sdl2_v.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 "../openttd.h"
#include "../gfx_func.h"
#include "../blitter/factory.hpp"
#include "../thread.h"
#include "../progress.h"
#include "../core/random_func.hpp"
#include "../core/math_func.hpp"
#include "../core/mem_func.hpp"
#include "../core/geometry_func.hpp"
#include "../fileio_func.h"
#include "../framerate_type.h"
#include "../window_func.h"
#include "sdl2_v.h"
#include <SDL.h>
#ifdef __EMSCRIPTEN__
# include <emscripten.h>
# include <emscripten/html5.h>
#endif
 
#include "../safeguards.h"
 
void VideoDriver_SDL_Base::MakeDirty(int left, int top, int width, int height)
{
  Rect r = {left, top, left + width, top + height};
  this->dirty_rect = BoundingRect(this->dirty_rect, r);
}
 
void VideoDriver_SDL_Base::CheckPaletteAnim()
{
  if (!CopyPalette(this->local_palette)) return;
  this->MakeDirty(0, 0, _screen.width, _screen.height);
}
 
static const Dimension default_resolutions[] = {
  {  640,  480 },
  {  800,  600 },
  { 1024,  768 },
  { 1152,  864 },
  { 1280,  800 },
  { 1280,  960 },
  { 1280, 1024 },
  { 1400, 1050 },
  { 1600, 1200 },
  { 1680, 1050 },
  { 1920, 1200 }
};
 
static void FindResolutions()
{
  _resolutions.clear();
 
  for (int display = 0; display < SDL_GetNumVideoDisplays(); display++) {
    for (int i = 0; i < SDL_GetNumDisplayModes(display); i++) {
      SDL_DisplayMode mode;
      SDL_GetDisplayMode(display, i, &mode);
 
      if (mode.w < 640 || mode.h < 480) continue;
      if (std::ranges::find(_resolutions, Dimension(mode.w, mode.h)) != _resolutions.end()) continue;
      _resolutions.emplace_back(mode.w, mode.h);
    }
  }
 
  /* We have found no resolutions, show the default list */
  if (_resolutions.empty()) {
    _resolutions.assign(std::begin(default_resolutions), std::end(default_resolutions));
  }
 
  SortResolutions();
}
 
static void GetAvailableVideoMode(uint *w, uint *h)
{
  /* All modes available? */
  if (!_fullscreen || _resolutions.empty()) return;
 
  /* Is the wanted mode among the available modes? */
  if (std::ranges::find(_resolutions, Dimension(*w, *h)) != _resolutions.end()) return;
 
  /* Use the closest possible resolution */
  uint best = 0;
  uint delta = Delta(_resolutions[0].width, *w) * Delta(_resolutions[0].height, *h);
  for (uint i = 1; i != _resolutions.size(); ++i) {
    uint newdelta = Delta(_resolutions[i].width, *w) * Delta(_resolutions[i].height, *h);
    if (newdelta < delta) {
      best = i;
      delta = newdelta;
    }
  }
  *w = _resolutions[best].width;
  *h = _resolutions[best].height;
}
 
static uint FindStartupDisplay(uint startup_display)
{
  int num_displays = SDL_GetNumVideoDisplays();
 
  /* If the user indicated a valid monitor, use that. */
  if (IsInsideBS(startup_display, 0, num_displays)) return startup_display;
 
  /* Mouse position decides which display to use. */
  int mx, my;
  SDL_GetGlobalMouseState(&mx, &my);
  for (int display = 0; display < num_displays; ++display) {
    SDL_Rect r;
    if (SDL_GetDisplayBounds(display, &r) == 0 && IsInsideBS(mx, r.x, r.w) && IsInsideBS(my, r.y, r.h)) {
      Debug(driver, 1, "SDL2: Mouse is at ({}, {}), use display {} ({}, {}, {}, {})", mx, my, display, r.x, r.y, r.w, r.h);
      return display;
    }
  }
 
  return 0;
}
 
void VideoDriver_SDL_Base::ClientSizeChanged(int w, int h, bool force)
{
  /* Allocate backing store of the new size. */
  if (this->AllocateBackingStore(w, h, force)) {
    CopyPalette(this->local_palette, true);
 
