wxWidgets/interface/vscroll.h

/////////////////////////////////////////////////////////////////////////////
// Name:        vscroll.h
// Purpose:     interface of wxVarHScrollHelper
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/**
    @class wxVarHScrollHelper
    @wxheader{vscroll.h}

    This class provides functions wrapping the
    wxVarScrollHelperBase class, targeted for
    horizontal-specific scrolling using wxHScrolledWindow.

    Like wxVarScrollHelperBase, this class is mostly only useful to those classes
    built into wxWidgets deriving from here, and this documentation is mostly
    only provided for referencing those functions provided. You will likely want
    to derive your window from wxHScrolledWindow rather than from here directly.

    @library{wxcore}
    @category{FIXME}

    @see wxHScrolledWindow, wxHVScrolledWindow, wxVScrolledWindow
*/
class wxVarHScrollHelper : public wxVarScrollHelperBase
{
public:
    /**
        Constructor taking the target window to be scrolled by this helper class.
        This will attach scroll event handlers to the target window to catch and
        handle scroll events appropriately.
    */
    wxVarHScrollHelper(wxWindow* winToScroll);

    /**
        This class forwards calls from
        wxVarScrollHelperBase::EstimateTotalSize
        to this function so derived classes can override either just the height or
        the width estimation, or just estimate both differently if desired in any
        wxHVScrolledWindow derived class.
        Please note that this function will not be called if @c EstimateTotalSize()
        is overridden in your derived class.
    */
    virtual wxCoord EstimateTotalWidth() const;

    /**
        Returns the number of columns the target window contains.

        @see SetColumnCount()
    */
    size_t GetColumnCount() const;

    /**
        Returns the index of the first visible column based on the scroll position.
    */
    size_t GetVisibleColumnsBegin() const;

    /**
        Returns the index of the last visible column based on the scroll position. This
        includes the last column even if it is only partially visible.
    */
    size_t GetVisibleColumnsEnd() const;

    /**
        Returns @true if the given column is currently visible (even if only
        partially visible) or @false otherwise.
    */
    bool IsColumnVisible(size_t column) const;

    /**
        This function must be overridden in the derived class, and should return the
        width of the given column in pixels.
    */
    virtual wxCoord OnGetColumnWidth(size_t column) const;

    /**
        This function doesn't have to be overridden but it may be useful to do so if
        calculating the columns' sizes is a relatively expensive operation as it gives
        your code a chance to calculate several of them at once and cache the result
        if necessary.
        @c OnGetColumnsWidthHint() is normally called just before
        OnGetColumnWidth() but you
        shouldn't rely on the latter being called for all columns in the interval
        specified here. It is also possible that OnGetColumnWidth() will be called for
        units outside of this interval, so this is really just a hint, not a promise.
        Finally, note that columnMin is inclusive, while columnMax is exclusive.
    */
    virtual void OnGetColumnsWidthHint(size_t columnMin,
                                       size_t columnMax) const;

    /**
        Triggers a refresh for just the given column's area of the window if it's
        visible.
    */
    virtual void RefreshColumn(size_t column);

    /**
        Triggers a refresh for the area between the specified range of columns given
        (inclusively).
    */
    virtual void RefreshColumns(size_t from, size_t to);

    /**
        Scroll by the specified number of pages which may be positive (to scroll right)
        or negative (to scroll left).
    */
    virtual bool ScrollColumnPages(int pages);

    /**
        Scroll by the specified number of columns which may be positive (to scroll
        right)
        or negative (to scroll left).
        Returns @true if the window was scrolled, @false otherwise (for
        example, if we're trying to scroll right but we are already showing the last
        column).
    */
    virtual bool ScrollColumns(int columns);

    /**
        Scroll to the specified column. It will become the first visible column in the
        window.
        Returns @true if we scrolled the window, @false if nothing was done.
    */
    bool ScrollToColumn(size_t column);

    /**
        Set the number of columns the window contains. The derived class must provide
        the widths for all columns with indices up to the one given here in it's
        OnGetColumnWidth() implementation.
    */
    void SetColumnCount(size_t columnCount);
};



/**
    @class wxVarVScrollHelper
    @wxheader{vscroll.h}

    This class provides functions wrapping the
    wxVarScrollHelperBase class, targeted for
    vertical-specific scrolling using wxVScrolledWindow.

