// **************************************************************************
// * This file is part of the FreeFileSync project. It is distributed under *
// * GNU General Public License: http://www.gnu.org/licenses/gpl.html       *
// * Copyright (C) Zenju (zenju AT gmx DOT de) - All Rights Reserved        *
// **************************************************************************

#include "grid.h"
#include <cassert>
#include <set>
#include <wx/settings.h>
#include <wx/listbox.h>
#include <wx/tooltip.h>
#include <wx/timer.h>
#include <wx/utils.h>
#include <zen/tick_count.h>
#include <zen/string_tools.h>
#include <zen/scope_guard.h>
#include <zen/utf.h>
#include <zen/format_unit.h>
#include "image_tools.h"
#include "rtl.h"

#ifdef ZEN_LINUX
#include <gtk/gtk.h>
#endif

using namespace zen;


wxColor zen::getColorSelectionGradientFrom() { return wxColor(137, 172, 255); } //blue: HSL: 158, 255, 196   HSV: 222, 0.46, 1
wxColor zen::getColorSelectionGradientTo  () { return wxColor(225, 234, 255); } //      HSL: 158, 255, 240   HSV: 222, 0.12, 1

void zen::clearArea(wxDC& dc, const wxRect& rect, const wxColor& col)
{
    wxDCPenChanger   dummy (dc, col);
    wxDCBrushChanger dummy2(dc, col);
    dc.DrawRectangle(rect);
}

namespace
{
//------------ Grid Constants --------------------------------
const double MOUSE_DRAG_ACCELERATION = 1.5; //unit: [rows / (pixel * sec)] -> same value as Explorer!
const int DEFAULT_COL_LABEL_HEIGHT = 24;
const int COLUMN_BORDER_LEFT       = 4; //for left-aligned text
const int COLUMN_LABEL_BORDER      = COLUMN_BORDER_LEFT;
const int COLUMN_MOVE_DELAY        = 5;  //unit: [pixel] (from Explorer)
const int COLUMN_MIN_WIDTH         = 40; //only honored when resizing manually!
const int ROW_LABEL_BORDER         = 3;
const int COLUMN_RESIZE_TOLERANCE  = 6; //unit [pixel]
const int COLUMN_FILL_GAP_TOLERANCE = 10; //enlarge column to fill full width when resizing

const wxColor COLOR_SELECTION_GRADIENT_NO_FOCUS_FROM = wxColour(192, 192, 192); //light grey  wxSystemSettings::GetColour(wxSYS_COLOUR_BTNSHADOW);
const wxColor COLOR_SELECTION_GRADIENT_NO_FOCUS_TO   = wxColour(228, 228, 228);

const wxColor COLOR_LABEL_GRADIENT_FROM = wxColour(200, 200, 200); //light grey
const wxColor COLOR_LABEL_GRADIENT_TO = *wxWHITE;

const wxColor COLOR_LABEL_GRADIENT_FROM_FOCUS = getColorSelectionGradientFrom();
const wxColor COLOR_LABEL_GRADIENT_TO_FOCUS   = COLOR_LABEL_GRADIENT_TO;

//wxColor getColorRowLabel         () { return wxPanel::GetClassDefaultAttributes  ().colBg; } //
wxColor getColorMainWinBackground() { return wxListBox::GetClassDefaultAttributes().colBg; } //cannot be initialized statically on wxGTK!

const wxColor colorGridLine = wxColour(192, 192, 192); //light grey

//------------------------------------------------------------

//another fix for yet another poor wxWidgets implementation (wxDCClipper does *not* stack)
hash_map<wxDC*, wxRect> clippingAreas; //associate "active" clipping area with each DC

class DcClipper
{
public:
    DcClipper(wxDC& dc, const wxRect& r) : dc_(dc)
    {
        auto it = clippingAreas.find(&dc);
        if (it != clippingAreas.end())
        {
            oldRect.reset(new wxRect(it->second));

            wxRect tmp = r;
            tmp.Intersect(*oldRect);    //better safe than sorry
            dc_.SetClippingRegion(tmp); //
            it->second = tmp;
        }
        else
        {
            dc_.SetClippingRegion(r);
            clippingAreas.insert(std::make_pair(&dc_, r));
        }
    }

    ~DcClipper()
    {
        dc_.DestroyClippingRegion();
        if (oldRect.get() != nullptr)
        {
            dc_.SetClippingRegion(*oldRect);
            clippingAreas[&dc_] = *oldRect;
        }
        else
            clippingAreas.erase(&dc_);
    }

private:
    std::unique_ptr<wxRect> oldRect;
    wxDC& dc_;
};
}

//----------------------------------------------------------------------------------------------------------------
const wxEventType zen::EVENT_GRID_MOUSE_LEFT_DOUBLE     = wxNewEventType();
const wxEventType zen::EVENT_GRID_COL_LABEL_MOUSE_LEFT  = wxNewEventType();
const wxEventType zen::EVENT_GRID_COL_LABEL_MOUSE_RIGHT = wxNewEventType();
const wxEventType zen::EVENT_GRID_COL_RESIZE            = wxNewEventType();
const wxEventType zen::EVENT_GRID_MOUSE_LEFT_DOWN       = wxNewEventType();
const wxEventType zen::EVENT_GRID_MOUSE_LEFT_UP         = wxNewEventType();
const wxEventType zen::EVENT_GRID_MOUSE_RIGHT_DOWN      = wxNewEventType();
const wxEventType zen::EVENT_GRID_MOUSE_RIGHT_UP        = wxNewEventType();
const wxEventType zen::EVENT_GRID_SELECT_RANGE          = wxNewEventType();
//----------------------------------------------------------------------------------------------------------------

void GridData::renderRowBackgound(wxDC& dc, const wxRect& rect, size_t row, bool enabled, bool selected, bool hasFocus)
{
    drawCellBackground(dc, rect, enabled, selected, hasFocus, getColorMainWinBackground());
}


void GridData::renderCell(Grid& grid, wxDC& dc, const wxRect& rect, size_t row, ColumnType colType)
{
    wxRect rectTmp = drawCellBorder(dc, rect);

    rectTmp.x     += COLUMN_BORDER_LEFT;
    rectTmp.width -= COLUMN_BORDER_LEFT;
    drawCellText(dc, rectTmp, getValue(row, colType), grid.IsEnabled());
}


size_t GridData::getBestSize(wxDC& dc, size_t row, ColumnType colType)
{
    return dc.GetTextExtent(getValue(row, colType)).GetWidth() + 2 * COLUMN_BORDER_LEFT; //some border on left and right side
}


wxRect GridData::drawCellBorder(wxDC& dc, const wxRect& rect) //returns remaining rectangle
{
    wxDCPenChanger dummy2(dc, wxPen(colorGridLine, 1, wxSOLID));
    dc.DrawLine(rect.GetBottomLeft(),  rect.GetBottomRight());
    dc.DrawLine(rect.GetBottomRight(), rect.GetTopRight() + wxPoint(0, -1));

    return wxRect(rect.GetTopLeft(), wxSize(rect.width - 1, rect.height - 1));
}


void GridData::drawCellBackground(wxDC& dc, const wxRect& rect, bool enabled, bool selected, bool hasFocus, const wxColor& backgroundColor)
{
    if (enabled)
    {
        if (selected)
        {
            //if (hasFocus)
            dc.GradientFillLinear(rect, getColorSelectionGradientFrom(), getColorSelectionGradientTo(), wxEAST);
            //else -> doesn't look too good...
            //    dc.GradientFillLinear(rect, COLOR_SELECTION_GRADIENT_NO_FOCUS_FROM, COLOR_SELECTION_GRADIENT_NO_FOCUS_TO, wxEAST);
        }
        else
            clearArea(dc, rect, backgroundColor);
    }
    else
        clearArea(dc, rect, wxSystemSettings::GetColour(wxSYS_COLOUR_BTNFACE));
}


namespace
{
#ifdef _MSC_VER
#pragma warning(disable:4428)	// VC wrongly issues warning C4428: universal-character-name encountered in source
#endif
const wchar_t ELLIPSIS = L'\u2026'; //...

template <class Function> inline
wxString getTruncatedText(const wxString& text, Function textFits)
{
    if (textFits(text))
        return text;

    //unlike Windows 7 Explorer, we truncate UTF-16 correctly: e.g. CJK-Ideogramm encodes to TWO wchar_t: utfCvrtTo<wxString>("\xf0\xa4\xbd\x9c");
    size_t low  = 0; //number of unicode chars!
    size_t high = unicodeLength(text); //

    for (;;)
    {
        const size_t middle = (low + high) / 2;

        wxString candidate(strBegin(text), findUnicodePos(text, middle));
        candidate += ELLIPSIS;

        if (high - low <= 1)
            return candidate;

        if (textFits(candidate))
            low = middle;
        else
            high = middle;
    }
}

void drawTextLabelFitting(wxDC& dc, const wxString& text, const wxRect& rect, int alignment)
{
    DcClipper clip(dc, rect); //wxDC::DrawLabel doesn't care about width, WTF?

    /*
    performance notes:
    wxDC::DrawLabel() is implemented in terms of both wxDC::GetMultiLineTextExtent() and wxDC::DrawText()
    wxDC::GetMultiLineTextExtent() is implemented in terms of wxDC::GetTextExtent()

    average total times:
    							Windows Linux
    single wxDC::DrawText()		 7µs     50µs
    wxDC::DrawLabel() +			10µs     90µs
    repeated GetTextExtent()
    */

    //truncate large texts and add ellipsis
    auto textFits = [&](const wxString& phrase) { return dc.GetTextExtent(phrase).GetWidth() <= rect.GetWidth(); };
    dc.DrawLabel(getTruncatedText(text, textFits), rect, alignment);
}
}


void GridData::drawCellText(wxDC& dc, const wxRect& rect, const wxString& text, bool enabled, int alignment)
{
    wxDCTextColourChanger dummy(dc, enabled ? dc.GetTextForeground() : wxSystemSettings::GetColour(wxSYS_COLOUR_GRAYTEXT));
    drawTextLabelFitting(dc, text, rect, alignment);
}


void GridData::renderColumnLabel(Grid& grid, wxDC& dc, const wxRect& rect, ColumnType colType, bool highlighted)
{
    wxRect rectTmp = drawColumnLabelBorder(dc, rect);
    drawColumnLabelBackground(dc, rectTmp, highlighted);

    rectTmp.x     += COLUMN_BORDER_LEFT;
    rectTmp.width -= COLUMN_BORDER_LEFT;
    drawColumnLabelText(dc, rectTmp, getColumnLabel(colType));
}


wxRect GridData::drawColumnLabelBorder(wxDC& dc, const wxRect& rect) //returns remaining rectangle
{
    //draw white line
    {
        wxDCPenChanger dummy(dc, *wxWHITE_PEN);
        dc.DrawLine(rect.GetTopLeft(), rect.GetBottomLeft());
    }

    //draw border (with gradient)
    {
        wxDCPenChanger dummy(dc, wxPen(wxSystemSettings::GetColour(wxSYS_COLOUR_3DSHADOW), 1, wxSOLID));
        dc.GradientFillLinear(wxRect(rect.GetTopRight(), rect.GetBottomRight()), dc.GetPen().GetColour(), COLOR_LABEL_GRADIENT_TO, wxNORTH);
        dc.DrawLine(rect.GetBottomLeft(), rect.GetBottomRight() + wxPoint(1, 0));
    }

    return wxRect(rect.x + 1, rect.y, rect.width - 2, rect.height - 1); //we really don't like wxRect::Deflate, do we?
}


void GridData::drawColumnLabelBackground(wxDC& dc, const wxRect& rect, bool highlighted)
{
    if (highlighted)
        dc.GradientFillLinear(rect, COLOR_LABEL_GRADIENT_FROM_FOCUS, COLOR_LABEL_GRADIENT_TO_FOCUS, wxNORTH);
    else //regular background gradient
        dc.GradientFillLinear(rect, COLOR_LABEL_GRADIENT_FROM, COLOR_LABEL_GRADIENT_TO, wxNORTH); //clear overlapping cells
}


void GridData::drawColumnLabelText(wxDC& dc, const wxRect& rect, const wxString& text)
{
    wxDCTextColourChanger dummy(dc, *wxBLACK); //accessibility: always set both foreground AND background colors!
    drawTextLabelFitting(dc, text, rect, wxALIGN_LEFT | wxALIGN_CENTER_VERTICAL);
}

//----------------------------------------------------------------------------------------------------------------
/*
                  SubWindow
                     /|\
                      |
     -----------------------------------
    |            |           |          |
CornerWin  RowLabelWin  ColLabelWin  MainWin

*/
class Grid::SubWindow : public wxWindow
{
public:
    SubWindow(Grid& parent) :
        wxWindow(&parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxWANTS_CHARS | wxBORDER_NONE, wxPanelNameStr),
        parent_(parent)
    {
        Connect(wxEVT_PAINT, wxPaintEventHandler(SubWindow::onPaintEvent), nullptr, this);
        Connect(wxEVT_SIZE,  wxSizeEventHandler (SubWindow::onSizeEvent),  nullptr, this);
        //http://wiki.wxwidgets.org/Flicker-Free_Drawing
        Connect(wxEVT_ERASE_BACKGROUND, wxEraseEventHandler(SubWindow::onEraseBackGround), nullptr, this);

        //SetDoubleBuffered(true); slow as hell!

