Feature: Hide block signals in GUI by default (#8688)

[openttd-github.git] / src / story_gui.cpp

/*
 * 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 story_gui.cpp GUI for stories. */

#include "stdafx.h"
#include "window_gui.h"
#include "strings_func.h"
#include "date_func.h"
#include "gui.h"
#include "story_base.h"
#include "core/geometry_func.hpp"
#include "company_func.h"
#include "command_func.h"
#include "widgets/dropdown_type.h"
#include "widgets/dropdown_func.h"
#include "sortlist_type.h"
#include "goal_base.h"
#include "viewport_func.h"
#include "window_func.h"
#include "company_base.h"
#include "tilehighlight_func.h"
#include "vehicle_base.h"

#include "widgets/story_widget.h"

#include "table/strings.h"
#include "table/sprites.h"

#include <numeric>

#include "safeguards.h"

static CursorID TranslateStoryPageButtonCursor(StoryPageButtonCursor cursor);

typedef GUIList<const StoryPage*> GUIStoryPageList;
typedef GUIList<const StoryPageElement*> GUIStoryPageElementList;

struct StoryBookWindow : Window {
protected:
        struct LayoutCacheElement {
                const StoryPageElement *pe;
                Rect bounds;
        };
        typedef std::vector<LayoutCacheElement> LayoutCache;

        enum class ElementFloat {
                None,
                Left,
                Right,
        };

        Scrollbar *vscroll;                ///< Scrollbar of the page text.
        mutable LayoutCache layout_cache;  ///< Cached element layout.

        GUIStoryPageList story_pages;      ///< Sorted list of pages.
        GUIStoryPageElementList story_page_elements; ///< Sorted list of page elements that belong to the current page.
        StoryPageID selected_page_id;      ///< Pool index of selected page.
        char selected_generic_title[255];  ///< If the selected page doesn't have a custom title, this buffer is used to store a generic page title.

        StoryPageElementID active_button_id; ///< Which button element the player is currently using

        static GUIStoryPageList::SortFunction * const page_sorter_funcs[];
        static GUIStoryPageElementList::SortFunction * const page_element_sorter_funcs[];

        /** (Re)Build story page list. */
        void BuildStoryPageList()
        {
                if (this->story_pages.NeedRebuild()) {
                        this->story_pages.clear();

                        for (const StoryPage *p : StoryPage::Iterate()) {
                                if (this->IsPageAvailable(p)) {
                                        this->story_pages.push_back(p);
                                }
                        }

                        this->story_pages.shrink_to_fit();
                        this->story_pages.RebuildDone();
                }

                this->story_pages.Sort();
        }

        /** Sort story pages by order value. */
        static bool PageOrderSorter(const StoryPage * const &a, const StoryPage * const &b)
        {
                return a->sort_value < b->sort_value;
        }

        /** (Re)Build story page element list. */
        void BuildStoryPageElementList()
        {
                if (this->story_page_elements.NeedRebuild()) {
                        this->story_page_elements.clear();

                        const StoryPage *p = GetSelPage();
                        if (p != nullptr) {
                                for (const StoryPageElement *pe : StoryPageElement::Iterate()) {
                                        if (pe->page == p->index) {
                                                this->story_page_elements.push_back(pe);
                                        }
                                }
                        }

                        this->story_page_elements.shrink_to_fit();
                        this->story_page_elements.RebuildDone();
                }

                this->story_page_elements.Sort();
                this->InvalidateStoryPageElementLayout();
        }

        /** Sort story page elements by order value. */
        static bool PageElementOrderSorter(const StoryPageElement * const &a, const StoryPageElement * const &b)
        {
                return a->sort_value < b->sort_value;
        }

        /*
         * Checks if a given page should be visible in the story book.
         * @param page The page to check.
         * @return True if the page should be visible, otherwise false.
         */
        bool IsPageAvailable(const StoryPage *page) const
        {
                return page->company == INVALID_COMPANY || page->company == this->window_number;
        }

        /**
         * Get instance of selected page.
         * @return Instance of selected page or nullptr if no page is selected.
         */
        StoryPage *GetSelPage() const
        {
                if (!_story_page_pool.IsValidID(selected_page_id)) return nullptr;
                return _story_page_pool.Get(selected_page_id);
        }

        /**
         * Get the page number of selected page.
         * @return Number of available pages before to the selected one, or -1 if no page is selected.
         */
        int GetSelPageNum() const
        {
                int page_number = 0;
                for (const StoryPage *p : this->story_pages) {
                        if (p->index == this->selected_page_id) {
                                return page_number;
                        }
                        page_number++;
                }
                return -1;
        }

        /**
         * Check if the selected page is also the first available page.
         */
        bool IsFirstPageSelected()
        {
                /* Verify that the selected page exist. */
                if (!_story_page_pool.IsValidID(this->selected_page_id)) return false;

                return this->story_pages.front()->index == this->selected_page_id;
        }

        /**
         * Check if the selected page is also the last available page.
         */
        bool IsLastPageSelected()
        {
                /* Verify that the selected page exist. */
                if (!_story_page_pool.IsValidID(this->selected_page_id)) return false;

                if (this->story_pages.size() <= 1) return true;
                const StoryPage *last = this->story_pages.back();
                return last->index == this->selected_page_id;
        }