    Like wxVarScrollHelperBase, this class is mostly only useful to those classes
    built into wxWidgets deriving from here, and this documentation is mostly
    only provided for referencing those functions provided. You will likely want
    to derive your window from wxVScrolledWindow rather than from here directly.

    @library{wxcore}
    @category{FIXME}

    @see wxHScrolledWindow, wxHVScrolledWindow, wxVScrolledWindow
*/
class wxVarVScrollHelper : public wxVarScrollHelperBase
{
public:
    /**
        Constructor taking the target window to be scrolled by this helper class.
        This will attach scroll event handlers to the target window to catch and
        handle scroll events appropriately.
    */
    wxVarVScrollHelper(wxWindow* winToScroll);

    /**
        This class forwards calls from
        wxVarScrollHelperBase::EstimateTotalSize
        to this function so derived classes can override either just the height or
        the width estimation, or just estimate both differently if desired in any
        wxHVScrolledWindow derived class.
        Please note that this function will not be called if @c EstimateTotalSize()
        is overridden in your derived class.
    */
    virtual wxCoord EstimateTotalHeight() const;

    /**
        Returns the number of rows the target window contains.

        @see SetRowCount()
    */
    size_t GetRowCount() const;

    /**
        Returns the index of the first visible row based on the scroll position.
    */
    size_t GetVisibleRowsBegin() const;

    /**
        Returns the index of the last visible row based on the scroll position. This
        includes the last row even if it is only partially visible.
    */
    size_t GetVisibleRowsEnd() const;

    /**
        Returns @true if the given row is currently visible (even if only
        partially visible) or @false otherwise.
    */
    bool IsRowVisible(size_t row) const;

    /**
        This function must be overridden in the derived class, and should return the
        height of the given row in pixels.
    */
    virtual wxCoord OnGetRowHeight(size_t row) const;

    /**
        This function doesn't have to be overridden but it may be useful to do so if
        calculating the rows' sizes is a relatively expensive operation as it gives
        your code a chance to calculate several of them at once and cache the result
        if necessary.
        @c OnGetRowsHeightHint() is normally called just before
        OnGetRowHeight() but you
        shouldn't rely on the latter being called for all rows in the interval
        specified here. It is also possible that OnGetRowHeight() will be called for
        units outside of this interval, so this is really just a hint, not a promise.
        Finally, note that rowMin is inclusive, while rowMax is exclusive.
    */
    virtual void OnGetRowsHeightHint(size_t rowMin, size_t rowMax) const;

    /**
        Triggers a refresh for just the given row's area of the window if it's visible.
    */
    virtual void RefreshRow(size_t row);

    /**
        Triggers a refresh for the area between the specified range of rows given
        (inclusively).
    */
    virtual void RefreshRows(size_t from, size_t to);

    /**
        Scroll by the specified number of pages which may be positive (to scroll down)
        or negative (to scroll up).
    */
    virtual bool ScrollRowPages(int pages);

    /**
        Scroll by the specified number of rows which may be positive (to scroll down)
        or negative (to scroll up).
        Returns @true if the window was scrolled, @false otherwise (for
        example, if we're trying to scroll down but we are already showing the last
        row).
    */
    virtual bool ScrollRows(int rows);

    /**
        Scroll to the specified row. It will become the first visible row in the window.
        Returns @true if we scrolled the window, @false if nothing was done.
    */
    bool ScrollToRow(size_t row);

    /**
        Set the number of rows the window contains. The derived class must provide the
        heights for all rows with indices up to the one given here in it's
        OnGetRowHeight() implementation.
    */
    void SetRowCount(size_t rowCount);
};



/**
    @class wxVarScrollHelperBase
    @wxheader{vscroll.h}

    This class provides all common base functionality for scroll calculations
    shared among all variable scrolled window implementations as well as
    automatic scrollbar functionality, saved scroll positions, controlling
    target windows to be scrolled, as well as defining all required virtual
    functions that need to be implemented for any orientation specific work.

