///////////////////////////////////////////////////////////////////////////////
// Name:        src/msw/notebook.cpp
// Purpose:     implementation of wxNotebook
// Author:      Vadim Zeitlin
// Created:     11.06.98
// Copyright:   (c) 1998 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
// Licence:     wxWindows licence
///////////////////////////////////////////////////////////////////////////////

// For compilers that support precompilation, includes "wx.h".
#include "wx/wxprec.h"


#if wxUSE_NOTEBOOK

#include "wx/notebook.h"

#ifndef WX_PRECOMP
    #include "wx/msw/wrapcctl.h" // include <commctrl.h> "properly"
    #include "wx/string.h"
    #include "wx/dc.h"
    #include "wx/log.h"
    #include "wx/event.h"
    #include "wx/app.h"
    #include "wx/dcclient.h"
    #include "wx/dcmemory.h"
    #include "wx/settings.h"
#endif  // WX_PRECOMP

#include "wx/imaglist.h"
#include "wx/renderer.h"
#include "wx/sysopt.h"

#include "wx/msw/private.h"
#include "wx/msw/dc.h"

#include <windowsx.h>
#include "wx/msw/winundef.h"

#include "wx/msw/private/darkmode.h"

#if wxUSE_UXTHEME
    #include "wx/msw/uxtheme.h"
#endif

// ----------------------------------------------------------------------------
// macros
// ----------------------------------------------------------------------------

// check that the page index is valid
#define IS_VALID_PAGE(nPage) ((nPage) < GetPageCount())

// you can set USE_NOTEBOOK_ANTIFLICKER to 0 for desktop Windows versions too
// to disable code which results in flicker-less notebook redrawing at the
// expense of some extra GDI resource consumption
#define USE_NOTEBOOK_ANTIFLICKER    1

// ----------------------------------------------------------------------------
// constants
// ----------------------------------------------------------------------------

// This is a work-around for missing defines in gcc-2.95 headers
#ifndef TCS_RIGHT
    #define TCS_RIGHT       0x0002
#endif

#ifndef TCS_VERTICAL
    #define TCS_VERTICAL    0x0080
#endif

#ifndef TCS_BOTTOM
    #define TCS_BOTTOM      TCS_RIGHT
#endif

// ----------------------------------------------------------------------------
// global variables
// ----------------------------------------------------------------------------

#if USE_NOTEBOOK_ANTIFLICKER

// the pointer to standard spin button wnd proc
static WXWNDPROC gs_wndprocNotebookSpinBtn = nullptr;

// the pointer to standard tab control wnd proc
static WXWNDPROC gs_wndprocNotebook = nullptr;

LRESULT APIENTRY
wxNotebookWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);

#endif // USE_NOTEBOOK_ANTIFLICKER

// ----------------------------------------------------------------------------
// global functions
// ----------------------------------------------------------------------------

static bool HasTroubleWithNonTopTabs()
{
    const int verComCtl32 = wxApp::GetComCtl32Version();

    // 600 is XP, 616 is Vista -- and both have a problem with tabs not on top
    // (but don't just test for >= 600 as Microsoft might decide to fix it in
    // later versions, who knows...)
    return verComCtl32 >= 600 && verComCtl32 <= 616;
}

// ----------------------------------------------------------------------------
// event table
// ----------------------------------------------------------------------------

wxBEGIN_EVENT_TABLE(wxNotebook, wxBookCtrlBase)
    EVT_SIZE(wxNotebook::OnSize)
    EVT_NAVIGATION_KEY(wxNotebook::OnNavigationKey)
wxEND_EVENT_TABLE()

// ============================================================================
// implementation
// ============================================================================

// ----------------------------------------------------------------------------
// wxNotebook construction
// ----------------------------------------------------------------------------

// common part of all ctors
void wxNotebook::Init()
{
#if wxUSE_UXTHEME
    m_hbrBackground = nullptr;
#endif // wxUSE_UXTHEME

#if USE_NOTEBOOK_ANTIFLICKER
    m_hasSubclassedUpdown = false;
#endif // USE_NOTEBOOK_ANTIFLICKER
}

// default for dynamic class
wxNotebook::wxNotebook()
{
  Init();
}

// the same arguments as for wxControl
wxNotebook::wxNotebook(wxWindow *parent,
                       wxWindowID id,
                       const wxPoint& pos,
                       const wxSize& size,
                       long style,
                       const wxString& name)
{
  Init();

  Create(parent, id, pos, size, style, name);
}

// Create() function
bool wxNotebook::Create(wxWindow *parent,
                        wxWindowID id,
                        const wxPoint& pos,
                        const wxSize& size,
                        long style,
                        const wxString& name)
{
    if ( (style & wxBK_ALIGN_MASK) == wxBK_DEFAULT )
    {
        style |= wxBK_TOP;
    }

#if !wxUSE_UXTHEME
    // ComCtl32 notebook tabs simply don't work unless they're on top if we
    // have uxtheme, we can work around it later (after control creation), but
    // if we have been compiled without uxtheme support, we have to clear those
    // styles
    if ( HasTroubleWithNonTopTabs() )
    {
        style &= ~(wxBK_BOTTOM | wxBK_LEFT | wxBK_RIGHT);
    }
#endif //wxUSE_UXTHEME

    LPCTSTR className = WC_TABCONTROL;

#if USE_NOTEBOOK_ANTIFLICKER
    // SysTabCtl32 class has natively CS_HREDRAW and CS_VREDRAW enabled and it
    // causes horrible flicker when resizing notebook, so get rid of it by
    // using a class without these styles (but otherwise identical to it)
    if ( !HasFlag(wxFULL_REPAINT_ON_RESIZE) )
    {
        static ClassRegistrar s_clsNotebook;
        if ( !s_clsNotebook.IsInitialized() )
        {
            // get a copy of standard class and modify it
            WNDCLASS wc;

            if ( ::GetClassInfo(nullptr, WC_TABCONTROL, &wc) )
            {
                gs_wndprocNotebook = wc.lpfnWndProc;
                wc.lpszClassName = wxT("_wx_SysTabCtl32");
                wc.style &= ~(CS_HREDRAW | CS_VREDRAW);
                wc.hInstance = wxGetInstance();
                wc.lpfnWndProc = wxNotebookWndProc;
                s_clsNotebook.Register(wc);
            }
            else
            {
                wxLogLastError(wxT("GetClassInfoEx(SysTabCtl32)"));
            }
        }

        // use our custom class if available but fall back to the standard
        // notebook if we failed to register it
        if ( s_clsNotebook.IsRegistered() )
        {
            // it's ok to use c_str() here as the static s_clsNotebook object
            // has sufficiently long lifetime
            className = s_clsNotebook.GetName().c_str();
        }
    }
#endif // USE_NOTEBOOK_ANTIFLICKER

    if ( !CreateControl(parent, id, pos, size, style | wxTAB_TRAVERSAL,
                        wxDefaultValidator, name) )
        return false;

    if ( !MSWCreateControl(className, wxEmptyString, pos, size) )
        return false;

    Bind(wxEVT_PAINT, &wxNotebook::OnPaint, this);

    // Inherit parent attributes and, unlike the default, also inherit the
    // parent background colour in order to blend in with its background if
    // it's set to a non-default value -- or if we're using dark mode, in which
    // the default colour always needs to be changed.
    InheritAttributes();
    if ( !UseBgCol() )
    {
        wxColour colBg;
        if ( parent->InheritsBackgroundColour() )
        {
            colBg = parent->GetBackgroundColour();
        }
        else if ( wxMSWDarkMode::IsActive() )
        {
            colBg = wxSystemSettings::GetColour(wxSYS_COLOUR_WINDOW);

