(svn r25652) -Fix: Improve text caret movement for complex scripts.

[openttd/fttd.git] / src / widget_type.h

/* $Id$ */

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file widget_type.h Definitions about widgets. */

#ifndef WIDGET_TYPE_H
#define WIDGET_TYPE_H

#include "core/alloc_type.hpp"
#include "core/bitmath_func.hpp"
#include "core/math_func.hpp"
#include "strings_type.h"
#include "gfx_type.h"
#include "window_type.h"

static const int WIDGET_LIST_END = -1; ///< indicate the end of widgets' list for vararg functions

/** Bits of the #WWT_MATRIX widget data. */
enum MatrixWidgetValues {
        /* Number of column bits of the WWT_MATRIX widget data. */
        MAT_COL_START = 0, ///< Lowest bit of the number of columns.
        MAT_COL_BITS  = 8, ///< Number of bits for the number of columns in the matrix.

        /* Number of row bits of the WWT_MATRIX widget data. */
        MAT_ROW_START = 8, ///< Lowest bit of the number of rows.
        MAT_ROW_BITS  = 8, ///< Number of bits for the number of rows in the matrix.
};

/** Values for an arrow widget */
enum ArrowWidgetValues {
        AWV_DECREASE, ///< Arrow to the left or in case of RTL to the right
        AWV_INCREASE, ///< Arrow to the right or in case of RTL to the left
        AWV_LEFT,     ///< Force the arrow to the left
        AWV_RIGHT,    ///< Force the arrow to the right
};

/**
 * Window widget types, nested widget types, and nested widget part types.
 */
enum WidgetType {
        /* Window widget types. */
        WWT_EMPTY,      ///< Empty widget, place holder to reserve space in widget array

        WWT_PANEL,      ///< Simple depressed panel
        WWT_INSET,      ///< Pressed (inset) panel, most commonly used as combo box _text_ area
        WWT_IMGBTN,     ///< (Toggle) Button with image
        WWT_IMGBTN_2,   ///< (Toggle) Button with diff image when clicked
        WWT_ARROWBTN,   ///< (Toggle) Button with an arrow
        WWT_TEXTBTN,    ///< (Toggle) Button with text
        WWT_TEXTBTN_2,  ///< (Toggle) Button with diff text when clicked
        WWT_LABEL,      ///< Centered label
        WWT_TEXT,       ///< Pure simple text
        WWT_MATRIX,     ///< Grid of rows and columns. @see MatrixWidgetValues
        WWT_FRAME,      ///< Frame
        WWT_CAPTION,    ///< Window caption (window title between closebox and stickybox)

        WWT_DEBUGBOX,   ///< NewGRF debug box (at top-right of a window, between WWT_CAPTION and WWT_SHADEBOX)
        WWT_SHADEBOX,   ///< Shade box (at top-right of a window, between WWT_DEBUGBOX and WWT_DEFSIZEBOX)
        WWT_DEFSIZEBOX, ///< Default window size box (at top-right of a window, between WWT_SHADEBOX and WWT_STICKYBOX)
        WWT_STICKYBOX,  ///< Sticky box (at top-right of a window, after WWT_DEFSIZEBOX)

        WWT_RESIZEBOX,  ///< Resize box (normally at bottom-right of a window)
        WWT_CLOSEBOX,   ///< Close box (at top-left of a window)
        WWT_DROPDOWN,   ///< Drop down list
        WWT_EDITBOX,    ///< a textbox for typing
        WWT_LAST,       ///< Last Item. use WIDGETS_END to fill up padding!!

        /* Nested widget types. */
        NWID_HORIZONTAL,      ///< Horizontal container.
        NWID_HORIZONTAL_LTR,  ///< Horizontal container that doesn't change the order of the widgets for RTL languages.
        NWID_VERTICAL,        ///< Vertical container.
        NWID_MATRIX,          ///< Matrix container.
        NWID_SPACER,          ///< Invisible widget that takes some space.
        NWID_SELECTION,       ///< Stacked widgets, only one visible at a time (eg in a panel with tabs).
        NWID_VIEWPORT,        ///< Nested widget containing a viewport.
        NWID_BUTTON_DROPDOWN, ///< Button with a drop-down.
        NWID_HSCROLLBAR,      ///< Horizontal scrollbar
        NWID_VSCROLLBAR,      ///< Vertical scrollbar

        /* Nested widget part types. */
        WPT_RESIZE,       ///< Widget part for specifying resizing.
        WPT_MINSIZE,      ///< Widget part for specifying minimal size.
        WPT_MINTEXTLINES, ///< Widget part for specifying minimal number of lines of text.
        WPT_FILL,         ///< Widget part for specifying fill.
        WPT_DATATIP,      ///< Widget part for specifying data and tooltip.
        WPT_PADDING,      ///< Widget part for specifying a padding.
        WPT_PIPSPACE,     ///< Widget part for specifying pre/inter/post space for containers.
        WPT_ENDCONTAINER, ///< Widget part to denote end of a container.
        WPT_FUNCTION,     ///< Widget part for calling a user function.
        WPT_SCROLLBAR,    ///< Widget part for attaching a scrollbar.

