I have spent about a week re-reading a section in my book on scroll bar messages ane i cant fr the life of me figure out how some of these functions work.... Ive been looking at the code for about 2 hours today and im still having trouble so i was wondering if anyone could make this more clear to me. my .cpp code is : #include <afxwin.h> #include "edit.h" CMyApp myApp; // CMyApp member functions: BOOL CMyApp::InitInstance () { m_pMainWnd = new CMainWindow; //makes m_pMainWnd point to CMainWindow m_pMainWnd->ShowWindow (m_nCmdShow); //tells windows to show the window m_pMainWnd->UpdateWindow (); //makes sure the window is updated? return TRUE; } //************************************************************************ //************************************************************************ //************************************************************************ //CMainWindow member functions and message map..... BEGIN_MESSAGE_MAP (CMainWindow, CFrameWnd) // <<< begins the message loop. ON_WM_CREATE () ON_WM_SIZE () ON_WM_PAINT () ON_WM_HSCROLL () ON_WM_VSCROLL () // this is the message that it will be looking for. END_MESSAGE_MAP () //ends the message LOOP //************************************************************************ //************************************************************************ //************************************************************************ CMainWindow::CMainWindow () { Create (NULL, _T ("Test Drawing In Windows."), WS_OVERLAPPEDWINDOW | WS_VSCROLL | WS_HSCROLL);// this prints Test Drawing In Windows on the title bar } //************************************************************************ //************************************************************************ //************************************************************************ int CMainWindow::OnCreate (LPCREATESTRUCT lpCreateStruct) { if (CFrameWnd::OnCreate (lpCreateStruct) == -1) return -1; // // Initialize internal width and height values based on screen metrics. // CClientDC dc (this); m_nCellWidth = dc.GetDeviceCaps (LOGPIXELSX); m_nCellHeight = dc.GetDeviceCaps (LOGPIXELSY); m_nViewWidth = 1000 ; m_nViewHeight = 1000 ; return 0; } //************************************************************************ //************************************************************************ //************************************************************************ void CMainWindow::OnSize (UINT nType, int cx, int cy) { CFrameWnd::OnSize (nType, cx, cy); // // Set the horizontal scrolling parameters. // int nHScrollMax = 0; m_nHScrollPos = m_nHPageSize = 0; if (cx < m_nViewWidth) { nHScrollMax = m_nViewWidth - 1; m_nHPageSize = cx; m_nHScrollPos = min (m_nHScrollPos, m_nViewWidth - m_nHPageSize - 1); } SCROLLINFO si; si.fMask = SIF_PAGE | SIF_RANGE | SIF_POS; si.nMin = 0; si.nMax = nHScrollMax; si.nPos = m_nHScrollPos; si.nPage = m_nHPageSize; SetScrollInfo (SB_HORZ, &si, TRUE); // // Set the vertical scrolling parameters. // int nVScrollMax = 0; m_nVScrollPos = m_nVPageSize = 0; if (cy < m_nViewHeight) { //if the client area height is less than the workspace height then execute nVScrollMax = m_nViewHeight - 1; m_nVPageSize = cy; // sets VPageSize to the client areas height m_nVScrollPos = min (m_nVScrollPos, m_nViewHeight - m_nVPageSize - 1); } si.fMask = SIF_PAGE | SIF_RANGE | SIF_POS; si.nMin = 0; si.nMax = nVScrollMax; si.nPos = m_nVScrollPos; si.nPage = m_nVPageSize; SetScrollInfo (SB_VERT, &si, TRUE); } //************************************************************************ //************************************************************************ //************************************************************************ void CMainWindow::OnPaint () // this is the paint command. { CPaintDC dc (this); // creates a paint device context. dc.SetWindowOrg (m_nHScrollPos, m_nVScrollPos); CBrush brush (HS_DIAGCROSS, RGB (255,0,0)); // sets the criscrosses to bright red. dc.SelectObject (&brush); //selects the brush into the DC (device