#if wxCHECK_VERSION(2, 9, 1)
        SetBackgroundStyle(wxBG_STYLE_PAINT);
#else
        SetBackgroundStyle(wxBG_STYLE_CUSTOM);
#endif

        Connect(wxEVT_SET_FOCUS,  wxFocusEventHandler(SubWindow::onFocus), nullptr, this);
        Connect(wxEVT_KILL_FOCUS, wxFocusEventHandler(SubWindow::onFocus), nullptr, this);
        Connect(wxEVT_CHILD_FOCUS, wxEventHandler(SubWindow::onChildFocus), nullptr, this);

        Connect(wxEVT_LEFT_DOWN,    wxMouseEventHandler(SubWindow::onMouseLeftDown  ), nullptr, this);
        Connect(wxEVT_LEFT_UP,      wxMouseEventHandler(SubWindow::onMouseLeftUp    ), nullptr, this);
        Connect(wxEVT_LEFT_DCLICK,  wxMouseEventHandler(SubWindow::onMouseLeftDouble), nullptr, this);
        Connect(wxEVT_RIGHT_DOWN,   wxMouseEventHandler(SubWindow::onMouseRightDown ), nullptr, this);
        Connect(wxEVT_RIGHT_UP,     wxMouseEventHandler(SubWindow::onMouseRightUp   ), nullptr, this);
        Connect(wxEVT_MOTION,       wxMouseEventHandler(SubWindow::onMouseMovement  ), nullptr, this);
        Connect(wxEVT_LEAVE_WINDOW, wxMouseEventHandler(SubWindow::onLeaveWindow    ), nullptr, this);
        Connect(wxEVT_MOUSEWHEEL,   wxMouseEventHandler(SubWindow::onMouseWheel     ), nullptr, this);
        Connect(wxEVT_MOUSE_CAPTURE_LOST, wxMouseCaptureLostEventHandler(SubWindow::onMouseCaptureLost), nullptr, this);

        Connect(wxEVT_CHAR,     wxKeyEventHandler(SubWindow::onChar   ), nullptr, this);
        Connect(wxEVT_KEY_UP,   wxKeyEventHandler(SubWindow::onKeyUp  ), nullptr, this);
        Connect(wxEVT_KEY_DOWN, wxKeyEventHandler(SubWindow::onKeyDown), nullptr, this);

        assert(GetClientAreaOrigin() == wxPoint()); //generally assumed when dealing with coordinates below
    }
    Grid& refParent() { return parent_; }
    const Grid& refParent() const { return parent_; }

    template <class T>
    bool sendEventNow(T&& event) //take both "rvalue + lvalues", return "true" if a suitable event handler function was found and executed, and the function did not call wxEvent::Skip.
    {
        if (wxEvtHandler* evtHandler = parent_.GetEventHandler())
            return evtHandler->ProcessEvent(event);
        return false;
    }

protected:
    void setToolTip(const wxString& text) //proper fix for wxWindow
    {
        wxToolTip* tt = GetToolTip();

        const wxString oldText = tt ? tt->GetTip() : wxString();
        if (text != oldText)
        {
            if (text.IsEmpty())
                SetToolTip(nullptr); //wxGTK doesn't allow wxToolTip with empty text!
            else
            {
                //wxWidgets bug: tooltip multiline property is defined by first tooltip text containing newlines or not (same is true for maximum width)
                if (!tt)
                    SetToolTip(new wxToolTip(L"a                                                                b\n\
                                                           a                                                                b")); //ugly, but is working (on Windows)
                tt = GetToolTip(); //should be bound by now
                if (tt)
                    tt->SetTip(text);
            }
        }
    }

private:
    virtual void render(wxDC& dc, const wxRect& rect) = 0;

    virtual void onFocus(wxFocusEvent& event) { event.Skip(); }
    virtual void onChildFocus(wxEvent& event) {} //wxGTK::wxScrolledWindow automatically scrolls to child window when child gets focus -> prevent!

    virtual void onMouseLeftDown  (wxMouseEvent& event) { event.Skip(); }
    virtual void onMouseLeftUp    (wxMouseEvent& event) { event.Skip(); }
    virtual void onMouseLeftDouble(wxMouseEvent& event) { event.Skip(); }
    virtual void onMouseRightDown (wxMouseEvent& event) { event.Skip(); }
    virtual void onMouseRightUp   (wxMouseEvent& event) { event.Skip(); }
    virtual void onMouseMovement  (wxMouseEvent& event) { event.Skip(); }
    virtual void onLeaveWindow    (wxMouseEvent& event) { event.Skip(); }
    virtual void onMouseCaptureLost(wxMouseCaptureLostEvent& event) { event.Skip(); }
    virtual void onChar   (wxKeyEvent& event) { event.Skip(); }
    virtual void onKeyUp  (wxKeyEvent& event) { event.Skip(); }
    virtual void onKeyDown(wxKeyEvent& event) { event.Skip(); }

    void onMouseWheel(wxMouseEvent& event)
    {
        /*
          MSDN, WM_MOUSEWHEEL: "Sent to the focus window when the mouse wheel is rotated.
          The DefWindowProc function propagates the message to the window's parent.
          There should be no internal forwarding of the message, since DefWindowProc propagates
          it up the parent chain until it finds a window that processes it."

          On OS X there is no such propagation! => we need a redirection (the same wxGrid implements)
         */
        if (wxEvtHandler* evtHandler = parent_.GetEventHandler())
            if (evtHandler->ProcessEvent(event))
                return;
        event.Skip();
    }

    void onPaintEvent(wxPaintEvent& event)
    {
        //wxAutoBufferedPaintDC dc(this); -> this one happily fucks up for RTL layout by not drawing the first column (x = 0)!
        BufferedPaintDC dc(*this, doubleBuffer);

        assert(GetSize() == GetClientSize());

        const wxRegion& updateReg = GetUpdateRegion();
        for (wxRegionIterator it = updateReg; it; ++it)
            render(dc, it.GetRect());
    }

    void onSizeEvent(wxSizeEvent& event)
    {
        Refresh();
        event.Skip();
    }

    void onEraseBackGround(wxEraseEvent& event) {}

    Grid& parent_;
    std::unique_ptr<wxBitmap> doubleBuffer;
};

//----------------------------------------------------------------------------------------------------------------
//----------------------------------------------------------------------------------------------------------------

class Grid::CornerWin : public SubWindow
{
public:
    CornerWin(Grid& parent) : SubWindow(parent) {}

private:
    virtual bool AcceptsFocus() const { return false; }

    virtual void render(wxDC& dc, const wxRect& rect)
    {
        const wxRect& clientRect = GetClientRect();

        dc.GradientFillLinear(clientRect, COLOR_LABEL_GRADIENT_FROM, COLOR_LABEL_GRADIENT_TO, wxNORTH);

        dc.SetPen(wxPen(wxSystemSettings::GetColour(wxSYS_COLOUR_3DSHADOW), 1, wxSOLID));

        {
            wxDCPenChanger dummy(dc, COLOR_LABEL_GRADIENT_TO);
            dc.DrawLine(clientRect.GetTopLeft(), clientRect.GetTopRight());
        }

        dc.GradientFillLinear(wxRect(clientRect.GetBottomLeft (), clientRect.GetTopLeft ()), dc.GetPen().GetColour(), COLOR_LABEL_GRADIENT_TO, wxNORTH);
        dc.GradientFillLinear(wxRect(clientRect.GetBottomRight(), clientRect.GetTopRight()), dc.GetPen().GetColour(), COLOR_LABEL_GRADIENT_TO, wxNORTH);

        dc.DrawLine(clientRect.GetBottomLeft(), clientRect.GetBottomRight());

        wxRect rectShrinked = clientRect;
        rectShrinked.Deflate(1);
        dc.SetPen(*wxWHITE_PEN);

        //dc.DrawLine(clientRect.GetTopLeft(), clientRect.GetTopRight() + wxPoint(1, 0));
        dc.DrawLine(rectShrinked.GetTopLeft(), rectShrinked.GetBottomLeft() + wxPoint(0, 1));
    }
};

//----------------------------------------------------------------------------------------------------------------
//----------------------------------------------------------------------------------------------------------------

class Grid::RowLabelWin : public SubWindow
{
public:
    RowLabelWin(Grid& parent) :
        SubWindow(parent),
        rowHeight(parent.GetCharHeight() + 2 + 1) {} //default height; don't call any functions on "parent" other than those from wxWindow during construction!
    //2 for some more space, 1 for bottom border (gives 15 + 2 + 1 on Windows, 17 + 2 + 1 on Ubuntu)

    int getBestWidth(ptrdiff_t rowFrom, ptrdiff_t rowTo)
    {
        wxClientDC dc(this);

        wxFont labelFont = GetFont();
        labelFont.SetWeight(wxFONTWEIGHT_BOLD);
        dc.SetFont(labelFont); //harmonize with RowLabelWin::render()!

        int bestWidth = 0;
        for (ptrdiff_t i = rowFrom; i <= rowTo; ++i)
            bestWidth = std::max(bestWidth, dc.GetTextExtent(formatRow(i)).GetWidth() + 2 * ROW_LABEL_BORDER);
        return bestWidth;
    }

    size_t getLogicalHeight() const { return refParent().getRowCount() * rowHeight; }

    ptrdiff_t getRowAtPos(ptrdiff_t posY) const //returns < 0 on invalid input, else row number within: [0, rowCount]; rowCount if out of range
    {
        if (posY >= 0 && rowHeight > 0)
        {
            const size_t row = posY / rowHeight;
            return std::min(row, refParent().getRowCount());
        }
        return -1;
    }

    ptrdiff_t getRowHeight() const { return std::max<ptrdiff_t>(1, rowHeight); } //guarantees to return size >= 1 !
    void setRowHeight(size_t height) { rowHeight = height; }

    wxRect getRowLabelArea(ptrdiff_t row) const
    {
        assert(GetClientAreaOrigin() == wxPoint());
        return wxRect(wxPoint(0, rowHeight * row),
                      wxSize(GetClientSize().GetWidth(), rowHeight));
    }

    std::pair<ptrdiff_t, ptrdiff_t> getRowsOnClient(const wxRect& clientRect) const //returns range [begin, end)
    {
        const int yFrom = refParent().CalcUnscrolledPosition(clientRect.GetTopLeft    ()).y;
        const int yTo   = refParent().CalcUnscrolledPosition(clientRect.GetBottomRight()).y;

        return std::make_pair(std::max<ptrdiff_t>(yFrom / rowHeight, 0),
                              std::min<ptrdiff_t>((yTo  / rowHeight) + 1, refParent().getRowCount()));
    }

private:
    static wxString formatRow(size_t row) { return toGuiString(row + 1); } //convert number to std::wstring including thousands separator

    virtual bool AcceptsFocus() const { return false; }

    virtual void render(wxDC& dc, const wxRect& rect)
    {
        if (IsEnabled())
            clearArea(dc, rect, getColorMainWinBackground());
        else
            clearArea(dc, rect, wxSystemSettings::GetColour(wxSYS_COLOUR_BTNFACE));

        wxFont labelFont = GetFont();
        labelFont.SetWeight(wxFONTWEIGHT_BOLD);
        dc.SetFont(labelFont); //harmonize with RowLabelWin::getBestWidth()!

        auto rowRange = getRowsOnClient(rect); //returns range [begin, end)
        for (auto row = rowRange.first; row < rowRange.second; ++row)
        {
            wxRect singleLabelArea = getRowLabelArea(row);
            if (singleLabelArea.GetHeight() > 0)
            {
                singleLabelArea.y = refParent().CalcScrolledPosition(singleLabelArea.GetTopLeft()).y;
                drawRowLabel(dc, singleLabelArea, row);
            }
        }
    }

    void drawRowLabel(wxDC& dc, const wxRect& rect, size_t row)
    {
        //clearArea(dc, rect, getColorRowLabel());
        dc.GradientFillLinear(rect, COLOR_LABEL_GRADIENT_FROM, COLOR_LABEL_GRADIENT_TO, wxWEST); //clear overlapping cells
        wxDCTextColourChanger dummy3(dc, *wxBLACK); //accessibility: always set both foreground AND background colors!