        /* Pushable window widget types. */
        WWT_MASK = 0x7F,

        WWB_PUSHBUTTON    = 1 << 7,

        WWT_PUSHBTN       = WWT_PANEL    | WWB_PUSHBUTTON,    ///< Normal push-button (no toggle button) with custom drawing
        WWT_PUSHTXTBTN    = WWT_TEXTBTN  | WWB_PUSHBUTTON,    ///< Normal push-button (no toggle button) with text caption
        WWT_PUSHIMGBTN    = WWT_IMGBTN   | WWB_PUSHBUTTON,    ///< Normal push-button (no toggle button) with image caption
        WWT_PUSHARROWBTN  = WWT_ARROWBTN | WWB_PUSHBUTTON,    ///< Normal push-button (no toggle button) with arrow caption
        NWID_PUSHBUTTON_DROPDOWN = NWID_BUTTON_DROPDOWN | WWB_PUSHBUTTON,
};

/** Different forms of sizing nested widgets, using NWidgetBase::AssignSizePosition() */
enum SizingType {
        ST_SMALLEST, ///< Initialize nested widget tree to smallest size. Also updates \e current_x and \e current_y.
        ST_RESIZE,   ///< Resize the nested widget tree.
};

/* Forward declarations. */
class NWidgetCore;
class Scrollbar;

/**
 * Baseclass for nested widgets.
 * @invariant After initialization, \f$current\_x = smallest\_x + n * resize\_x, for n \geq 0\f$.
 * @invariant After initialization, \f$current\_y = smallest\_y + m * resize\_y, for m \geq 0\f$.
 * @ingroup NestedWidgets
 */
class NWidgetBase : public ZeroedMemoryAllocator {
public:
        NWidgetBase(WidgetType tp);

        virtual void SetupSmallestSize(Window *w, bool init_array) = 0;
        virtual void AssignSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height, bool rtl) = 0;

        virtual void FillNestedArray(NWidgetBase **array, uint length) = 0;

        virtual NWidgetCore *GetWidgetFromPos(int x, int y) = 0;
        virtual NWidgetBase *GetWidgetOfType(WidgetType tp);

        virtual bool IsHighlighted() const { return false; }
        virtual TextColour GetHighlightColour() const { return TC_INVALID; }
        virtual void SetHighlighted(TextColour highlight_colour) {}

        /**
         * Set additional space (padding) around the widget.
         * @param top    Amount of additional space above the widget.
         * @param right  Amount of additional space right of the widget.
         * @param bottom Amount of additional space below the widget.
         * @param left   Amount of additional space left of the widget.
         */
        inline void SetPadding(uint8 top, uint8 right, uint8 bottom, uint8 left)
        {
                this->padding_top = top;
                this->padding_right = right;
                this->padding_bottom = bottom;
                this->padding_left = left;
        }

        inline uint GetHorizontalStepSize(SizingType sizing) const;
        inline uint GetVerticalStepSize(SizingType sizing) const;

        virtual void Draw(const Window *w) = 0;
        virtual void SetDirty(const Window *w) const;

        WidgetType type;      ///< Type of the widget / nested widget.
        uint fill_x;          ///< Horizontal fill stepsize (from initial size, \c 0 means not resizable).
        uint fill_y;          ///< Vertical fill stepsize (from initial size, \c 0 means not resizable).
        uint resize_x;        ///< Horizontal resize step (\c 0 means not resizable).
        uint resize_y;        ///< Vertical resize step (\c 0 means not resizable).
        /* Size of the widget in the smallest window possible.
         * Computed by #SetupSmallestSize() followed by #AssignSizePosition().
         */
        uint smallest_x;      ///< Smallest horizontal size of the widget in a filled window.
        uint smallest_y;      ///< Smallest vertical size of the widget in a filled window.
        /* Current widget size (that is, after resizing). */
        uint current_x;       ///< Current horizontal size (after resizing).
        uint current_y;       ///< Current vertical size (after resizing).

        uint pos_x;           ///< Horizontal position of top-left corner of the widget in the window.
        uint pos_y;           ///< Vertical position of top-left corner of the widget in the window.

        NWidgetBase *next;    ///< Pointer to next widget in container. Managed by parent container widget.
        NWidgetBase *prev;    ///< Pointer to previous widget in container. Managed by parent container widget.

        uint8 padding_top;    ///< Paddings added to the top of the widget. Managed by parent container widget.
        uint8 padding_right;  ///< Paddings added to the right of the widget. Managed by parent container widget.
        uint8 padding_bottom; ///< Paddings added to the bottom of the widget. Managed by parent container widget.
        uint8 padding_left;   ///< Paddings added to the left of the widget. Managed by parent container widget.

protected:
        inline void StoreSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height);
};

/**
 * Get the horizontal sizing step.
 * @param sizing Type of resize being performed.
 */
inline uint NWidgetBase::GetHorizontalStepSize(SizingType sizing) const
{
        return (sizing == ST_RESIZE) ? this->resize_x : this->fill_x;
}

/**
 * Get the vertical sizing step.
 * @param sizing Type of resize being performed.
 */
inline uint NWidgetBase::GetVerticalStepSize(SizingType sizing) const
{
        return (sizing == ST_RESIZE) ? this->resize_y : this->fill_y;
}

/**
 * Store size and position.
 * @param sizing       Type of resizing to perform.
 * @param x            Horizontal offset of the widget relative to the left edge of the window.
 * @param y            Vertical offset of the widget relative to the top edge of the window.
 * @param given_width  Width allocated to the widget.
 * @param given_height Height allocated to the widget.
 */
inline void NWidgetBase::StoreSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height)
{
        this->pos_x = x;
        this->pos_y = y;
        if (sizing == ST_SMALLEST) {
                this->smallest_x = given_width;
                this->smallest_y = given_height;
        }
        this->current_x = given_width;
        this->current_y = given_height;
}