        /**
         * Updates the content of selected page.
         */
        void RefreshSelectedPage()
        {
                /* Generate generic title if selected page have no custom title. */
                StoryPage *page = this->GetSelPage();
                if (page != nullptr && page->title == nullptr) {
                        SetDParam(0, GetSelPageNum() + 1);
                        GetString(selected_generic_title, STR_STORY_BOOK_GENERIC_PAGE_ITEM, lastof(selected_generic_title));
                }

                this->story_page_elements.ForceRebuild();
                this->BuildStoryPageElementList();

                if (this->active_button_id != INVALID_STORY_PAGE_ELEMENT) ResetObjectToPlace();

                this->vscroll->SetCount(this->GetContentHeight());
                this->SetWidgetDirty(WID_SB_SCROLLBAR);
                this->SetWidgetDirty(WID_SB_SEL_PAGE);
                this->SetWidgetDirty(WID_SB_PAGE_PANEL);
        }

        /**
         * Selects the previous available page before the currently selected page.
         */
        void SelectPrevPage()
        {
                if (!_story_page_pool.IsValidID(this->selected_page_id)) return;

                /* Find the last available page which is previous to the current selected page. */
                const StoryPage *last_available;
                last_available = nullptr;
                for (const StoryPage *p : this->story_pages) {
                        if (p->index == this->selected_page_id) {
                                if (last_available == nullptr) return; // No previous page available.
                                this->SetSelectedPage(last_available->index);
                                return;
                        }
                        last_available = p;
                }
        }

        /**
         * Selects the next available page after the currently selected page.
         */
        void SelectNextPage()
        {
                if (!_story_page_pool.IsValidID(this->selected_page_id)) return;

                /* Find selected page. */
                for (auto iter = this->story_pages.begin(); iter != this->story_pages.end(); iter++) {
                        const StoryPage *p = *iter;
                        if (p->index == this->selected_page_id) {
                                /* Select the page after selected page. */
                                iter++;
                                if (iter != this->story_pages.end()) {
                                        this->SetSelectedPage((*iter)->index);
                                }
                                return;
                        }
                }
        }

        /**
         * Builds the page selector drop down list.
         */
        DropDownList BuildDropDownList() const
        {
                DropDownList list;
                uint16 page_num = 1;
                for (const StoryPage *p : this->story_pages) {
                        bool current_page = p->index == this->selected_page_id;
                        DropDownListStringItem *item = nullptr;
                        if (p->title != nullptr) {
                                item = new DropDownListCharStringItem(p->title, p->index, current_page);
                        } else {
                                /* No custom title => use a generic page title with page number. */
                                DropDownListParamStringItem *str_item =
                                                new DropDownListParamStringItem(STR_STORY_BOOK_GENERIC_PAGE_ITEM, p->index, current_page);
                                str_item->SetParam(0, page_num);
                                item = str_item;
                        }

                        list.emplace_back(item);
                        page_num++;
                }

                return list;
        }

        /**
         * Get the width available for displaying content on the page panel.
         */
        uint GetAvailablePageContentWidth() const
        {
                return this->GetWidget<NWidgetCore>(WID_SB_PAGE_PANEL)->current_x - WD_FRAMETEXT_LEFT - WD_FRAMETEXT_RIGHT - 1;
        }

        /**
         * Counts how many pixels of height that are used by Date and Title
         * (excluding marginal after Title, as each body element has
         * an empty row before the element).
         * @param max_width Available width to display content.
         * @return the height in pixels.
         */
        uint GetHeadHeight(int max_width) const
        {
                StoryPage *page = this->GetSelPage();
                if (page == nullptr) return 0;
                int height = 0;

                /* Title lines */
                height += FONT_HEIGHT_NORMAL; // Date always use exactly one line.
                SetDParamStr(0, page->title != nullptr ? page->title : this->selected_generic_title);
                height += GetStringHeight(STR_STORY_BOOK_TITLE, max_width);

                return height;
        }

        /**
         * Decides which sprite to display for a given page element.
         * @param pe The page element.
         * @return The SpriteID of the sprite to display.
         * @pre pe.type must be SPET_GOAL or SPET_LOCATION.
         */
        SpriteID GetPageElementSprite(const StoryPageElement &pe) const
        {
                switch (pe.type) {
                        case SPET_GOAL: {
                                Goal *g = Goal::Get((GoalID) pe.referenced_id);
                                if (g == nullptr) return SPR_IMG_GOAL_BROKEN_REF;
                                return g->completed ? SPR_IMG_GOAL_COMPLETED : SPR_IMG_GOAL;
                        }
                        case SPET_LOCATION:
                                return SPR_IMG_VIEW_LOCATION;
                        default:
                                NOT_REACHED();
                }
        }

        /**
         * Get the height in pixels used by a page element.
         * @param pe The story page element.
         * @param max_width Available width to display content.
         * @return the height in pixels.
         */
        uint GetPageElementHeight(const StoryPageElement &pe, int max_width) const
        {
                switch (pe.type) {
                        case SPET_TEXT:
                                SetDParamStr(0, pe.text);
                                return GetStringHeight(STR_BLACK_RAW_STRING, max_width);

                        case SPET_GOAL:
                        case SPET_LOCATION: {
                                Dimension sprite_dim = GetSpriteSize(GetPageElementSprite(pe));
                                return sprite_dim.height;
                        }

                        case SPET_BUTTON_PUSH:
                        case SPET_BUTTON_TILE:
                        case SPET_BUTTON_VEHICLE: {
                                Dimension dim = GetStringBoundingBox(pe.text, FS_NORMAL);
                                return dim.height + WD_BEVEL_TOP + WD_BEVEL_BOTTOM + WD_FRAMETEXT_TOP + WD_FRAMETEXT_BOTTOM;
                        }