        //label text
        wxRect textRect = rect;
        textRect.Deflate(1);
        {
            DcClipper clip(dc, textRect); //wxDC::DrawLabel doesn't care about with, WTF?
            dc.DrawLabel(formatRow(row), textRect, wxALIGN_CENTRE);
        }

        //border lines
        {
            wxDCPenChanger dummy(dc, *wxWHITE_PEN);
            dc.DrawLine(rect.GetTopLeft(), rect.GetTopRight());
        }
        {
            wxDCPenChanger dummy(dc, wxPen(wxSystemSettings::GetColour(wxSYS_COLOUR_3DSHADOW), 1, wxSOLID));
            dc.DrawLine(rect.GetTopLeft(),     rect.GetBottomLeft());
            dc.DrawLine(rect.GetBottomLeft(),  rect.GetBottomRight());
            dc.DrawLine(rect.GetBottomRight(), rect.GetTopRight() + wxPoint(0, -1));
        }
    }

    virtual void onMouseLeftDown(wxMouseEvent& event) { refParent().redirectRowLabelEvent(event); }
    virtual void onMouseMovement(wxMouseEvent& event) { refParent().redirectRowLabelEvent(event); }
    virtual void onMouseLeftUp  (wxMouseEvent& event) { refParent().redirectRowLabelEvent(event); }

    ptrdiff_t rowHeight;
};


namespace
{
class ColumnResizing
{
public:
    ColumnResizing(wxWindow& wnd, size_t col, size_t compPos, ptrdiff_t startWidth, int clientPosX) :
        wnd_(wnd), col_(col), compPos_(compPos), startWidth_(startWidth), clientPosX_(clientPosX)
    {
        wnd_.CaptureMouse();
    }
    ~ColumnResizing()
    {
        if (wnd_.HasCapture())
            wnd_.ReleaseMouse();
    }

    size_t    getColumn      () const { return col_; }
    size_t    getComponentPos() const { return compPos_; }
    ptrdiff_t getStartWidth  () const { return startWidth_; }
    int       getStartPosX   () const { return clientPosX_; }

private:
    wxWindow& wnd_;
    const size_t    col_;
    const size_t    compPos_;
    const ptrdiff_t startWidth_;
    const int       clientPosX_;
};


class ColumnMove
{
public:
    ColumnMove(wxWindow& wnd, size_t colFrom, size_t compPos, int clientPosX) :
        wnd_(wnd),
        colFrom_(colFrom),
        compPos_(compPos),
        colTo_(colFrom),
        clientPosX_(clientPosX),
        singleClick_(true) { wnd_.CaptureMouse(); }
    ~ColumnMove() { if (wnd_.HasCapture()) wnd_.ReleaseMouse(); }

    size_t  getColumnFrom() const { return colFrom_; }
    size_t& refColumnTo() { return colTo_; }
    size_t  getComponentPos() const { return compPos_; }
    int     getStartPosX () const { return clientPosX_; }

    bool isRealMove() const { return !singleClick_; }
    void setRealMove() { singleClick_ = false; }

private:
    wxWindow& wnd_;
    const size_t colFrom_;
    const size_t compPos_;
    size_t colTo_;
    const int clientPosX_;
    bool singleClick_;
};
}

//----------------------------------------------------------------------------------------------------------------

class Grid::ColLabelWin : public SubWindow
{
public:
    ColLabelWin(Grid& parent) : SubWindow(parent) {}

private:
    virtual bool AcceptsFocus() const { return false; }

    virtual void render(wxDC& dc, const wxRect& rect)
    {
        if (IsEnabled())
            clearArea(dc, rect, getColorMainWinBackground());
        else
            clearArea(dc, rect, wxSystemSettings::GetColour(wxSYS_COLOUR_BTNFACE));

        wxFont labelFont = GetFont();
        labelFont.SetWeight(wxFONTWEIGHT_BOLD);
        dc.SetFont(labelFont);

        wxDCTextColourChanger dummy(dc, wxSystemSettings::GetColour(wxSYS_COLOUR_WINDOWTEXT)); //use user setting for labels

        const int colLabelHeight = refParent().colLabelHeight;

        wxPoint labelAreaTL(refParent().CalcScrolledPosition(wxPoint(0, 0)).x, 0); //client coordinates

        std::vector<std::vector<ColumnWidth>> compAbsWidths = refParent().getColWidths(); //resolve stretched widths
        for (auto iterComp = compAbsWidths.begin(); iterComp != compAbsWidths.end(); ++iterComp)
            for (auto iterCol = iterComp->begin(); iterCol != iterComp->end(); ++iterCol)
            {
                const size_t col = iterCol - iterComp->begin();
                const int width  = iterCol->width_; //don't use unsigned for calculations!

                if (labelAreaTL.x > rect.GetRight())
                    return; //done
                if (labelAreaTL.x + width > rect.x)
                    drawColumnLabel(dc, wxRect(labelAreaTL, wxSize(width, colLabelHeight)), col, iterCol->type_, iterComp - compAbsWidths.begin());
                labelAreaTL.x += width;
            }
    }

    void drawColumnLabel(wxDC& dc, const wxRect& rect, size_t col, ColumnType colType, size_t compPos)
    {
        if (auto dataView = refParent().getDataProvider(compPos))
        {
            const bool isHighlighted = activeResizing ? col == activeResizing->getColumn    () && compPos == activeResizing->getComponentPos() : //highlight column on mouse-over
                                       activeMove     ? col == activeMove    ->getColumnFrom() && compPos == activeMove    ->getComponentPos() :
                                       highlight      ? col == highlight->first                && compPos == highlight->second :
                                       false;

            DcClipper clip(dc, rect);
            dataView->renderColumnLabel(refParent(), dc, rect, colType, isHighlighted);

            //draw move target location
            if (refParent().columnMoveAllowed(compPos))
                if (activeMove && activeMove->isRealMove() && activeMove->getComponentPos() == compPos)
                {
                    if (col + 1 == activeMove->refColumnTo()) //handle pos 1, 2, .. up to "at end" position
                        dc.GradientFillLinear(wxRect(rect.GetTopRight(), rect.GetBottomRight() + wxPoint(-2, 0)), *wxBLUE, COLOR_LABEL_GRADIENT_TO, wxNORTH);
                    else if (col == activeMove->refColumnTo() && col == 0) //pos 0
                        dc.GradientFillLinear(wxRect(rect.GetTopLeft(), rect.GetBottomLeft() + wxPoint(2, 0)), *wxBLUE, COLOR_LABEL_GRADIENT_TO, wxNORTH);
                }
        }
    }

    virtual void onMouseLeftDown(wxMouseEvent& event)
    {
        if (FindFocus() != &refParent().getMainWin())
            refParent().getMainWin().SetFocus();

        activeResizing.reset();
        activeMove.reset();

        if (Opt<ColAction> action = refParent().clientPosToColumnAction(event.GetPosition()))
        {
            if (action->wantResize)
            {
                if (!event.LeftDClick()) //double-clicks never seem to arrive here; why is this checked at all???
                    if (Opt<ptrdiff_t> colWidth = refParent().getColWidth(action->col, action->compPos))
                        activeResizing.reset(new ColumnResizing(*this, action->col, action->compPos, *colWidth, event.GetPosition().x));
            }
            else //a move or single click
                activeMove.reset(new ColumnMove(*this, action->col, action->compPos, event.GetPosition().x));
        }
        event.Skip();
    }

    virtual void onMouseLeftUp(wxMouseEvent& event)
    {
        activeResizing.reset(); //nothing else to do, actual work done by onMouseMovement()

        if (activeMove)
        {
            const size_t compPos = activeMove->getComponentPos();
            if (activeMove->isRealMove())
            {
                if (refParent().columnMoveAllowed(compPos))
                {
                    const auto colFrom = activeMove->getColumnFrom();
                    auto       colTo   = activeMove->refColumnTo();

                    if (colTo > colFrom) //simulate "colFrom" deletion
                        --colTo;

                    refParent().moveColumn(colFrom, colTo, compPos);
                }
            }
            else //notify single label click
            {
                if (const Opt<ColumnType> colType = refParent().colToType(activeMove->getColumnFrom(), compPos))
                    sendEventNow(GridClickEvent(EVENT_GRID_COL_LABEL_MOUSE_LEFT, event, -1, *colType, compPos));
            }
            activeMove.reset();
        }

        refParent().updateWindowSizes(); //looks strange if done during onMouseMovement()
        refParent().Refresh();
        event.Skip();
    }

    virtual void onMouseCaptureLost(wxMouseCaptureLostEvent& event)
    {
        activeResizing.reset();
        activeMove.reset();
        Refresh();
        //event.Skip(); -> we DID handle it!
    }

    virtual void onMouseLeftDouble(wxMouseEvent& event)
    {
        if (Opt<ColAction> action = refParent().clientPosToColumnAction(event.GetPosition()))
            if (action->wantResize)
            {
                //auto-size visible range on double-click
                const ptrdiff_t bestWidth = refParent().getBestColumnSize(action->col, action->compPos); //return -1 on error
                if (bestWidth >= 0)
                {
                    refParent().setColWidthAndNotify(bestWidth, action->col, action->compPos);
                    refParent().Refresh(); //refresh main grid as well!
                }
            }
        event.Skip();
    }

    virtual void onMouseMovement(wxMouseEvent& event)
    {
        if (activeResizing)
        {
            const auto col     = activeResizing->getColumn();
            const auto compPos = activeResizing->getComponentPos();

            const ptrdiff_t newWidth = activeResizing->getStartWidth() + event.GetPosition().x - activeResizing->getStartPosX();

            //set width tentatively
            refParent().setColWidthAndNotify(newWidth, col, compPos);

            //check if there's a small gap after last column, if yes, fill it
            int gapWidth = GetClientSize().GetWidth() - refParent().getColWidthsSum(GetClientSize().GetWidth());
            if (std::abs(gapWidth) < COLUMN_FILL_GAP_TOLERANCE)
                refParent().setColWidthAndNotify(newWidth + gapWidth, col, compPos);

            refParent().Refresh(); //refresh columns on main grid as well!
        }
        else if (activeMove)
        {
            const int clientPosX = event.GetPosition().x;
            if (std::abs(clientPosX - activeMove->getStartPosX()) > COLUMN_MOVE_DELAY) //real move (not a single click)
            {
                activeMove->setRealMove();

                const auto col = refParent().clientPosToMoveTargetColumn(event.GetPosition(), activeMove->getComponentPos());
                if (col >= 0)
                    activeMove->refColumnTo() = col;
            }
        }
        else
        {
            if (const Opt<ColAction> action = refParent().clientPosToColumnAction(event.GetPosition()))
            {
                highlight.reset(new std::pair<size_t, size_t>(action->col, action->compPos));

                if (action->wantResize)
                    SetCursor(wxCURSOR_SIZEWE); //set window-local only! :)
                else
                    SetCursor(*wxSTANDARD_CURSOR);
            }
            else
            {
                highlight.reset();
                SetCursor(*wxSTANDARD_CURSOR);
            }
        }