/**
 * Base class for a resizable nested widget.
 * @ingroup NestedWidgets
 */
class NWidgetResizeBase : public NWidgetBase {
public:
        NWidgetResizeBase(WidgetType tp, uint fill_x, uint fill_y);

        void SetMinimalSize(uint min_x, uint min_y);
        void SetMinimalTextLines(uint8 min_lines, uint8 spacing, FontSize size);
        void SetFill(uint fill_x, uint fill_y);
        void SetResize(uint resize_x, uint resize_y);

        void AssignSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height, bool rtl);

        uint min_x; ///< Minimal horizontal size of only this widget.
        uint min_y; ///< Minimal vertical size of only this widget.
};

/** Nested widget flags that affect display and interaction withe 'real' widgets. */
enum NWidgetDisplay {
        /* Generic. */
        NDB_LOWERED         = 0, ///< Widget is lowered (pressed down) bit.
        NDB_DISABLED        = 1, ///< Widget is disabled (greyed out) bit.
        /* Viewport widget. */
        NDB_NO_TRANSPARENCY = 2, ///< Viewport is never transparent.
        NDB_SHADE_GREY      = 3, ///< Shade viewport to grey-scale.
        NDB_SHADE_DIMMED    = 4, ///< Display dimmed colours in the viewport.
        /* Button dropdown widget. */
        NDB_DROPDOWN_ACTIVE = 5, ///< Dropdown menu of the button dropdown widget is active. @see #NWID_BUTTON_DRPDOWN
        /* Scrollbar widget. */
        NDB_SCROLLBAR_UP    = 6, ///< Up-button is lowered bit.
        NDB_SCROLLBAR_DOWN  = 7, ///< Down-button is lowered bit.
        /* Generic. */
        NDB_HIGHLIGHT       = 8, ///< Highlight of widget is on.

        ND_LOWERED  = 1 << NDB_LOWERED,                ///< Bit value of the lowered flag.
        ND_DISABLED = 1 << NDB_DISABLED,               ///< Bit value of the disabled flag.
        ND_HIGHLIGHT = 1 << NDB_HIGHLIGHT,             ///< Bit value of the highlight flag.
        ND_NO_TRANSPARENCY = 1 << NDB_NO_TRANSPARENCY, ///< Bit value of the 'no transparency' flag.
        ND_SHADE_GREY      = 1 << NDB_SHADE_GREY,      ///< Bit value of the 'shade to grey' flag.
        ND_SHADE_DIMMED    = 1 << NDB_SHADE_DIMMED,    ///< Bit value of the 'dimmed colours' flag.
        ND_DROPDOWN_ACTIVE = 1 << NDB_DROPDOWN_ACTIVE, ///< Bit value of the 'dropdown active' flag.
        ND_SCROLLBAR_UP    = 1 << NDB_SCROLLBAR_UP,    ///< Bit value of the 'scrollbar up' flag.
        ND_SCROLLBAR_DOWN  = 1 << NDB_SCROLLBAR_DOWN,  ///< Bit value of the 'scrollbar down' flag.
        ND_SCROLLBAR_BTN   = ND_SCROLLBAR_UP | ND_SCROLLBAR_DOWN, ///< Bit value of the 'scrollbar up' or 'scrollbar down' flag.
};
DECLARE_ENUM_AS_BIT_SET(NWidgetDisplay)

/**
 * Base class for a 'real' widget.
 * @ingroup NestedWidgets
 */
class NWidgetCore : public NWidgetResizeBase {
public:
        NWidgetCore(WidgetType tp, Colours colour, uint fill_x, uint fill_y, uint32 widget_data, StringID tool_tip);

        void SetIndex(int index);
        void SetDataTip(uint32 widget_data, StringID tool_tip);

        inline void SetLowered(bool lowered);
        inline bool IsLowered() const;
        inline void SetDisabled(bool disabled);
        inline bool IsDisabled() const;

        /* virtual */ void FillNestedArray(NWidgetBase **array, uint length);
        /* virtual */ NWidgetCore *GetWidgetFromPos(int x, int y);
        /* virtual */ bool IsHighlighted() const;
        /* virtual */ TextColour GetHighlightColour() const;
        /* virtual */ void SetHighlighted(TextColour highlight_colour);

        NWidgetDisplay disp_flags; ///< Flags that affect display and interaction with the widget.
        Colours colour;            ///< Colour of this widget.
        int index;                 ///< Index of the nested widget in the widget array of the window (\c -1 means 'not used').
        uint32 widget_data;        ///< Data of the widget. @see Widget::data
        StringID tool_tip;         ///< Tooltip of the widget. @see Widget::tootips
        int scrollbar_index;       ///< Index of an attached scrollbar.
        TextColour highlight_colour; ///< Colour of highlight.
};

/**
 * Highlight the widget or not.
 * @param highlight_colour Widget must be highlighted (blink).
 */
inline void NWidgetCore::SetHighlighted(TextColour highlight_colour)
{
        this->disp_flags = highlight_colour != TC_INVALID ? SETBITS(this->disp_flags, ND_HIGHLIGHT) : CLRBITS(this->disp_flags, ND_HIGHLIGHT);
        this->highlight_colour = highlight_colour;
}

/** Return whether the widget is highlighted. */
inline bool NWidgetCore::IsHighlighted() const
{
        return HasBit(this->disp_flags, NDB_HIGHLIGHT);
}

/** Return the colour of the highlight. */
inline TextColour NWidgetCore::GetHighlightColour() const
{
        return this->highlight_colour;
}

/**
 * Lower or raise the widget.
 * @param lowered Widget must be lowered (drawn pressed down).
 */
inline void NWidgetCore::SetLowered(bool lowered)
{
        this->disp_flags = lowered ? SETBITS(this->disp_flags, ND_LOWERED) : CLRBITS(this->disp_flags, ND_LOWERED);
}

