Cleanup: Dropped unused code

[TortoiseGit.git] / ext / ResizableLib / ResizableLayout.cpp

/////////////////////////////////////////////////////////////////////////////
//
// This file is part of ResizableLib
// http://sourceforge.net/projects/resizablelib
//
// Copyright (C) 2000-2004 by Paolo Messina
// http://www.geocities.com/ppescher - mailto:ppescher@hotmail.com
//
// The contents of this file are subject to the Artistic License (the "License").
// You may not use this file except in compliance with the License. 
// You may obtain a copy of the License at:
// http://www.opensource.org/licenses/artistic-license.html
//
// If you find this code useful, credits would be nice!
//
/////////////////////////////////////////////////////////////////////////////

/*!
 *  @file
 *  @brief Implementation of the CResizableLayout class.
 */

#include "stdafx.h"
#include "ResizableLayout.h"
#include "ResizableVersion.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

/*!
 *  @internal Constant used to detect clipping and refresh properties
 *
 *  @note In August 2002 Platform SDK, some guy at MS thought it was time
 *        to add the missing symbol BS_TYPEMASK, but forgot its original
 *        meaning and so now he's telling us not to use that symbol because
 *        its value is likely to change in the future SDK releases, including
 *        all the BS_* style bits in the mask, not just the button's type
 *        as the symbol's name suggests.
 *     @n So now we're forced to define another symbol, great!
 */
#define _BS_TYPEMASK 0x0000000FL

/*!
 *  This function adds a new control to the layout manager and sets anchor
 *  points for its top-left and bottom-right corners.
 *  
 *  @param hWnd Window handle to the control to be added
 *  @param anchorTopLeft Anchor point for the top-left corner
 *  @param anchorBottomRight Anchor point for the bottom-right corner
 *
 *  @remarks Overlapping controls, like group boxes and the controls inside,
 *           must be added from the outer controls to the inner ones, to let
 *           the clipping routines work correctly.
 *
 *  @sa AddAnchorCallback RemoveAnchor
 */
void CResizableLayout::AddAnchor(HWND hWnd, ANCHOR anchorTopLeft, ANCHOR anchorBottomRight)
{
        CWnd* pParent = GetResizableWnd();

        // child window must be valid
        ASSERT(::IsWindow(hWnd));
        // must be child of parent window
        ASSERT(::IsChild(pParent->GetSafeHwnd(), hWnd));

        // get parent window's rect
        CRect rectParent;
        GetTotalClientRect(&rectParent);
        // and child control's rect
        CRect rectChild;
        ::GetWindowRect(hWnd, &rectChild);
        ::MapWindowPoints(NULL, pParent->m_hWnd, (LPPOINT)&rectChild, 2);

        // adjust position, if client area has been scrolled
        rectChild.OffsetRect(-rectParent.TopLeft());

        // go calculate margins
        CSize marginTopLeft, marginBottomRight;

        // calculate margin for the top-left corner

        marginTopLeft.cx = rectChild.left - rectParent.Width() * anchorTopLeft.cx / 100;
        marginTopLeft.cy = rectChild.top - rectParent.Height() * anchorTopLeft.cy / 100;
        
        // calculate margin for the bottom-right corner

        marginBottomRight.cx = rectChild.right - rectParent.Width() * anchorBottomRight.cx / 100;
        marginBottomRight.cy = rectChild.bottom - rectParent.Height() * anchorBottomRight.cy / 100;

        // prepare the structure
        LAYOUTINFO layout(hWnd, anchorTopLeft, marginTopLeft,
                anchorBottomRight, marginBottomRight);

        // get control's window class
        GetClassName(hWnd, layout.sWndClass, MAX_PATH);

        // initialize resize properties (overridable)
        InitResizeProperties(layout);

        // must not be already there!
        // (this is probably due to a duplicate call to AddAnchor)
        POSITION pos;
        ASSERT(!m_mapLayout.Lookup(hWnd, pos));

        // add to the list and the map
        pos = m_listLayout.AddTail(layout);
        m_mapLayout.SetAt(hWnd, pos);
}