        //update tooltip
        const wxString toolTip = [&]() -> wxString
        {
            const wxPoint absPos = refParent().CalcUnscrolledPosition(event.GetPosition());
            if (const auto colInfo = refParent().getColumnAtPos(absPos.x)) //returns (column type, compPos)
            {
                if (auto prov = refParent().getDataProvider(colInfo->second))
                    return prov->getToolTip(colInfo->first);
            }
            return wxString();
        }();
        setToolTip(toolTip);

        Refresh();
        event.Skip();
    }

    virtual void onLeaveWindow(wxMouseEvent& event)
    {
        highlight.reset(); //wxEVT_LEAVE_WINDOW does not respect mouse capture! -> however highlight is drawn unconditionally during move/resize!
        Refresh();
        event.Skip();
    }

    virtual void onMouseRightDown(wxMouseEvent& event)
    {
        if (const Opt<ColAction> action = refParent().clientPosToColumnAction(event.GetPosition()))
        {
            if (const Opt<ColumnType> colType = refParent().colToType(action->col, action->compPos))
                sendEventNow(GridClickEvent(EVENT_GRID_COL_LABEL_MOUSE_RIGHT, event, -1, *colType, action->compPos)); //notify right click
        }
        event.Skip();
    }

    std::unique_ptr<ColumnResizing> activeResizing;
    std::unique_ptr<ColumnMove>     activeMove;
    std::unique_ptr<std::pair<size_t, size_t>> highlight; //(column, component) mouse-over
};

//----------------------------------------------------------------------------------------------------------------
namespace
{
const wxEventType EVENT_GRID_HAS_SCROLLED = wxNewEventType(); //internal to Grid::MainWin::ScrollWindow()
}
//----------------------------------------------------------------------------------------------------------------

class Grid::MainWin : public SubWindow
{
public:
    MainWin(Grid& parent,
            RowLabelWin& rowLabelWin,
            ColLabelWin& colLabelWin) : SubWindow(parent),
        rowLabelWin_(rowLabelWin),
        colLabelWin_(colLabelWin),
        selectionAnchor(0),
        gridUpdatePending(false)
    {
        Connect(EVENT_GRID_HAS_SCROLLED, wxEventHandler(MainWin::onRequestWindowUpdate), nullptr, this);
    }

    ~MainWin() { assert(!gridUpdatePending); }

    void makeRowVisible(size_t row)
    {
        const wxRect labelRect = rowLabelWin_.getRowLabelArea(row); //returns empty rect if column not found
        if (labelRect.height > 0)
        {
            int scrollPosX = 0;
            refParent().GetViewStart(&scrollPosX, nullptr);

            int pixelsPerUnitY = 0;
            refParent().GetScrollPixelsPerUnit(nullptr, &pixelsPerUnitY);
            if (pixelsPerUnitY <= 0) return;

            const int clientPosY = refParent().CalcScrolledPosition(labelRect.GetTopLeft()).y;
            if (clientPosY < 0)
            {
                const int scrollPosY = labelRect.GetTopLeft().y / pixelsPerUnitY;
                refParent().Scroll(scrollPosX, scrollPosY);
                refParent().updateWindowSizes(); //may show horizontal scroll bar
            }
            else if (clientPosY + labelRect.GetHeight() > rowLabelWin_.GetClientSize().GetHeight())
            {
                auto execScroll = [&](int clientHeight)
                {
                    const int scrollPosY = std::ceil((labelRect.GetTopLeft().y - clientHeight +
                                                      labelRect.GetHeight()) / static_cast<double>(pixelsPerUnitY));
                    refParent().Scroll(scrollPosX, scrollPosY);
                    refParent().updateWindowSizes(); //may show horizontal scroll bar
                };

                const int clientHeightBefore = rowLabelWin_.GetClientSize().GetHeight();
                execScroll(clientHeightBefore);

                //client height may decrease after scroll due to a new horizontal scrollbar, resulting in a partially visible last row
                const int clientHeightAfter = rowLabelWin_.GetClientSize().GetHeight();
                if (clientHeightAfter < clientHeightBefore)
                    execScroll(clientHeightAfter);
            }
        }
    }

    void setCursor(size_t row, size_t compPos)
    {
        cursor = std::make_pair(row, compPos);
        activeSelection.reset(); //e.g. user might search with F3 while holding down left mouse button
        selectionAnchor = row;
    }
    std::pair<size_t, size_t> getCursor() const { return cursor; } // (row, component position)

private:
    virtual void render(wxDC& dc, const wxRect& rect)
    {
        if (IsEnabled())
            clearArea(dc, rect, getColorMainWinBackground());
        else
            clearArea(dc, rect, wxSystemSettings::GetColour(wxSYS_COLOUR_BTNFACE));

        dc.SetFont(GetFont()); //harmonize with Grid::getBestColumnSize()

        wxDCTextColourChanger dummy(dc, wxSystemSettings::GetColour(wxSYS_COLOUR_WINDOWTEXT)); //use user setting for labels

        const int rowHeight = rowLabelWin_.getRowHeight();

        //why again aren't we using RowLabelWin::getRowsOnClient() here?
        const wxPoint topLeft     = refParent().CalcUnscrolledPosition(rect.GetTopLeft());
        const wxPoint bottomRight = refParent().CalcUnscrolledPosition(rect.GetBottomRight());

        const int rowFirst = std::max(topLeft    .y / rowHeight, 0); // [rowFirst, rowLast)
        const int rowLast  = std::min(bottomRight.y / rowHeight + 1, static_cast<int>(refParent().getRowCount()));

        wxPoint cellAreaTL(refParent().CalcScrolledPosition(wxPoint(0, 0))); //client coordinates

        std::vector<std::vector<ColumnWidth>> compAbsWidths = refParent().getColWidths(); //resolve stretched widths
        for (auto iterComp = compAbsWidths.begin(); iterComp != compAbsWidths.end(); ++iterComp)
        {
            const ptrdiff_t compWidth = std::accumulate(iterComp->begin(), iterComp->end(), static_cast<ptrdiff_t>(0),
            [](ptrdiff_t sum, const ColumnWidth& cw) { return sum + cw.width_; });

            const size_t compPos = iterComp - compAbsWidths.begin();
            if (auto prov = refParent().getDataProvider(compPos))
            {
                //draw background lines
                {
                    DcClipper dummy2(dc, rect); //solve issues with drawBackground() painting in area outside of rect (which is not also refreshed by renderCell()) -> keep small scope!
                    for (int row = rowFirst; row < rowLast; ++row)
                        drawBackground(*prov, dc, wxRect(cellAreaTL + wxPoint(0, row * rowHeight), wxSize(compWidth, rowHeight)), row, compPos);
                }

                //draw single cells, column by column
                for (auto iterCol = iterComp->begin(); iterCol != iterComp->end(); ++iterCol)
                {
                    const int width = iterCol->width_; //don't use unsigned for calculations!

                    if (cellAreaTL.x > rect.GetRight())
                        return; //done

                    if (cellAreaTL.x + width > rect.x)
                        for (int row = rowFirst; row < rowLast; ++row)
                        {
                            const wxRect& cellRect = wxRect(cellAreaTL.x, cellAreaTL.y + row * rowHeight, width, rowHeight);
                            DcClipper clip(dc, cellRect);
                            prov->renderCell(refParent(), dc, cellRect, row, iterCol->type_);
                        }
                    cellAreaTL.x += width;
                }
            }
            else
                cellAreaTL.x += compWidth;
        }
    }

    void drawBackground(GridData& prov, wxDC& dc, const wxRect& rect, size_t row, size_t compPos)
    {
        Grid& grid = refParent();
        //check if user is currently selecting with mouse
        bool drawSelection = grid.isSelected(row, compPos);
        if (activeSelection)
        {
            const size_t rowFrom = std::min(activeSelection->getStartRow(), activeSelection->getCurrentRow());
            const size_t rowTo   = std::max(activeSelection->getStartRow(), activeSelection->getCurrentRow());

            if (compPos == activeSelection->getComponentPos() && rowFrom <= row && row <= rowTo)
                drawSelection = activeSelection->isPositiveSelect(); //overwrite default
        }

        prov.renderRowBackgound(dc, rect, row, grid.IsEnabled(), drawSelection, wxWindow::FindFocus() == &grid.getMainWin());
    }

    virtual void onMouseLeftDown (wxMouseEvent& event) { onMouseDown(event); }
    virtual void onMouseLeftUp   (wxMouseEvent& event) { onMouseUp  (event); }
    virtual void onMouseRightDown(wxMouseEvent& event) { onMouseDown(event); }
    virtual void onMouseRightUp  (wxMouseEvent& event) { onMouseUp  (event); }

    virtual void onMouseLeftDouble(wxMouseEvent& event)
    {
        const wxPoint absPos = refParent().CalcUnscrolledPosition(event.GetPosition());
        const auto row       = rowLabelWin_.getRowAtPos(absPos.y); //return -1 for invalid position; >= rowCount if out of range
        if (row >= 0)
        {
            const auto colInfo = refParent().getColumnAtPos(absPos.x); //returns (column type, compPos)

            const ColumnType colType = colInfo ? colInfo->first  : DUMMY_COLUMN_TYPE;
            const ptrdiff_t  compPos = colInfo ? colInfo->second : -1;
            //client is interested in all double-clicks, even those outside of the grid!
            sendEventNow(GridClickEvent(EVENT_GRID_MOUSE_LEFT_DOUBLE, event, row, colType, compPos));
        }
        event.Skip();
    }

    void onMouseDown(wxMouseEvent& event) //handle left and right mouse button clicks (almost) the same
    {
        if (wxWindow::FindFocus() != this) //doesn't seem to happen automatically for right mouse button
            SetFocus();

        const wxPoint absPos = refParent().CalcUnscrolledPosition(event.GetPosition());
        const ptrdiff_t  row = rowLabelWin_.getRowAtPos(absPos.y); //return -1 for invalid position; >= rowCount if out of range
        if (row >= 0)
        {
            const auto       colInfo = refParent().getColumnAtPos(absPos.x); //returns (column type, compPos)
            const ColumnType colType = colInfo ? colInfo->first  : DUMMY_COLUMN_TYPE;
            const ptrdiff_t  compPos = colInfo ? colInfo->second : -1;

            if (!event.RightDown() || !refParent().isSelected(row, compPos)) //do NOT start a new selection if user right-clicks on a selected area!
            {
                if (event.ControlDown())
                {
                    if (compPos >= 0)
                        activeSelection.reset(new MouseSelection(*this, row, compPos, !refParent().isSelected(row, compPos)));
                }
                else if (event.ShiftDown())
                {
                    if (compPos >= 0)
                        activeSelection.reset(new MouseSelection(*this, selectionAnchor, compPos, true));
                    refParent().clearSelectionAllAndNotify();
                }
                else
                {
                    if (compPos >= 0)
                        activeSelection.reset(new MouseSelection(*this, row, compPos, true));
                    refParent().clearSelectionAllAndNotify();
                }
            }

            //notify event *after* potential "clearSelectionAllAndNotify()" above: a client should first receive a GridRangeSelectEvent for clearing the grid, if necessary,
            //then GridClickEvent and the associated GridRangeSelectEvent one after the other
            GridClickEvent mouseEvent(event.RightDown() ? EVENT_GRID_MOUSE_RIGHT_DOWN : EVENT_GRID_MOUSE_LEFT_DOWN, event, row, colType, compPos);
            sendEventNow(mouseEvent);

