jan-04 15:29 
I'm looking for a solution which works with modeless dialogs.
I've tried many ways of doing this, but my modeless dialogs are always displayed in the same location. I can verify that the position of each dialog is correctly saved, but when i Create() the dialog and ShowWindow(), the dialogs always appear at the same place.
I have tried using DoModal on the dialogs in question using your code here, and other suggested methods of making this work, but the dialog is always centred.
Somebody MUST have a solution for this. MicroAngelo does it well. Essentially I have a main dialog, with 2 child palette windows. I need to be able to save and restore the positions of the palette (or tool) windows.
Would really appreciate some help guys
View your digital photos and images with ease using the ultimate desktop image manager for Microsoft Windows
Download your free copy of SlideShow Desktop today from

GeneraliModeless dialogs PinmemberJase Jennings13-Jan-04 15:26 
GeneralSaving MDI Windows PinmemberGreg Online30-Dec-02 11:29 
GeneralRe: Saving MDI Windows Pinmemberfz256-Nov-03 15:17 
GeneralSame Old Problem... PinmemberJames R. Twine7-Jun-01 10:33 
GeneralRe: Same Old Problem... Pinmembermberchtold7-Apr-07 18:47 
GeneralRe: Same Old Problem... PinmemberJames R. Twine8-Apr-07 4:23 
QuestionWhat about min/maximize Pinmembermarcus784-Jun-01 7:21 
AnswerRe: What about min/maximize PinmemberScot Brennecke4-Jun-01 23:05 
AnswerRe: What about min/maximize PinmemberJames Pullicino4-Jun-01 23:15 
AnswerRe: What about min/maximize Pinmemberabadura9-Aug-06 21:43 
AnswerRe: What about min/maximize PinmemberMichal Kowalski6-Jun-01 21:11 
GeneralRe: What about min/maximize PinmemberJames Pullicino7-Jun-01 21:18 
GeneralRe: What about min/maximize - solution for CDialog PinmemberYann C11-Jun-01 6:06 
GeneralRe: What about min/maximize - solution for CDialog PinmemberDTigran13-Jul-03 4:12 
GeneralRe: What about min/maximize PinmemberJames Pullicino19-Jun-01 5:12 
AnswerRe: What about min/maximize Pinmemberddas-edEn12-Feb-12 22:02 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

| Advertise | Privacy | Mobile
Web04 | 2.8.141029.1 | Last Updated 31 May 2001
Article Copyright 2001 by [James Pullicino]
Everything else Copyright © CodeProject, 1999-2014
Terms of Service
Layout: fixed | fluid