/** Return whether the widget is lowered. */
inline bool NWidgetCore::IsLowered() const
{
        return HasBit(this->disp_flags, NDB_LOWERED);
}

/**
 * Disable (grey-out) or enable the widget.
 * @param disabled Widget must be disabled.
 */
inline void NWidgetCore::SetDisabled(bool disabled)
{
        this->disp_flags = disabled ? SETBITS(this->disp_flags, ND_DISABLED) : CLRBITS(this->disp_flags, ND_DISABLED);
}

/** Return whether the widget is disabled. */
inline bool NWidgetCore::IsDisabled() const
{
        return HasBit(this->disp_flags, NDB_DISABLED);
}


/**
 * Baseclass for container widgets.
 * @ingroup NestedWidgets
 */
class NWidgetContainer : public NWidgetBase {
public:
        NWidgetContainer(WidgetType tp);
        ~NWidgetContainer();

        void Add(NWidgetBase *wid);
        /* virtual */ void FillNestedArray(NWidgetBase **array, uint length);

        /** Return whether the container is empty. */
        inline bool IsEmpty() { return head == NULL; }

        /* virtual */ NWidgetBase *GetWidgetOfType(WidgetType tp);

protected:
        NWidgetBase *head; ///< Pointer to first widget in container.
        NWidgetBase *tail; ///< Pointer to last widget in container.
};

/** Display planes with zero size for #NWidgetStacked. */
enum StackedZeroSizePlanes {
        SZSP_VERTICAL = INT_MAX / 2, ///< Display plane with zero size horizontally, and filling and resizing vertically.
        SZSP_HORIZONTAL,             ///< Display plane with zero size vertically, and filling and resizing horizontally.
        SZSP_NONE,                   ///< Display plane with zero size in both directions (none filling and resizing).

        SZSP_BEGIN = SZSP_VERTICAL,  ///< First zero-size plane.
};

/**
 * Stacked widgets, widgets all occupying the same space in the window.
 * #NWID_SELECTION allows for selecting one of several panels (planes) to tbe displayed. All planes must have the same size.
 * Since all planes are also initialized, switching between different planes can be done while the window is displayed.
 *
 * There are also a number of special planes (defined in #StackedZeroSizePlanes) that have zero size in one direction (and are stretchable in
 * the other direction) or have zero size in both directions. They are used to make all child planes of the widget disappear.
 * Unlike switching between the regular display planes (that all have the same size), switching from or to one of the zero-sized planes means that
 * a #Windows::ReInit() is needed to re-initialize the window since its size changes.
 */
class NWidgetStacked : public NWidgetContainer {
public:
        NWidgetStacked();

        void SetIndex(int index);

        void SetupSmallestSize(Window *w, bool init_array);
        void AssignSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height, bool rtl);
        /* virtual */ void FillNestedArray(NWidgetBase **array, uint length);

        /* virtual */ void Draw(const Window *w);
        /* virtual */ NWidgetCore *GetWidgetFromPos(int x, int y);

        void SetDisplayedPlane(int plane);

        int shown_plane; ///< Plane being displayed (for #NWID_SELECTION only).
        int index;       ///< If non-negative, index in the #Window::nested_array.
};

/** Nested widget container flags, */
enum NWidContainerFlags {
        NCB_EQUALSIZE = 0, ///< Containers should keep all their (resizing) children equally large.

        NC_NONE = 0,                       ///< All flags cleared.
        NC_EQUALSIZE = 1 << NCB_EQUALSIZE, ///< Value of the #NCB_EQUALSIZE flag.
};
DECLARE_ENUM_AS_BIT_SET(NWidContainerFlags)

/** Container with pre/inter/post child space. */
class NWidgetPIPContainer : public NWidgetContainer {
public:
        NWidgetPIPContainer(WidgetType tp, NWidContainerFlags flags = NC_NONE);

        void SetPIP(uint8 pip_pre, uint8 pip_inter, uint8 pip_post);

        /* virtual */ void Draw(const Window *w);
        /* virtual */ NWidgetCore *GetWidgetFromPos(int x, int y);

protected:
        NWidContainerFlags flags; ///< Flags of the container.
        uint8 pip_pre;            ///< Amount of space before first widget.
        uint8 pip_inter;          ///< Amount of space between widgets.
        uint8 pip_post;           ///< Amount of space after last widget.
};

/**
 * Horizontal container.
 * @ingroup NestedWidgets
 */
class NWidgetHorizontal : public NWidgetPIPContainer {
public:
        NWidgetHorizontal(NWidContainerFlags flags = NC_NONE);

        void SetupSmallestSize(Window *w, bool init_array);
        void AssignSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height, bool rtl);
};

/**
 * Horizontal container that doesn't change the direction of the widgets for RTL languages.
 * @ingroup NestedWidgets
 */
class NWidgetHorizontalLTR : public NWidgetHorizontal {
public:
        NWidgetHorizontalLTR(NWidContainerFlags flags = NC_NONE);

        void AssignSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height, bool rtl);
};

/**
 * Vertical container.
 * @ingroup NestedWidgets
 */
class NWidgetVertical : public NWidgetPIPContainer {
public:
        NWidgetVertical(NWidContainerFlags flags = NC_NONE);

        void SetupSmallestSize(Window *w, bool init_array);
        void AssignSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height, bool rtl);
};