            // We also need to change the foreground in this case to ensure a
            // good contrast with the dark background.
            SetForegroundColour(
                wxSystemSettings::GetColour(wxSYS_COLOUR_WINDOWTEXT)
            );
        }

        if ( colBg.IsOk() )
            SetBackgroundColour(colBg);
    }

#if wxUSE_UXTHEME
    if ( HasFlag(wxNB_NOPAGETHEME) ||
            wxSystemOptions::IsFalse(wxT("msw.notebook.themed-background")) )
    {
        SetBackgroundColour(GetThemeBackgroundColour());
    }
    else // use themed background by default
    {
        // create backing store
        UpdateBgBrush();
    }

    // comctl32.dll 6.0 doesn't support non-top tabs with visual styles (the
    // control is simply not rendered correctly), so we disable themes
    // if possible, otherwise we simply clear the styles.
    if ( HasTroubleWithNonTopTabs() &&
            (style & (wxBK_BOTTOM | wxBK_LEFT | wxBK_RIGHT)) )
    {
        // check if we use themes at all -- if we don't, we're still okay
        if ( wxUxThemeIsActive() )
        {
            ::SetWindowTheme(GetHwnd(), L"", L"");

            // correct the background color for the new non-themed control
            SetBackgroundColour(GetThemeBackgroundColour());
        }
    }
#endif // wxUSE_UXTHEME

    return true;
}

WXDWORD wxNotebook::MSWGetStyle(long style, WXDWORD *exstyle) const
{
    WXDWORD tabStyle = wxControl::MSWGetStyle(style, exstyle);

    tabStyle |= WS_TABSTOP | TCS_TABS;

    if ( style & wxNB_MULTILINE )
        tabStyle |= TCS_MULTILINE;
    if ( style & wxNB_FIXEDWIDTH )
        tabStyle |= TCS_FIXEDWIDTH;

    if ( style & wxBK_BOTTOM )
        tabStyle |= TCS_RIGHT;
    else if ( style & wxBK_LEFT )
        tabStyle |= TCS_VERTICAL;
    else if ( style & wxBK_RIGHT )
        tabStyle |= TCS_VERTICAL | TCS_RIGHT;

    return tabStyle;
}

int wxNotebook::MSWGetToolTipMessage() const
{
    return TCM_GETTOOLTIPS;
}

wxNotebook::~wxNotebook()
{
    // Make sure we don't try to repaint the notebook any more: not only is
    // this useless, it can also crash when calling member functions of a
    // half-destroyed object.
    Unbind(wxEVT_PAINT, &wxNotebook::OnPaint, this);

#if wxUSE_UXTHEME
    if ( m_hbrBackground )
        ::DeleteObject((HBRUSH)m_hbrBackground);
#endif // wxUSE_UXTHEME
}

// ----------------------------------------------------------------------------
// wxNotebook accessors
// ----------------------------------------------------------------------------

size_t wxNotebook::GetPageCount() const
{
    // consistency check
    wxASSERT( (int)m_pages.size() == TabCtrl_GetItemCount(GetHwnd()) );

    return m_pages.size();
}

int wxNotebook::GetRowCount() const
{
    return TabCtrl_GetRowCount(GetHwnd());
}

int wxNotebook::SetSelection(size_t nPage)
{
    wxCHECK_MSG( IS_VALID_PAGE(nPage), wxNOT_FOUND, wxT("notebook page out of range") );

    if ( m_selection == wxNOT_FOUND || nPage != (size_t)m_selection )
    {
        if ( SendPageChangingEvent(nPage) )
        {
            // program allows the page change
            const int selectionOld = m_selection;

            UpdateSelection(nPage);

            (void)TabCtrl_SetCurSel(GetHwnd(), nPage);

            SendPageChangedEvent(selectionOld, nPage);
        }
    }

    return m_selection;
}

void wxNotebook::UpdateSelection(int selNew)
{
    if ( m_selection != wxNOT_FOUND )
        m_pages[m_selection]->Show(false);

    if ( selNew != wxNOT_FOUND )
    {
        wxNotebookPage *pPage = m_pages[selNew];
        pPage->Show(true);

        // In addition to showing the page, we also want to give focus to it to
        // make it possible to work with it from keyboard easily. However there
        // are two exceptions: first, don't touch the focus at all if the
        // notebook itself is not currently shown.
        if ( ::IsWindowVisible(GetHwnd()) )
        {
            // And second, don't give focus away if the tab control itself has
            // it, as this is how the native property sheets behave: if you
            // explicitly click on the tab label giving it focus, it will
            // remain after switching to another page. But if the focus was
            // inside the notebook page, it switches to the new page.
            if ( !HasFocus() )
                pPage->SetFocus();
        }
    }

    m_selection = selNew;
}

int wxNotebook::ChangeSelection(size_t nPage)
{
    wxCHECK_MSG( IS_VALID_PAGE(nPage), wxNOT_FOUND, wxT("notebook page out of range") );

    const int selOld = m_selection;

    if ( m_selection == wxNOT_FOUND || nPage != (size_t)m_selection )
    {
        (void)TabCtrl_SetCurSel(GetHwnd(), nPage);

        UpdateSelection(nPage);
    }

    return selOld;
}

bool wxNotebook::SetPageText(size_t nPage, const wxString& strText)
{
    wxCHECK_MSG( IS_VALID_PAGE(nPage), false, wxT("notebook page out of range") );

    TC_ITEM tcItem;
    tcItem.mask = TCIF_TEXT;
    tcItem.pszText = wxMSW_CONV_LPTSTR(strText);

    if ( !HasFlag(wxNB_MULTILINE) )
        return TabCtrl_SetItem(GetHwnd(), nPage, &tcItem) != 0;

    // multiline - we need to set new page size if a line is added or removed
    int rows = GetRowCount();
    bool ret = TabCtrl_SetItem(GetHwnd(), nPage, &tcItem) != 0;

    if ( ret && rows != GetRowCount() )
    {
        const wxRect r = GetPageSize();
        const size_t count = m_pages.size();
        for ( size_t page = 0; page < count; page++ )
            m_pages[page]->SetSize(r);
    }

    return ret;
}

wxString wxNotebook::GetPageText(size_t nPage) const
{
    wxCHECK_MSG( IS_VALID_PAGE(nPage), wxEmptyString, wxT("notebook page out of range") );

    wxChar buf[256];
    TC_ITEM tcItem;
    tcItem.mask = TCIF_TEXT;
    tcItem.pszText = buf;
    tcItem.cchTextMax = WXSIZEOF(buf);

    wxString str;
    if ( TabCtrl_GetItem(GetHwnd(), nPage, &tcItem) )
        str = tcItem.pszText;

    return str;
}

int wxNotebook::GetPageImage(size_t nPage) const
{
    wxCHECK_MSG( IS_VALID_PAGE(nPage), wxNOT_FOUND, wxT("notebook page out of range") );

    TC_ITEM tcItem;
    tcItem.mask = TCIF_IMAGE;

    return TabCtrl_GetItem(GetHwnd(), nPage, &tcItem) ? tcItem.iImage
                                                      : wxNOT_FOUND;
}

bool wxNotebook::SetPageImage(size_t nPage, int nImage)
{
    wxCHECK_MSG( IS_VALID_PAGE(nPage), false, wxT("notebook page out of range") );