/*!
 *  This function adds a placeholder to the layout manager, that will be
 *  dinamically set by a callback function whenever required.
 *
 *  @return The return value is an integer used to distinguish between
 *          different placeholders in the callback implementation.
 *
 *  @remarks You must override @ref ArrangeLayoutCallback to provide layout
 *           information.
 *
 *  @sa AddAnchor ArrangeLayoutCallback ArrangeLayout
 */
UINT_PTR CResizableLayout::AddAnchorCallback()
{
        // one callback control cannot rely upon another callback control's
        // size and/or position (they're updated all together at the end)
        // it can however use a non-callback control, calling GetAnchorPosition()

        // add to the list
        LAYOUTINFO layout;
        layout.nCallbackID = m_listLayoutCB.GetCount() + 1;
        m_listLayoutCB.AddTail(layout);
        return layout.nCallbackID;
}

/*!
 *  This function is called for each placeholder added to the layout manager
 *  and must be overridden to provide the necessary layout information.
 *  
 *  @param layout Reference to a LAYOUTINFO structure to be filled with
 *         layout information for the specified placeholder.
 *         On input, nCallbackID is the identification number
 *         returned by AddAnchorCallback. On output, anchor points and
 *         the window handle must be set and valid.
 *  
 *  @return The return value is @c TRUE if the layout information has been
 *          provided successfully, @c FALSE to skip this placeholder.
 *
 *  @remarks When implementing this function, unknown placeholders should be
 *           passed to the base class. Unhandled cases will fire an assertion
 *           in the debug version.
 *
 *  @sa AddAnchorCallback ArrangeLayout LAYOUTINFO
 */
BOOL CResizableLayout::ArrangeLayoutCallback(LAYOUTINFO& layout) const
{
        UNREFERENCED_PARAMETER(layout);
        
        ASSERT(FALSE); // must be overridden, if callback is used
        
        return FALSE; // no useful output data
}

/*!
 *  This function should be called in resizable window classes whenever the
 *  controls layout should be updated, usually after a resize operation.
 *
 *  @remarks All the controls added to the layout are moved and resized at
 *           once for performace reasons, so all the controls are in their
 *           old position when AddAnchorCallback is called.
 *           To know where a control will be placed use GetAnchorPosition.
 *  
 *  @sa AddAnchor AddAnchorCallback ArrangeLayoutCallback GetAnchorPosition
 */
void CResizableLayout::ArrangeLayout() const
{
        // common vars
        UINT uFlags;
        LAYOUTINFO layout;
        CRect rectParent, rectChild;
        INT_PTR count = m_listLayout.GetCount();
        INT_PTR countCB = m_listLayoutCB.GetCount();

        if (count + countCB == 0)
                return;

        // get parent window's rect
        GetTotalClientRect(&rectParent);

        // reposition child windows
        HDWP hdwp = ::BeginDeferWindowPos (static_cast<int>(count + countCB));
        
        POSITION pos = m_listLayout.GetHeadPosition();
        while (pos != NULL)
        {
                // get layout info
                layout = m_listLayout.GetNext(pos);
                
                // calculate new child's position, size and flags for SetWindowPos
                CalcNewChildPosition(layout, rectParent, rectChild, uFlags);

                // only if size or position changed
                if ((uFlags & (SWP_NOMOVE|SWP_NOSIZE)) != (SWP_NOMOVE|SWP_NOSIZE))
                {
                        hdwp = ::DeferWindowPos(hdwp, layout.hWnd, NULL, rectChild.left,
                                rectChild.top, rectChild.Width(), rectChild.Height(), uFlags);
                }
        }

        // for callback items you may use GetAnchorPosition to know the
        // new position and size of a non-callback item after resizing

        pos = m_listLayoutCB.GetHeadPosition();
        while (pos != NULL)
        {
                // get layout info
                layout = m_listLayoutCB.GetNext(pos);
                // request layout data
                if (!ArrangeLayoutCallback(layout))
                        continue;

                // calculate new child's position, size and flags for SetWindowPos
                CalcNewChildPosition(layout, rectParent, rectChild, uFlags);

