story_gui.cpp

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/*
 * 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/>.
 */
 
#include "stdafx.h"
#include "window_gui.h"
#include "strings_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 "story_cmd.h"
 
#include "widgets/story_widget.h"
 
#include "table/strings.h"
#include "table/sprites.h"
 
#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;                
  mutable LayoutCache layout_cache;  
 
  GUIStoryPageList story_pages;      
  GUIStoryPageElementList story_page_elements; 
  StoryPageID selected_page_id;      
  std::string selected_generic_title;  
 
  StoryPageElementID active_button_id; 
 
  static GUIStoryPageList::SortFunction * const page_sorter_funcs[];
  static GUIStoryPageElementList::SortFunction * const page_element_sorter_funcs[];
 
  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();
  }
 
  static bool PageOrderSorter(const StoryPage * const &a, const StoryPage * const &b)
  {
    return a->sort_value < b->sort_value;
  }
 
  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();
  }
 
  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;
  }
 
  StoryPage *GetSelPage() const
  {
    if (!_story_page_pool.IsValidID(selected_page_id)) return nullptr;
    return _story_page_pool.Get(selected_page_id);
  }
 
  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;
  }
 
  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;
  }
 
  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;
  }
 
  void RefreshSelectedPage()
  {
    /* Generate generic title if selected page have no custom title. */
    StoryPage *page = this->GetSelPage();
    if (page != nullptr && page->title.empty()) {
      SetDParam(0, GetSelPageNum() + 1);
      selected_generic_title = GetString(STR_STORY_BOOK_GENERIC_PAGE_ITEM);
    }
 
    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);
  }
 
  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;
    }
  }
 
  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;
      }
    }
  }
 
  DropDownList BuildDropDownList() const
  {
    DropDownList list;
    uint16_t page_num = 1;
    for (const StoryPage *p : this->story_pages) {
      bool current_page = p->index == this->selected_page_id;
      if (!p->title.empty()) {
        list.push_back(std::make_unique<DropDownListStringItem>(p->title, p->index, current_page));
      } else {
        /* No custom title => use a generic page title with page number. */
        SetDParam(0, page_num);
        list.push_back(std::make_unique<DropDownListStringItem>(STR_STORY_BOOK_GENERIC_PAGE_ITEM, p->index, current_page));
      }
      page_num++;
    }
 
    return list;
  }
 
  uint GetAvailablePageContentWidth() const
  {
    return this->GetWidget<NWidgetCore>(WID_SB_PAGE_PANEL)->current_x - WidgetDimensions::scaled.frametext.Horizontal() - 1;
  }
 
  uint GetHeadHeight(int max_width) const
  {
    StoryPage *page = this->GetSelPage();
    if (page == nullptr) return 0;
    int height = 0;
 
    /* Title lines */
    height += GetCharacterHeight(FS_NORMAL); // Date always use exactly one line.
    SetDParamStr(0, !page->title.empty() ? page->title : this->selected_generic_title);
    height += GetStringHeight(STR_STORY_BOOK_TITLE, max_width);
 
    return height;
  }
 
  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();
    }
  }
 
  uint GetPageElementHeight(const StoryPageElement &pe, int max_width) const
  {
    switch (pe.type) {
      case SPET_TEXT:
        SetDParamStr(0, pe.text);
        return GetStringHeight(STR_JUST_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 + WidgetDimensions::scaled.framerect.Vertical() + WidgetDimensions::scaled.frametext.Vertical();
      }
 
      default:
        NOT_REACHED();
    }
    return 0;
  }
 
  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;
    }
  }
 
  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 + WidgetDimensions::scaled.framerect.Vertical() + WidgetDimensions::scaled.frametext.Vertical();
      }
 
      default:
        NOT_REACHED(); // only buttons can float
    }
  }
 
  void InvalidateStoryPageElementLayout()
  {
    this->layout_cache.clear();
  }
 
  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 = GetCharacterHeight(FS_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 * GetCharacterHeight(FS_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;
        }
      }
    }
  }
 
  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;
  }
 
  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 + WidgetDimensions::scaled.frametext.left, width, text_top, string_id, TC_BLACK);
 
    y_offset += element_height;
  }
 
  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);
 
        Command<CMD_STORY_PAGE_BUTTON>::Post(0, pe.index, 0);
        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(GetCharacterHeight(FS_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.clear();
    this->selected_page_id = INVALID_STORY_PAGE;
 
    this->active_button_id = INVALID_STORY_PAGE_ELEMENT;
 
    this->OnInvalidateData(-1);
  }
 
  void UpdatePrevNextDisabledState()
  {
    this->SetWidgetDisabledState(WID_SB_PREV_PAGE, story_pages.empty() || this->IsFirstPageSelected());
    this->SetWidgetDisabledState(WID_SB_NEXT_PAGE, story_pages.empty() || this->IsLastPageSelected());
    this->SetWidgetDirty(WID_SB_PREV_PAGE);
    this->SetWidgetDirty(WID_SB_NEXT_PAGE);
  }
 
  void SetSelectedPage(uint16_t 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(WidgetID widget) const override
  {
    switch (widget) {
      case WID_SB_SEL_PAGE: {
        StoryPage *page = this->GetSelPage();
        SetDParamStr(0, page != nullptr && !page->title.empty() ? 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, WidgetID widget) const override
  {
    if (widget != WID_SB_PAGE_PANEL) return;
 