    BlitterFactory::GetCurrentBlitter()->PostResize();
 
    GameSizeChanged();
  }
}
 
bool VideoDriver_SDL_Base::CreateMainWindow(uint w, uint h, uint flags)
{
  if (this->sdl_window != nullptr) return true;
 
  flags |= SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE;
 
  if (_fullscreen) {
    flags |= SDL_WINDOW_FULLSCREEN;
  }
 
  int x = SDL_WINDOWPOS_UNDEFINED, y = SDL_WINDOWPOS_UNDEFINED;
  SDL_Rect r;
  if (SDL_GetDisplayBounds(this->startup_display, &r) == 0) {
    x = r.x + std::max(0, r.w - static_cast<int>(w)) / 2;
    y = r.y + std::max(0, r.h - static_cast<int>(h)) / 4; // decent desktops have taskbars at the bottom
  }
 
  std::string caption = VideoDriver::GetCaption();
  this->sdl_window = SDL_CreateWindow(
    caption.c_str(),
    x, y,
    w, h,
    flags);
 
  if (this->sdl_window == nullptr) {
    Debug(driver, 0, "SDL2: Couldn't allocate a window to draw on: {}", SDL_GetError());
    return false;
  }
 
  std::string icon_path = FioFindFullPath(BASESET_DIR, "openttd.32.bmp");
  if (!icon_path.empty()) {
    /* Give the application an icon */
    SDL_Surface *icon = SDL_LoadBMP(icon_path.c_str());
    if (icon != nullptr) {
      /* Get the colourkey, which will be magenta */
      uint32_t rgbmap = SDL_MapRGB(icon->format, 255, 0, 255);
 
      SDL_SetColorKey(icon, SDL_TRUE, rgbmap);
      SDL_SetWindowIcon(this->sdl_window, icon);
      SDL_FreeSurface(icon);
    }
  }
 
  return true;
}
 
bool VideoDriver_SDL_Base::CreateMainSurface(uint w, uint h, bool resize)
{
  GetAvailableVideoMode(&w, &h);
  Debug(driver, 1, "SDL2: using mode {}x{}", w, h);
 
  if (!this->CreateMainWindow(w, h)) return false;
  if (resize) SDL_SetWindowSize(this->sdl_window, w, h);
  this->ClientSizeChanged(w, h, true);
 
  /* When in full screen, we will always have the mouse cursor
   * within the window, even though SDL does not give us the
   * appropriate event to know this. */
  if (_fullscreen) _cursor.in_window = true;
 
  return true;
}
 
bool VideoDriver_SDL_Base::ClaimMousePointer()
{
  /* Emscripten never claims the pointer, so we do not need to change the cursor visibility. */
#ifndef __EMSCRIPTEN__
  SDL_ShowCursor(0);
#endif
  return true;
}
 
void VideoDriver_SDL_Base::EditBoxGainedFocus()
{
  if (!this->edit_box_focused) {
    SDL_StartTextInput();
    this->edit_box_focused = true;
  }
}
 
void VideoDriver_SDL_Base::EditBoxLostFocus()
{
  if (this->edit_box_focused) {
    SDL_StopTextInput();
    this->edit_box_focused = false;
  }
}
 
std::vector<int> VideoDriver_SDL_Base::GetListOfMonitorRefreshRates()
{
  std::vector<int> rates = {};
  for (int i = 0; i < SDL_GetNumVideoDisplays(); i++) {
    SDL_DisplayMode mode = {};
    if (SDL_GetDisplayMode(i, 0, &mode) != 0) continue;
    if (mode.refresh_rate != 0) rates.push_back(mode.refresh_rate);
  }
  return rates;
}
 
 
struct SDLVkMapping {
  const SDL_Keycode vk_from;
  const uint8_t vk_count;
  const uint8_t map_to;
  const bool unprintable;
 
  constexpr SDLVkMapping(SDL_Keycode vk_first, SDL_Keycode vk_last, uint8_t map_first, [[maybe_unused]] uint8_t map_last, bool unprintable)
    : vk_from(vk_first), vk_count(vk_last - vk_first + 1), map_to(map_first), unprintable(unprintable)
  {
    assert((vk_last - vk_first) == (map_last - map_first));
  }
};
 