                        default:
                                NOT_REACHED();
                }
                return 0;
        }

        /**
         * Get the float style of a page element.
         * @param pe The story page element.
         * @return The float style.
         */
        ElementFloat GetPageElementFloat(const StoryPageElement &pe) const
        {
                switch (pe.type) {
                        case SPET_BUTTON_PUSH:
                        case SPET_BUTTON_TILE:
                        case SPET_BUTTON_VEHICLE: {
                                StoryPageButtonFlags flags = StoryPageButtonData{ pe.referenced_id }.GetFlags();
                                if (flags & SPBF_FLOAT_LEFT) return ElementFloat::Left;
                                if (flags & SPBF_FLOAT_RIGHT) return ElementFloat::Right;
                                return ElementFloat::None;
                        }

                        default:
                                return ElementFloat::None;
                }
        }

        /**
         * Get the width a page element would use if it was floating left or right.
         * @param pe The story page element.
         * @return The calculated width of the element.
         */
        int GetPageElementFloatWidth(const StoryPageElement &pe) const
        {
                switch (pe.type) {
                        case SPET_BUTTON_PUSH:
                        case SPET_BUTTON_TILE:
                        case SPET_BUTTON_VEHICLE: {
                                Dimension dim = GetStringBoundingBox(pe.text, FS_NORMAL);
                                return dim.width + WD_BEVEL_LEFT + WD_BEVEL_RIGHT + WD_FRAMETEXT_LEFT + WD_FRAMETEXT_RIGHT;
                        }

                        default:
                                NOT_REACHED(); // only buttons can float
                }
        }

        /** Invalidate the current page layout */
        void InvalidateStoryPageElementLayout()
        {
                this->layout_cache.clear();
        }

        /** Create the page layout if it is missing */
        void EnsureStoryPageElementLayout() const
        {
                /* Assume if the layout cache has contents it is valid */
                if (!this->layout_cache.empty()) return;

                StoryPage *page = this->GetSelPage();
                if (page == nullptr) return;
                int max_width = GetAvailablePageContentWidth();
                int element_dist = FONT_HEIGHT_NORMAL;

                /* Make space for the header */
                int main_y = GetHeadHeight(max_width) + element_dist;

                /* Current bottom of left/right column */
                int left_y = main_y;
                int right_y = main_y;
                /* Current width of left/right column, 0 indicates no content in column */
                int left_width = 0;
                int right_width = 0;
                /* Indexes into element cache for yet unresolved floats */
                std::vector<size_t> left_floats;
                std::vector<size_t> right_floats;

                /* Build layout */
                for (const StoryPageElement *pe : this->story_page_elements) {
                        ElementFloat fl = this->GetPageElementFloat(*pe);

                        if (fl == ElementFloat::None) {
                                /* Verify available width */
                                const int min_required_width = 10 * FONT_HEIGHT_NORMAL;
                                int left_offset = (left_width == 0) ? 0 : (left_width + element_dist);
                                int right_offset = (right_width == 0) ? 0 : (right_width + element_dist);
                                if (left_offset + right_offset + min_required_width >= max_width) {
                                        /* Width of floats leave too little for main content, push down */
                                        main_y = std::max(main_y, left_y);
                                        main_y = std::max(main_y, right_y);
                                        left_width = right_width = 0;
                                        left_offset = right_offset = 0;
                                        /* Do not add element_dist here, to keep together elements which were supposed to float besides each other. */
                                }
                                /* Determine height */
                                const int available_width = max_width - left_offset - right_offset;
                                const int height = GetPageElementHeight(*pe, available_width);
                                /* Check for button that needs extra margin */
                                if (left_offset == 0 && right_offset == 0) {
                                        switch (pe->type) {
                                                case SPET_BUTTON_PUSH:
                                                case SPET_BUTTON_TILE:
                                                case SPET_BUTTON_VEHICLE:
                                                        left_offset = right_offset = available_width / 5;
                                                        break;
                                                default:
                                                        break;
                                        }
                                }
                                /* Position element in main column */
                                LayoutCacheElement ce{ pe, {} };
                                ce.bounds.left = left_offset;
                                ce.bounds.right = max_width - right_offset;
                                ce.bounds.top = main_y;
                                main_y += height;
                                ce.bounds.bottom = main_y;
                                this->layout_cache.push_back(ce);
                                main_y += element_dist;
                                /* Clear all floats */
                                left_width = right_width = 0;
                                left_y = right_y = main_y = std::max({main_y, left_y, right_y});
                                left_floats.clear();
                                right_floats.clear();
                        } else {
                                /* Prepare references to correct column */
                                int &cur_width = (fl == ElementFloat::Left) ? left_width : right_width;
                                int &cur_y = (fl == ElementFloat::Left) ? left_y : right_y;
                                std::vector<size_t> &cur_floats = (fl == ElementFloat::Left) ? left_floats : right_floats;
                                /* Position element */
                                cur_width = std::max(cur_width, this->GetPageElementFloatWidth(*pe));
                                LayoutCacheElement ce{ pe, {} };
                                ce.bounds.left = (fl == ElementFloat::Left) ? 0 : (max_width - cur_width);
                                ce.bounds.right = (fl == ElementFloat::Left) ? cur_width : max_width;
                                ce.bounds.top = cur_y;
                                cur_y += GetPageElementHeight(*pe, cur_width);
                                ce.bounds.bottom = cur_y;
                                cur_floats.push_back(this->layout_cache.size());
                                this->layout_cache.push_back(ce);
                                cur_y += element_dist;
                                /* Update floats in column to all have the same width */
                                for (size_t index : cur_floats) {
                                        LayoutCacheElement &ce = this->layout_cache[index];
                                        ce.bounds.left = (fl == ElementFloat::Left) ? 0 : (max_width - cur_width);
                                        ce.bounds.right = (fl == ElementFloat::Left) ? cur_width : max_width;
                                }
                        }
                }
        }