    Documentation of this class is provided specifically for referencing use
    of the functions provided by this class for use with the variable scrolled
    windows that derive from here. You will likely want to derive your window
    from one of the already implemented variable scrolled windows rather than
    from wxVarScrollHelperBase directly.

    @library{wxcore}
    @category{FIXME}

    @see wxHScrolledWindow, wxHVScrolledWindow, wxVScrolledWindow
*/
class wxVarScrollHelperBase
{
public:
    /**
        Constructor taking the target window to be scrolled by this helper class.
        This will attach scroll event handlers to the target window to catch and
        handle scroll events appropriately.
    */
    wxVarScrollHelperBase(wxWindow* winToScroll);

    /**
        Virtual destructor for detaching scroll event handlers attached with this
        helper class.
    */
    ~wxVarScrollHelperBase();

    /**
        Translates the logical coordinate given to the current device coordinate.
        For example, if the window is scrolled 10 units and each scroll unit
        represents 10 device units (which may not be the case since this class allows
        for variable scroll unit sizes), a call to this function with a coordinate of
        15 will return -85.

        @see CalcUnscrolledPosition()
    */
    int CalcScrolledPosition(int coord) const;

    /**
        Translates the device coordinate given to the corresponding logical
        coordinate. For example, if the window is scrolled 10 units and each scroll
        unit represents 10 device units (which may not be the case since this class
        allows for variable scroll unit sizes), a call to this function with a
        coordinate of 15 will return 115.

        @see CalcScrolledPosition()
    */
    int CalcUnscrolledPosition(int coord) const;

    /**
        With physical scrolling on (when this is @true), the device origin is
        changed properly when a wxPaintDC is prepared,
        children are actually moved and laid out properly, and the contents of the
        window (pixels) are actually moved. When this is @false, you are
        responsible for repainting any invalidated areas of the window yourself to
        account for the new scroll position.
    */
    void EnablePhysicalScrolling(bool scrolling = true);

    /**
        When the number of scroll units change, we try to estimate the total size of
        all units when the full window size is needed (i.e. to calculate the scrollbar
        thumb size). This is a rather expensive operation in terms of unit access, so
        if the user code may estimate the average size better or faster than we do, it
        should override this function to implement its own logic. This function should
        return the best guess for the total virtual window size.
        Note that although returning a totally wrong value would still work, it risks
        resulting in very strange scrollbar behaviour so this function should really
        try to make the best guess possible.
    */
    virtual wxCoord EstimateTotalSize() const;

    /**
        This function needs to be overridden in the in the derived class to return the
        window size with respect to the opposing orientation. If this is a vertical
        scrolled window, it should return the height.

        @see GetOrientationTargetSize()
    */
    virtual int GetNonOrientationTargetSize() const;

    /**
        This function need to be overridden to return the orientation that this helper
        is working with, either @c wxHORIZONTAL or @c wxVERTICAL.
    */
    virtual wxOrientation GetOrientation() const;

    /**
        This function needs to be overridden in the in the derived class to return the
        window size with respect to the orientation this helper is working with. If
        this is a vertical scrolled window, it should return the width.

        @see GetNonOrientationTargetSize()
    */
    virtual int GetOrientationTargetSize() const;

    /**
        This function will return the target window this helper class is currently
        scrolling.