#define AS(x, z) {x, x, z, z, false}
#define AM(x, y, z, w) {x, y, z, w, false}
#define AS_UP(x, z) {x, x, z, z, true}
#define AM_UP(x, y, z, w) {x, y, z, w, true}
 
static constexpr SDLVkMapping _vk_mapping[] = {
  /* Pageup stuff + up/down */
  AS_UP(SDLK_PAGEUP,   WKC_PAGEUP),
  AS_UP(SDLK_PAGEDOWN, WKC_PAGEDOWN),
  AS_UP(SDLK_UP,     WKC_UP),
  AS_UP(SDLK_DOWN,   WKC_DOWN),
  AS_UP(SDLK_LEFT,   WKC_LEFT),
  AS_UP(SDLK_RIGHT,  WKC_RIGHT),
 
  AS_UP(SDLK_HOME,   WKC_HOME),
  AS_UP(SDLK_END,    WKC_END),
 
  AS_UP(SDLK_INSERT, WKC_INSERT),
  AS_UP(SDLK_DELETE, WKC_DELETE),
 
  /* Map letters & digits */
  AM(SDLK_a, SDLK_z, 'A', 'Z'),
  AM(SDLK_0, SDLK_9, '0', '9'),
 
  AS_UP(SDLK_ESCAPE,    WKC_ESC),
  AS_UP(SDLK_PAUSE,     WKC_PAUSE),
  AS_UP(SDLK_BACKSPACE, WKC_BACKSPACE),
 
  AS(SDLK_SPACE,     WKC_SPACE),
  AS(SDLK_RETURN,    WKC_RETURN),
  AS(SDLK_TAB,       WKC_TAB),
 
  /* Function keys */
  AM_UP(SDLK_F1, SDLK_F12, WKC_F1, WKC_F12),
 
  /* Numeric part. */
  AS(SDLK_KP_1,        '1'),
  AS(SDLK_KP_2,        '2'),
  AS(SDLK_KP_3,        '3'),
  AS(SDLK_KP_4,        '4'),
  AS(SDLK_KP_5,        '5'),
  AS(SDLK_KP_6,        '6'),
  AS(SDLK_KP_7,        '7'),
  AS(SDLK_KP_8,        '8'),
  AS(SDLK_KP_9,        '9'),
  AS(SDLK_KP_0,        '0'),
  AS(SDLK_KP_DIVIDE,   WKC_NUM_DIV),
  AS(SDLK_KP_MULTIPLY, WKC_NUM_MUL),
  AS(SDLK_KP_MINUS,    WKC_NUM_MINUS),
  AS(SDLK_KP_PLUS,     WKC_NUM_PLUS),
  AS(SDLK_KP_ENTER,    WKC_NUM_ENTER),
  AS(SDLK_KP_PERIOD,   WKC_NUM_DECIMAL),
 
  /* Other non-letter keys */
  AS(SDLK_SLASH,        WKC_SLASH),
  AS(SDLK_SEMICOLON,    WKC_SEMICOLON),
  AS(SDLK_EQUALS,       WKC_EQUALS),
  AS(SDLK_LEFTBRACKET,  WKC_L_BRACKET),
  AS(SDLK_BACKSLASH,    WKC_BACKSLASH),
  AS(SDLK_RIGHTBRACKET, WKC_R_BRACKET),
 
  AS(SDLK_QUOTE,   WKC_SINGLEQUOTE),
  AS(SDLK_COMMA,   WKC_COMMA),
  AS(SDLK_MINUS,   WKC_MINUS),
  AS(SDLK_PERIOD,  WKC_PERIOD)
};
 
static uint ConvertSdlKeyIntoMy(SDL_Keysym *sym, char32_t *character)
{
  uint key = 0;
  bool unprintable = false;
 
  for (const auto &map : _vk_mapping) {
    if (IsInsideBS(sym->sym, map.vk_from, map.vk_count)) {
      key = sym->sym - map.vk_from + map.map_to;
      unprintable = map.unprintable;
      break;
    }
  }
 