        /**
         * Get the total height of the content displayed in this window.
         * @return the height in pixels
         */
        uint GetContentHeight()
        {
                this->EnsureStoryPageElementLayout();

                /* The largest bottom coordinate of any element is the height of the content */
                uint max_y = std::accumulate(this->layout_cache.begin(), this->layout_cache.end(), 0, [](uint max_y, const LayoutCacheElement &ce) -> uint { return std::max<uint>(max_y, ce.bounds.bottom); });

                return max_y;
        }

        /**
         * Draws a page element that is composed of a sprite to the left and a single line of
         * text after that. These page elements are generally clickable and are thus called
         * action elements.
         * @param y_offset Current y_offset which will get updated when this method has completed its drawing.
         * @param width Width of the region available for drawing.
         * @param line_height Height of one line of text.
         * @param action_sprite The sprite to draw.
         * @param string_id The string id to draw.
         * @return the number of lines.
         */
        void DrawActionElement(int &y_offset, int width, int line_height, SpriteID action_sprite, StringID string_id = STR_JUST_RAW_STRING) const
        {
                Dimension sprite_dim = GetSpriteSize(action_sprite);
                uint element_height = std::max(sprite_dim.height, (uint)line_height);

                uint sprite_top = y_offset + (element_height - sprite_dim.height) / 2;
                uint text_top = y_offset + (element_height - line_height) / 2;

                DrawSprite(action_sprite, PAL_NONE, 0, sprite_top);
                DrawString(sprite_dim.width + WD_FRAMETEXT_LEFT, width, text_top, string_id, TC_BLACK);

                y_offset += element_height;
        }

        /**
         * Internal event handler for when a page element is clicked.
         * @param pe The clicked page element.
         */
        void OnPageElementClick(const StoryPageElement& pe)
        {
                switch (pe.type) {
                        case SPET_TEXT:
                                /* Do nothing. */
                                break;

                        case SPET_LOCATION:
                                if (_ctrl_pressed) {
                                        ShowExtraViewportWindow((TileIndex)pe.referenced_id);
                                } else {
                                        ScrollMainWindowToTile((TileIndex)pe.referenced_id);
                                }
                                break;

                        case SPET_GOAL:
                                ShowGoalsList((CompanyID)this->window_number);
                                break;

                        case SPET_BUTTON_PUSH:
                                if (this->active_button_id != INVALID_STORY_PAGE_ELEMENT) ResetObjectToPlace();
                                this->active_button_id = pe.index;
                                this->SetTimeout();
                                this->SetWidgetDirty(WID_SB_PAGE_PANEL);

                                DoCommandP(0, pe.index, 0, CMD_STORY_PAGE_BUTTON);
                                break;

                        case SPET_BUTTON_TILE:
                                if (this->active_button_id == pe.index) {
                                        ResetObjectToPlace();
                                        this->active_button_id = INVALID_STORY_PAGE_ELEMENT;
                                } else {
                                        CursorID cursor = TranslateStoryPageButtonCursor(StoryPageButtonData{ pe.referenced_id }.GetCursor());
                                        SetObjectToPlaceWnd(cursor, PAL_NONE, HT_RECT, this);
                                        this->active_button_id = pe.index;
                                }
                                this->SetWidgetDirty(WID_SB_PAGE_PANEL);
                                break;

                        case SPET_BUTTON_VEHICLE:
                                if (this->active_button_id == pe.index) {
                                        ResetObjectToPlace();
                                        this->active_button_id = INVALID_STORY_PAGE_ELEMENT;
                                } else {
                                        CursorID cursor = TranslateStoryPageButtonCursor(StoryPageButtonData{ pe.referenced_id }.GetCursor());
                                        SetObjectToPlaceWnd(cursor, PAL_NONE, HT_VEHICLE, this);
                                        this->active_button_id = pe.index;
                                }
                                this->SetWidgetDirty(WID_SB_PAGE_PANEL);
                                break;

                        default:
                                NOT_REACHED();
                }
        }

public:
        StoryBookWindow(WindowDesc *desc, WindowNumber window_number) : Window(desc)
        {
                this->CreateNestedTree();
                this->vscroll = this->GetScrollbar(WID_SB_SCROLLBAR);
                this->vscroll->SetStepSize(FONT_HEIGHT_NORMAL);

                /* Initialize page sort. */
                this->story_pages.SetSortFuncs(StoryBookWindow::page_sorter_funcs);
                this->story_pages.ForceRebuild();
                this->BuildStoryPageList();
                this->story_page_elements.SetSortFuncs(StoryBookWindow::page_element_sorter_funcs);
                /* story_page_elements will get built by SetSelectedPage */

                this->FinishInitNested(window_number);
                this->owner = (Owner)this->window_number;