/**
 * Matrix container with implicitly equal sized (virtual) sub-widgets.
 * This widget must have exactly one sub-widget. After that this sub-widget
 * is used to draw all of the data within the matrix piece by piece.
 * DrawWidget and OnClick calls will be done to that sub-widget, where the
 * 16 high bits are used to encode the index into the matrix.
 * @ingroup NestedWidgets
 */
class NWidgetMatrix : public NWidgetPIPContainer {
public:
        NWidgetMatrix();

        void SetIndex(int index);
        void SetColour(Colours colour);
        void SetClicked(int clicked);
        void SetCount(int count);
        void SetScrollbar(Scrollbar *sb);

        void SetupSmallestSize(Window *w, bool init_array);
        void AssignSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height, bool rtl);
        /* virtual */ void FillNestedArray(NWidgetBase **array, uint length);

        /* virtual */ NWidgetCore *GetWidgetFromPos(int x, int y);
        /* virtual */ void Draw(const Window *w);
protected:
        int index;      ///< If non-negative, index in the #Window::nested_array.
        Colours colour; ///< Colour of this widget.
        int clicked;    ///< The currently clicked widget.
        int count;      ///< Amount of valid widgets.
        Scrollbar *sb;  ///< The scrollbar we're associated with.
private:
        int widget_w;   ///< The width of the child widget including inter spacing.
        int widget_h;   ///< The height of the child widget including inter spacing.
        int widgets_x;  ///< The number of visible widgets in horizontal direction.
        int widgets_y;  ///< The number of visible widgets in vertical direction.

        void GetScrollOffsets(int &start_x, int &start_y, int &base_offs_x, int &base_offs_y);
};


/**
 * Spacer widget.
 * @ingroup NestedWidgets
 */
class NWidgetSpacer : public NWidgetResizeBase {
public:
        NWidgetSpacer(int length, int height);

        void SetupSmallestSize(Window *w, bool init_array);
        /* virtual */ void FillNestedArray(NWidgetBase **array, uint length);

        /* virtual */ void Draw(const Window *w);
        /* virtual */ void SetDirty(const Window *w) const;
        /* virtual */ NWidgetCore *GetWidgetFromPos(int x, int y);
};

/**
 * Nested widget with a child.
 * @ingroup NestedWidgets
 */
class NWidgetBackground : public NWidgetCore {
public:
        NWidgetBackground(WidgetType tp, Colours colour, int index, NWidgetPIPContainer *child = NULL);
        ~NWidgetBackground();

        void Add(NWidgetBase *nwid);
        void SetPIP(uint8 pip_pre, uint8 pip_inter, uint8 pip_post);

        void SetupSmallestSize(Window *w, bool init_array);
        void AssignSizePosition(SizingType sizing, uint x, uint y, uint given_width, uint given_height, bool rtl);

        /* virtual */ void FillNestedArray(NWidgetBase **array, uint length);

        /* virtual */ void Draw(const Window *w);
        /* virtual */ NWidgetCore *GetWidgetFromPos(int x, int y);
        /* virtual */ NWidgetBase *GetWidgetOfType(WidgetType tp);

private:
        NWidgetPIPContainer *child; ///< Child widget.
};

/**
 * Nested widget to display a viewport in a window.
 * After initializing the nested widget tree, call #InitializeViewport(). After changing the window size,
 * call #UpdateViewportCoordinates() eg from Window::OnResize().
 * If the #display_flags field contains the #ND_NO_TRANSPARENCY bit, the viewport will disable transparency.
 * Shading to grey-scale is controlled with the #ND_SHADE_GREY bit (used for B&W news papers), the #ND_SHADE_DIMMED gives dimmed colours (for colour news papers).
 * @todo Class derives from #NWidgetCore, but does not use #colour, #widget_data, or #tool_tip.
 * @ingroup NestedWidgets
 */
class NWidgetViewport : public NWidgetCore {
public:
        NWidgetViewport(int index);

        /* virtual */ void SetupSmallestSize(Window *w, bool init_array);
        /* virtual */ void Draw(const Window *w);

        void InitializeViewport(Window *w, uint32 follow_flags, ZoomLevel zoom);
        void UpdateViewportCoordinates(Window *w);
};

/**
 * Scrollbar data structure
 */
class Scrollbar {
private:
        const bool is_vertical; ///< Scrollbar has vertical orientation.
        uint16 count;           ///< Number of elements in the list.
        uint16 cap;             ///< Number of visible elements of the scroll bar.
        uint16 pos;             ///< Index of first visible item of the list.
        uint16 stepsize;        ///< Distance to scroll, when pressing the buttons or using the wheel.

public:
        /** Stepping sizes when scrolling */
        enum ScrollbarStepping {
                SS_RAW,             ///< Step in single units.
                SS_SMALL,           ///< Step in #stepsize units.
                SS_BIG,             ///< Step in #cap units.
        };

        Scrollbar(bool is_vertical) : is_vertical(is_vertical), stepsize(1)
        {
        }

        /**
         * Gets the number of elements in the list
         * @return the number of elements
         */
        inline uint16 GetCount() const
        {
                return this->count;
        }

        /**
         * Gets the number of visible elements of the scrollbar
         * @return the number of visible elements
         */
        inline uint16 GetCapacity() const
        {
                return this->cap;
        }

        /**
         * Gets the position of the first visible element in the list
         * @return the position of the element
         */
        inline uint16 GetPosition() const
        {
                return this->pos;
        }

        /**
         * Checks whether given current item is visible in the list
         * @param item to check
         * @return true iff the item is visible
         */
        inline bool IsVisible(uint16 item) const
        {
                return IsInsideBS(item, this->GetPosition(), this->GetCapacity());
        }