  /* check scancode for BACKQUOTE key, because we want the key left of "1", not anything else (on non-US keyboards) */
  if (sym->scancode == SDL_SCANCODE_GRAVE) key = WKC_BACKQUOTE;
 
  /* META are the command keys on mac */
  if (sym->mod & KMOD_GUI)   key |= WKC_META;
  if (sym->mod & KMOD_SHIFT) key |= WKC_SHIFT;
  if (sym->mod & KMOD_CTRL)  key |= WKC_CTRL;
  if (sym->mod & KMOD_ALT)   key |= WKC_ALT;
 
  /* The mod keys have no character. Prevent '?' */
  if (sym->mod & KMOD_GUI ||
    sym->mod & KMOD_CTRL ||
    sym->mod & KMOD_ALT ||
    unprintable) {
    *character = WKC_NONE;
  } else {
    *character = sym->sym;
  }
 
  return key;
}
 
static uint ConvertSdlKeycodeIntoMy(SDL_Keycode kc)
{
  uint key = 0;
 
  for (const auto &map : _vk_mapping) {
    if (IsInsideBS(kc, map.vk_from, map.vk_count)) {
      key = kc - map.vk_from + map.map_to;
      break;
    }
  }
 
  /* check scancode for BACKQUOTE key, because we want the key left
   * of "1", not anything else (on non-US keyboards) */
  SDL_Scancode sc = SDL_GetScancodeFromKey(kc);
  if (sc == SDL_SCANCODE_GRAVE) key = WKC_BACKQUOTE;
 
  return key;
}
 
bool VideoDriver_SDL_Base::PollEvent()
{
  SDL_Event ev;
 
  if (!SDL_PollEvent(&ev)) return false;
 
  switch (ev.type) {
    case SDL_MOUSEMOTION: {
      int32_t x = ev.motion.x;
      int32_t y = ev.motion.y;
 
      if (_cursor.fix_at) {
        /* Get all queued mouse events now in case we have to warp the cursor. In the
         * end, we only care about the current mouse position and not bygone events. */
        while (SDL_PeepEvents(&ev, 1, SDL_GETEVENT, SDL_MOUSEMOTION, SDL_MOUSEMOTION)) {
          x = ev.motion.x;
          y = ev.motion.y;
        }
      }
 
      if (_cursor.UpdateCursorPosition(x, y)) {
        SDL_WarpMouseInWindow(this->sdl_window, _cursor.pos.x, _cursor.pos.y);
      }
      HandleMouseEvents();
      break;
    }
 
    case SDL_MOUSEWHEEL: {
      if (ev.wheel.y > 0) {
        _cursor.wheel--;
      } else if (ev.wheel.y < 0) {
        _cursor.wheel++;
      }
 
      /* Handle 2D scrolling. */
      const float SCROLL_BUILTIN_MULTIPLIER = 14.0f;
#if SDL_VERSION_ATLEAST(2, 18, 0)
      _cursor.v_wheel -= ev.wheel.preciseY * SCROLL_BUILTIN_MULTIPLIER * _settings_client.gui.scrollwheel_multiplier;
      _cursor.h_wheel += ev.wheel.preciseX * SCROLL_BUILTIN_MULTIPLIER * _settings_client.gui.scrollwheel_multiplier;
#else
      _cursor.v_wheel -= static_cast<float>(ev.wheel.y * SCROLL_BUILTIN_MULTIPLIER * _settings_client.gui.scrollwheel_multiplier);
      _cursor.h_wheel += static_cast<float>(ev.wheel.x * SCROLL_BUILTIN_MULTIPLIER * _settings_client.gui.scrollwheel_multiplier);
#endif
      _cursor.wheel_moved = true;
      break;
    }
 
    case SDL_MOUSEBUTTONDOWN:
      if (_rightclick_emulate && SDL_GetModState() & KMOD_CTRL) {
        ev.button.button = SDL_BUTTON_RIGHT;
      }
 