    TC_ITEM tcItem;
    tcItem.mask = TCIF_IMAGE;
    tcItem.iImage = nImage;

    return TabCtrl_SetItem(GetHwnd(), nPage, &tcItem) != 0;
}

void wxNotebook::OnImagesChanged()
{
    wxImageList* const iml = GetUpdatedImageListFor(this);

    (void) TabCtrl_SetImageList(GetHwnd(), iml ? GetHimagelistOf(iml) : nullptr);
}

// ----------------------------------------------------------------------------
// wxNotebook size settings
// ----------------------------------------------------------------------------

wxRect wxNotebook::GetPageSize() const
{
    wxRect r;

    RECT rc;
    ::GetClientRect(GetHwnd(), &rc);

    // This check is to work around a bug in TabCtrl_AdjustRect which will
    // cause a crash on win2k or on XP with themes disabled if either
    // wxNB_MULTILINE is used or tabs are placed on a side, if the rectangle
    // is too small.
    //
    // The value of 20 is chosen arbitrarily but seems to work
    if ( rc.right > 20 && rc.bottom > 20 )
    {
        (void)TabCtrl_AdjustRect(GetHwnd(), false, &rc);

        wxCopyRECTToRect(rc, r);
    }

    return r;
}

void wxNotebook::SetPageSize(const wxSize& size)
{
    // transform the page size into the notebook size
    RECT rc;
    rc.left =
    rc.top = 0;
    rc.right = size.x;
    rc.bottom = size.y;

    (void)TabCtrl_AdjustRect(GetHwnd(), true, &rc);

    // and now set it
    SetSize(rc.right - rc.left, rc.bottom - rc.top);
}

void wxNotebook::SetPadding(const wxSize& padding)
{
    TabCtrl_SetPadding(GetHwnd(), padding.x, padding.y);
}

// Windows-only at present. Also, you must use the wxNB_FIXEDWIDTH
// style.
void wxNotebook::SetTabSize(const wxSize& sz)
{
    ::SendMessage(GetHwnd(), TCM_SETITEMSIZE, 0, MAKELPARAM(sz.x, sz.y));
}

wxRect wxNotebook::GetTabRect(size_t page) const
{
    wxRect r;
    wxCHECK_MSG(IS_VALID_PAGE(page), r, wxT("invalid notebook page"));

    RECT rect;
    if (TabCtrl_GetItemRect(GetHwnd(), page, &rect))
        r = wxRectFromRECT(rect);

    return r;
}

wxSize wxNotebook::CalcSizeFromPage(const wxSize& sizePage) const
{
    // we can't use TabCtrl_AdjustRect here because it only works for wxNB_TOP
    wxSize sizeTotal = sizePage;

    wxSize tabSize;
    if ( GetPageCount() > 0 )
    {
        RECT rect;
        if ( TabCtrl_GetItemRect(GetHwnd(), 0, &rect) )
        {
            tabSize.x = rect.right - rect.left;
            tabSize.y = rect.bottom - rect.top;
        }
    }

    const int rows = GetRowCount();

    // add an extra margin in both directions
    const int MARGIN = FromDIP(8);
    if ( IsVertical() )
    {
        sizeTotal.x += MARGIN;
        sizeTotal.y += tabSize.y * rows + MARGIN;
    }
    else // horizontal layout
    {
        sizeTotal.x += tabSize.x * rows + MARGIN;
        sizeTotal.y += MARGIN;
    }

    return sizeTotal;
}

void wxNotebook::AdjustPageSize(wxNotebookPage *page)
{
    wxCHECK_RET( page, wxT("null page in wxNotebook::AdjustPageSize") );

    const wxRect r = GetPageSize();
    if ( !r.IsEmpty() )
    {
        page->SetSize(r);
    }
}

// ----------------------------------------------------------------------------
// wxNotebook operations
// ----------------------------------------------------------------------------

// remove one page from the notebook, without deleting
wxNotebookPage *wxNotebook::DoRemovePage(size_t nPage)
{
    wxNotebookPage *pageRemoved = wxNotebookBase::DoRemovePage(nPage);
    if ( !pageRemoved )
        return nullptr;

    // hide the removed page to maintain the invariant that only the
    // selected page is visible and others are hidden:
    pageRemoved->Show(false);

    if ( !TabCtrl_DeleteItem(GetHwnd(), nPage) )
        wxLogLastError(wxS("TabCtrl_DeleteItem()"));

    if ( m_pages.empty() )
    {
        // no selection any more, the notebook becomes empty
        m_selection = wxNOT_FOUND;
    }
    else // notebook still not empty
    {
        int selNew = TabCtrl_GetCurSel(GetHwnd());
        if ( selNew != wxNOT_FOUND )
        {
            // No selection change, just refresh the current selection.
            // Because it could be that the selection index changed
            // we need to update it.
            // Note: this does not mean the selection itself changed.
            m_selection = selNew;
            m_pages[m_selection]->Refresh();
        }
        else if (int(nPage) == m_selection)
        {
            // The selection was deleted.

            // Determine new selection.
            if (m_selection == int(GetPageCount()))
                selNew = m_selection - 1;
            else
                selNew = m_selection;

            // m_selection must be always valid so reset it before calling
            // SetSelection()
            m_selection = wxNOT_FOUND;
            SetSelection(selNew);
        }
        else
        {
            wxFAIL; // Windows did not behave ok.
        }
    }

    return pageRemoved;
}

// remove all pages
bool wxNotebook::DeleteAllPages()
{
    wxBookCtrlBase::DeleteAllPages();

    if ( !TabCtrl_DeleteAllItems(GetHwnd()) )
        wxLogLastError(wxS("TabCtrl_DeleteAllItems()"));

    return true;
}

// same as AddPage() but does it at given position
bool wxNotebook::InsertPage(size_t nPage,
                            wxNotebookPage *pPage,
                            const wxString& strText,
                            bool bSelect,
                            int imageId)
{
    wxCHECK_MSG( pPage != nullptr, false, wxT("null page in wxNotebook::InsertPage") );
    wxCHECK_MSG( IS_VALID_PAGE(nPage) || nPage == GetPageCount(), false,
                 wxT("invalid index in wxNotebook::InsertPage") );

    wxASSERT_MSG( pPage->GetParent() == this,
                    wxT("notebook pages must have notebook as parent") );

    // add a new tab to the control
    // ----------------------------

    // init all fields to 0
    TC_ITEM tcItem;
    wxZeroMemory(tcItem);

    // set the image, if any
    if ( imageId != -1 )
    {
        tcItem.mask |= TCIF_IMAGE;
        tcItem.iImage  = imageId;
    }

    // and the text
    if ( !strText.empty() )
    {
        tcItem.mask |= TCIF_TEXT;
        tcItem.pszText = wxMSW_CONV_LPTSTR(strText);
    }

    // hide the page: unless it is selected, it shouldn't be shown (and if it
    // is selected it will be shown later)
    pPage->Show(false);


    // fit the notebook page to the tab control's display area: this should be
    // done before adding it to the notebook or TabCtrl_InsertItem() will
    // change the notebooks size itself!
    AdjustPageSize(pPage);

    // finally do insert it
    if ( TabCtrl_InsertItem(GetHwnd(), nPage, &tcItem) == -1 )
    {
        wxLogError(wxT("Can't create the notebook page '%s'."), strText);

        return false;
    }

    // need to update the bg brush when the first page is added
    // so the first panel gets the correct themed background
    if ( m_pages.empty() )
    {
#if wxUSE_UXTHEME
        UpdateBgBrush();
#endif // wxUSE_UXTHEME
    }

    // succeeded: save the pointer to the page
    m_pages.insert(m_pages.begin() + nPage, pPage);