context) dc.SetBkColor (RGB (0,0,0)); // sets the background color to BLACK dc.Rectangle (0,0,1000,1000);//Draws a rectangle that is 10000 by 10000 } //************************************************************************ //************************************************************************ //************************************************************************ void CMainWindow::OnHScroll (UINT nCode, UINT nPos, CScrollBar* pScrollBar) { int nDelta; // // Compute the horizontal scroll distance, or "delta." // switch (nCode) { case SB_LINELEFT: nDelta = -LINESIZE; break; case SB_PAGELEFT: nDelta = -m_nHPageSize; break; case SB_THUMBTRACK: nDelta = (int) nPos - m_nHScrollPos; break; case SB_PAGERIGHT: nDelta = m_nHPageSize; break; case SB_LINERIGHT: nDelta = LINESIZE; break; default: // Ignore other scroll bar messages return; } // // Adjust the delta if adding it to the current scroll position would // cause an underrun or overrun. // int nScrollPos = m_nHScrollPos + nDelta; int nMaxPos = m_nViewWidth - m_nHPageSize; if (nScrollPos < 0) nDelta = -m_nHScrollPos; else if (nScrollPos > nMaxPos) nDelta = nMaxPos - m_nHScrollPos; // // Update the scroll position and scroll the window. // if (nDelta != 0) { m_nHScrollPos += nDelta; SetScrollPos (SB_HORZ, m_nHScrollPos, TRUE); ScrollWindow (-nDelta, 0); } } //************************************************************************ //************************************************************************ //************************************************************************ void CMainWindow::OnVScroll (UINT nCode, UINT nPos, CScrollBar* pScrollBar) { int nDelta; // // Compute the vertical scroll distance, or "delta." // switch (nCode) { case SB_LINEUP: nDelta = -LINESIZE; break; case SB_PAGEUP: nDelta = -m_nVPageSize; break; case SB_THUMBTRACK: nDelta = (int) nPos - m_nVScrollPos; break; case SB_PAGEDOWN: nDelta = m_nVPageSize; break; case SB_LINEDOWN: nDelta = LINESIZE; break; default: // Ignore other scroll bar messages return; } // // Adjust the delta if adding it to the current scroll position would // cause an underrun or overrun. // int nScrollPos = m_nVScrollPos + nDelta; int nMaxPos = m_nViewHeight - m_nVPageSize; if (nScrollPos < 0) nDelta = -m_nVScrollPos; else if (nScrollPos > nMaxPos) nDelta = nMaxPos - m_nVScrollPos; // // Update the scroll position and scroll the window. // if (nDelta != 0) { m_nVScrollPos += nDelta; SetScrollPos (SB_VERT, m_nVScrollPos, TRUE); ScrollWindow (0, -nDelta); } } and my .h file code is : #define LINESIZE 8 class CMyApp : public CWinApp { public: virtual BOOL InitInstance(); // Need to declare this function so that the window itself can be printed. }; class CMainWindow : public CFrameWnd { protected: int m_nCellWidth; int m_nCellHeight; // Cell height in pixels int m_nRibbonWidth; // Ribbon width in pixels int m_nViewWidth; // Workspace width in pixels int m_nViewHeight; // Workspace height in pixels int m_nHScrollPos; // Horizontal scroll position int m_nVScrollPos; // Vertical scroll position int m_nHPageSize; // Horizontal page size int m_nVPageSize; // Vertical page size public: CMainWindow(); protected: afx_msg void OnPaint (); // Gives the main window access to the OnPaint message it will need to output the painting to the screen. afx_msg int OnCreate (LPCREATESTRUCT lpCreateStruct); afx_msg void OnSize (UINT nType, int cx, int cy); afx_msg void OnHScroll (UINT nCode, UINT nPos, CScrollBar* pScrollBar); afx_msg void OnVScroll (UINT nCode, UINT nPos, CScrollBar* pScrollBar); DECLARE_MESSAGE_MAP () //Declares the messape map MFC gives you. }; The OnSize Message confuses me the most... i dont see how any of it works or what it does.... And the If statements at the bottom of each Scroll message confuses me also... I copied the code out of the books example. If you need to books example instead of mine just say so. TY :) GIMPS

Atualy im BEGGINING to understand it...... but yea.... any additional help is always welcome :-D GIMPS