                // only if size or position changed
                if ((uFlags & (SWP_NOMOVE|SWP_NOSIZE)) != (SWP_NOMOVE|SWP_NOSIZE))
                {
                        hdwp = ::DeferWindowPos(hdwp, layout.hWnd, NULL, rectChild.left,
                                rectChild.top, rectChild.Width(), rectChild.Height(), uFlags);
                }
        }

        // finally move all the windows at once
        ::EndDeferWindowPos(hdwp);
}

/*!
 *  @internal This function adds or removes a control window region
 *  to or from the specified clipping region, according to its layout
 *  properties.
 */
void CResizableLayout::ClipChildWindow(const LAYOUTINFO& layout,
                                                                           CRgn* pRegion) const
{
        // obtain window position
        CRect rect;
        ::GetWindowRect(layout.hWnd, &rect);
#if (_WIN32_WINNT >= 0x0501)
        //! @todo decide when to clip client only or non-client too (themes?)
        //! (leave disabled meanwhile, until I find a good solution)
        //! @note wizard97 with watermark bitmap and themes won't look good!
        // if (real_WIN32_WINNT >= 0x501)
        //      ::SendMessage(layout.hWnd, WM_NCCALCSIZE, FALSE, (LPARAM)&rect);
#endif
        ::MapWindowPoints(NULL, GetResizableWnd()->m_hWnd, (LPPOINT)&rect, 2);

        // use window region if any
        CRgn rgn;
        rgn.CreateRectRgn(0,0,0,0);
        switch (::GetWindowRgn(layout.hWnd, rgn))
        {
        case COMPLEXREGION:
        case SIMPLEREGION:
                rgn.OffsetRgn(rect.TopLeft());
                break;

        default:
                rgn.SetRectRgn(&rect);
        }

        // get the clipping property
        BOOL bClipping = layout.properties.bAskClipping ?
                LikesClipping(layout) : layout.properties.bCachedLikesClipping;

        // modify region accordingly
        if (bClipping)
                pRegion->CombineRgn(pRegion, &rgn, RGN_DIFF);
        else
                pRegion->CombineRgn(pRegion, &rgn, RGN_OR);
}

/*!
 *  This function retrieves the clipping region for the current layout.
 *  It can be used to draw directly inside the region, without applying
 *  clipping as the ClipChildren function does.
 *  
 *  @param pRegion Pointer to a CRegion object that holds the
 *         calculated clipping region upon return
 *
 *  @deprecated For anti-flickering ClipChildren should be preferred
 *              as it is more complete for platform compatibility.
 *              It will probably become a private function.
 */
void CResizableLayout::GetClippingRegion(CRgn* pRegion) const
{
        CWnd* pWnd = GetResizableWnd();

        // System's default clipping area is screen's size,
        // not enough for max track size, for example:
        // if screen is 1024 x 768 and resizing border is 4 pixels,
        // maximized size is 1024+4*2=1032 x 768+4*2=776,
        // but max track size is 4 pixels bigger 1036 x 780 (don't ask me why!)
        // So, if you resize the window to maximum size, the last 4 pixels
        // are clipped out by the default clipping region, that gets created
        // as soon as you call clipping functions (my guess).

        // reset clipping region to the whole client area
        CRect rect;
        pWnd->GetClientRect(&rect);
        pRegion->CreateRectRgnIndirect(&rect);

        // clip only anchored controls
        LAYOUTINFO layout;
        POSITION pos = m_listLayout.GetHeadPosition();
        while (pos != NULL)
        {
                // get layout info
                layout = m_listLayout.GetNext(pos);
                
                if (::IsWindowVisible(layout.hWnd))
                        ClipChildWindow(layout, pRegion);
        }
        pos = m_listLayoutCB.GetHeadPosition();
        while (pos != NULL)
        {
                // get layout info
                layout = m_listLayoutCB.GetNext(pos);
                // request data
                if (!ArrangeLayoutCallback(layout))
                        continue;

                if (::IsWindowVisible(layout.hWnd))
                        ClipChildWindow(layout, pRegion);
        }
//! @todo Has XP changed this??? It doesn't seem correct anymore!
/*
        // fix for RTL layouts (1 pixel of horz offset)
        if (pWnd->GetExStyle() & WS_EX_LAYOUTRTL)
                pRegion->OffsetRgn(-1,0);
*/
}