        @see SetTargetWindow()
    */
    wxWindow* GetTargetWindow() const;

    /**
        Returns the index of the first visible unit based on the scroll position.
    */
    size_t GetVisibleBegin() const;

    /**
        Returns the index of the last visible unit based on the scroll position. This
        includes the last unit even if it is only partially visible.
    */
    size_t GetVisibleEnd() const;

    /**
        Returns @true if the given scroll unit is currently visible (even if only
        partially visible) or @false otherwise.
    */
    bool IsVisible(size_t unit) const;

    /**
        This function must be overridden in the derived class, and should return the
        size of the given unit in pixels.
    */
    virtual wxCoord OnGetUnitSize(size_t unit) const;

    /**
        This function doesn't have to be overridden but it may be useful to do so if
        calculating the units' sizes is a relatively expensive operation as it gives
        your code a chance to calculate several of them at once and cache the result
        if necessary.
        @c OnGetUnitsSizeHint() is normally called just before
        OnGetUnitSize() but you
        shouldn't rely on the latter being called for all units in the interval
        specified here. It is also possible that OnGetUnitSize() will be called for
        units outside of this interval, so this is really just a hint, not a promise.
        Finally, note that unitMin is inclusive, while unitMax is exclusive.
    */
    virtual void OnGetUnitsSizeHint(size_t unitMin, size_t unitMax) const;

    /**
        Recalculate all parameters and repaint all units.
    */
    virtual void RefreshAll();

    /**
        Normally the window will scroll itself, but in some rare occasions you might
        want it to scroll (part of) another window (e.g. a child of it in order to
        scroll only a portion the area between the scrollbars like a spreadsheet where
        only the cell area will move).

        @see GetTargetWindow()
    */
    void SetTargetWindow(wxWindow* target);

    /**
        Update the thumb size shown by the scrollbar.
    */
    virtual void UpdateScrollbar();

    /**
        Returns the virtual scroll unit under the device unit given accounting for
        scroll position or @c wxNOT_FOUND if none (i.e. if it is below the last
        item).
    */
    int VirtualHitTest(wxCoord coord) const;
};



/**
    @class wxVScrolledWindow
    @wxheader{vscroll.h}

    In the name of this class, "V" may stand for "variable" because it can be
    used for scrolling rows of variable heights; "virtual", because it is not
    necessary to know the heights of all rows in advance -- only those which
    are shown on the screen need to be measured; or even "vertical", because
    this class only supports scrolling vertically.

    In any case, this is a generalization of the
    wxScrolledWindow class which can be only used when
    all rows have the same heights. It lacks some other wxScrolledWindow features
    however, notably it can't scroll only a rectangle of the window and not its
    entire client area.

    To use this class, you need to derive from it and implement the
    wxVarVScrollHelper::OnGetRowHeight pure virtual
    method. You also must call wxVarVScrollHelper::SetRowCount
    to let the base class know how many rows it should display, but from that
    moment on the scrolling is handled entirely by wxVScrolledWindow. You only
    need to draw the visible part of contents in your @c OnPaint() method as
    usual. You should use wxVarVScrollHelper::GetVisibleRowsBegin
    and wxVarVScrollHelper::GetVisibleRowsEnd to
    select the lines to display. Note that the device context origin is not shifted
    so the first visible row always appears at the point (0, 0) in physical as
    well as logical coordinates.

    @library{wxcore}
    @category{miscwnd}

    @see wxHScrolledWindow, wxHVScrolledWindow
*/
class wxVScrolledWindow : public wxPanel
{
public:
    //@{
    /**
        This is the normal constructor, no need to call @c Create() after using this
        one.
        Note that @c wxVSCROLL is always automatically added to our style, there is
        no need to specify it explicitly.