    // we may need to adjust the size again if the notebook size changed:
    // normally this only happens for the first page we add (the tabs which
    // hadn't been there before are now shown) but for a multiline notebook it
    // can happen for any page at all as a new row could have been started
    if ( m_pages.size() == 1 || HasFlag(wxNB_MULTILINE) )
    {
        AdjustPageSize(pPage);

        // Additionally, force the layout of the notebook itself by posting a
        // size event to it. If we don't do it, notebooks with pages on the
        // left or the right side may fail to account for the fact that they
        // are now big enough to fit all all of their pages on one row and
        // still reserve space for the second row of tabs, see #1792.
        const wxSize s = GetSize();
        ::PostMessage(GetHwnd(), WM_SIZE, SIZE_RESTORED, MAKELPARAM(s.x, s.y));
    }

    // now deal with the selection
    // ---------------------------

    // if the inserted page is before the selected one, we must update the
    // index of the selected page
    if ( int(nPage) <= m_selection )
    {
        // one extra page added
        m_selection++;
    }

    DoSetSelectionAfterInsertion(nPage, bSelect);

    InvalidateBestSize();

    return true;
}

// This can be defined to help with debugging this code by visually
// highlighting the rectangle passed to it.
#ifdef WXDEBUG_NOTEBOOK_HITTEST
static void ShowHitbox(wxWindow *w, wxRect r, bool text, bool refresh)
{
    wxBrush green(wxColor(0, 200, 0));
    wxBrush blue(wxColor(0, 0, 200));

    wxScreenDC dc;

    if (refresh)
    {
        w->Refresh();
        w->Update();
    }

    r.x += (r.width / 2)+2;
    w->ClientToScreen(&r.x, &r.y);
    if (text)
        dc.SetBrush(green);
    else
        dc.SetBrush(blue);

    dc.DrawRectangle(r);
}
#endif // WXDEBUG_NOTEBOOK_HITTEST

int wxNotebook::MSWHitTestLeftRight(const wxPoint& pt, long *flags) const
{
    long dummy;
    if (!flags)
        flags = &dummy;

    *flags = wxBK_HITTEST_NOWHERE;

    wxRect r = GetRect();
    if (!r.Contains(pt))
    {
        return -1;
    }

    const size_t pages = GetPageCount();
    if (!pages)
    {
        *flags |= wxBK_HITTEST_ONPAGE;
        return -1;
    }

    if (GetPageSize().Contains(pt))
    {
        *flags = wxBK_HITTEST_ONPAGE;
        return -1;
    }

    int item = wxNOT_FOUND;

    const wxDirection tabDir = GetTabOrientation();
    for (size_t i = 0; i < pages; i++)
    {
        r = GetTabRect(i);
        if (!r.Contains(pt))
            continue;

        item = i;

        // If the user doesn't care about the flags we are done here.
        if (flags == &dummy)
            break;

        // Default assumption.
        *flags = wxBK_HITTEST_ONITEM;

        // Just a magic number between the icon and the start of the text
        // I checked with different resolutions and it seems to be about right.
        // My assumption was that the icon and the label are both centered in
        // the tab and this assumption seems to be mostly right with this
        // adjustment offset being required.
        int gap = 8;

        TCHAR buffer[256];
        TCITEM ti;
        ti.mask = TCIF_IMAGE | TCIF_TEXT;
        ti.cchTextMax = WXSIZEOF(buffer);
        ti.pszText = buffer;
        TabCtrl_GetItem(GetHwnd(), i, &ti);

        wxRect tabRect;
        wxRect imageRect;

        // If the tab has an image, we need to check if the mouse is over it.
        if (ti.iImage != -1)
        {
            const wxIcon& icon = GetImage(ti.iImage);
            if (icon.IsOk())
                imageRect = icon.GetSize();
        }

        // The label text and the icon (if available) is centered in the tab,
        // so we need to find out the size of that.
        const wxString label = ti.pszText;
        if (!label.empty())
        {
            // This is intentional and not a bug. :) On left/right the font is
            // rotated 90 degree so we have to account for that by flipping
            // width with height.
            GetTextExtent(label, &tabRect.height, &tabRect.width);
        }

        // The tab has neither a text nor an icon
        if (label.empty() && imageRect.width == 0)
            break;

        if (!label.empty())
        {
            tabRect.x = r.x + (r.width - tabRect.width) / 2;
            if (tabDir == wxLEFT)
            {
                if (imageRect.height)
                    tabRect.y = r.y + (r.height - tabRect.height - gap - imageRect.height) / 2;
                else
                    tabRect.y = r.y + (r.height - tabRect.height - imageRect.height) / 2;
            }
            else
            {
                if (imageRect.height)
                    tabRect.y = r.y + (r.height - tabRect.height + gap + imageRect.height) / 2;
                else
                    tabRect.y = r.y + (r.height - tabRect.height) / 2;
            }

#ifdef WXDEBUG_NOTEBOOK_HITTEST
            ::ShowHitbox(const_cast<wxWindow *>(this), tabRect, true, true);
#endif
            if (tabRect.Contains(pt))
            {
                *flags = wxBK_HITTEST_ONLABEL;
                break;
            }
        }

        if (imageRect.height)
        {
            double scale = GetDPIScaleFactor();

            // When the tab has no text and only an icon, the position of the
            // icon is moving around a bit when scaling is applied. So I
            // checked with various resolutions and scaling settings to make
            // sure that the hitbox is where it is supposed to be. Otherwise
            // the hitbox is so far off the mark that the user will consider it
            // a bug as the flag is not reported where it is expected.
            // To get this numbers I switched the scaling factor (have to
            // restart the app in between) and look where the hitbox is
            // located, then adjust the values until they look right.
            int displacement;
            if (scale <= 1.0)
                displacement = 3;
            else if (scale <= 1.25)
                displacement = 8;
            else if (scale <= 1.50)
                displacement = 14;
            else if (scale <= 1.75)
                displacement = 3;
            else if (scale <= 2.00)
                displacement = 6;
            else
                displacement = 12;

            imageRect.x = r.x + (r.width - imageRect.width) / 2;
            if (tabDir == wxLEFT)
            {
                if (!label.empty())
                    imageRect.y = tabRect.y + tabRect.height + gap;
                else
                    imageRect.y = r.y - displacement + (r.height - imageRect.height) / 2;
            }
            else
            {
                if (!label.empty())
                    imageRect.y = r.y + (r.height - imageRect.height - gap - tabRect.height) / 2;
                else
                    imageRect.y = r.y - displacement + (r.height - imageRect.height) / 2;
            }

#ifdef WXDEBUG_NOTEBOOK_HITTEST
            ::ShowHitbox(const_cast<wxWindow *>(this), imageRect, false, false);
#endif
            if (imageRect.Contains(pt))
            {
                *flags = wxBK_HITTEST_ONICON;
                break;
            }
        }

        break;
    }

    return item;
}

int wxNotebook::HitTest(const wxPoint& pt, long *flags) const
{
    // In Windows there is a bug so that the flags are not properly reported
    // for left/right orientation, so we have to do it manually.
    // It seems that the tabs are evaluated the same as if they were top/bottom
    // oriented, because if multiple tabs are stacked the flags are quite different
    // for each tab on the x axis.
    const wxDirection tabDir = GetTabOrientation();
    if (tabDir == wxLEFT || tabDir == wxRIGHT)
        return MSWHitTestLeftRight(pt, flags);