//! @internal @brief Implements GetAncestor(pWnd->GetSafeHwnd(), GA_ROOT)
inline CWnd* GetRootParentWnd(CWnd* pWnd)
{
        // GetAncestor API not present, emulate
        if (!(pWnd->GetStyle() & WS_CHILD))
                return NULL;
        while (pWnd->GetStyle() & WS_CHILD)
                pWnd = pWnd->GetParent();
        return pWnd;
}

/*!
 *  This function enables or restores clipping on the specified DC when
 *  appropriate. It should be called whenever drawing on the window client
 *  area to avoid flickering.
 *  
 *  @param pDC Pointer to the target device context 
 *  @param bUndo Flag that specifies wether to restore the clipping region
 *  
 *  @return The return value is @c TRUE if the clipping region has been
 *          modified, @c FALSE if clipping was not necessary.
 *
 *  @remarks For anti-flickering to work, you should wrap your
 *           @c WM_ERASEBKGND message handler inside a pair of calls to
 *           this function, with the last parameter set to @c TRUE first
 *           and to @c FALSE at the end.
 */
BOOL CResizableLayout::ClipChildren(CDC* pDC, BOOL bUndo)
{
#if (_WIN32_WINNT >= 0x0501 && !defined(RSZLIB_NO_XP_DOUBLE_BUFFER))
        // clipping not necessary when double-buffering enabled
        if (real_WIN32_WINNT >= 0x0501)
        {
                CWnd *pWnd = GetRootParentWnd(GetResizableWnd());
                if (pWnd == NULL)
                        pWnd = GetResizableWnd();
                if (pWnd->GetExStyle() & WS_EX_COMPOSITED)
                        return FALSE;
        }
#endif

        HDC hDC = pDC->GetSafeHdc();
        HWND hWnd = GetResizableWnd()->GetSafeHwnd();

        m_nOldClipRgn = -1; // invalid region by default

        // Some controls (such as transparent toolbars and standard controls
        // with XP theme enabled) send a WM_ERASEBKGND msg to the parent
        // to draw themselves, in which case we must not enable clipping.

        // We check that the window associated with the DC is the
        // resizable window and not a child control.

        if (!bUndo && (hWnd == ::WindowFromDC(hDC)))
        {
                // save old DC clipping region
                m_nOldClipRgn = ::GetClipRgn(hDC, m_hOldClipRgn);

                // clip out supported child windows
                CRgn rgnClip;
                GetClippingRegion(&rgnClip);
                ::ExtSelectClipRgn(hDC, rgnClip, RGN_AND);

                return TRUE;
        }

        // restore old clipping region, only if modified and valid
        if (bUndo && m_nOldClipRgn >= 0)
        {
                if (m_nOldClipRgn == 1)
                        ::SelectClipRgn(hDC, m_hOldClipRgn);
                else
                        ::SelectClipRgn(hDC, NULL);
                
                return TRUE;
        }

        return FALSE;
}

/*!
 *  This function is used by this class, and should be used by derived
 *  classes too, in place of the standard GetClientRect. It can be useful
 *  for windows with scrollbars or expanding windows, to provide the true
 *  client area, including even those parts which are not visible.
 *  
 *  @param lpRect Pointer to the RECT structure that holds the result
 *
 *  @remarks Override this function to provide the client area the class uses
 *           to perform layout calculations, both when adding controls and
 *           when rearranging the layout.
 *        @n The base implementation simply calls @c GetClientRect
 */
void CResizableLayout::GetTotalClientRect(LPRECT lpRect) const
{
        GetResizableWnd()->GetClientRect(lpRect);
}