        @param parent
            The parent window, must not be @NULL
        @param id
            The identifier of this window, wxID_ANY by default
        @param pos
            The initial window position
        @param size
            The initial window size
        @param style
            The window style. There are no special style bits defined for
            this class.
        @param name
            The name for this window; usually not used
    */
    wxVScrolledWindow();
    wxVScrolledWindow(wxWindow* parent, wxWindowID id = wxID_ANY,
                      const wxPoint& pos = wxDefaultPosition,
                      const wxSize& size = wxDefaultSize,
                      long style = 0,
                      const wxString& name = wxPanelNameStr);
    //@}

    /**
        Same as the @ref wxvscrolledwindow() "non-default constuctor"
        but returns status code: @true if ok, @false if the window couldn't
        be created.
        Just as with the constructor above, the @c wxVSCROLL style is always used,
        there is no need to specify it explicitly.
    */
    bool Create(wxWindow* parent, wxWindowID id = wxID_ANY,
                const wxPoint& pos = wxDefaultPosition,
                const wxSize& size = wxDefaultSize,
                long style = 0,
                const wxString& name = wxPanelNameStr);

    //@{
    /**
        The following functions provide backwards compatibility for applications
        originally built using wxVScrolledWindow in 2.6 or 2.8. Originally,
        wxVScrolledWindow referred to scrolling "lines". We now use "units" in
        wxVarScrollHelperBase to avoid implying any orientation (since the functions
        are used for both horizontal and vertical scrolling in derived classes). And
        in the new wxVScrolledWindow and wxHScrolledWindow classes, we refer to them
        as "rows" and "columns", respectively. This is to help clear some confusion
        in not only those classes, but also in wxHVScrolledWindow where functions
        are inherited from both.
        You are encouraged to update any existing code using these function to use
        the new replacements mentioned below, and avoid using these functions for
        any new code as they are deprecated.

        Deprecated for wxVarVScrollHelper::SetRowCount.
    */
    size_t GetFirstVisibleLine();
    const size_t GetLastVisibleLine();
    const size_t GetLineCount();
    const int HitTest(wxCoord x, wxCoord y);
    const int HitTest(const wxPoint& pt);
    const virtual wxCoord OnGetLineHeight(size_t line);
    const virtual void OnGetLinesHint(size_t lineMin,
                                      size_t lineMax);
    const virtual void RefreshLine(size_t line);
    virtual void RefreshLines(size_t from, size_t to);
    virtual bool ScrollLines(int lines);
    virtual bool ScrollPages(int pages);
    bool ScrollToLine(size_t line);
    void SetLineCount(size_t count);
    //@}
};



/**
    @class wxHVScrolledWindow
    @wxheader{vscroll.h}

    This window inherits all functionality of both vertical and horizontal,
    variable scrolled windows. It automatically handles everything needed to
    scroll both axis simultaneously with both variable row heights and variable
    column widths.

    This is a generalization of the wxScrolledWindow
    class which can be only used when all rows and columns are the same size. It
    lacks some other wxScrolledWindow features however, notably it can't scroll
    only a rectangle of the window and not its entire client area.

    To use this class, you must derive from it and implement both the
    wxVarVScrollHelper::OnGetRowHeight and
    wxVarHScrollHelper::OnGetColumnWidth pure virtual
    methods to let the base class know how many rows and columns it should
    display. You also need to set the total rows and columns the window contains,
    but from that moment on the scrolling is handled entirely by
    wxHVScrolledWindow. You only need to draw the visible part of contents in
    your @c OnPaint() method as usual. You should use
    wxVarHVScrollHelper::GetVisibleBegin
    and wxVarHVScrollHelper::GetVisibleEnd to select the
    lines to display. Note that the device context origin is not shifted so the
    first visible row and column always appear at the point (0, 0) in physical
    as well as logical coordinates.

    @library{wxcore}
    @category{FIXME}

    @see wxHScrolledWindow, wxVScrolledWindow
*/
class wxHVScrolledWindow : public wxPanel
{
public:
    //@{
    /**
        This is the normal constructor, no need to call @c Create() after using this
        one.
        Note that @c wxHSCROLL and @c wxVSCROLL are always automatically added
        to our styles, there is no need to specify it explicitly.