            Refresh();
        }
        event.Skip(); //allow changing focus
    }

    void onMouseUp(wxMouseEvent& event)
    {
        if (activeSelection)
        {
            const size_t rowCount = refParent().getRowCount();
            if (rowCount > 0)
            {
                if (activeSelection->getCurrentRow() < rowCount)
                {
                    cursor.first = activeSelection->getCurrentRow();
                    selectionAnchor = activeSelection->getStartRow(); //allowed to be "out of range"
                }
                else if (activeSelection->getStartRow() < rowCount) //don't change cursor if "to" and "from" are out of range
                {
                    cursor.first = rowCount - 1;
                    selectionAnchor = activeSelection->getStartRow(); //allowed to be "out of range"
                }
                else //total selection "out of range"
                    selectionAnchor = cursor.first;
            }
            //slight deviation from Explorer: change cursor while dragging mouse! -> unify behavior with shift + direction keys

            refParent().selectRangeAndNotify(activeSelection->getStartRow  (), //from
                                             activeSelection->getCurrentRow(), //to
                                             activeSelection->getComponentPos(),
                                             activeSelection->isPositiveSelect());
            activeSelection.reset();
        }

        //this one may point to row which is not in visible area!
        const wxPoint absPos = refParent().CalcUnscrolledPosition(event.GetPosition());

        const auto row     = rowLabelWin_.getRowAtPos(absPos.y); //return -1 for invalid position; >= rowCount if out of range
        const auto colInfo = refParent().getColumnAtPos(absPos.x); //returns optional pair (column type, compPos)

        const ColumnType colType = colInfo ? colInfo->first  : DUMMY_COLUMN_TYPE; //we probably should notify even if colInfo is invalid!
        const ptrdiff_t  compPos = colInfo ? colInfo->second : -1;

        //notify click event after the range selection! e.g. this makes sure the selection is applied before showing a context menu
        sendEventNow(GridClickEvent(event.RightUp() ? EVENT_GRID_MOUSE_RIGHT_UP : EVENT_GRID_MOUSE_LEFT_UP, event, row, colType, compPos));

        Refresh();
        event.Skip(); //allow changing focus
    }

    virtual void onMouseCaptureLost(wxMouseCaptureLostEvent& event)
    {
        activeSelection.reset();
        Refresh();
        //event.Skip(); -> we DID handle it!
    }

    virtual void onMouseMovement(wxMouseEvent& event)
    {
        if (activeSelection)
            activeSelection->evalMousePos(); //eval on both mouse movement + timer event!

        //change tooltip
        const wxString toolTip = [&]() -> wxString
        {
            const ptrdiff_t rowCount = refParent().getRowCount();
            const wxPoint absPos = refParent().CalcUnscrolledPosition(event.GetPosition());

            const auto row     = rowLabelWin_.getRowAtPos(absPos.y); //return -1 for invalid position; >= rowCount if out of range
            const auto colInfo = refParent().getColumnAtPos(absPos.x); //returns (column type, compPos)
            if (colInfo && 0 <= row && row < rowCount)
            {
                if (auto prov = refParent().getDataProvider(colInfo->second))
                    return prov->getToolTip(row, colInfo->first);
            }
            return wxString();
        }();

        setToolTip(toolTip);

        event.Skip();
    }

    virtual void onKeyDown(wxKeyEvent& event)
    {
        int keyCode = event.GetKeyCode();
        if (GetLayoutDirection() == wxLayout_RightToLeft)
        {
            if (keyCode == WXK_LEFT)
                keyCode = WXK_RIGHT;
            else if (keyCode == WXK_RIGHT)
                keyCode = WXK_LEFT;
            else if (keyCode == WXK_NUMPAD_LEFT)
                keyCode = WXK_NUMPAD_RIGHT;
            else if (keyCode == WXK_NUMPAD_RIGHT)
                keyCode = WXK_NUMPAD_LEFT;
        }

        const ptrdiff_t rowCount = refParent().getRowCount();
        if (rowCount <= 0 || refParent().comp.empty())
        {
            event.Skip();
            return;
        }

        auto setSingleSelection = [&](ptrdiff_t row, ptrdiff_t compPos)
        {
            numeric::confine<ptrdiff_t>(row,     0, rowCount - 1);
            numeric::confine<ptrdiff_t>(compPos, 0, refParent().comp.size() - 1);
            refParent().setGridCursor(row, compPos); //behave like an "external" set cursor!
        };

        auto setSelectionRange = [&](ptrdiff_t row)
        {
            //unlike "setSingleSelection" this function doesn't seem to belong into Grid: management of selectionAnchor should be local

            numeric::confine<ptrdiff_t>(row, 0, rowCount - 1);

            auto& comp = refParent().comp;
            std::for_each(comp.begin(), comp.end(), [](Grid::Component& c) { c.selection.clear(); }); //clear selection, do NOT fire event
            refParent().selectRangeAndNotify(selectionAnchor, row, cursor.second); //set new selection + fire event

            cursor.first = row; //don't call setCursor() since it writes to "selectionAnchor"!
            this->makeRowVisible(row);
            refParent().Refresh();
        };

        switch (keyCode)
        {
            case WXK_UP:
            case WXK_NUMPAD_UP:
                if (event.ShiftDown())
                    setSelectionRange(cursor.first - 1);
                else if (event.ControlDown())
                    refParent().scrollDelta(0, -1);
                else
                    setSingleSelection(cursor.first - 1, cursor.second);
                return; //swallow event: wxScrolledWindow, wxWidgets 2.9.3 on Kubuntu x64 processes arrow keys: prevent this!

            case WXK_DOWN:
            case WXK_NUMPAD_DOWN:
                if (event.ShiftDown())
                    setSelectionRange(cursor.first + 1);
                else if (event.ControlDown())
                    refParent().scrollDelta(0, 1);
                else
                    setSingleSelection(cursor.first + 1, cursor.second);
                return; //swallow event

            case WXK_LEFT:
            case WXK_NUMPAD_LEFT:
                if (event.ControlDown())
                    refParent().scrollDelta(-1, 0);
                else if (event.ShiftDown())
                    ;
                else
                    setSingleSelection(cursor.first, cursor.second - 1);
                return;

            case WXK_RIGHT:
            case WXK_NUMPAD_RIGHT:
                if (event.ControlDown())
                    refParent().scrollDelta(1, 0);
                else if (event.ShiftDown())
                    ;
                else
                    setSingleSelection(cursor.first, cursor.second + 1);
                return;

            case WXK_HOME:
            case WXK_NUMPAD_HOME:
                if (event.ShiftDown())
                    setSelectionRange(0);
                else if (event.ControlDown())
                    setSingleSelection(0, 0);
                else
                    setSingleSelection(0, cursor.second);
                return;

            case WXK_END:
            case WXK_NUMPAD_END:
                if (event.ShiftDown())
                    setSelectionRange(rowCount - 1);
                else if (event.ControlDown())
                    setSingleSelection(rowCount - 1, refParent().comp.size() - 1);
                else
                    setSingleSelection(rowCount - 1, cursor.second);
                return;

            case WXK_PAGEUP:
            case WXK_NUMPAD_PAGEUP:
                if (event.ShiftDown())
                    setSelectionRange(cursor.first - GetClientSize().GetHeight() / rowLabelWin_.getRowHeight());
                else if (event.ControlDown())
                    ;
                else
                    setSingleSelection(cursor.first - GetClientSize().GetHeight() / rowLabelWin_.getRowHeight(), cursor.second);
                return;

            case WXK_PAGEDOWN:
            case WXK_NUMPAD_PAGEDOWN:
                if (event.ShiftDown())
                    setSelectionRange(cursor.first + GetClientSize().GetHeight() / rowLabelWin_.getRowHeight());
                else if (event.ControlDown())
                    ;
                else
                    setSingleSelection(cursor.first + GetClientSize().GetHeight() / rowLabelWin_.getRowHeight(), cursor.second);
                return;

            case 'A':  //Ctrl + A - select all
                if (event.ControlDown())
                    refParent().selectRangeAndNotify(0, rowCount, cursor.second);
                break;

            case WXK_NUMPAD_ADD: //CTRL + '+' - auto-size all
                if (event.ControlDown())
                    refParent().autoSizeColumns(cursor.second);
                return;
        }

        event.Skip();
    }

    virtual void onFocus(wxFocusEvent& event) { Refresh(); event.Skip(); }

    class MouseSelection : private wxEvtHandler
    {
    public:
        MouseSelection(MainWin& wnd, size_t rowStart, size_t compPos, bool positiveSelect) :
            wnd_(wnd), rowStart_(rowStart), compPos_(compPos), rowCurrent_(rowStart), positiveSelect_(positiveSelect), toScrollX(0), toScrollY(0),
            tickCountLast(getTicks()),
            ticksPerSec_(ticksPerSec())
        {
            wnd_.CaptureMouse();
            timer.Connect(wxEVT_TIMER, wxEventHandler(MouseSelection::onTimer), nullptr, this);
            timer.Start(100); //timer interval in ms
            evalMousePos();
        }
        ~MouseSelection() { if (wnd_.HasCapture()) wnd_.ReleaseMouse(); }

        size_t getStartRow     () const { return rowStart_;       }
        size_t getComponentPos () const { return compPos_;        }
        size_t getCurrentRow   () const { return rowCurrent_;     }
        bool   isPositiveSelect() const { return positiveSelect_; } //are we selecting or unselecting?

        void evalMousePos()
        {
            double deltaTime = 0;
            if (ticksPerSec_ > 0)
            {
                const TickVal now = getTicks(); //isValid() on error
                deltaTime = static_cast<double>(dist(tickCountLast, now)) / ticksPerSec_; //unit: [sec]
                tickCountLast = now;
            }

            wxMouseState mouseState = wxGetMouseState();
            const wxPoint clientPos = wnd_.ScreenToClient(wxPoint(mouseState.GetX(), mouseState.GetY()));
            const wxSize clientSize = wnd_.GetClientSize();
            assert(wnd_.GetClientAreaOrigin() == wxPoint());

            //scroll while dragging mouse
            const int overlapPixY = clientPos.y < 0 ? clientPos.y :
                                    clientPos.y >= clientSize.GetHeight() ? clientPos.y - (clientSize.GetHeight() - 1) : 0;
            const int overlapPixX = clientPos.x < 0 ? clientPos.x :
                                    clientPos.x >= clientSize.GetWidth() ? clientPos.x - (clientSize.GetWidth() - 1) : 0;

            int pixelsPerUnitY = 0;
            wnd_.refParent().GetScrollPixelsPerUnit(nullptr, &pixelsPerUnitY);
            if (pixelsPerUnitY <= 0) return;

            const double mouseDragSpeedIncScrollU = pixelsPerUnitY > 0 ? MOUSE_DRAG_ACCELERATION * wnd_.rowLabelWin_.getRowHeight() / pixelsPerUnitY : 0; //unit: [scroll units / (pixel * sec)]

            auto autoScroll = [&](int overlapPix, double& toScroll)
            {
                if (overlapPix != 0)
                {
                    const double scrollSpeed = overlapPix * mouseDragSpeedIncScrollU; //unit: [scroll units / sec]
                    toScroll += scrollSpeed * deltaTime;
                }
                else
                    toScroll = 0;
            };

            autoScroll(overlapPixX, toScrollX);
            autoScroll(overlapPixY, toScrollY);

            if (toScrollX != 0 || toScrollY != 0)
            {
                wnd_.refParent().scrollDelta(static_cast<int>(toScrollX), static_cast<int>(toScrollY)); //
                toScrollX -= static_cast<int>(toScrollX); //rounds down for positive numbers, up for negative,
                toScrollY -= static_cast<int>(toScrollY); //exactly what we want
            }

            {
                //select current row *after* scrolling
                wxPoint clientPosTrimmed = clientPos;
                numeric::confine(clientPosTrimmed.y, 0, clientSize.GetHeight() - 1); //do not select row outside client window!