        /**
         * Is the scrollbar vertical or not?
         * @return True iff the scrollbar is vertical.
         */
        inline bool IsVertical() const
        {
                return this->is_vertical;
        }

        /**
         * Set the distance to scroll when using the buttons or the wheel.
         * @param stepsize Scrolling speed.
         */
        void SetStepSize(uint16 stepsize)
        {
                assert(stepsize > 0);
                this->stepsize = stepsize;
        }

        /**
         * Sets the number of elements in the list
         * @param num the number of elements in the list
         * @note updates the position if needed
         */
        void SetCount(int num)
        {
                assert(num >= 0);
                assert(num <= MAX_UVALUE(uint16));

                this->count = num;
                num -= this->cap;
                if (num < 0) num = 0;
                if (num < this->pos) this->pos = num;
        }

        /**
         * Set the capacity of visible elements.
         * @param capacity the new capacity
         * @note updates the position if needed
         */
        void SetCapacity(int capacity)
        {
                assert(capacity > 0);
                assert(capacity <= MAX_UVALUE(uint16));

                this->cap = capacity;
                if (this->cap + this->pos > this->count) this->pos = max(0, this->count - this->cap);
        }

        void SetCapacityFromWidget(Window *w, int widget, int padding = 0);

        /**
         * Sets the position of the first visible element
         * @param position the position of the element
         */
        void SetPosition(int position)
        {
                assert(position >= 0);
                assert(this->count <= this->cap ? (position == 0) : (position + this->cap <= this->count));
                this->pos = position;
        }

        /**
         * Updates the position of the first visible element by the given amount.
         * If the position would be too low or high it will be clamped appropriately
         * @param difference the amount of change requested
         * @param unit The stepping unit of \a difference
         */
        void UpdatePosition(int difference, ScrollbarStepping unit = SS_SMALL)
        {
                if (difference == 0) return;
                switch (unit) {
                        case SS_SMALL: difference *= this->stepsize; break;
                        case SS_BIG:   difference *= this->cap; break;
                        default: break;
                }
                this->SetPosition(Clamp(this->pos + difference, 0, max(this->count - this->cap, 0)));
        }

        /**
         * Scroll towards the given position; if the item is visible nothing
         * happens, otherwise it will be shown either at the bottom or top of
         * the window depending on where in the list it was.
         * @param position the position to scroll towards.
         */
        void ScrollTowards(int position)
        {
                if (position < this->GetPosition()) {
                        /* scroll up to the item */
                        this->SetPosition(position);
                } else if (position >= this->GetPosition() + this->GetCapacity()) {
                        /* scroll down so that the item is at the bottom */
                        this->SetPosition(position - this->GetCapacity() + 1);
                }
        }

        int GetScrolledRowFromWidget(int clickpos, const Window * const w, int widget, int padding = 0, int line_height = -1) const;
};

/**
 * Nested widget to display and control a scrollbar in a window.
 * Also assign the scrollbar to other widgets using #SetScrollbar() to make the mousewheel work.
 * @ingroup NestedWidgets
 */
class NWidgetScrollbar : public NWidgetCore, public Scrollbar {
public:
        NWidgetScrollbar(WidgetType tp, Colours colour, int index);

        /* virtual */ void SetupSmallestSize(Window *w, bool init_array);
        /* virtual */ void Draw(const Window *w);

        static void InvalidateDimensionCache();
        static Dimension GetVerticalDimension();
        static Dimension GetHorizontalDimension();

private:
        static Dimension vertical_dimension;   ///< Cached size of vertical scrollbar button.
        static Dimension horizontal_dimension; ///< Cached size of horizontal scrollbar button.
};

/**
 * Leaf widget.
 * @ingroup NestedWidgets
 */
class NWidgetLeaf : public NWidgetCore {
public:
        NWidgetLeaf(WidgetType tp, Colours colour, int index, uint16 data, StringID tip);

        /* virtual */ void SetupSmallestSize(Window *w, bool init_array);
        /* virtual */ void Draw(const Window *w);

        bool ButtonHit(const Point &pt);

        static void InvalidateDimensionCache();
private:
        static Dimension shadebox_dimension;  ///< Cached size of a shadebox widget.
        static Dimension debugbox_dimension;  ///< Cached size of a debugbox widget.
        static Dimension defsizebox_dimension; ///< Cached size of a defsizebox widget.
        static Dimension stickybox_dimension; ///< Cached size of a stickybox widget.
        static Dimension resizebox_dimension; ///< Cached size of a resizebox widget.
        static Dimension closebox_dimension;  ///< Cached size of a closebox widget.
};

/**
 * Return the biggest possible size of a nested widget.
 * @param base      Base size of the widget.
 * @param max_space Available space for the widget.
 * @param step      Stepsize of the widget.
 * @return Biggest possible size of the widget, assuming that \a base may only be incremented by \a step size steps.
 */
static inline uint ComputeMaxSize(uint base, uint max_space, uint step)
{
        if (base >= max_space || step == 0) return base;
        if (step == 1) return max_space;
        uint increment = max_space - base;
        increment -= increment % step;
        return base + increment;
}