        @param parent
            The parent window, must not be @NULL
        @param id
            The identifier of this window, wxID_ANY by default
        @param pos
            The initial window position
        @param size
            The initial window size
        @param style
            The window style. There are no special style bits defined for
            this class.
        @param name
            The name for this window; usually not used
    */
    wxHVScrolledWindow();
    wxHVScrolledWindow(wxWindow* parent,
                       wxWindowID id = wxID_ANY,
                       const wxPoint& pos = wxDefaultPosition,
                       const wxSize& size = wxDefaultSize,
                       long style = 0,
                       const wxString& name = wxPanelNameStr);
    //@}

    /**
        Same as the @ref wxhvscrolledwindow() "non-default constuctor"
        but returns status code: @true if ok, @false if the window couldn't
        be created.
        Just as with the constructor above, the @c wxHSCROLL and @c wxVSCROLL
        styles are always used, there is no need to specify it explicitly.
    */
    bool Create(wxWindow* parent, wxWindowID id = wxID_ANY,
                const wxPoint& pos = wxDefaultPosition,
                const wxSize& size = wxDefaultSize,
                long style = 0,
                const wxString& name = wxPanelNameStr);
};



/**
    @class wxVarHVScrollHelper
    @wxheader{vscroll.h}

    This class provides functions wrapping the
    wxVarHScrollHelper and
    wxVarVScrollHelper classes, targeted for
    scrolling a window in both axis using
    wxHVScrolledWindow. Since this class is also
    the join class of the horizontal and vertical scrolling functionality, it
    also addresses some wrappers that help avoid the need to specify class scope
    in your wxHVScrolledWindow-derived class when using wxVarScrollHelperBase
    functionality.

    Like all three of it's scroll helper base classes, this class is mostly only
    useful to those classes built into wxWidgets deriving from here, and this
    documentation is mostly only provided for referencing those functions
    provided. You will likely want to derive your window from wxHVScrolledWindow
    rather than from here directly.

    @library{wxcore}
    @category{FIXME}

    @see wxHScrolledWindow, wxHVScrolledWindow, wxVScrolledWindow
*/
class wxVarHVScrollHelper : public wxVarVScrollHelper
{
public:
    /**
        Constructor taking the target window to be scrolled by this helper class.
        This will attach scroll event handlers to the target window to catch and
        handle scroll events appropriately.
    */
    wxVarHVScrollHelper(wxWindow* winToScroll);

    /**
        With physical scrolling on (when this is @true), the device origin is
        changed properly when a wxPaintDC is prepared,
        children are actually moved and laid out properly, and the contents of the
        window (pixels) are actually moved. When this is @false, you are
        responsible for repainting any invalidated areas of the window yourself to
        account for the new scroll position.

        @param vscrolling
            Specifies if physical scrolling should be turned on when scrolling
        vertically.
        @param hscrolling
            Specifies if physical scrolling should be turned on when scrolling
        horizontally.
    */
    void EnablePhysicalScrolling(bool vscrolling = true,
                                 bool hscrolling = true);

    /**
        Returns the number of columns and rows the target window contains.

        @see SetRowColumnCount()
    */
    wxSize GetRowColumnCount() const;

    /**
        Returns the index of the first visible column and row based on the current
        scroll position.
    */
    wxPosition GetVisibleBegin() const;

    /**
        Returns the index of the last visible column and row based on the scroll
        position. This includes any partially visible columns or rows.
    */
    wxPosition GetVisibleEnd() const;

    //@{
    /**
        Returns @true if both the given row and column are currently visible
        (even if only partially visible) or @false otherwise.
    */
    bool IsVisible(size_t row, size_t column) const;
    const bool IsVisible(const wxPosition& pos) const;
    //@}

    //@{
    /**
        Triggers a refresh for just the area shared between the given row and column
        of the window if it is visible.
    */
    virtual void RefreshRowColumn(size_t row, size_t column);
    virtual void RefreshRowColumn(const wxPosition& pos);
    //@}

    //@{
    /**
        Triggers a refresh for the visible area shared between all given rows and
        columns (inclusive) of the window. If the target window for both orientations
        is the same, the rectangle of cells is refreshed; if the target windows
        differ, the entire client size opposite the orientation direction is
        refreshed between the specified limits.
    */
    virtual void RefreshRowsColumns(size_t fromRow, size_t toRow,
                                    size_t fromColumn,
                                    size_t toColumn);
    virtual void RefreshRowsColumns(const wxPosition& from,
                                    const wxPosition& to);
    //@}