                const wxPoint absPos = wnd_.refParent().CalcUnscrolledPosition(clientPosTrimmed);
                const ptrdiff_t newRow = wnd_.rowLabelWin_.getRowAtPos(absPos.y); //return -1 for invalid position; >= rowCount if out of range
                if (newRow >= 0)
                    if (rowCurrent_ != newRow)
                    {
                        rowCurrent_ = newRow;
                        wnd_.Refresh();
                    }
            }
        }

    private:
        void onTimer(wxEvent& event) { evalMousePos(); }

        MainWin& wnd_;
        const size_t rowStart_;
        const size_t compPos_;
        ptrdiff_t rowCurrent_;
        const bool positiveSelect_;
        wxTimer timer;
        double toScrollX; //count outstanding scroll units to scroll while dragging mouse
        double toScrollY; //
        TickVal tickCountLast;
        const std::int64_t ticksPerSec_;
    };

    virtual void ScrollWindow(int dx, int dy, const wxRect* rect)
    {
        wxWindow::ScrollWindow(dx, dy, rect);
        rowLabelWin_.ScrollWindow(0, dy, rect);
        colLabelWin_.ScrollWindow(dx, 0, rect);

        //attention, wxGTK call sequence: wxScrolledWindow::Scroll() -> wxScrolledHelperNative::Scroll() -> wxScrolledHelperNative::DoScroll()
        //which *first* calls us, MainWin::ScrollWindow(), and *then* internally updates m_yScrollPosition
        //=> we cannot use CalcUnscrolledPosition() here which gives the wrong/outdated value!!!
        //=> we need to update asynchronously:
        //=> don't use plain async event => severe performance issues on wxGTK!
        //=> can't use idle event neither: too few idle events on Windows, e.g. NO idle events while mouse drag-scrolling!
        //=> solution: send single async event at most!
        if (!gridUpdatePending) //without guarding, the number of outstanding async events can get very high during scrolling!! test case: Ubuntu: 170; Windows: 20
        {
            gridUpdatePending = true;
            wxCommandEvent scrollEvent(EVENT_GRID_HAS_SCROLLED);
            AddPendingEvent(scrollEvent); //asynchronously call updateAfterScroll()
        }
    }

    void onRequestWindowUpdate(wxEvent& event)
    {
        assert(gridUpdatePending);
        ZEN_ON_SCOPE_EXIT(gridUpdatePending = false);

        refParent().updateWindowSizes(false); //row label width has changed -> do *not* update scrollbars: recursion on wxGTK! -> still a problem, now that we're called async??
        rowLabelWin_.Update(); //update while dragging scroll thumb
    }

    RowLabelWin& rowLabelWin_;
    ColLabelWin& colLabelWin_;

    std::unique_ptr<MouseSelection> activeSelection; //bound while user is selecting with mouse

    std::pair<ptrdiff_t, ptrdiff_t> cursor; //(row, component position), always valid! still unsigned type to facilitate "onKeyDown()"
    size_t selectionAnchor;
    bool gridUpdatePending;
};

//----------------------------------------------------------------------------------------------------------------
//----------------------------------------------------------------------------------------------------------------

Grid::Grid(wxWindow* parent,
           wxWindowID id,
           const wxPoint& pos,
           const wxSize& size,
           long style,
           const wxString& name) : wxScrolledWindow(parent, id, pos, size, style | wxWANTS_CHARS, name),
    showScrollbarX(SB_SHOW_AUTOMATIC),
    showScrollbarY(SB_SHOW_AUTOMATIC),
    colLabelHeight(DEFAULT_COL_LABEL_HEIGHT),
    drawRowLabel(true),
    comp(1),
    colSizeOld(0)
{
    Connect(wxEVT_PAINT,            wxPaintEventHandler(Grid::onPaintEvent     ), nullptr, this);
    Connect(wxEVT_ERASE_BACKGROUND, wxEraseEventHandler(Grid::onEraseBackGround), nullptr, this);
    Connect(wxEVT_SIZE,             wxSizeEventHandler (Grid::onSizeEvent      ), nullptr, this);

    cornerWin_   = new CornerWin  (*this); //
    rowLabelWin_ = new RowLabelWin(*this); //owership handled by "this"
    colLabelWin_ = new ColLabelWin(*this); //
    mainWin_     = new MainWin    (*this, *rowLabelWin_, *colLabelWin_); //

    SetTargetWindow(mainWin_);

    SetInitialSize(size); //"Most controls will use this to set their initial size" -> why not

    assert(GetClientSize() == GetSize()); //borders are NOT allowed for Grid
    //reason: updateWindowSizes() wants to use "GetSize()" as a "GetClientSize()" including scrollbars
}


void Grid::updateWindowSizes(bool updateScrollbar)
{
    /* We have to deal with TWO nasty circular dependencies:
    1.
    	rowLabelWidth
    	    /|\
    	mainWin::client width
    	    /|\
    	SetScrollbars -> show/hide horizontal scrollbar depending on client width
    	    /|\
    	mainWin::client height -> possibly trimmed by horizontal scrollbars
    	    /|\
    	rowLabelWidth

    2.
    	mainWin_->GetClientSize()
    	    /|\
    	SetScrollbars -> show/hide scrollbars depending on whether client size is big enough
    	    /|\
    	GetClientSize(); -> possibly trimmed by scrollbars
    	    /|\
    	mainWin_->GetClientSize()  -> also trimmed, since it's a sub-window!
    */

    //break this vicious circle:

    //harmonize with Grid::GetSizeAvailableForScrollTarget()!

    //1. calculate row label width independent from scrollbars
    const int mainWinHeightGross = std::max(GetSize().GetHeight() - colLabelHeight, 0); //independent from client sizes and scrollbars!
    const ptrdiff_t logicalHeight = rowLabelWin_->getLogicalHeight();                   //

    int rowLabelWidth = 0;
    if (drawRowLabel && logicalHeight > 0)
    {
        ptrdiff_t yFrom = CalcUnscrolledPosition(wxPoint(0, 0)).y;
        ptrdiff_t yTo   = CalcUnscrolledPosition(wxPoint(0, mainWinHeightGross - 1)).y ;
        numeric::confine<ptrdiff_t>(yFrom, 0, logicalHeight - 1);
        numeric::confine<ptrdiff_t>(yTo,   0, logicalHeight - 1);

        const ptrdiff_t rowFrom = rowLabelWin_->getRowAtPos(yFrom);
        const ptrdiff_t rowTo   = rowLabelWin_->getRowAtPos(yTo);
        if (rowFrom >= 0 && rowTo >= 0)
            rowLabelWidth = rowLabelWin_->getBestWidth(rowFrom, rowTo);
    }

    auto getMainWinSize = [&](const wxSize& clientSize) { return wxSize(std::max(0, clientSize.GetWidth() - rowLabelWidth), std::max(0, clientSize.GetHeight() - colLabelHeight)); };

    auto setScrollbars2 = [&](int logWidth, int logHeight) //replace SetScrollbars, which loses precision to pixelsPerUnitX for some brain-dead reason
    {
        int ppsuX = 0; //pixel per scroll unit
        int ppsuY = 0;
        GetScrollPixelsPerUnit(&ppsuX, &ppsuY);

        const int ppsuNew = rowLabelWin_->getRowHeight();
        if (ppsuX != ppsuNew || ppsuY != ppsuNew) //support polling!
            SetScrollRate(ppsuNew, ppsuNew); //internally calls AdjustScrollbars()!

        mainWin_->SetVirtualSize(logWidth, logHeight);
        AdjustScrollbars(); //lousy wxWidgets design decision: internally calls mainWin_->GetClientSize() without considering impact of scrollbars!
        //Attention: setting scrollbars triggers *synchronous* resize event if scrollbars are shown or hidden! => updateWindowSizes() recursion! (Windows)
    };

    //2. update managed windows' sizes: just assume scrollbars are already set correctly, even if they may not be (yet)!
    //this ensures mainWin_->SetVirtualSize() and AdjustScrollbars() are working with the correct main window size, unless sb change later, which triggers a recalculation anyway!
    const wxSize mainWinSize = getMainWinSize(GetClientSize());

    cornerWin_  ->SetSize(0, 0, rowLabelWidth, colLabelHeight);
    rowLabelWin_->SetSize(0, colLabelHeight, rowLabelWidth, mainWinSize.GetHeight());
    colLabelWin_->SetSize(rowLabelWidth, 0, mainWinSize.GetWidth(), colLabelHeight);
    mainWin_    ->SetSize(rowLabelWidth, colLabelHeight, mainWinSize.GetWidth(), mainWinSize.GetHeight());

    //avoid flicker in wxWindowMSW::HandleSize() when calling ::EndDeferWindowPos() where the sub-windows are moved only although they need to be redrawn!
    colLabelWin_->Refresh();
    mainWin_    ->Refresh();

    //3. update scrollbars: "guide wxScrolledHelper to not screw up too much"
    if (updateScrollbar)
    {
        const int mainWinWidthGross = getMainWinSize(GetSize()).GetWidth();

        if (logicalHeight <= mainWinHeightGross &&
            getColWidthsSum(mainWinWidthGross) <= mainWinWidthGross &&
            //this special case needs to be considered *only* when both scrollbars are flexible:
            showScrollbarX == SB_SHOW_AUTOMATIC &&
            showScrollbarY == SB_SHOW_AUTOMATIC)
            setScrollbars2(0, 0); //no scrollbars required at all! -> wxScrolledWindow requires active help to detect this special case!
        else
        {
            const int logicalWidthTmp = getColWidthsSum(mainWinSize.GetWidth()); //assuming vertical scrollbar stays as it is...
            setScrollbars2(logicalWidthTmp, logicalHeight); //if scrollbars are shown or hidden a new resize event recurses into updateWindowSizes()
            /*
            is there a risk of endless recursion? No, 2-level recursion at most, consider the following 6 cases:

            <----------gw---------->
            <----------nw------>
            ------------------------  /|\   /|\
            |                   |  |   |     |
            |     main window   |  |   nh    |
            |                   |  |   |     gh
            ------------------------  \|/    |
            |                   |  |         |
            ------------------------        \|/
            	gw := gross width
            	nw := net width := gross width - sb size
            	gh := gross height
            	nh := net height := gross height - sb size

            There are 6 cases that can occur:
            ---------------------------------
            	lw := logical width
            	lh := logical height

            1. lw <= gw && lh <= gh  => no scrollbars needed

            2. lw > gw  && lh > gh   => need both scrollbars

            3. lh > gh
            	4.1 lw <= nw         => need vertical scrollbar only
            	4.2 nw < lw <= gw    => need both scrollbars

            4. lw > gw
            	3.1 lh <= nh         => need horizontal scrollbar only
            	3.2 nh < lh <= gh    => need both scrollbars
            */
        }
    }
}


wxSize Grid::GetSizeAvailableForScrollTarget(const wxSize& size)
{
    //harmonize with Grid::updateWindowSizes()!