      switch (ev.button.button) {
        case SDL_BUTTON_LEFT:
          _left_button_down = true;
          break;
 
        case SDL_BUTTON_RIGHT:
          _right_button_down = true;
          _right_button_clicked = true;
          break;
 
        default: break;
      }
      HandleMouseEvents();
      break;
 
    case SDL_MOUSEBUTTONUP:
      if (_rightclick_emulate) {
        _right_button_down = false;
        _left_button_down = false;
        _left_button_clicked = false;
      } else if (ev.button.button == SDL_BUTTON_LEFT) {
        _left_button_down = false;
        _left_button_clicked = false;
      } else if (ev.button.button == SDL_BUTTON_RIGHT) {
        _right_button_down = false;
      }
      HandleMouseEvents();
      break;
 
    case SDL_QUIT:
      HandleExitGameRequest();
      break;
 
    case SDL_KEYDOWN: // Toggle full-screen on ALT + ENTER/F
      if ((ev.key.keysym.mod & (KMOD_ALT | KMOD_GUI)) &&
          (ev.key.keysym.sym == SDLK_RETURN || ev.key.keysym.sym == SDLK_f)) {
        if (ev.key.repeat == 0) ToggleFullScreen(!_fullscreen);
      } else {
        char32_t character;
 
        uint keycode = ConvertSdlKeyIntoMy(&ev.key.keysym, &character);
        // Only handle non-text keys here. Text is handled in
        // SDL_TEXTINPUT below.
        if (!this->edit_box_focused ||
          keycode == WKC_DELETE ||
          keycode == WKC_NUM_ENTER ||
          keycode == WKC_LEFT ||
          keycode == WKC_RIGHT ||
          keycode == WKC_UP ||
          keycode == WKC_DOWN ||
          keycode == WKC_HOME ||
          keycode == WKC_END ||
          keycode & WKC_META ||
          keycode & WKC_CTRL ||
          keycode & WKC_ALT ||
          (keycode >= WKC_F1 && keycode <= WKC_F12) ||
          !IsValidChar(character, CS_ALPHANUMERAL)) {
          HandleKeypress(keycode, character);
        }
      }
      break;
 
    case SDL_TEXTINPUT: {
      if (!this->edit_box_focused) break;
      SDL_Keycode kc = SDL_GetKeyFromName(ev.text.text);
      uint keycode = ConvertSdlKeycodeIntoMy(kc);
 
      if (keycode == WKC_BACKQUOTE && FocusedWindowIsConsole()) {
        char32_t character;
        Utf8Decode(&character, ev.text.text);
        HandleKeypress(keycode, character);
      } else {
        HandleTextInput(ev.text.text);
      }
      break;
    }
    case SDL_WINDOWEVENT: {
      if (ev.window.event == SDL_WINDOWEVENT_EXPOSED) {
        // Force a redraw of the entire screen.
        this->MakeDirty(0, 0, _screen.width, _screen.height);
      } else if (ev.window.event == SDL_WINDOWEVENT_SIZE_CHANGED) {
        int w = std::max(ev.window.data1, 64);
        int h = std::max(ev.window.data2, 64);
        CreateMainSurface(w, h, w != ev.window.data1 || h != ev.window.data2);
      } else if (ev.window.event == SDL_WINDOWEVENT_ENTER) {
        // mouse entered the window, enable cursor
        _cursor.in_window = true;
        /* Ensure pointer lock will not occur. */
        SDL_SetRelativeMouseMode(SDL_FALSE);
      } else if (ev.window.event == SDL_WINDOWEVENT_LEAVE) {
        // mouse left the window, undraw cursor
        UndrawMouseCursor();
        _cursor.in_window = false;
      }
      break;
    }
  }
 
  return true;
}
 
static std::optional<std::string_view> InitializeSDL()
{
  /* Check if the video-driver is already initialized. */
  if (SDL_WasInit(SDL_INIT_VIDEO) != 0) return std::nullopt;
 
  if (SDL_InitSubSystem(SDL_INIT_VIDEO) < 0) return SDL_GetError();
  return std::nullopt;
}
 
std::optional<std::string_view> VideoDriver_SDL_Base::Initialize()
{
  this->UpdateAutoResolution();
 
  auto error = InitializeSDL();
  if (error) return error;
 