    TC_HITTESTINFO hitTestInfo;
    hitTestInfo.pt.x = pt.x;
    hitTestInfo.pt.y = pt.y;
    int item = TabCtrl_HitTest(GetHwnd(), &hitTestInfo);

    if ( flags )
    {
        *flags = 0;

        if ((hitTestInfo.flags & TCHT_NOWHERE) == TCHT_NOWHERE)
        {
            wxASSERT( item == wxNOT_FOUND );
            *flags |= wxBK_HITTEST_NOWHERE;
            if ( GetPageSize().Contains(pt) )
                *flags |= wxBK_HITTEST_ONPAGE;
        }
        else if ((hitTestInfo.flags & TCHT_ONITEM) == TCHT_ONITEM)
            *flags |= wxBK_HITTEST_ONITEM;
        else if ((hitTestInfo.flags & TCHT_ONITEMICON) == TCHT_ONITEMICON)
            *flags |= wxBK_HITTEST_ONICON;
        else if ((hitTestInfo.flags & TCHT_ONITEMLABEL) == TCHT_ONITEMLABEL)
            *flags |= wxBK_HITTEST_ONLABEL;
    }

    return item;
}

// ----------------------------------------------------------------------------
// flicker-less notebook redraw
// ----------------------------------------------------------------------------

#if USE_NOTEBOOK_ANTIFLICKER

// wnd proc for the spin button
LRESULT APIENTRY
wxNotebookSpinBtnWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch ( message )
    {
        case WM_ERASEBKGND:
            return 0;

        case WM_PAINT:
            if ( wxMSWDarkMode::PaintIfNecessary(hwnd, gs_wndprocNotebookSpinBtn) )
                return 0;
            break;
    }

    return ::CallWindowProc(CASTWNDPROC gs_wndprocNotebookSpinBtn,
                            hwnd, message, wParam, lParam);
}

LRESULT APIENTRY
wxNotebookWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    return ::CallWindowProc(CASTWNDPROC gs_wndprocNotebook,
                            hwnd, message, wParam, lParam);
}

void wxNotebook::OnEraseBackground(wxEraseEvent& WXUNUSED(event))
{
    // do nothing here
}

namespace
{

// Note that FromDIP() should _not_ be used here, as 2px offset is used
// even in high DPI.
constexpr int selectedOffset = 2;
constexpr int labelOffset = 3*selectedOffset;

// This function expands the passed in rectangle in place and returns the
// clipping rectangle which should be used when drawing it.
wxRect
ExpandSelectedTab(wxRect& rectTab, wxDirection tabOrient)
{
    // Selected tab literally stands out, so make it bigger -- but clip
    // drawing to ensure we don't draw the inner border of the inflated
    // selected tab rectangle, it shouldn't overflow into the notebook
    // page area.
    rectTab.Inflate(selectedOffset);

    wxRect rectClip = rectTab;
    switch ( tabOrient )
    {
        case wxTOP:
            rectClip.height -= selectedOffset;
            break;

        case wxBOTTOM:
            rectClip.y += selectedOffset;
            rectClip.height -= selectedOffset;
            break;

        case wxLEFT:
            rectClip.width -= selectedOffset;
            break;

        case wxRIGHT:
            rectClip.x += selectedOffset;
            rectClip.width -= selectedOffset;
            break;

        default:
            wxFAIL_MSG("unreachable");
    }

    return rectClip;
}

// Flags may include:
// - wxCONTROL_SELECTED for the currently selected tab
// - wxCONTROL_CURRENT for the "hot" tab, i.e. the one under mouse pointer
// - wxCONTROL_SPECIAL for the first tab.
//
// Note that this function relies on the appropriate pen being selected into
// the DC and uses the current pen for drawing the tab borders.
void
DrawNotebookTab(wxWindow* win,
                wxDC& dc,
                const wxRect& rectOrig,
                const wxString& label,
                const wxBitmap& image,
                wxDirection tabOrient,
                int flags = wxCONTROL_NONE)
{
    wxRect rectTab = rectOrig;
    wxColour colTab;
    if ( flags & wxCONTROL_SELECTED )
    {
        dc.SetClippingRegion(ExpandSelectedTab(rectTab, tabOrient));

        colTab = win->GetBackgroundColour();
    }
    else // not the selected tab
    {
        // All tab rectangles overlap the previous one to avoid double pixel
        // borders between them in Windows 10 flat look, except for the first
        // one which has nothing to overlap.
        if ( !(flags & wxCONTROL_SPECIAL) )
        {
            switch ( tabOrient )
            {
                case wxTOP:
                case wxBOTTOM:
                    rectTab.x--;
                    rectTab.width++;
                    break;

                case wxLEFT:
                case wxRIGHT:
                    rectTab.y--;
                    rectTab.height++;
                    break;

                default:
                    wxFAIL_MSG("unreachable");
            }
        }

        if ( flags & wxCONTROL_CURRENT )
            colTab = wxSystemSettings::GetColour(wxSYS_COLOUR_HOTLIGHT);
        else
            colTab = wxSystemSettings::GetColour(wxSYS_COLOUR_BTNSHADOW);
    }

    dc.SetBrush(colTab);
    dc.DrawRectangle(rectTab);

    wxRect rectLabel = rectOrig;
    if ( flags & wxCONTROL_SELECTED )
    {
        dc.DestroyClippingRegion();

        // Also shift the label to mimic the native control which makes it "pop
        // up" for the selected tab (with "up" being "in the tab direction").
        switch ( tabOrient )
        {
            case wxTOP:
                rectLabel.y -= selectedOffset;
                break;

            case wxBOTTOM:
                rectLabel.y += selectedOffset;
                break;

            case wxLEFT:
                rectLabel.x -= selectedOffset;
                break;

            case wxRIGHT:
                rectLabel.x += selectedOffset;
                break;

            default:
                wxFAIL_MSG("unreachable");
        }
    }

    rectLabel.Deflate(labelOffset);

    wxString text;
    int mnemonicIndex = wxControl::FindAccelIndex(label, &text);

    // Draw the label and the image, if any.
    switch ( tabOrient )
    {
        case wxTOP:
        case wxBOTTOM:
            // We can use an existing helper that will do everything for us.
            dc.DrawLabel(text, image, rectLabel,
                         wxALIGN_LEFT | wxALIGN_CENTER_VERTICAL,
                         mnemonicIndex);
            break;

        case wxLEFT:
        case wxRIGHT:
            {
                const wxSize textSize = dc.GetTextExtent(text);

                // Exchange width and height because we're drawing text
                // vertically.
                wxSize totalSize{textSize.y, textSize.x};

                int textOfs = 0;
                wxSize imageSize;
                if ( image.IsOk() )
                {
                    imageSize = image.GetSize();

                    // Use label offset for the gap between image and the label
                    // too because why not.
                    totalSize.y += imageSize.y + labelOffset;

                    if ( imageSize.x > totalSize.x )
                    {
                        textOfs = (imageSize.x - totalSize.x) / 2;
                        totalSize.x = imageSize.x;
                    }
                }

                // Native control actually draws text bottom/top aligned in the
                // first/only row but centers them if there is more than one
                // row of tabs. Don't bother with this, especially because it's
                // really not obvious that it looks any better and just center
                // them always.
                const wxRect rect = wxRect(totalSize).CentreIn(rectLabel);

                if ( tabOrient == wxLEFT )
                {
                    int y = rect.y + textSize.x;

                    dc.DrawRotatedText(text, rect.x + textOfs, y, 90.0);

                    if ( image.IsOk() )
                        dc.DrawBitmap(image, rect.x, y + labelOffset, true);
                }
                else // tabOrient == wxRIGHT
                {
                    int y = rect.y;

                    if ( image.IsOk() )
                    {
                        dc.DrawBitmap(image, rect.x, y, true);