    //1. calculate row label width independent from scrollbars
    const int mainWinHeightGross = std::max(size.GetHeight() - colLabelHeight, 0); //independent from client sizes and scrollbars!
    const ptrdiff_t logicalHeight = rowLabelWin_->getLogicalHeight();              //

    int rowLabelWidth = 0;
    if (drawRowLabel && logicalHeight > 0)
    {
        ptrdiff_t yFrom = CalcUnscrolledPosition(wxPoint(0, 0)).y;
        ptrdiff_t yTo   = CalcUnscrolledPosition(wxPoint(0, mainWinHeightGross - 1)).y ;
        numeric::confine<ptrdiff_t>(yFrom, 0, logicalHeight - 1);
        numeric::confine<ptrdiff_t>(yTo,   0, logicalHeight - 1);

        const ptrdiff_t rowFrom = rowLabelWin_->getRowAtPos(yFrom);
        const ptrdiff_t rowTo   = rowLabelWin_->getRowAtPos(yTo);
        if (rowFrom >= 0 && rowTo >= 0)
            rowLabelWidth = rowLabelWin_->getBestWidth(rowFrom, rowTo);
    }

    return size - wxSize(rowLabelWidth, colLabelHeight);
}


void Grid::onPaintEvent(wxPaintEvent& event) { wxPaintDC dc(this); }


void Grid::setColumnLabelHeight(int height)
{
    colLabelHeight = std::max(0, height);
    updateWindowSizes();
}


void Grid::showRowLabel(bool show)
{
    drawRowLabel = show;
    updateWindowSizes();
}


std::vector<size_t> Grid::getSelectedRows(size_t compPos) const
{
    return compPos < comp.size() ? comp[compPos].selection.get() : std::vector<size_t>();
}


void Grid::scrollDelta(int deltaX, int deltaY)
{
    int scrollPosX = 0;
    int scrollPosY = 0;
    GetViewStart(&scrollPosX, &scrollPosY);

    scrollPosX += deltaX;
    scrollPosY += deltaY;

    scrollPosX = std::max(0, scrollPosX); //wxScrollHelper::Scroll() will exit prematurely if input happens to be "-1"!
    scrollPosY = std::max(0, scrollPosY); //

    Scroll(scrollPosX, scrollPosY);
    updateWindowSizes(); //may show horizontal scroll bar
}


void Grid::redirectRowLabelEvent(wxMouseEvent& event)
{
    event.m_x = 0;
    if (wxEvtHandler* evtHandler = mainWin_->GetEventHandler())
        evtHandler->ProcessEvent(event);

    if (event.ButtonDown() && wxWindow::FindFocus() != mainWin_)
        mainWin_->SetFocus();
}


size_t Grid::getRowCount() const
{
    return comp.empty() ? 0 : comp.front().dataView_ ? comp.front().dataView_->getRowCount() : 0;
}


void Grid::Refresh(bool eraseBackground, const wxRect* rect)
{
    const size_t rowCountNew = getRowCount();
    if (colSizeOld != rowCountNew)
    {
        colSizeOld = rowCountNew;
        std::for_each(comp.begin(), comp.end(), [&](Component& c) { c.selection.init(rowCountNew); });
        updateWindowSizes();
    }
    wxScrolledWindow::Refresh(eraseBackground, rect);
}


void Grid::setRowHeight(size_t height)
{
    rowLabelWin_->setRowHeight(height);
    updateWindowSizes();
    Refresh();
}


void Grid::setColumnConfig(const std::vector<Grid::ColumnAttribute>& attr, size_t compPos)
{
    if (compPos < comp.size())
    {
        //hold ownership of non-visible columns
        comp[compPos].oldColAttributes = attr;

        std::vector<VisibleColumn> visibleCols;
        std::for_each(attr.begin(), attr.end(),
                      [&](const ColumnAttribute& ca)
        {
            if (ca.visible_)
                visibleCols.push_back(Grid::VisibleColumn(ca.type_, ca.offset_, ca.stretch_));
        });

        //"ownership" of visible columns is now within Grid
        comp[compPos].visibleCols = visibleCols;

        updateWindowSizes();
        Refresh();
    }
}


std::vector<Grid::ColumnAttribute> Grid::getColumnConfig(size_t compPos) const
{
    if (compPos < comp.size())
    {
        //get non-visible columns (+ outdated visible ones)
        std::vector<ColumnAttribute> output = comp[compPos].oldColAttributes;

        auto iterVcols    = comp[compPos].visibleCols.begin();
        auto iterVcolsend = comp[compPos].visibleCols.end();

        //update visible columns but keep order of non-visible ones!
        std::for_each(output.begin(), output.end(),
                      [&](ColumnAttribute& ca)
        {
            if (ca.visible_)
            {
                if (iterVcols != iterVcolsend)
                {
                    ca.type_    = iterVcols->type_;
                    ca.stretch_ = iterVcols->stretch_;
                    ca.offset_  = iterVcols->offset_;
                    ++iterVcols;
                }
                else
                    assert(false);
            }
        });
        assert(iterVcols == iterVcolsend);

        return output;
    }
    return std::vector<ColumnAttribute>();
}


void Grid::showScrollBars(Grid::ScrollBarStatus horizontal, Grid::ScrollBarStatus vertical)
{
    if (showScrollbarX == horizontal &&
        showScrollbarY == vertical) return; //support polling!

    showScrollbarX = horizontal;
    showScrollbarY = vertical;

#if defined ZEN_WIN || defined ZEN_MAC
    //handled by Grid::SetScrollbar
#elif defined ZEN_LINUX //get rid of scrollbars, but preserve scrolling behavior!
    //the following wxGTK approach is pretty much identical to wxWidgets 2.9 ShowScrollbars() code!

    auto mapStatus = [](ScrollBarStatus sbStatus) -> GtkPolicyType
    {
        switch (sbStatus)
        {
            case SB_SHOW_AUTOMATIC:
                return GTK_POLICY_AUTOMATIC;
            case SB_SHOW_ALWAYS:
                return GTK_POLICY_ALWAYS;
            case SB_SHOW_NEVER:
                return GTK_POLICY_NEVER;
        }
        assert(false);
        return GTK_POLICY_AUTOMATIC;
    };

    GtkWidget* gridWidget = wxWindow::m_widget;
    GtkScrolledWindow* scrolledWindow = GTK_SCROLLED_WINDOW(gridWidget);
    ::gtk_scrolled_window_set_policy(scrolledWindow,
                                     mapStatus(horizontal),
                                     mapStatus(vertical));
#endif

    updateWindowSizes();

    /*
    wxWidgets >= 2.9 ShowScrollbars() is next to useless since it doesn't
    honor wxSHOW_SB_ALWAYS on OS X, so let's ditch it and avoid more non-portability surprises

    #if wxCHECK_VERSION(2, 9, 0)
    auto mapStatus = [](ScrollBarStatus sbStatus) -> wxScrollbarVisibility
    {
        switch (sbStatus)
        {
            case SB_SHOW_AUTOMATIC:
                return wxSHOW_SB_DEFAULT;
            case SB_SHOW_ALWAYS:
                return wxSHOW_SB_ALWAYS;
            case SB_SHOW_NEVER:
                return wxSHOW_SB_NEVER;
        }
        assert(false);
        return wxSHOW_SB_DEFAULT;
    };
    ShowScrollbars(mapStatus(horizontal), mapStatus(vertical));
    #endif
    */
}

#if defined ZEN_WIN || defined ZEN_MAC
void Grid::SetScrollbar(int orientation, int position, int thumbSize, int range, bool refresh)
{
    ScrollBarStatus sbStatus = SB_SHOW_AUTOMATIC;
    if (orientation == wxHORIZONTAL)
        sbStatus = showScrollbarX;
    else if (orientation == wxVERTICAL)
        sbStatus = showScrollbarY;
    else
        assert(false);

    switch (sbStatus)
    {
        case SB_SHOW_AUTOMATIC:
            wxScrolledWindow::SetScrollbar(orientation, position, thumbSize, range, refresh);
            break;

        case SB_SHOW_ALWAYS:
            if (range <= 1) //scrollbars hidden if range == 0 or 1
                wxScrolledWindow::SetScrollbar(orientation, 0, 199999, 200000, refresh);
            else
                wxScrolledWindow::SetScrollbar(orientation, position, thumbSize, range, refresh);
            break;

        case SB_SHOW_NEVER:
            wxScrolledWindow::SetScrollbar(orientation, 0, 0, 0, refresh);
            break;
    }
}
#endif

//get rid of scrollbars, but preserve scrolling behavior!
#ifdef ZEN_WIN
#ifdef __MINGW32__ //MinGW is clueless...
#define WM_MOUSEHWHEEL                  0x020E
#endif

WXLRESULT Grid::MSWDefWindowProc(WXUINT nMsg, WXWPARAM wParam, WXLPARAM lParam)
{
    //we land here if wxWindowMSW::MSWWindowProc() couldn't handle the message
    //http://msdn.microsoft.com/en-us/library/windows/desktop/ms645614(v=vs.85).aspx
    if (nMsg == WM_MOUSEHWHEEL) //horizontal wheel
    {
        const int distance  = GET_WHEEL_DELTA_WPARAM(wParam);
        const int delta     = WHEEL_DELTA;
        int rotations = distance / delta;

        if (GetLayoutDirection() == wxLayout_RightToLeft)
            rotations = -rotations;

        static int linesPerRotation = -1;
        if (linesPerRotation < 0)
            if (!::SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0, &linesPerRotation, 0))
                linesPerRotation = 3;

        scrollDelta(rotations * linesPerRotation, 0); //in scroll units
        return 0; //"If an application processes this message, it should return zero."
    }

    return wxScrolledWindow::MSWDefWindowProc(nMsg, wParam, lParam);
}
#endif


wxWindow& Grid::getCornerWin  () { return *cornerWin_;   }
wxWindow& Grid::getRowLabelWin() { return *rowLabelWin_; }
wxWindow& Grid::getColLabelWin() { return *colLabelWin_; }
wxWindow& Grid::getMainWin    () { return *mainWin_;     }
const wxWindow& Grid::getMainWin() const { return *mainWin_; }


wxRect Grid::getColumnLabelArea(ColumnType colType, size_t compPos) const
{
    std::vector<std::vector<ColumnWidth>> compAbsWidths = getColWidths(); //resolve negative/stretched widths
    if (compPos < compAbsWidths.size())
    {
        auto iterComp = compAbsWidths.begin() + compPos;

        auto iterCol = std::find_if(iterComp->begin(), iterComp->end(), [&](const ColumnWidth& cw) { return cw.type_ == colType; });
        if (iterCol != iterComp->end())
        {
            ptrdiff_t posX = std::accumulate(compAbsWidths.begin(), iterComp, static_cast<ptrdiff_t>(0),
                                             [](ptrdiff_t sum, const std::vector<ColumnWidth>& cols)
            {
                return sum + std::accumulate(cols.begin(), cols.end(), static_cast<ptrdiff_t>(0),
                [](ptrdiff_t val2, const ColumnWidth& cw) { return val2 + cw.width_; });
            });

            posX += std::accumulate(iterComp->begin(), iterCol, static_cast<ptrdiff_t>(0),
            [](ptrdiff_t sum, const ColumnWidth& cw) { return sum + cw.width_; });

            return wxRect(wxPoint(posX, 0), wxSize(iterCol->width_, colLabelHeight));
        }
    }
    return wxRect();
}


Opt<Grid::ColAction> Grid::clientPosToColumnAction(const wxPoint& pos) const
{
    const int absPosX = CalcUnscrolledPosition(pos).x;
    if (absPosX >= 0)
    {
        ptrdiff_t accuWidth = 0;

        std::vector<std::vector<ColumnWidth>> compAbsWidths = getColWidths(); //resolve stretched widths
        for (auto iterComp = compAbsWidths.begin(); iterComp != compAbsWidths.end(); ++iterComp)
        {
            const size_t compPos =  iterComp - compAbsWidths.begin();
            const int resizeTolerance = columnResizeAllowed(compPos) ? COLUMN_RESIZE_TOLERANCE : 0;

            for (auto iterCol = iterComp->begin(); iterCol != iterComp->end(); ++iterCol)
            {
                const size_t col = iterCol - iterComp->begin();

                accuWidth += iterCol->width_;
                if (std::abs(absPosX - accuWidth) < resizeTolerance)
                {
                    ColAction out = {};
                    out.wantResize = true;
                    out.col        = col;
                    out.compPos    = compPos;
                    return out;
                }
                else if (absPosX < accuWidth)
                {
                    ColAction out = {};
                    out.wantResize = false;
                    out.col        = col;
                    out.compPos    = compPos;
                    return out;
                }
            }
        }
    }
    return NoValue();
}


void Grid::moveColumn(size_t colFrom, size_t colTo, size_t compPos)
{
    if (compPos < comp.size())
    {
        auto& visibleCols = comp[compPos].visibleCols;
        if (colFrom < visibleCols.size() &&
            colTo   < visibleCols.size() &&
            colTo != colFrom)
        {
            const auto colAtt = visibleCols[colFrom];
            visibleCols.erase (visibleCols.begin() + colFrom);
            visibleCols.insert(visibleCols.begin() + colTo, colAtt);
        }
    }
}


ptrdiff_t Grid::clientPosToMoveTargetColumn(const wxPoint& pos, size_t compPos) const
{
    std::vector<std::vector<ColumnWidth>> compAbsWidths = getColWidths(); //resolve negative/stretched widths
    if (compPos < compAbsWidths.size())
    {
        auto iterComp = compAbsWidths.begin() + compPos;
        const int absPosX = CalcUnscrolledPosition(pos).x;

        ptrdiff_t accuWidth = std::accumulate(compAbsWidths.begin(), iterComp, static_cast<ptrdiff_t>(0),
                                              [](ptrdiff_t sum, const std::vector<ColumnWidth>& cols)
        {
            return sum + std::accumulate(cols.begin(), cols.end(), static_cast<ptrdiff_t>(0),
            [](ptrdiff_t sum2, const ColumnWidth& cw) { return sum2 + cw.width_; });
        });

        for (auto iterCol = iterComp->begin(); iterCol != iterComp->end(); ++iterCol)
        {
            const ptrdiff_t width  = iterCol->width_; //beware dreaded unsigned conversions!
            accuWidth += width;

            if (absPosX < accuWidth - width / 2)
                return iterCol - iterComp->begin();
        }
        return iterComp->size();
    }
    return -1;
}