    //@{
    /**
        Scroll to the specified row and column. It will become the first visible row
        and column in the window. Returns @true if we scrolled the window,
        @false if nothing was done.
    */
    bool ScrollToRowColumn(size_t row, size_t column);
    bool ScrollToRowColumn(const wxPosition& pos);
    //@}

    /**
        Set the number of rows and columns the target window will contain. The
        derived class must provide the sizes for all rows and columns with indices up
        to the ones given here in it's wxVarVScrollHelper::OnGetRowHeight
        and wxVarHScrollHelper::OnGetColumnWidth implementations,
        respectively.
    */
    void SetRowColumnCount(size_t rowCount, size_t columnCount);

    //@{
    /**
        Returns the virtual scroll unit under the device unit given accounting for
        scroll position or @c wxNOT_FOUND (for the row, column, or possibly both
        values) if none.
    */
    wxPosition VirtualHitTest(wxCoord x, wxCoord y) const;
    const wxPosition  VirtualHitTest(const wxPoint& pos) const;
    //@}
};



/**
    @class wxHScrolledWindow
    @wxheader{vscroll.h}

    In the name of this class, "H" stands for "horizontal" because it can be
    used for scrolling columns of variable widths. It is not necessary to know
    the widths of all columns in advance -- only those which are shown on the
    screen need to be measured.

    In any case, this is a generalization of the
    wxScrolledWindow class which can be only used when
    all columns have the same widths. It lacks some other wxScrolledWindow features
    however, notably it can't scroll only a rectangle of the window and not its
    entire client area.

    To use this class, you need to derive from it and implement the
    wxVarHScrollHelper::OnGetColumnWidth pure virtual
    method. You also must call wxVarHScrollHelper::SetColumnCount
    to let the base class know how many columns it should display, but from that
    moment on the scrolling is handled entirely by wxHScrolledWindow. You only
    need to draw the visible part of contents in your @c OnPaint() method as
    usual. You should use wxVarHScrollHelper::GetVisibleColumnsBegin
    and wxVarHScrollHelper::GetVisibleColumnsEnd to
    select the lines to display. Note that the device context origin is not shifted
    so the first visible column always appears at the point (0, 0) in physical as
    well as logical coordinates.

    @library{wxcore}
    @category{FIXME}

    @see wxHVScrolledWindow, wxVScrolledWindow
*/
class wxHScrolledWindow : public wxPanel
{
public:
    //@{
    /**
        This is the normal constructor, no need to call @c Create() after using this
        one.
        Note that @c wxHSCROLL is always automatically added to our style, there is
        no need to specify it explicitly.

        @param parent
            The parent window, must not be @NULL
        @param id
            The identifier of this window, wxID_ANY by default
        @param pos
            The initial window position
        @param size
            The initial window size
        @param style
            The window style. There are no special style bits defined for
            this class.
        @param name
            The name for this window; usually not used
    */
    wxHScrolledWindow();
    wxHScrolledWindow(wxWindow* parent, wxWindowID id = wxID_ANY,
                      const wxPoint& pos = wxDefaultPosition,
                      const wxSize& size = wxDefaultSize,
                      long style = 0,
                      const wxString& name = wxPanelNameStr);
    //@}

    /**
        Same as the @ref wxhscrolledwindow() "non-default constuctor"
        but returns status code: @true if ok, @false if the window couldn't
        be created.
        Just as with the constructor above, the @c wxHSCROLL style is always used,
        there is no need to specify it explicitly.
    */
    bool Create(wxWindow* parent, wxWindowID id = wxID_ANY,
                const wxPoint& pos = wxDefaultPosition,
                const wxSize& size = wxDefaultSize,
                long style = 0,
                const wxString& name = wxPanelNameStr);
};