                        y += imageSize.y + labelOffset;
                    }

                    dc.DrawRotatedText(text, rect.GetRight() - textOfs, y, -90.0);
                }

                // TODO: We don't underline mnemonic when drawing vertically.
            }
            break;

        default:
            wxFAIL_MSG("unreachable");
    }
}

} // anonymous namespace

void wxNotebook::MSWNotebookPaint()
{
    // This is tricky: GetTabRect() may result in a nested WM_PAINT when the
    // native control decides to generate it from its Tab_CalcPaintMetrics()
    // for some reason (this happens at least when using multiple tab rows), so
    // we need to call it before creating wxPaintDC as otherwise the current
    // paint DC would be invalidated by EndPaint() while we use it, see #25700.
    wxRect rectTabArea;

    // This is more than just an optimization: calling GetTabRect(0) for an
    // empty control is not allowed and would assert.
    if ( GetPageCount() > 0 )
        rectTabArea = GetTabRect(0);

    // Now create and use the DC.
    wxPaintDC dc(this);
    dc.Clear();

    const wxDirection tabOrient = GetTabOrientation();

    const wxSize sizeWindow = GetClientSize();
    const int selected = GetSelection();
    const wxPoint posCursor = ScreenToClient(wxGetMousePosition());

    const auto drawTab = [this, &dc, tabOrient](wxRect rect, size_t n, int flags)
    {
        if ( n == 0 )
            flags |= wxCONTROL_SPECIAL;

        DrawNotebookTab(this, dc, rect,
                        GetPageText(n),
                        GetImageBitmapFor(this, GetPageImage(n)),
                        tabOrient,
                        flags);
    };

    const size_t pages = GetPageCount();
    if ( !pages )
        return;

    // Start by erasing the tabs area background.
    rectTabArea = ExpandSelectedTab(rectTabArea, tabOrient);
    if ( tabOrient == wxTOP || tabOrient == wxBOTTOM )
        rectTabArea.SetRight(sizeWindow.x);
    else
        rectTabArea.SetBottom(sizeWindow.y);
    dc.SetBrush(wxSystemSettings::GetColour(wxSYS_COLOUR_BTNFACE));
    dc.SetPen(*wxTRANSPARENT_PEN);
    dc.DrawRectangle(rectTabArea);

    // Set colour for tab borders (it's not really the same as menu bar colour,
    // but this seems to look acceptable, so use it for now).
    dc.SetPen(wxSystemSettings::GetColour(wxSYS_COLOUR_MENUBAR));

    // Draw the separating line of the tab area.
    wxPoint ptStart = rectTabArea.GetTopLeft();
    wxPoint ptEnd = rectTabArea.GetBottomRight();
    switch ( tabOrient )
    {
        case wxTOP:
            ptStart.y = ptEnd.y;
            break;

        case wxBOTTOM:
            ptEnd.y = ptStart.y;
            break;

        case wxLEFT:
            ptStart.x = ptEnd.x;
            break;

        case wxRIGHT:
            ptEnd.x = ptStart.x;
            break;

        default:
            wxFAIL_MSG("unreachable");
    }

    dc.DrawLine(ptStart, ptEnd);

    // Then draw all the individual tabs.
    for ( size_t n = 0; n < pages; ++n )
    {
        if ( static_cast<int>(n) == selected )
        {
            // We're going to draw this one after all the other ones as it
            // overlaps them.
            continue;
        }

        const wxRect rect = GetTabRect(n);

        // For horizontal tabs, some of them can be scrolled out of view, skip
        // drawing them just in case we have zillions of tabs to avoid drawing
        // the off-screen ones unnecessarily.
        if ( rect.x > sizeWindow.x )
        {
            // This tab, and all the remaining ones, can't be seen anyhow, so
            // don't bother drawing them.
            break;
        }

        // We can't track the "hot" tab when using non-top tabs as the native
        // control doesn't refresh them on mouse move (it seems to switch to
        // comctl32.dll v5-like implementation in this case), so don't paint
        // them specially.
        int flags = wxCONTROL_NONE;
        if ( tabOrient == wxTOP && rect.Contains(posCursor) )
            flags |= wxCONTROL_CURRENT;

        drawTab(rect, n, flags);
    }

    if ( selected != wxNOT_FOUND )
        drawTab(GetTabRect(selected), selected, wxCONTROL_SELECTED);
}

void wxNotebook::OnPaint(wxPaintEvent& event)
{
    // We can rely on the default implementation if we don't have a custom
    // background colour (note that it is always set when using dark mode).
    if ( !m_hasBgCol )
    {
        event.Skip();
        return;
    }

    if ( wxMSWDarkMode::IsActive() )
    {
        // We can't use default painting in dark mode, it just doesn't work
        // there, whichever theme we use, so draw everything ourselves.
        MSWNotebookPaint();
        return;
    }

    wxPaintDC dc(this);

    RECT rc;
    ::GetClientRect(GetHwnd(), &rc);
    if ( !rc.right || !rc.bottom )
        return;

    wxBitmap bmp(rc.right, rc.bottom);
    wxMemoryDC memdc(bmp);

    const HDC hdc = GetHdcOf(memdc);

    // The drawing logic of the native tab control is absolutely impenetrable
    // but observation shows that in the current Windows versions (XP and 7),
    // the tab control always erases its entire background in its window proc
    // when the tabs are top-aligned but does not do it when the tabs are in
    // any other position.
    //
    // This means that we can't rely on our background colour being used for
    // the blank area in the tab row because this doesn't work in the default
    // top-aligned case, hence the hack with ExtFloodFill() below. But it also
    // means that we still do need to erase the DC to account for the other
    // cases.
    //
    // Moreover, just in case some very old or very new (or even future,
    // although it seems unlikely that this is ever going to change by now)
    // version of Windows didn't do it like this, do both things in all cases
    // instead of optimizing away the one of them which doesn't do anything for
    // the effectively used tab orientation -- better safe than fast.

    // Notice that we use our own background here, not the background used for
    // the pages, because the tab row background must blend with the parent and
    // so the background colour inherited from it (if any) must be used.
    AutoHBRUSH hbr(wxColourToRGB(GetBackgroundColour()));

    ::FillRect(hdc, &rc, hbr);

    MSWDefWindowProc(WM_PAINT, (WPARAM)hdc, 0);

    // At least for the top-aligned tabs, our background colour was overwritten
    // and so we now replace the default background with our colour. This is
    // horribly inefficient, of course, but seems to be the only way to do it.
    if ( UseBgCol() )
    {
        SelectInHDC selectBrush(hdc, hbr);

        // Find the point which must contain the default background colour:
        // this is a hack, of course, but using this point "close" to the
        // corner seems to work fine in practice.
        int x = 0,
            y = 0;

        switch ( GetWindowStyle() & wxBK_ALIGN_MASK )
        {
            case wxBK_TOP:
                x = rc.right - 2;
                y = 2;
                break;

            case wxBK_BOTTOM:
                x = rc.right - 2;
                y = rc.bottom - 2;
                break;

            case wxBK_LEFT:
                x = 2;
                y = rc.bottom - 2;
                break;

            case wxBK_RIGHT:
                x = 2;
                y = rc.bottom - 2;
                break;
        }