/*!
 *  This function is used to determine if a control needs to be painted when
 *  it is moved or resized by the layout manager.
 *  
 *  @param layout Reference to a @c LAYOUTINFO structure for the control
 *  @param rectOld Reference to a @c RECT structure that holds the control
 *         position and size before the layout update
 *  @param rectNew Reference to a @c RECT structure that holds the control
 *         position and size after the layout update
 *  
 *  @return The return value is @c TRUE if the control should be freshly
 *          painted after a layout update, @c FALSE if not necessary.
 *
 *  @remarks The default implementation tries to identify windows that
 *           need refresh by their class name and window style.
 *        @n Override this function if you need a different behavior or if
 *           you have custom controls that fail to be identified.
 *
 *  @sa LikesClipping InitResizeProperties
 */
BOOL CResizableLayout::NeedsRefresh(const LAYOUTINFO& layout,
                                                                const CRect& rectOld, const CRect& rectNew) const
{
        if (layout.bMsgSupport)
        {
                REFRESHPROPERTY refresh;
                refresh.rcOld = rectOld;
                refresh.rcNew = rectNew;
                if (Send_NeedsRefresh(layout.hWnd, &refresh))
                        return refresh.bNeedsRefresh;
        }

        int nDiffWidth = (rectNew.Width() - rectOld.Width());
        int nDiffHeight = (rectNew.Height() - rectOld.Height());

        // is the same size?
        if (nDiffWidth == 0 && nDiffHeight == 0)
                return FALSE;

        // optimistic, no need to refresh
        BOOL bRefresh = FALSE;

        // window classes that need refresh when resized
        if (0 == lstrcmp(layout.sWndClass, WC_STATIC))
        {
                DWORD style = ::GetWindowLong(layout.hWnd, GWL_STYLE);

                switch (style & SS_TYPEMASK)
                {
                case SS_LEFT:
                case SS_CENTER:
                case SS_RIGHT:
                        // word-wrapped text
                        bRefresh = bRefresh || (nDiffWidth != 0);
                        // vertically centered text
                        if (style & SS_CENTERIMAGE)
                                bRefresh = bRefresh || (nDiffHeight != 0);
                        break;

                case SS_LEFTNOWORDWRAP:
                        // text with ellipsis
                        if (style & SS_ELLIPSISMASK)
                                bRefresh = bRefresh || (nDiffWidth != 0);
                        // vertically centered text
                        if (style & SS_CENTERIMAGE)
                                bRefresh = bRefresh || (nDiffHeight != 0);
                        break;

                case SS_ENHMETAFILE:
                case SS_BITMAP:
                case SS_ICON:
                        // images
                case SS_BLACKFRAME:
                case SS_GRAYFRAME:
                case SS_WHITEFRAME:
                case SS_ETCHEDFRAME:
                        // and frames
                        bRefresh = TRUE;
                        break;
                }
                return bRefresh;
        }

        // window classes that don't redraw client area correctly
        // when the hor scroll pos changes due to a resizing
        BOOL bHScroll = FALSE;
        if (0 == lstrcmp(layout.sWndClass, WC_LISTBOX))
                bHScroll = TRUE;

        // fix for horizontally scrollable windows, if wider
        if (bHScroll && (nDiffWidth > 0))
        {
                // get max scroll position
                SCROLLINFO info;
                info.cbSize = sizeof(SCROLLINFO);
                info.fMask = SIF_PAGE | SIF_POS | SIF_RANGE;
                if (::GetScrollInfo(layout.hWnd, SB_HORZ, &info))
                {
                        // subtract the page size
                        info.nMax -= __max(info.nPage - 1, 0);
                }

                // resizing will cause the text to scroll on the right
                // because the scrollbar is going beyond the right limit
                if ((info.nMax > 0) && (info.nPos + nDiffWidth > info.nMax))
                {
                        // needs repainting, due to horiz scrolling
                        bRefresh = TRUE;
                }
        }

        return bRefresh;
}

/*!
 *  This function is used to determine if a control can be safely clipped
 *  out of the parent window client area when it is repainted, usually
 *  after a resize operation.
 *  
 *  @param layout Reference to a @c LAYOUTINFO structure for the control
 *  
 *  @return The return value is @c TRUE if clipping is supported by the
 *          control, @c FALSE otherwise.
 *
 *  @remarks The default implementation tries to identify @a clippable
 *           windows by their class name and window style.
 *        @n Override this function if you need a different behavior or if
 *           you have custom controls that fail to be identified.
 *
 *  @sa NeedsRefresh InitResizeProperties
 */
BOOL CResizableLayout::LikesClipping(const LAYOUTINFO& layout) const
{
        if (layout.bMsgSupport)
        {
                CLIPPINGPROPERTY clipping;
                if (Send_LikesClipping(layout.hWnd, &clipping))
                        return clipping.bLikesClipping;
        }