                /* Initialize selected vars. */
                this->selected_generic_title[0] = '\0';
                this->selected_page_id = INVALID_STORY_PAGE;

                this->active_button_id = INVALID_STORY_PAGE_ELEMENT;

                this->OnInvalidateData(-1);
        }

        /**
         * Updates the disabled state of the prev/next buttons.
         */
        void UpdatePrevNextDisabledState()
        {
                this->SetWidgetDisabledState(WID_SB_PREV_PAGE, story_pages.size() == 0 || this->IsFirstPageSelected());
                this->SetWidgetDisabledState(WID_SB_NEXT_PAGE, story_pages.size() == 0 || this->IsLastPageSelected());
                this->SetWidgetDirty(WID_SB_PREV_PAGE);
                this->SetWidgetDirty(WID_SB_NEXT_PAGE);
        }

        /**
         * Sets the selected page.
         * @param page_index pool index of the page to select.
         */
        void SetSelectedPage(uint16 page_index)
        {
                if (this->selected_page_id != page_index) {
                        if (this->active_button_id) ResetObjectToPlace();
                        this->active_button_id = INVALID_STORY_PAGE_ELEMENT;
                        this->selected_page_id = page_index;
                        this->RefreshSelectedPage();
                        this->UpdatePrevNextDisabledState();
                }
        }

        void SetStringParameters(int widget) const override
        {
                switch (widget) {
                        case WID_SB_SEL_PAGE: {
                                StoryPage *page = this->GetSelPage();
                                SetDParamStr(0, page != nullptr && page->title != nullptr ? page->title : this->selected_generic_title);
                                break;
                        }
                        case WID_SB_CAPTION:
                                if (this->window_number == INVALID_COMPANY) {
                                        SetDParam(0, STR_STORY_BOOK_SPECTATOR_CAPTION);
                                } else {
                                        SetDParam(0, STR_STORY_BOOK_CAPTION);
                                        SetDParam(1, this->window_number);
                                }
                                break;
                }
        }

        void OnPaint() override
        {
                /* Detect if content has changed height. This can happen if a
                 * multi-line text contains eg. {COMPANY} and that company is
                 * renamed.
                 */
                if (this->vscroll->GetCount() != this->GetContentHeight()) {
                        this->vscroll->SetCount(this->GetContentHeight());
                        this->SetWidgetDirty(WID_SB_SCROLLBAR);
                        this->SetWidgetDirty(WID_SB_PAGE_PANEL);
                }

                this->DrawWidgets();
        }

        void DrawWidget(const Rect &r, int widget) const override
        {
                if (widget != WID_SB_PAGE_PANEL) return;

                StoryPage *page = this->GetSelPage();
                if (page == nullptr) return;

                const int x = r.left + WD_FRAMETEXT_LEFT;
                const int y = r.top + WD_FRAMETEXT_TOP;
                const int right = r.right - WD_FRAMETEXT_RIGHT;
                const int bottom = r.bottom - WD_FRAMETEXT_BOTTOM;

                /* Set up a clipping region for the panel. */
                DrawPixelInfo tmp_dpi;
                if (!FillDrawPixelInfo(&tmp_dpi, x, y, right - x + 1, bottom - y + 1)) return;

                DrawPixelInfo *old_dpi = _cur_dpi;
                _cur_dpi = &tmp_dpi;

                /* Draw content (now coordinates given to Draw** are local to the new clipping region). */
                int line_height = FONT_HEIGHT_NORMAL;
                const int scrollpos = this->vscroll->GetPosition();
                int y_offset = -scrollpos;

                /* Date */
                if (page->date != INVALID_DATE) {
                        SetDParam(0, page->date);
                        DrawString(0, right - x, y_offset, STR_JUST_DATE_LONG, TC_BLACK);
                }
                y_offset += line_height;

                /* Title */
                SetDParamStr(0, page->title != nullptr ? page->title : this->selected_generic_title);
                y_offset = DrawStringMultiLine(0, right - x, y_offset, bottom - y, STR_STORY_BOOK_TITLE, TC_BLACK, SA_TOP | SA_HOR_CENTER);

                /* Page elements */
                this->EnsureStoryPageElementLayout();
                for (const LayoutCacheElement &ce : this->layout_cache) {
                        y_offset = ce.bounds.top - scrollpos;
                        switch (ce.pe->type) {
                                case SPET_TEXT:
                                        SetDParamStr(0, ce.pe->text);
                                        y_offset = DrawStringMultiLine(ce.bounds.left, ce.bounds.right, ce.bounds.top - scrollpos, ce.bounds.bottom - scrollpos, STR_JUST_RAW_STRING, TC_BLACK, SA_TOP | SA_LEFT);
                                        break;

                                case SPET_GOAL: {
                                        Goal *g = Goal::Get((GoalID) ce.pe->referenced_id);
                                        StringID string_id = g == nullptr ? STR_STORY_BOOK_INVALID_GOAL_REF : STR_JUST_RAW_STRING;
                                        if (g != nullptr) SetDParamStr(0, g->text);
                                        DrawActionElement(y_offset, ce.bounds.right - ce.bounds.left, line_height, GetPageElementSprite(*ce.pe), string_id);
                                        break;
                                }

                                case SPET_LOCATION:
                                        SetDParamStr(0, ce.pe->text);
                                        DrawActionElement(y_offset, ce.bounds.right - ce.bounds.left, line_height, GetPageElementSprite(*ce.pe));
                                        break;

                                case SPET_BUTTON_PUSH:
                                case SPET_BUTTON_TILE:
                                case SPET_BUTTON_VEHICLE: {
                                        const int tmargin = WD_BEVEL_TOP + WD_FRAMETEXT_TOP;
                                        const FrameFlags frame = this->active_button_id == ce.pe->index ? FR_LOWERED : FR_NONE;
                                        const Colours bgcolour = StoryPageButtonData{ ce.pe->referenced_id }.GetColour();