Opt<ColumnType> Grid::colToType(size_t col, size_t compPos) const
{
    if (compPos < comp.size() && col < comp[compPos].visibleCols.size())
        return comp[compPos].visibleCols[col].type_;
    return NoValue();
}


ptrdiff_t Grid::getRowAtPos(int posY) const { return rowLabelWin_->getRowAtPos(posY); }


Opt<std::pair<ColumnType, size_t>> Grid::getColumnAtPos(int posX) const
{
    if (posX >= 0)
    {
        std::vector<std::vector<ColumnWidth>> compAbsWidths = getColWidths(); //resolve negative/stretched widths

        ptrdiff_t accWidth = 0;
        for (auto iterComp = compAbsWidths.begin(); iterComp != compAbsWidths.end(); ++iterComp)
            for (auto iterCol = iterComp->begin(); iterCol != iterComp->end(); ++iterCol)
            {
                accWidth += iterCol->width_;
                if (posX < accWidth)
                {
                    const size_t compPos = iterComp - compAbsWidths.begin();
                    return std::make_pair(iterCol->type_, compPos);
                }
            }
    }
    return NoValue();
}


wxRect Grid::getCellArea(size_t row, ColumnType colType, size_t compPos) const
{
    const wxRect& colArea = getColumnLabelArea(colType, compPos);
    const wxRect& rowArea = rowLabelWin_->getRowLabelArea(row);
    return wxRect(wxPoint(colArea.x, rowArea.y), wxSize(colArea.width, rowArea.height));
}


void Grid::setGridCursor(size_t row, size_t compPos)
{
    if (compPos < comp.size())
    {
        mainWin_->setCursor(row, compPos);
        mainWin_->makeRowVisible(row);

        std::for_each(comp.begin(), comp.end(), [](Grid::Component& c) { c.selection.clear(); }); //clear selection, do NOT fire event
        selectRangeAndNotify(row, row, compPos); //set new selection + fire event

        mainWin_->Refresh();
        rowLabelWin_->Refresh(); //row labels! (Kubuntu)
    }
}


void Grid::selectRangeAndNotify(ptrdiff_t rowFrom, ptrdiff_t rowTo, size_t compPos, bool positive)
{
    if (compPos < comp.size())
    {
        //sort + convert to half-open range
        auto rowFirst = std::min(rowFrom, rowTo);
        auto rowLast  = std::max(rowFrom, rowTo) + 1;

        const size_t rowCount = getRowCount();
        numeric::confine<ptrdiff_t>(rowFirst, 0, rowCount);
        numeric::confine<ptrdiff_t>(rowLast,  0, rowCount);

        comp[compPos].selection.selectRange(rowFirst, rowLast, positive);

        //notify event
        GridRangeSelectEvent selectionEvent(rowFirst, rowLast, compPos, positive);
        if (wxEvtHandler* evtHandler = GetEventHandler())
            evtHandler->ProcessEvent(selectionEvent);

        mainWin_->Refresh();
    }
}


void Grid::clearSelection(bool emitSelectRangeEvent, size_t compPos)
{
    if (compPos < comp.size())
    {
        comp[compPos].selection.clear();
        mainWin_->Refresh();

        if (emitSelectRangeEvent)
        {
            //notify event, even if we're not triggered by user interaction
            GridRangeSelectEvent unselectionEvent(0, 0, compPos, false);
            if (wxEvtHandler* evtHandler = GetEventHandler())
                evtHandler->ProcessEvent(unselectionEvent);
        }
    }
}


void Grid::clearSelectionAllAndNotify()
{
    for (size_t compPos = 0; compPos < comp.size(); ++compPos)
        clearSelection(true, compPos);
}


void Grid::scrollTo(size_t row)
{
    const wxRect labelRect = rowLabelWin_->getRowLabelArea(row); //returns empty rect if column not found
    if (labelRect.height > 0)
    {
        int pixelsPerUnitY = 0;
        GetScrollPixelsPerUnit(nullptr, &pixelsPerUnitY);
        if (pixelsPerUnitY > 0)
        {
            const int scrollPosYNew = labelRect.GetTopLeft().y / pixelsPerUnitY;
            int scrollPosXOld = 0;
            int scrollPosYOld = 0;
            GetViewStart(&scrollPosXOld, &scrollPosYOld);

            if (scrollPosYOld != scrollPosYNew) //support polling
            {
                Scroll(scrollPosXOld, scrollPosYNew);
                updateWindowSizes(); //may show horizontal scroll bar
                Refresh();
            }
        }
    }
}


std::pair<size_t, size_t> Grid::getGridCursor() const
{
    return mainWin_->getCursor();
}


ptrdiff_t Grid::getBestColumnSize(size_t col, size_t compPos) const
{
    if (compPos < comp.size())
    {
        const auto& visibleCols = comp[compPos].visibleCols;
        auto dataView = comp[compPos].dataView_;
        if (dataView && col < visibleCols.size())
        {
            const ColumnType type = visibleCols[col].type_;

            wxClientDC dc(mainWin_);
            dc.SetFont(mainWin_->GetFont()); //harmonize with MainWin::render()

            size_t maxSize = 0;

            auto rowRange = rowLabelWin_->getRowsOnClient(mainWin_->GetClientRect()); //returns range [begin, end)
            for (auto row = rowRange.first; row < rowRange.second; ++row)
                maxSize = std::max(maxSize, dataView->getBestSize(dc, row, type));

            return maxSize;
        }
    }
    return -1;
}


void Grid::setColWidthAndNotify(ptrdiff_t width, size_t col, size_t compPos, bool notifyAsync)
{
    if (compPos < comp.size() && col < comp[compPos].visibleCols.size())
    {
        VisibleColumn& vcRs = comp[compPos].visibleCols[col];
        const int mainWinWidth = mainWin_->GetClientSize().GetWidth();
        const ptrdiff_t stretchTotal = getStretchTotal();
        const ptrdiff_t stretchedWithCol = getColStretchedWidth(vcRs.stretch_, stretchTotal, mainWinWidth);

        vcRs.offset_ = width - stretchedWithCol; //width := stretchedWidth + offset

        //CAVEATS:
        //I. fixed-size columns: normalize offset so that resulting width is at least COLUMN_MIN_WIDTH: this is NOT enforced by getColWidths()!
        //II. stretched columns: do not allow user to set offsets so small that they result in negative (non-normalized) widths: this gives an
        //unusual delay when enlarging the column again later
        vcRs.offset_ = std::max(vcRs.offset_, COLUMN_MIN_WIDTH - stretchedWithCol);

        //III. resizing any column should normalize *all* other stretched columns' offsets considering current mainWinWidth!
        // test case:
        //1. have columns, both fixed-size and stretched, fit whole window width
        //2. shrink main window width so that horizontal scrollbars are shown despite the streched column
        //3. shrink a fixed-size column so that the scrollbars vanish and columns cover full width again
        //4. now verify that the stretched column is resizing immediately if main window is enlarged again
        std::for_each(comp.begin(), comp.end(), [&](Component& c)
        {
            std::for_each(c.visibleCols.begin(), c.visibleCols.end(), [&](VisibleColumn& vc)
            {
                if (vc.stretch_ > 0) //normalize stretched columns only
                {
                    const ptrdiff_t stretchedWidth = Grid::getColStretchedWidth(vc.stretch_, stretchTotal, mainWinWidth);
                    vc.offset_ = std::max(vc.offset_, COLUMN_MIN_WIDTH - stretchedWidth);
                }
            });
        });

        GridColumnResizeEvent sizeEvent(vcRs.offset_, vcRs.type_, compPos);
        if (wxEvtHandler* evtHandler = GetEventHandler())
        {
            if (notifyAsync)
                evtHandler->AddPendingEvent(sizeEvent);
            else
                evtHandler->ProcessEvent(sizeEvent);
        }
    }
    else
        assert(false);
}


void Grid::autoSizeColumns(size_t compPos)
{
    if (compPos < comp.size() && comp[compPos].allowColumnResize)
    {
        auto& visibleCols = comp[compPos].visibleCols;
        for (auto it = visibleCols.begin(); it != visibleCols.end(); ++it)
        {
            const size_t col = it - visibleCols.begin();
            const ptrdiff_t bestWidth = getBestColumnSize(col, compPos); //return -1 on error
            if (bestWidth >= 0)
                setColWidthAndNotify(bestWidth, col, compPos, true);
        }
        updateWindowSizes();
        Refresh();
    }
}


ptrdiff_t Grid::getStretchTotal() const //sum of all stretch factors
{
    return std::accumulate(comp.begin(), comp.end(), static_cast<ptrdiff_t>(0),
                           [](ptrdiff_t sum, const Component& c)
    {
        return sum + std::accumulate(c.visibleCols.begin(), c.visibleCols.end(), static_cast<ptrdiff_t>(0),
        [](ptrdiff_t val2, const Grid::VisibleColumn& vc) { return val2 + vc.stretch_; });
    });
}


ptrdiff_t Grid::getColStretchedWidth(ptrdiff_t stretch, ptrdiff_t stretchTotal, int mainWinWidth) //final width := stretchedWidth + (normalized) offset
{
    return stretchTotal > 0 ? mainWinWidth * stretch / stretchTotal : 0; //rounds down! => not all of clientWidth is correctly distributed according to stretch factors
}


std::vector<std::vector<Grid::ColumnWidth>> Grid::getColWidths() const
{
    return getColWidths(mainWin_->GetClientSize().GetWidth());
}


std::vector<std::vector<Grid::ColumnWidth>> Grid::getColWidths(int mainWinWidth) const //evaluate stretched columns; structure matches "comp"
{
    std::vector<std::vector<ColumnWidth>> output;

    const ptrdiff_t stretchTotal = getStretchTotal();

    std::for_each(comp.begin(), comp.end(), [&](const Component& c)
    {
        output.push_back(std::vector<ColumnWidth>());
        auto& compWidths = output.back();

        std::for_each(c.visibleCols.begin(), c.visibleCols.end(), [&](const VisibleColumn& vc)
        {
            ptrdiff_t widthNormalized = Grid::getColStretchedWidth(vc.stretch_, stretchTotal, mainWinWidth) + vc.offset_;

            if (vc.stretch_ > 0)
                widthNormalized = std::max(widthNormalized, static_cast<ptrdiff_t>(COLUMN_MIN_WIDTH)); //normalization really needed here: e.g. smaller main window would result in negative width
            else
                widthNormalized = std::max(widthNormalized, static_cast<ptrdiff_t>(0)); //support smaller width than COLUMN_MIN_WIDTH if set via configuration

            compWidths.push_back(Grid::ColumnWidth(vc.type_, widthNormalized));
        });
    });
    return output;
}


ptrdiff_t Grid::getColWidthsSum(int mainWinWidth) const
{
    auto widths = getColWidths(mainWinWidth);
    return std::accumulate(widths.begin(), widths.end(), static_cast<ptrdiff_t>(0),
                           [](ptrdiff_t sum, const std::vector<Grid::ColumnWidth>& cols)
    {
        return sum + std::accumulate(cols.begin(), cols.end(), static_cast<ptrdiff_t>(0),
        [](ptrdiff_t val2, const Grid::ColumnWidth& cw) { return val2 + cw.width_; });
    });
};