        DWORD style = ::GetWindowLong(layout.hWnd, GWL_STYLE);

        // skip windows that wants background repainted
        if (0 == lstrcmp(layout.sWndClass, WC_BUTTON))
        {
                CRect rect;
                switch (style & _BS_TYPEMASK)
                {
                case BS_GROUPBOX:
                        return FALSE;

                case BS_OWNERDRAW:
                        // ownerdraw buttons must return correct hittest code
                        // to notify their transparency to the system and this library
                        // or they could use the registered message (more reliable)
                        ::GetWindowRect(layout.hWnd, &rect);
                        ::SendMessage(layout.hWnd, WM_NCCALCSIZE, FALSE, (LPARAM)&rect);
                        if ( HTTRANSPARENT == ::SendMessage(layout.hWnd,
                                WM_NCHITTEST, 0, MAKELPARAM(rect.left, rect.top)) )
                                return FALSE;
                        break;
                }
                return TRUE;
        }
        else if (0 == lstrcmp(layout.sWndClass, WC_STATIC))
        {
                switch (style & SS_TYPEMASK)
                {
                case SS_LEFT:
                case SS_CENTER:
                case SS_RIGHT:
                case SS_LEFTNOWORDWRAP:
                        // text
                case SS_BLACKRECT:
                case SS_GRAYRECT:
                case SS_WHITERECT:
                        // filled rects
                case SS_ETCHEDHORZ:
                case SS_ETCHEDVERT:
                        // etched lines
                case SS_BITMAP:
                        // bitmaps
                        return TRUE;
                        break;

                case SS_ICON:
                case SS_ENHMETAFILE:
                        if (style & SS_CENTERIMAGE)
                                return FALSE;
                        return TRUE;
                        break;

                default:
                        return FALSE;
                }
        }

        // assume the others like clipping
        return TRUE;
}


/*!
 *  @internal This function calculates the new size and position of a
 *  control in the layout and flags for @c SetWindowPos
 */
void CResizableLayout::CalcNewChildPosition(const LAYOUTINFO& layout,
                                                const CRect &rectParent, CRect &rectChild, UINT& uFlags) const
{
        CWnd* pParent = GetResizableWnd();

        ::GetWindowRect(layout.hWnd, &rectChild);
        ::MapWindowPoints(NULL, pParent->m_hWnd, (LPPOINT)&rectChild, 2);
        
        CRect rectNew;

        // calculate new top-left corner
        rectNew.left = layout.marginTopLeft.cx + rectParent.Width() * layout.anchorTopLeft.cx / 100;
        rectNew.top = layout.marginTopLeft.cy + rectParent.Height() * layout.anchorTopLeft.cy / 100;
        
        // calculate new bottom-right corner
        rectNew.right = layout.marginBottomRight.cx + rectParent.Width() * layout.anchorBottomRight.cx / 100;
        rectNew.bottom = layout.marginBottomRight.cy + rectParent.Height() * layout.anchorBottomRight.cy / 100;

        // adjust position, if client area has been scrolled
        rectNew.OffsetRect(rectParent.TopLeft());

        // get the refresh property
        BOOL bRefresh = layout.properties.bAskRefresh ?
                NeedsRefresh(layout, rectChild, rectNew) : layout.properties.bCachedNeedsRefresh;

        // set flags 
        uFlags = SWP_NOZORDER | SWP_NOACTIVATE | SWP_NOREPOSITION;
        if (bRefresh)
                uFlags |= SWP_NOCOPYBITS;
        if (rectNew.TopLeft() == rectChild.TopLeft())
                uFlags |= SWP_NOMOVE;
        if (rectNew.Size() == rectChild.Size())
                uFlags |= SWP_NOSIZE;