/**
 * @defgroup NestedWidgetParts Hierarchical widget parts
 * To make nested widgets easier to enter, nested widget parts have been created. They allow the tree to be defined in a flat array of parts.
 *
 * - Leaf widgets start with a #NWidget(WidgetType tp, Colours col, int16 idx) part.
 *   Next, specify its properties with one or more of
 *   - #SetMinimalSize Define the minimal size of the widget.
 *   - #SetFill Define how the widget may grow to make it nicely.
 *   - #SetDataTip Define the data and the tooltip of the widget.
 *   - #SetResize Define how the widget may resize.
 *   - #SetPadding Create additional space around the widget.
 *
 * - To insert a nested widget tree from an external source, nested widget part #NWidgetFunction exists.
 *   For further customization, the #SetPadding part may be used.
 *
 * - Space widgets (#NWidgetSpacer) start with a #NWidget(WidgetType tp), followed by one or more of
 *   - #SetMinimalSize Define the minimal size of the widget.
 *   - #SetFill Define how the widget may grow to make it nicely.
 *   - #SetResize Define how the widget may resize.
 *   - #SetPadding Create additional space around the widget.
 *
 * - Container widgets #NWidgetHorizontal, #NWidgetHorizontalLTR, #NWidgetVertical, and #NWidgetMatrix, start with a #NWidget(WidgetType tp) part.
 *   Their properties are derived from the child widgets so they cannot be specified.
 *   You can however use
 *   - #SetPadding Define additional padding around the container.
 *   - #SetPIP Set additional pre/inter/post child widget space.
 *   .
 *   Underneath these properties, all child widgets of the container must be defined. To denote that they are childs, add an indent before the nested widget parts of
 *   the child widgets (it has no meaning for the compiler but it makes the widget parts easier to read).
 *   Below the last child widget, use an #EndContainer part. This part should be aligned with the #NWidget part that started the container.
 *
 * - Stacked widgets #NWidgetStacked map each of their children onto the same space. It behaves like a container, except there is no pre/inter/post space,
 *   so the widget does not support #SetPIP. #SetPadding is allowed though.
 *   Like the other container widgets, below the last child widgets, a #EndContainer part should be used to denote the end of the stacked widget.
 *
 * - Background widgets #NWidgetBackground start with a #NWidget(WidgetType tp, Colours col, int16 idx) part.
 *   What follows depends on how the widget is used.
 *   - If the widget is used as a leaf widget, that is, to create some space in the window to display a viewport or some text, use the properties of the
 *     leaf widgets to define how it behaves.
 *   - If the widget is used a background behind other widgets, it is considered to be a container widgets. Use the properties listed there to define its
 *     behaviour.
 *   .
 *   In both cases, the background widget \b MUST end with a #EndContainer widget part.
 *
 * @see NestedWidgets
 */

/**
 * Widget part for storing data and tooltip information.
 * @ingroup NestedWidgetParts
 */
struct NWidgetPartDataTip {
        uint16 data;      ///< Data value of the widget.
        StringID tooltip; ///< Tooltip of the widget.
};

/**
 * Widget part for storing basic widget information.
 * @ingroup NestedWidgetParts
 */
struct NWidgetPartWidget {
        Colours colour; ///< Widget colour.
        int16 index;    ///< Widget index in the widget array.
};

/**
 * Widget part for storing padding.
 * @ingroup NestedWidgetParts
 */
struct NWidgetPartPaddings {
        uint8 top, right, bottom, left; ///< Paddings for all directions.
};

/**
 * Widget part for storing pre/inter/post spaces.
 * @ingroup NestedWidgetParts
 */
struct NWidgetPartPIP {
        uint8 pre, inter, post; ///< Amount of space before/between/after child widgets.
};

/**
 * Widget part for storing minimal text line data.
 * @ingroup NestedWidgetParts
 */
struct NWidgetPartTextLines {
        uint8 lines;   ///< Number of text lines.
        uint8 spacing; ///< Extra spacing around lines.
        FontSize size; ///< Font size of text lines.
};

/**
 * Pointer to function returning a nested widget.
 * @param biggest_index Pointer to storage for collecting the biggest index used in the nested widget.
 * @return Nested widget (tree).
 * @post \c *biggest_index must contain the value of the biggest index in the returned tree.
 */
typedef NWidgetBase *NWidgetFunctionType(int *biggest_index);

/**
 * Partial widget specification to allow NWidgets to be written nested.
 * @ingroup NestedWidgetParts
 */
struct NWidgetPart {
        WidgetType type;                         ///< Type of the part. @see NWidgetPartType.
        union {
                Point xy;                        ///< Part with an x/y size.
                NWidgetPartDataTip data_tip;     ///< Part with a data/tooltip.
                NWidgetPartWidget widget;        ///< Part with a start of a widget.
                NWidgetPartPaddings padding;     ///< Part with paddings.
                NWidgetPartPIP pip;              ///< Part with pre/inter/post spaces.
                NWidgetPartTextLines text_lines; ///< Part with text line data.
                NWidgetFunctionType *func_ptr;   ///< Part with a function call.
                NWidContainerFlags cont_flags;   ///< Part with container flags.
        } u;
};

/**
 * Widget part function for setting the resize step.
 * @param dx Horizontal resize step. 0 means no horizontal resizing.
 * @param dy Vertical resize step. 0 means no vertical resizing.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetResize(int16 dx, int16 dy)
{
        NWidgetPart part;

        part.type = WPT_RESIZE;
        part.u.xy.x = dx;
        part.u.xy.y = dy;

        return part;
}

/**
 * Widget part function for setting the minimal size.
 * @param x Horizontal minimal size.
 * @param y Vertical minimal size.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetMinimalSize(int16 x, int16 y)
{
        NWidgetPart part;

        part.type = WPT_MINSIZE;
        part.u.xy.x = x;
        part.u.xy.y = y;