  FindResolutions();
  Debug(driver, 2, "Resolution for display: {}x{}", _cur_resolution.width, _cur_resolution.height);
 
  return std::nullopt;
}
 
std::optional<std::string_view> VideoDriver_SDL_Base::Start(const StringList &param)
{
  if (BlitterFactory::GetCurrentBlitter()->GetScreenDepth() == 0) return "Only real blitters supported";
 
  auto error = this->Initialize();
  if (error) return error;
 
#ifdef SDL_HINT_MOUSE_AUTO_CAPTURE
  if (GetDriverParamBool(param, "no_mouse_capture")) {
    /* By default SDL captures the mouse, while a button is pressed.
     * This is annoying during debugging, when OpenTTD is suspended while the button was pressed.
     */
    if (!SDL_SetHint(SDL_HINT_MOUSE_AUTO_CAPTURE, "0")) return SDL_GetError();
  }
#endif
 
#ifdef SDL_HINT_APP_NAME
  SDL_SetHint(SDL_HINT_APP_NAME, "OpenTTD");
#endif
 
  this->startup_display = FindStartupDisplay(GetDriverParamInt(param, "display", -1));
 
  if (!CreateMainSurface(_cur_resolution.width, _cur_resolution.height, false)) {
    return SDL_GetError();
  }
 
  const char *dname = SDL_GetCurrentVideoDriver();
  Debug(driver, 1, "SDL2: using driver '{}'", dname);
 
  this->driver_info = this->GetName();
  this->driver_info += " (";
  this->driver_info += dname;
  this->driver_info += ")";
 
  MarkWholeScreenDirty();
 
  SDL_StopTextInput();
  this->edit_box_focused = false;
 
#ifdef __EMSCRIPTEN__
  this->is_game_threaded = false;
#else
  this->is_game_threaded = !GetDriverParamBool(param, "no_threads") && !GetDriverParamBool(param, "no_thread");
#endif
 
  return std::nullopt;
}
 
void VideoDriver_SDL_Base::Stop()
{
  SDL_QuitSubSystem(SDL_INIT_VIDEO);
  if (SDL_WasInit(SDL_INIT_EVERYTHING) == 0) {
    SDL_Quit(); // If there's nothing left, quit SDL
  }
}
 
void VideoDriver_SDL_Base::InputLoop()
{
  uint32_t mod = SDL_GetModState();
  const Uint8 *keys = SDL_GetKeyboardState(nullptr);
 
  bool old_ctrl_pressed = _ctrl_pressed;
 
  _ctrl_pressed  = !!(mod & KMOD_CTRL);
  _shift_pressed = !!(mod & KMOD_SHIFT);
 
  /* Speedup when pressing tab, except when using ALT+TAB
   * to switch to another application. */
  this->fast_forward_key_pressed = keys[SDL_SCANCODE_TAB] && (mod & KMOD_ALT) == 0;
 
  /* Determine which directional keys are down. */
  _dirkeys =
    (keys[SDL_SCANCODE_LEFT]  ? 1 : 0) |
    (keys[SDL_SCANCODE_UP]    ? 2 : 0) |
    (keys[SDL_SCANCODE_RIGHT] ? 4 : 0) |
    (keys[SDL_SCANCODE_DOWN]  ? 8 : 0);
 
  if (old_ctrl_pressed != _ctrl_pressed) HandleCtrlChanged();
}
 
void VideoDriver_SDL_Base::LoopOnce()
{
  if (_exit_game) {
#ifdef __EMSCRIPTEN__
    /* Emscripten is event-driven, and as such the main loop is inside
     * the browser. So if _exit_game goes true, the main loop ends (the
     * cancel call), but we still have to call the cleanup that is
     * normally done at the end of the main loop for non-Emscripten.
     * After that, Emscripten just halts, and the HTML shows a nice
     * "bye, see you next time" message. */
    extern void PostMainLoop();
    PostMainLoop();
 