        // update rect
        rectChild = rectNew;
}

/*!
 *  This function calculates the top, left, bottom, right margins for a
 *  given size of the specified control.
 *  
 *  @param hWnd Window handle to a control in the layout
 *  @param sizeChild Size of the control to use in calculations
 *  @param rectMargins Holds the calculated margins
 *  
 *  @return The return value is @c TRUE if successful, @c FALSE otherwise
 *
 *  @remarks This function can be used to infer the parent window size
 *           from the size of one of its child controls.
 *           It is used to implement cascading of size constraints.
 */
BOOL CResizableLayout::GetAnchorMargins(HWND hWnd, const CSize &sizeChild, CRect &rectMargins) const
{
        POSITION pos;
        if (!m_mapLayout.Lookup(hWnd, pos))
                return FALSE;

        const LAYOUTINFO& layout = m_listLayout.GetAt(pos);

        // augmented size, relative to anchor points
        CSize size = sizeChild + layout.marginTopLeft - layout.marginBottomRight;

        // percent of parent size occupied by this control
        CSize percent(layout.anchorBottomRight.cx - layout.anchorTopLeft.cx,
                layout.anchorBottomRight.cy - layout.anchorTopLeft.cy);

        // calculate total margins
        rectMargins.left = size.cx * layout.anchorTopLeft.cx / percent.cx + layout.marginTopLeft.cx;
        rectMargins.top = size.cy * layout.anchorTopLeft.cy / percent.cy + layout.marginTopLeft.cy;
        rectMargins.right = size.cx * (100 - layout.anchorBottomRight.cx) / percent.cx - layout.marginBottomRight.cx;
        rectMargins.bottom = size.cy * (100 - layout.anchorBottomRight.cy) / percent.cy - layout.marginBottomRight.cy;

        return TRUE;
}

/*!
 *  This function is used to set the initial resize properties of a control
 *  in the layout, that are stored in the @c properties member of the
 *  related @c LAYOUTINFO structure.
 *  
 *  @param layout Reference to the @c LAYOUTINFO structure to be set
 *
 *  @remarks The various flags are used to specify whether the resize
 *           properties (clipping, refresh) can change at run-time, and a new
 *           call to the property querying functions is needed at every
 *           layout update, or they are static properties, and the cached
 *           value is used whenever necessary.
 *        @n The default implementation sends a registered message to the 
 *           control, giving it the opportunity to specify its resize
 *           properties, which takes precedence if the message is supported.
 *           It then sets the @a clipping property as static, calling
 *           @c LikesClipping only once, and the @a refresh property as
 *           dynamic, causing @c NeedsRefresh to be called every time.
 *        @n This should be right for most situations, as the need for
 *           @a refresh usually depends on the size fo a control, while the
 *           support for @a clipping is usually linked to the specific type
 *           of control, which is unlikely to change at run-time, but you can
 *           still override this function if a different beahvior is needed.
 *
 *  @sa LikesClipping NeedsRefresh LAYOUTINFO RESIZEPROPERTIES
 */
void CResizableLayout::InitResizeProperties(LAYOUTINFO &layout) const
{
        // check if custom window supports this library
        // (properties must be correctly set by the window)
        layout.bMsgSupport = Send_QueryProperties(layout.hWnd, &layout.properties);

        // default properties
        if (!layout.bMsgSupport)
        {
                // clipping property is assumed as static
                layout.properties.bAskClipping = FALSE;
                layout.properties.bCachedLikesClipping = LikesClipping(layout);
                // refresh property is assumed as dynamic
                layout.properties.bAskRefresh = TRUE;
        }
}

/*!
 *  This function modifies a window to enable resizing functionality.
 *  This affects the window style, size, system menu and appearance.
 *  
 *  @param lpCreateStruct Pointer to a @c CREATESTRUCT structure, usually
 *         passed by the system to the window procedure in a @c WM_CREATE
 *         or @c WM_NCCREATE
 *  
 *  @remarks The function is intended to be called only inside a @c WM_CREATE
 *           or @c WM_NCCREATE message handler.
 */
void CResizableLayout::MakeResizable(LPCREATESTRUCT lpCreateStruct)
{
        if (lpCreateStruct->style & WS_CHILD)
                return;

        CWnd* pWnd = GetResizableWnd();