        ::ExtFloodFill(hdc, x, y, ::GetSysColor(COLOR_BTNFACE), FLOODFILLSURFACE);
    }

    dc.Blit(0, 0, rc.right, rc.bottom, &memdc, 0, 0);
}

#endif // USE_NOTEBOOK_ANTIFLICKER

// ----------------------------------------------------------------------------
// wxNotebook callbacks
// ----------------------------------------------------------------------------

void wxNotebook::OnSize(wxSizeEvent& event)
{
    if ( GetPageCount() == 0 )
    {
        // Prevents droppings on resize, but does cause some flicker
        // when there are no pages.
        Refresh();
        event.Skip();
        return;
    }
    else
    {
        // Without this, we can sometimes get droppings at the edges
        // of a notebook, for example a notebook in a splitter window.
        // This needs to be reconciled with the RefreshRect calls
        // at the end of this function, which weren't enough to prevent
        // the droppings.

        wxSize sz = GetClientSize();

        // Refresh right side
        wxRect rect(sz.x-4, 0, 4, sz.y);
        RefreshRect(rect);

        // Refresh bottom side
        rect = wxRect(0, sz.y-4, sz.x, 4);
        RefreshRect(rect);

        // Refresh left side
        rect = wxRect(0, 0, 4, sz.y);
        RefreshRect(rect);
    }

    // fit all the notebook pages to the tab control's display area

    RECT rc;
    rc.left = rc.top = 0;
    GetSize((int *)&rc.right, (int *)&rc.bottom);

    // save the total size, we'll use it below
    int widthNbook = rc.right - rc.left,
        heightNbook = rc.bottom - rc.top;

    // there seems to be a bug in the implementation of TabCtrl_AdjustRect(): it
    // returns completely false values for multiline tab controls after the tabs
    // are added but before getting the first WM_SIZE (off by ~50 pixels, see
    //
    // http://sf.net/tracker/index.php?func=detail&aid=645323&group_id=9863&atid=109863
    //
    // and the only work around I could find was this ugly hack... without it
    // simply toggling the "multiline" checkbox in the notebook sample resulted
    // in a noticeable page displacement
    if ( HasFlag(wxNB_MULTILINE) )
    {
        // avoid an infinite recursion: we get another notification too!
        static bool s_isInOnSize = false;

        if ( !s_isInOnSize )
        {
            s_isInOnSize = true;
            SendMessage(GetHwnd(), WM_SIZE, SIZE_RESTORED,
                    MAKELPARAM(rc.right, rc.bottom));
            s_isInOnSize = false;
        }

        // The best size depends on the number of rows of tabs, which can
        // change when the notepad is resized.
        InvalidateBestSize();
    }

#if wxUSE_UXTHEME
    // background bitmap size has changed, update the brush using it too
    UpdateBgBrush();
#endif // wxUSE_UXTHEME

    (void)TabCtrl_AdjustRect(GetHwnd(), false, &rc);

    int width = rc.right - rc.left,
        height = rc.bottom - rc.top;
    size_t nCount = m_pages.size();
    for ( size_t nPage = 0; nPage < nCount; nPage++ ) {
        wxNotebookPage *pPage = m_pages[nPage];
        pPage->SetSize(rc.left, rc.top, width, height);
    }


    // unless we had already repainted everything, we now need to refresh
    if ( !HasFlag(wxFULL_REPAINT_ON_RESIZE) )
    {
        // invalidate areas not covered by pages
        RefreshRect(wxRect(0, 0, widthNbook, rc.top), false);
        RefreshRect(wxRect(0, rc.top, rc.left, height), false);
        RefreshRect(wxRect(0, rc.bottom, widthNbook, heightNbook - rc.bottom),
                    false);
        RefreshRect(wxRect(rc.right, rc.top, widthNbook - rc.right, height),
                    false);
    }

#if USE_NOTEBOOK_ANTIFLICKER
    // subclass the spin control used by the notebook to scroll pages to
    // prevent it from flickering on resize
    if ( !m_hasSubclassedUpdown )
    {
        // iterate over all child windows to find spin button
        for ( HWND child = ::GetWindow(GetHwnd(), GW_CHILD);
              child;
              child = ::GetWindow(child, GW_HWNDNEXT) )
        {
            wxWindow *childWindow = wxFindWinFromHandle((WXHWND)child);

            // see if it exists, if no wxWindow found then assume it's the spin
            // btn
            if ( !childWindow )
            {
                // subclass the spin button to override WM_ERASEBKGND
                if ( !gs_wndprocNotebookSpinBtn )
                    gs_wndprocNotebookSpinBtn = wxGetWindowProc(child);

                wxSetWindowProc(child, wxNotebookSpinBtnWndProc);
                m_hasSubclassedUpdown = true;
                break;
            }
        }
    }
#endif // USE_NOTEBOOK_ANTIFLICKER

    event.Skip();
}

void wxNotebook::OnNavigationKey(wxNavigationKeyEvent& event)
{
    if ( event.IsWindowChange() ) {
        // change pages
        AdvanceSelection(event.GetDirection());
    }
    else {
        // we get this event in 3 cases
        //
        // a) one of our pages might have generated it because the user TABbed
        // out from it in which case we should propagate the event upwards and
        // our parent will take care of setting the focus to prev/next sibling
        //
        // or
        //
        // b) the parent panel wants to give the focus to us so that we
        // forward it to our selected page. We can't deal with this in
        // OnSetFocus() because we don't know which direction the focus came
        // from in this case and so can't choose between setting the focus to
        // first or last panel child
        //
        // or
        //
        // c) we ourselves (see MSWTranslateMessage) generated the event
        //
        wxWindow * const parent = GetParent();

        // the wxObject* casts are required to avoid MinGW GCC 2.95.3 ICE
        const bool isFromParent = event.GetEventObject() == (wxObject*) parent;
        const bool isFromSelf = event.GetEventObject() == (wxObject*) this;
        const bool isForward = event.GetDirection();

        if ( isFromSelf && !isForward )
        {
            // focus is currently on notebook tab and should leave
            // it backwards (Shift-TAB)
            event.SetCurrentFocus(this);
            if ( !parent->HandleWindowEvent(event) )
            {
                // if the parent didn't handle this event, the notebook
                // must be its only child accepting focus, so let the page
                // handle it to wrap around to the last control in tab order
                if ( m_selection != wxNOT_FOUND )
                {
                    wxWindow* page = m_pages[m_selection];
                    page->HandleWindowEvent(event);
                }
            }
        }
        else if ( isFromParent || isFromSelf )
        {
            // no, it doesn't come from child, case (b) or (c): forward to a
            // page but only if entering notebook page (i.e. direction is
            // backwards (Shift-TAB) something from out-of-notebook, or
            // direction is forward (TAB) from ourselves),
            if ( m_selection != wxNOT_FOUND &&
                    (!event.GetDirection() || isFromSelf) )
            {
                // so that the page knows that the event comes from it's parent
                // and is being propagated downwards
                event.SetEventObject(this);

                wxWindow *page = m_pages[m_selection];
                if ( !page->HandleWindowEvent(event) )
                {
                    page->SetFocus();
                }
                //else: page manages focus inside it itself
            }
            else // otherwise set the focus to the notebook itself
            {
                SetFocus();
            }
        }
        else
        {
            // it comes from our child, case (a), pass to the parent, but only
            // if the direction is forwards. Otherwise set the focus to the
            // notebook itself. The notebook is always the 'first' control of a
            // page.
            if ( !isForward )
            {
                SetFocus();
            }
            else if ( parent )
            {
                event.SetCurrentFocus(this);
                if ( !parent->HandleWindowEvent(event) )
                {
                    // if the parent didn't handle this event, the notebook
                    // must be its only child accepting focus, so take it
                    event.Skip(false);
                    SetFocus();
                }
             }
        }
    }
}

bool wxNotebook::SetBackgroundColour(const wxColour& colour)
{
    if ( !wxNotebookBase::SetBackgroundColour(colour) )
        return false;