                                        DrawFrameRect(ce.bounds.left, ce.bounds.top - scrollpos, ce.bounds.right, ce.bounds.bottom - scrollpos - 1, bgcolour, frame);

                                        SetDParamStr(0, ce.pe->text);
                                        DrawString(ce.bounds.left + WD_BEVEL_LEFT, ce.bounds.right - WD_BEVEL_RIGHT, ce.bounds.top + tmargin - scrollpos, STR_JUST_RAW_STRING, TC_WHITE, SA_CENTER);
                                        break;
                                }

                                default: NOT_REACHED();
                        }
                }

                /* Restore clipping region. */
                _cur_dpi = old_dpi;
        }

        void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize) override
        {
                if (widget != WID_SB_SEL_PAGE && widget != WID_SB_PAGE_PANEL) return;

                Dimension d;
                d.height = FONT_HEIGHT_NORMAL;
                d.width = 0;

                switch (widget) {
                        case WID_SB_SEL_PAGE: {

                                /* Get max title width. */
                                for (size_t i = 0; i < this->story_pages.size(); i++) {
                                        const StoryPage *s = this->story_pages[i];

                                        if (s->title != nullptr) {
                                                SetDParamStr(0, s->title);
                                        } else {
                                                SetDParamStr(0, this->selected_generic_title);
                                        }
                                        Dimension title_d = GetStringBoundingBox(STR_BLACK_RAW_STRING);

                                        if (title_d.width > d.width) {
                                                d.width = title_d.width;
                                        }
                                }

                                d.width += padding.width;
                                d.height += padding.height;
                                *size = maxdim(*size, d);
                                break;
                        }

                        case WID_SB_PAGE_PANEL: {
                                d.height *= 5;
                                d.height += padding.height + WD_FRAMETEXT_TOP + WD_FRAMETEXT_BOTTOM;
                                *size = maxdim(*size, d);
                                break;
                        }
                }

        }

        void OnResize() override
        {
                this->InvalidateStoryPageElementLayout();
                this->vscroll->SetCapacityFromWidget(this, WID_SB_PAGE_PANEL, WD_FRAMETEXT_TOP + WD_FRAMETEXT_BOTTOM);
                this->vscroll->SetCount(this->GetContentHeight());
        }

        void OnClick(Point pt, int widget, int click_count) override
        {
                switch (widget) {
                        case WID_SB_SEL_PAGE: {
                                DropDownList list = this->BuildDropDownList();
                                if (!list.empty()) {
                                        /* Get the index of selected page. */
                                        int selected = 0;
                                        for (size_t i = 0; i < this->story_pages.size(); i++) {
                                                const StoryPage *p = this->story_pages[i];
                                                if (p->index == this->selected_page_id) break;
                                                selected++;
                                        }

                                        ShowDropDownList(this, std::move(list), selected, widget);
                                }
                                break;
                        }

                        case WID_SB_PREV_PAGE:
                                this->SelectPrevPage();
                                break;

                        case WID_SB_NEXT_PAGE:
                                this->SelectNextPage();
                                break;

                        case WID_SB_PAGE_PANEL: {
                                int clicked_y = this->vscroll->GetScrolledRowFromWidget(pt.y, this, WID_SB_PAGE_PANEL, WD_FRAMETEXT_TOP);
                                this->EnsureStoryPageElementLayout();

                                for (const LayoutCacheElement &ce : this->layout_cache) {
                                        if (clicked_y >= ce.bounds.top && clicked_y < ce.bounds.bottom && pt.x >= ce.bounds.left && pt.x < ce.bounds.right) {
                                                this->OnPageElementClick(*ce.pe);
                                                return;
                                        }
                                }
                        }
                }
        }

        void OnDropdownSelect(int widget, int index) override
        {
                if (widget != WID_SB_SEL_PAGE) return;

                /* index (which is set in BuildDropDownList) is the page id. */
                this->SetSelectedPage(index);
        }

        /**
         * Some data on this window has become invalid.
         * @param data Information about the changed data.
         *   -1     Rebuild page list and refresh current page;
         *   >= 0   Id of the page that needs to be refreshed. If it is not the current page, nothing happens.
         * @param gui_scope Whether the call is done from GUI scope. You may not do everything when not in GUI scope. See #InvalidateWindowData() for details.
         */
        void OnInvalidateData(int data = 0, bool gui_scope = true) override
        {
                if (!gui_scope) return;

                /* If added/removed page, force rebuild. Sort order never change so just a
                 * re-sort is never needed.
                 */
                if (data == -1) {
                        this->story_pages.ForceRebuild();
                        this->BuildStoryPageList();

                        /* Was the last page removed? */
                        if (this->story_pages.size() == 0) {
                                this->selected_generic_title[0] = '\0';
                        }

                        /* Verify page selection. */
                        if (!_story_page_pool.IsValidID(this->selected_page_id)) {
                                this->selected_page_id = INVALID_STORY_PAGE;
                        }
                        if (this->selected_page_id == INVALID_STORY_PAGE && this->story_pages.size() > 0) {
                                /* No page is selected, but there exist at least one available.
                                 * => Select first page.
                                 */
                                this->SetSelectedPage(this->story_pages[0]->index);
                        }