#if (_WIN32_WINNT >= 0x0501 && !defined(RSZLIB_NO_XP_DOUBLE_BUFFER))
        // enable double-buffering on supported platforms
        pWnd->ModifyStyleEx(0, WS_EX_COMPOSITED);
#endif

        if (!(lpCreateStruct->style & WS_THICKFRAME))
        {
                // set resizable style
                pWnd->ModifyStyle(DS_MODALFRAME, WS_THICKFRAME);
                // keep client area
                CRect rect(CPoint(lpCreateStruct->x, lpCreateStruct->y),
                        CSize(lpCreateStruct->cx, lpCreateStruct->cy));
                pWnd->SendMessage(WM_NCCALCSIZE, FALSE, (LPARAM)&rect);
                // adjust size to reflect new style
                ::AdjustWindowRectEx(&rect, pWnd->GetStyle(),
                        ::IsMenu(pWnd->GetMenu()->GetSafeHmenu()), pWnd->GetExStyle());
                pWnd->SetWindowPos(NULL, 0, 0, rect.Width(), rect.Height(),
                        SWP_NOSENDCHANGING|SWP_NOMOVE|SWP_NOZORDER|SWP_NOACTIVATE|SWP_NOREPOSITION);
                // update dimensions
                lpCreateStruct->cx = rect.Width();
                lpCreateStruct->cy = rect.Height();
        }
}

/*!
 *  This function should be called inside the parent window @c WM_NCCALCSIZE
 *  message handler to help eliminate flickering.
 *  
 *  @param bAfterDefault Flag that specifies wether the call is made before
 *         or after the default handler
 *  @param lpncsp Pointer to the @c NCCALCSIZE_PARAMS structure that is
 *         passed to the message handler
 *  @param lResult Reference to the result of the message handler.
 *         It contains the default handler result on input and the value to
 *         return from the window procedure on output.
 *  
 *  @remarks This function fixes the annoying flickering effect that is
 *           visible when resizing the top or left edges of the window
 *           (at least on a "left to right" Windows localized version).
 */
void CResizableLayout::HandleNcCalcSize(BOOL bAfterDefault, LPNCCALCSIZE_PARAMS lpncsp, LRESULT &lResult)
{
        // prevent useless complication when size is not changing
        // prevent recursion when resetting the window region (see below)
        if ((lpncsp->lppos->flags & SWP_NOSIZE)
#if (_WIN32_WINNT >= 0x0501)
                || m_bNoRecursion
#endif
                )
                return;

        if (!bAfterDefault)
        {
                // save a copy before default handler gets called
                m_rectClientBefore = lpncsp->rgrc[2];
        }
        else // after default WM_NCCALCSIZE msg processing
        {
                if (lResult != 0)
                {
                        // default handler already uses an advanced validation policy, give up
                        return;
                }
                // default calculated client rect
                RECT &rectClientAfter = lpncsp->rgrc[0];

                // intersection between old and new client area is to be preserved
                // set source and destination rects to this intersection
                RECT &rectPreserve = lpncsp->rgrc[1];
                ::IntersectRect(&rectPreserve, &rectClientAfter, &m_rectClientBefore);
                lpncsp->rgrc[2] = rectPreserve;

                lResult = WVR_VALIDRECTS;

                // FIX: window region must be updated before the result of the
                //              WM_NCCALCSIZE message gets processed by the system,
                //              otherwise the old window region will clip the client
                //              area during the preservation process.
                //              This is especially evident on WinXP when the non-client
                //              area is rendered with Visual Styles enabled and the
                //              windows have a non rectangular region.
#if (_WIN32_WINNT >= 0x0501)
                //! @todo change rt check to only if themed frame. what about custom wnd region?
                if (real_WIN32_WINNT >= 0x0501)
                {
                        CWnd* pWnd = GetResizableWnd();
                        DWORD dwStyle = pWnd->GetStyle();
                        if ((dwStyle & (WS_CAPTION|WS_MAXIMIZE)) == WS_CAPTION)
                        {
                                m_bNoRecursion = TRUE;
                                pWnd->SetWindowRgn(NULL, FALSE);
                                m_bNoRecursion = FALSE;
                        }
                }
#endif
        }
}