#if wxUSE_UXTHEME
    UpdateBgBrush();
#endif // wxUSE_UXTHEME

#if USE_NOTEBOOK_ANTIFLICKER
    Unbind(wxEVT_ERASE_BACKGROUND, &wxNotebook::OnEraseBackground, this);
    if ( m_hasBgCol || !wxUxThemeIsActive() )
    {
        Bind(wxEVT_ERASE_BACKGROUND, &wxNotebook::OnEraseBackground, this);
    }
#endif // USE_NOTEBOOK_ANTIFLICKER

    return true;
}

#if wxUSE_UXTHEME

WXHBRUSH wxNotebook::QueryBgBitmap()
{
    RECT rc;
    ::GetClientRect(GetHwnd(), &rc);
    if ( ::IsRectEmpty(&rc) )
        return 0;

    wxUxThemeHandle theme(this, L"TAB");
    if ( !theme )
        return 0;

    ClientHDC hDC(GetHwnd());

    RECT rcBg;
    ::GetThemeBackgroundContentRect(theme,
                                    (HDC) hDC,
                                    TABP_PANE,
                                    0,
                                    &rc,
                                    &rcBg);

    m_bgBrushAdj = wxPoint(rcBg.left, rcBg.top);
    ::OffsetRect(&rcBg, -rcBg.left, -rcBg.top);

    ::GetThemeBackgroundExtent
                            (
                                theme,
                                (HDC) hDC,
                                TABP_PANE,
                                0,
                                &rcBg,
                                &rc
                            );

    MemoryHDC hDCMem(hDC);
    CompatibleBitmap hBmp(hDC, rcBg.right, rcBg.bottom);

    {
        SelectInHDC selectBmp(hDCMem, hBmp);
        theme.DrawBackground(hDCMem, rc, TABP_PANE);
    } // deselect bitmap from the memory HDC before using it

    return (WXHBRUSH)::CreatePatternBrush(hBmp);
}

void wxNotebook::UpdateBgBrush()
{
    if ( m_hbrBackground )
        ::DeleteObject((HBRUSH)m_hbrBackground);

    if ( !m_hasBgCol && wxUxThemeIsActive() )
    {
        m_hbrBackground = QueryBgBitmap();
    }
    else // no themes or we've got user-defined solid colour
    {
        m_hbrBackground = nullptr;
    }
}

bool wxNotebook::MSWPrintChild(WXHDC hDC, wxWindow *child)
{
    const wxRect r = GetPageSize();
    if ( r.IsEmpty() )
        return false;

    RECT rc;
    wxCopyRectToRECT(r, rc);

    // map rect to the coords of the window we're drawing in
    if ( child )
        wxMapWindowPoints(GetHwnd(), GetHwndOf(child), &rc);

    // If we're using a solid colour (for example if we've switched off
    // theming for this notebook), paint it
    if (UseBgCol())
    {
        wxBrush brush(GetBackgroundColour());
        HBRUSH hbr = GetHbrushOf(brush);

        ::FillRect((HDC) hDC, &rc, hbr);

        return true;
    }
    else // No solid background colour, try to use themed background.
    {
        wxUxThemeHandle theme(child, L"TAB");
        if ( theme )
        {
            // we have the content area (page size), but we need to draw all of the
            // background for it to be aligned correctly
            ::GetThemeBackgroundExtent
                                    (
                                        theme,
                                        (HDC) hDC,
                                        TABP_PANE,
                                        0,
                                        &rc,
                                        &rc
                                    );

            theme.DrawBackground((HDC) hDC, rc, TABP_PANE);
            return true;
        }
    }

    return wxNotebookBase::MSWPrintChild(hDC, child);
}

#endif // wxUSE_UXTHEME

// Windows only: attempts to get colour for UX theme page background
wxColour wxNotebook::GetThemeBackgroundColour() const
{
    if ( wxMSWDarkMode::IsActive() )
    {
        // We know the colour used in dark mode as we draw the notebook
        // ourselves, so just return it (especially because the code below
        // would return totally inappropriate light mode colour).
        return GetBackgroundColour();
    }

#if wxUSE_UXTHEME
    if (wxUxThemeIsActive())
    {
        wxUxThemeHandle hTheme(this, L"TAB");
        if (hTheme)
        {
            // Probe the colour of the background: note that we need to use a
            // bitmap bigger than 1*1 because it may have borders of different
            // colour. But this size should hopefully be enough for the central
            // pixel not to belong to any border.
            const wxSize size(10, 10);

            wxBitmap bmp(size);
            wxMemoryDC memdc(bmp);
            hTheme.DrawBackground(GetHdcOf(memdc), size, TABP_PANE);

            wxColour colour;
            if ( memdc.GetPixel(size.x/2, size.y/2, &colour) )
                return colour;
        }
    }
#endif // wxUSE_UXTHEME

    return GetBackgroundColour();
}

// ----------------------------------------------------------------------------
// wxNotebook base class virtuals
// ----------------------------------------------------------------------------

#if wxUSE_CONSTRAINTS

// override these 2 functions to do nothing: everything is done in OnSize

void wxNotebook::SetConstraintSizes(bool WXUNUSED(recurse))
{
  // don't set the sizes of the pages - their correct size is not yet known
  wxControl::SetConstraintSizes(false);
}

bool wxNotebook::DoPhase(int WXUNUSED(nPhase))
{
  return true;
}

#endif // wxUSE_CONSTRAINTS

// ----------------------------------------------------------------------------
// wxNotebook Windows message handlers
// ----------------------------------------------------------------------------

bool wxNotebook::MSWOnScroll(int orientation, WXWORD nSBCode,
                             WXWORD pos, WXHWND control)
{
    // don't generate EVT_SCROLLWIN events for the WM_SCROLLs coming from the
    // up-down control
    if ( control )
        return false;

    return wxNotebookBase::MSWOnScroll(orientation, nSBCode, pos, control);
}

bool wxNotebook::MSWOnNotify(int idCtrl, WXLPARAM lParam, WXLPARAM* result)
{
  wxBookCtrlEvent event(wxEVT_NULL, m_windowId);

  NMHDR* hdr = (NMHDR *)lParam;
  switch ( hdr->code ) {
    case TCN_SELCHANGE:
      event.SetEventType(wxEVT_NOTEBOOK_PAGE_CHANGED);
      break;

    case TCN_SELCHANGING:
      event.SetEventType(wxEVT_NOTEBOOK_PAGE_CHANGING);
      break;

    default:
      return wxControl::MSWOnNotify(idCtrl, lParam, result);
  }

  event.SetSelection(TabCtrl_GetCurSel(GetHwnd()));
  event.SetOldSelection(m_selection);
  event.SetEventObject(this);
  event.SetInt(idCtrl);

  // Change the selection before generating the event as its handler should
  // already see the new page selected.
  if ( hdr->code == TCN_SELCHANGE )
  {
      UpdateSelection(event.GetSelection());

      // We need to update the tabs after the selection change when drawing
      // them ourselves, otherwise the previously selected tab is not redrawn.
      if ( wxMSWDarkMode::IsActive() )
          Refresh();
  }

  bool processed = HandleWindowEvent(event);
  *result = !event.IsAllowed();
  return processed;
}

#endif // wxUSE_NOTEBOOK