        return part;
}

/**
 * Widget part function for setting the minimal text lines.
 * @param lines   Number of text lines.
 * @param spacing Extra spacing required.
 * @param size    Font size of text.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetMinimalTextLines(uint8 lines, uint8 spacing, FontSize size = FS_NORMAL)
{
        NWidgetPart part;

        part.type = WPT_MINTEXTLINES;
        part.u.text_lines.lines = lines;
        part.u.text_lines.spacing = spacing;
        part.u.text_lines.size = size;

        return part;
}

/**
 * Widget part function for setting filling.
 * @param fill_x Horizontal filling step from minimal size.
 * @param fill_y Vertical filling step from minimal size.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetFill(uint fill_x, uint fill_y)
{
        NWidgetPart part;

        part.type = WPT_FILL;
        part.u.xy.x = fill_x;
        part.u.xy.y = fill_y;

        return part;
}

/**
 * Widget part function for denoting the end of a container
 * (horizontal, vertical, WWT_FRAME, WWT_INSET, or WWT_PANEL).
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart EndContainer()
{
        NWidgetPart part;

        part.type = WPT_ENDCONTAINER;

        return part;
}

/**
 * Widget part function for setting the data and tooltip.
 * @param data Data of the widget.
 * @param tip  Tooltip of the widget.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetDataTip(uint16 data, StringID tip)
{
        NWidgetPart part;

        part.type = WPT_DATATIP;
        part.u.data_tip.data = data;
        part.u.data_tip.tooltip = tip;

        return part;
}

/**
 * Widget part function for setting the data and tooltip of WWT_MATRIX widgets
 * @param cols Number of columns. \c 0 means to use draw columns with width according to the resize step size.
 * @param rows Number of rows. \c 0 means to use draw rows with height according to the resize step size.
 * @param tip  Tooltip of the widget.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetMatrixDataTip(uint8 cols, uint8 rows, StringID tip)
{
        return SetDataTip((rows << MAT_ROW_START) | (cols << MAT_COL_START), tip);
}

/**
 * Widget part function for setting additional space around a widget.
 * Parameters start above the widget, and are specified in clock-wise direction.
 * @param top The padding above the widget.
 * @param right The padding right of the widget.
 * @param bottom The padding below the widget.
 * @param left The padding left of the widget.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetPadding(uint8 top, uint8 right, uint8 bottom, uint8 left)
{
        NWidgetPart part;

        part.type = WPT_PADDING;
        part.u.padding.top = top;
        part.u.padding.right = right;
        part.u.padding.bottom = bottom;
        part.u.padding.left = left;

        return part;
}

/**
 * Widget part function for setting a padding.
 * @param padding The padding to use for all directions.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetPadding(uint8 padding)
{
        return SetPadding(padding, padding, padding, padding);
}

/**
 * Widget part function for setting a pre/inter/post spaces.
 * @param pre The amount of space before the first widget.
 * @param inter The amount of space between widgets.
 * @param post The amount of space after the last widget.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetPIP(uint8 pre, uint8 inter, uint8 post)
{
        NWidgetPart part;

        part.type = WPT_PIPSPACE;
        part.u.pip.pre = pre;
        part.u.pip.inter = inter;
        part.u.pip.post = post;

        return part;
}

/**
 * Attach a scrollbar to a widget.
 * The scrollbar is controlled when using the mousewheel on the widget.
 * Multiple widgets can refer to the same scrollbar to make the mousewheel work in all of them.
 * @param index Widget index of the scrollbar.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart SetScrollbar(int index)
{
        NWidgetPart part;

        part.type = WPT_SCROLLBAR;
        part.u.widget.index = index;

        return part;
}

/**
 * Widget part function for starting a new 'real' widget.
 * @param tp  Type of the new nested widget.
 * @param col Colour of the new widget.
 * @param idx Index of the widget in the widget array.
 * @note with #WWT_PANEL, #WWT_FRAME, #WWT_INSET, a new container is started.
 *       Child widgets must have a index bigger than the parent index.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart NWidget(WidgetType tp, Colours col, int16 idx = -1)
{
        NWidgetPart part;

        part.type = tp;
        part.u.widget.colour = col;
        part.u.widget.index = idx;

        return part;
}

/**
 * Widget part function for starting a new horizontal container, vertical container, or spacer widget.
 * @param tp         Type of the new nested widget, #NWID_HORIZONTAL(_LTR), #NWID_VERTICAL, #NWID_SPACER, #NWID_SELECTION, and #NWID_MATRIX.
 * @param cont_flags Flags for the containers (#NWID_HORIZONTAL(_LTR) and #NWID_VERTICAL).
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart NWidget(WidgetType tp, NWidContainerFlags cont_flags = NC_NONE)
{
        NWidgetPart part;

        part.type = tp;
        part.u.cont_flags = cont_flags;

        return part;
}

/**
 * Obtain a nested widget (sub)tree from an external source.
 * @param func_ptr Pointer to function that returns the tree.
 * @ingroup NestedWidgetParts
 */
static inline NWidgetPart NWidgetFunction(NWidgetFunctionType *func_ptr)
{
        NWidgetPart part;

        part.type = WPT_FUNCTION;
        part.u.func_ptr = func_ptr;

        return part;
}

NWidgetContainer *MakeNWidgets(const NWidgetPart *parts, int count, int *biggest_index, NWidgetContainer *container);
NWidgetContainer *MakeWindowNWidgetTree(const NWidgetPart *parts, int count, int *biggest_index, NWidgetStacked **shade_select);

NWidgetBase *MakeCompanyButtonRows(int *biggest_index, int widget_first, int widget_last, int max_length, StringID button_tooltip);

#endif /* WIDGET_TYPE_H */