                        this->SetWidgetDisabledState(WID_SB_SEL_PAGE, this->story_pages.size() == 0);
                        this->SetWidgetDirty(WID_SB_SEL_PAGE);
                        this->UpdatePrevNextDisabledState();
                } else if (data >= 0 && this->selected_page_id == data) {
                        this->RefreshSelectedPage();
                }
        }

        void OnTimeout() override
        {
                this->active_button_id = INVALID_STORY_PAGE_ELEMENT;
                this->SetWidgetDirty(WID_SB_PAGE_PANEL);
        }

        void OnPlaceObject(Point pt, TileIndex tile) override
        {
                const StoryPageElement *const pe = StoryPageElement::GetIfValid(this->active_button_id);
                if (pe == nullptr || pe->type != SPET_BUTTON_TILE) {
                        ResetObjectToPlace();
                        this->active_button_id = INVALID_STORY_PAGE_ELEMENT;
                        this->SetWidgetDirty(WID_SB_PAGE_PANEL);
                        return;
                }

                DoCommandP(tile, pe->index, 0, CMD_STORY_PAGE_BUTTON);
                ResetObjectToPlace();
        }

        bool OnVehicleSelect(const Vehicle *v) override
        {
                const StoryPageElement *const pe = StoryPageElement::GetIfValid(this->active_button_id);
                if (pe == nullptr || pe->type != SPET_BUTTON_VEHICLE) {
                        ResetObjectToPlace();
                        this->active_button_id = INVALID_STORY_PAGE_ELEMENT;
                        this->SetWidgetDirty(WID_SB_PAGE_PANEL);
                        return false;
                }

                /* Check that the vehicle matches the requested type */
                StoryPageButtonData data{ pe->referenced_id };
                VehicleType wanted_vehtype = data.GetVehicleType();
                if (wanted_vehtype != VEH_INVALID && wanted_vehtype != v->type) return false;

                DoCommandP(0, pe->index, v->index, CMD_STORY_PAGE_BUTTON);
                ResetObjectToPlace();
                return true;
        }

        void OnPlaceObjectAbort() override
        {
                this->active_button_id = INVALID_STORY_PAGE_ELEMENT;
                this->SetWidgetDirty(WID_SB_PAGE_PANEL);
        }
};

GUIStoryPageList::SortFunction * const StoryBookWindow::page_sorter_funcs[] = {
        &PageOrderSorter,
};

GUIStoryPageElementList::SortFunction * const StoryBookWindow::page_element_sorter_funcs[] = {
        &PageElementOrderSorter,
};

static const NWidgetPart _nested_story_book_widgets[] = {
        NWidget(NWID_HORIZONTAL),
                NWidget(WWT_CLOSEBOX, COLOUR_BROWN),
                NWidget(WWT_CAPTION, COLOUR_BROWN, WID_SB_CAPTION), SetDataTip(STR_JUST_STRING, STR_TOOLTIP_WINDOW_TITLE_DRAG_THIS),
                NWidget(WWT_SHADEBOX, COLOUR_BROWN),
                NWidget(WWT_DEFSIZEBOX, COLOUR_BROWN),
                NWidget(WWT_STICKYBOX, COLOUR_BROWN),
        EndContainer(),
        NWidget(NWID_HORIZONTAL), SetFill(1, 1),
                NWidget(NWID_VERTICAL), SetFill(1, 1),
                        NWidget(WWT_PANEL, COLOUR_BROWN, WID_SB_PAGE_PANEL), SetResize(1, 1), SetScrollbar(WID_SB_SCROLLBAR), EndContainer(),
                        NWidget(NWID_HORIZONTAL),
                                NWidget(WWT_TEXTBTN, COLOUR_BROWN, WID_SB_PREV_PAGE), SetMinimalSize(100, 0), SetFill(0, 0), SetDataTip(STR_STORY_BOOK_PREV_PAGE, STR_STORY_BOOK_PREV_PAGE_TOOLTIP),
                                NWidget(NWID_BUTTON_DROPDOWN, COLOUR_BROWN, WID_SB_SEL_PAGE), SetMinimalSize(93, 12), SetFill(1, 0),
                                                                                                                SetDataTip(STR_BLACK_RAW_STRING, STR_STORY_BOOK_SEL_PAGE_TOOLTIP), SetResize(1, 0),
                                NWidget(WWT_TEXTBTN, COLOUR_BROWN, WID_SB_NEXT_PAGE), SetMinimalSize(100, 0), SetFill(0, 0), SetDataTip(STR_STORY_BOOK_NEXT_PAGE, STR_STORY_BOOK_NEXT_PAGE_TOOLTIP),
                        EndContainer(),
                EndContainer(),
                NWidget(NWID_VERTICAL), SetFill(0, 1),
                        NWidget(NWID_VSCROLLBAR, COLOUR_BROWN, WID_SB_SCROLLBAR),
                        NWidget(WWT_RESIZEBOX, COLOUR_BROWN),
                EndContainer(),
        EndContainer(),
};

static WindowDesc _story_book_desc(
        WDP_CENTER, "view_story", 400, 300,
        WC_STORY_BOOK, WC_NONE,
        0,
        _nested_story_book_widgets, lengthof(_nested_story_book_widgets)
);