    StoryPage *page = this->GetSelPage();
    if (page == nullptr) return;
 
    Rect fr = r.Shrink(WidgetDimensions::scaled.frametext);
 
    /* Set up a clipping region for the panel. */
    DrawPixelInfo tmp_dpi;
    if (!FillDrawPixelInfo(&tmp_dpi, fr)) return;
 
    AutoRestoreBackup dpi_backup(_cur_dpi, &tmp_dpi);
 
    /* Draw content (now coordinates given to Draw** are local to the new clipping region). */
    fr = fr.Translate(-fr.left, -fr.top);
    int line_height = GetCharacterHeight(FS_NORMAL);
    const int scrollpos = this->vscroll->GetPosition();
    int y_offset = -scrollpos;
 
    /* Date */
    if (page->date != CalendarTime::INVALID_DATE) {
      SetDParam(0, page->date);
      DrawString(0, fr.right, y_offset, STR_JUST_DATE_LONG, TC_BLACK);
    }
    y_offset += line_height;
 
    /* Title */
    SetDParamStr(0, !page->title.empty() ? page->title : this->selected_generic_title);
    y_offset = DrawStringMultiLine(0, fr.right, y_offset, fr.bottom, 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 = WidgetDimensions::scaled.bevel.top + WidgetDimensions::scaled.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 + WidgetDimensions::scaled.bevel.left, ce.bounds.right - WidgetDimensions::scaled.bevel.right, ce.bounds.top + tmargin - scrollpos, STR_JUST_RAW_STRING, TC_WHITE, SA_CENTER);
          break;
        }
 
        default: NOT_REACHED();
      }
    }
  }
 
  void UpdateWidgetSize(WidgetID widget, Dimension *size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension *fill, [[maybe_unused]] Dimension *resize) override
  {
    if (widget != WID_SB_SEL_PAGE && widget != WID_SB_PAGE_PANEL) return;
 
    Dimension d;
    d.height = GetCharacterHeight(FS_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.empty()) {
            SetDParamStr(0, s->title);
          } else {
            SetDParamStr(0, this->selected_generic_title);
          }
          Dimension title_d = GetStringBoundingBox(STR_JUST_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 + WidgetDimensions::scaled.frametext.Vertical();
        *size = maxdim(*size, d);
        break;
      }
    }
 
  }
 
  void OnResize() override
  {
    this->InvalidateStoryPageElementLayout();
    this->vscroll->SetCapacityFromWidget(this, WID_SB_PAGE_PANEL, WidgetDimensions::scaled.frametext.Vertical());
    this->vscroll->SetCount(this->GetContentHeight());
  }
 
  void OnClick([[maybe_unused]] Point pt, WidgetID widget, [[maybe_unused]] 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, WidgetDimensions::scaled.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(WidgetID widget, int index) override
  {
    if (widget != WID_SB_SEL_PAGE) return;
 
    /* index (which is set in BuildDropDownList) is the page id. */
    this->SetSelectedPage(index);
  }
 
  void OnInvalidateData([[maybe_unused]] int data = 0, [[maybe_unused]] 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.empty()) {
        this->selected_generic_title.clear();
      }
 
      /* 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.empty()) {
        /* 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.empty());
      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([[maybe_unused]] 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;
    }
 
    Command<CMD_STORY_PAGE_BUTTON>::Post(tile, pe->index, 0);
    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;
 
    Command<CMD_STORY_PAGE_BUTTON>::Post(0, pe->index, v->index);
    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 constexpr NWidgetPart _nested_story_book_widgets[] = {
  NWidget(NWID_HORIZONTAL),
    NWidget(WWT_CLOSEBOX, COLOUR_BROWN),
    NWidget(WWT_CAPTION, COLOUR_BROWN, WID_SB_CAPTION), SetDataTip(STR_JUST_STRING1, 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),
    NWidget(WWT_PANEL, COLOUR_BROWN, WID_SB_PAGE_PANEL), SetResize(1, 1), SetScrollbar(WID_SB_SCROLLBAR), EndContainer(),
    NWidget(NWID_VSCROLLBAR, COLOUR_BROWN, 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_JUST_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),
    NWidget(WWT_RESIZEBOX, COLOUR_BROWN),
  EndContainer(),
};
 
static WindowDesc _story_book_desc(__FILE__, __LINE__,
  WDP_AUTO, "view_story", 400, 300,
  WC_STORY_BOOK, WC_NONE,
  0,
  std::begin(_nested_story_book_widgets), std::end(_nested_story_book_widgets)
);
 
static WindowDesc _story_book_gs_desc(__FILE__, __LINE__,
  WDP_CENTER, "view_story_gs", 400, 300,
  WC_STORY_BOOK, WC_NONE,
  0,
  std::begin(_nested_story_book_widgets), std::end(_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;
  }
}
 
void ShowStoryBook(CompanyID company, uint16_t page_id, bool centered)
{
  if (!Company::IsValidID(company)) company = (CompanyID)INVALID_COMPANY;
 
  StoryBookWindow *w = AllocateWindowDescFront<StoryBookWindow>(centered ? &_story_book_gs_desc : &_story_book_desc, company, true);
  if (page_id != INVALID_STORY_PAGE) w->SetSelectedPage(page_id);
}