    emscripten_cancel_main_loop();
    emscripten_exit_pointerlock();
    /* In effect, the game ends here. As emscripten_set_main_loop() caused
     * the stack to be unwound, the code after MainLoop() in
     * openttd_main() is never executed. */
    if (_game_mode == GM_BOOTSTRAP) {
      EM_ASM(if (window["openttd_bootstrap_reload"]) openttd_bootstrap_reload());
    } else {
      EM_ASM(if (window["openttd_exit"]) openttd_exit());
    }
#endif
    return;
  }
 
  this->Tick();
 
/* Emscripten is running an event-based mainloop; there is already some
 * downtime between each iteration, so no need to sleep. */
#ifndef __EMSCRIPTEN__
  this->SleepTillNextTick();
#endif
}
 
void VideoDriver_SDL_Base::MainLoop()
{
#ifdef __EMSCRIPTEN__
  /* Run the main loop event-driven, based on RequestAnimationFrame. */
  emscripten_set_main_loop_arg(&this->EmscriptenLoop, this, 0, 1);
#else
  this->StartGameThread();
 
  while (!_exit_game) {
    LoopOnce();
  }
 
  this->StopGameThread();
#endif
}
 
bool VideoDriver_SDL_Base::ChangeResolution(int w, int h)
{
  return CreateMainSurface(w, h, true);
}
 
bool VideoDriver_SDL_Base::ToggleFullscreen(bool fullscreen)
{
  /* Remember current window size */
  int w, h;
  SDL_GetWindowSize(this->sdl_window, &w, &h);
 
  if (fullscreen) {
    /* Find fullscreen window size */
    SDL_DisplayMode dm;
    if (SDL_GetCurrentDisplayMode(SDL_GetWindowDisplayIndex(this->sdl_window), &dm) < 0) {
      Debug(driver, 0, "SDL_GetCurrentDisplayMode() failed: {}", SDL_GetError());
    } else {
      SDL_SetWindowSize(this->sdl_window, dm.w, dm.h);
    }
  }
 
  Debug(driver, 1, "SDL2: Setting {}", fullscreen ? "fullscreen" : "windowed");
  int ret = SDL_SetWindowFullscreen(this->sdl_window, fullscreen ? SDL_WINDOW_FULLSCREEN : 0);
  if (ret == 0) {
    /* Switching resolution succeeded, set fullscreen value of window. */
    _fullscreen = fullscreen;
    if (!fullscreen) SDL_SetWindowSize(this->sdl_window, w, h);
  } else {
    Debug(driver, 0, "SDL_SetWindowFullscreen() failed: {}", SDL_GetError());
  }
 
  InvalidateWindowClassesData(WC_GAME_OPTIONS, 3);
  return ret == 0;
}
 
bool VideoDriver_SDL_Base::AfterBlitterChange()
{
  assert(BlitterFactory::GetCurrentBlitter()->GetScreenDepth() != 0);
  int w, h;
  SDL_GetWindowSize(this->sdl_window, &w, &h);
  return CreateMainSurface(w, h, false);
}
 
Dimension VideoDriver_SDL_Base::GetScreenSize() const
{
  SDL_DisplayMode mode;
  if (SDL_GetCurrentDisplayMode(this->startup_display, &mode) != 0) return VideoDriver::GetScreenSize();
 
  return { static_cast<uint>(mode.w), static_cast<uint>(mode.h) };
}
 
bool VideoDriver_SDL_Base::LockVideoBuffer()
{
  if (this->buffer_locked) return false;
  this->buffer_locked = true;
 
  _screen.dst_ptr = this->GetVideoPointer();
  assert(_screen.dst_ptr != nullptr);
 
  return true;
}
 
void VideoDriver_SDL_Base::UnlockVideoBuffer()
{
  if (_screen.dst_ptr != nullptr) {
    /* Hand video buffer back to the drawing backend. */
    this->ReleaseVideoPointer();
    _screen.dst_ptr = nullptr;
  }
 
  this->buffer_locked = false;
}