static CursorID TranslateStoryPageButtonCursor(StoryPageButtonCursor cursor)
{
        switch (cursor) {
                case SPBC_MOUSE:          return SPR_CURSOR_MOUSE;
                case SPBC_ZZZ:            return SPR_CURSOR_ZZZ;
                case SPBC_BUOY:           return SPR_CURSOR_BUOY;
                case SPBC_QUERY:          return SPR_CURSOR_QUERY;
                case SPBC_HQ:             return SPR_CURSOR_HQ;
                case SPBC_SHIP_DEPOT:     return SPR_CURSOR_SHIP_DEPOT;
                case SPBC_SIGN:           return SPR_CURSOR_SIGN;
                case SPBC_TREE:           return SPR_CURSOR_TREE;
                case SPBC_BUY_LAND:       return SPR_CURSOR_BUY_LAND;
                case SPBC_LEVEL_LAND:     return SPR_CURSOR_LEVEL_LAND;
                case SPBC_TOWN:           return SPR_CURSOR_TOWN;
                case SPBC_INDUSTRY:       return SPR_CURSOR_INDUSTRY;
                case SPBC_ROCKY_AREA:     return SPR_CURSOR_ROCKY_AREA;
                case SPBC_DESERT:         return SPR_CURSOR_DESERT;
                case SPBC_TRANSMITTER:    return SPR_CURSOR_TRANSMITTER;
                case SPBC_AIRPORT:        return SPR_CURSOR_AIRPORT;
                case SPBC_DOCK:           return SPR_CURSOR_DOCK;
                case SPBC_CANAL:          return SPR_CURSOR_CANAL;
                case SPBC_LOCK:           return SPR_CURSOR_LOCK;
                case SPBC_RIVER:          return SPR_CURSOR_RIVER;
                case SPBC_AQUEDUCT:       return SPR_CURSOR_AQUEDUCT;
                case SPBC_BRIDGE:         return SPR_CURSOR_BRIDGE;
                case SPBC_RAIL_STATION:   return SPR_CURSOR_RAIL_STATION;
                case SPBC_TUNNEL_RAIL:    return SPR_CURSOR_TUNNEL_RAIL;
                case SPBC_TUNNEL_ELRAIL:  return SPR_CURSOR_TUNNEL_ELRAIL;
                case SPBC_TUNNEL_MONO:    return SPR_CURSOR_TUNNEL_MONO;
                case SPBC_TUNNEL_MAGLEV:  return SPR_CURSOR_TUNNEL_MAGLEV;
                case SPBC_AUTORAIL:       return SPR_CURSOR_AUTORAIL;
                case SPBC_AUTOELRAIL:     return SPR_CURSOR_AUTOELRAIL;
                case SPBC_AUTOMONO:       return SPR_CURSOR_AUTOMONO;
                case SPBC_AUTOMAGLEV:     return SPR_CURSOR_AUTOMAGLEV;
                case SPBC_WAYPOINT:       return SPR_CURSOR_WAYPOINT;
                case SPBC_RAIL_DEPOT:     return SPR_CURSOR_RAIL_DEPOT;
                case SPBC_ELRAIL_DEPOT:   return SPR_CURSOR_ELRAIL_DEPOT;
                case SPBC_MONO_DEPOT:     return SPR_CURSOR_MONO_DEPOT;
                case SPBC_MAGLEV_DEPOT:   return SPR_CURSOR_MAGLEV_DEPOT;
                case SPBC_CONVERT_RAIL:   return SPR_CURSOR_CONVERT_RAIL;
                case SPBC_CONVERT_ELRAIL: return SPR_CURSOR_CONVERT_ELRAIL;
                case SPBC_CONVERT_MONO:   return SPR_CURSOR_CONVERT_MONO;
                case SPBC_CONVERT_MAGLEV: return SPR_CURSOR_CONVERT_MAGLEV;
                case SPBC_AUTOROAD:       return SPR_CURSOR_AUTOROAD;
                case SPBC_AUTOTRAM:       return SPR_CURSOR_AUTOTRAM;
                case SPBC_ROAD_DEPOT:     return SPR_CURSOR_ROAD_DEPOT;
                case SPBC_BUS_STATION:    return SPR_CURSOR_BUS_STATION;
                case SPBC_TRUCK_STATION:  return SPR_CURSOR_TRUCK_STATION;
                case SPBC_ROAD_TUNNEL:    return SPR_CURSOR_ROAD_TUNNEL;
                case SPBC_CLONE_TRAIN:    return SPR_CURSOR_CLONE_TRAIN;
                case SPBC_CLONE_ROADVEH:  return SPR_CURSOR_CLONE_ROADVEH;
                case SPBC_CLONE_SHIP:     return SPR_CURSOR_CLONE_SHIP;
                case SPBC_CLONE_AIRPLANE: return SPR_CURSOR_CLONE_AIRPLANE;
                case SPBC_DEMOLISH:       return ANIMCURSOR_DEMOLISH;
                case SPBC_LOWERLAND:      return ANIMCURSOR_LOWERLAND;
                case SPBC_RAISELAND:      return ANIMCURSOR_RAISELAND;
                case SPBC_PICKSTATION:    return ANIMCURSOR_PICKSTATION;
                case SPBC_BUILDSIGNALS:   return ANIMCURSOR_BUILDSIGNALS;
                default: return SPR_CURSOR_QUERY;
        }
}

/**
 * Raise or create the story book window for \a company, at page \a page_id.
 * @param company 'Owner' of the story book, may be #INVALID_COMPANY.
 * @param page_id Page to open, may be #INVALID_STORY_PAGE.
 */
void ShowStoryBook(CompanyID company, uint16 page_id)
{
        if (!Company::IsValidID(company)) company = (CompanyID)INVALID_COMPANY;

        StoryBookWindow *w = AllocateWindowDescFront<StoryBookWindow>(&_story_book_desc, company, true);
        if (page_id != INVALID_STORY_PAGE) w->SetSelectedPage(page_id);
}