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/>.
 */

#ifdef WITH_SDL2

#include "../stdafx.h"
#include "../openttd.h"
#include "../gfx_func.h"
#include "../rev.h"
#include "../blitter/factory.hpp"
#include "../network/network.h"
#include "../thread.h"
#include "../progress.h"
#include "../core/random_func.hpp"
#include "../core/math_func.hpp"
#include "../fileio_func.h"
#include "../framerate_type.h"
#include "../window_func.h"
#include "sdl2_v.h"
#include <SDL.h>
#include <mutex>
#include <condition_variable>
#include <algorithm>

#include "../safeguards.h"

static FVideoDriver_SDL iFVideoDriver_SDL;

static SDL_Window *_sdl_window;
static SDL_Surface *_sdl_surface;
static SDL_Surface *_sdl_realscreen;

static bool _draw_threaded;
static std::recursive_mutex *_draw_mutex = nullptr;
static std::condition_variable_any *_draw_signal = nullptr;
static volatile bool _draw_continue;
static Palette _local_palette;
static SDL_Palette *_sdl_palette;

#define MAX_DIRTY_RECTS 100
static SDL_Rect _dirty_rects[MAX_DIRTY_RECTS];
static int _num_dirty_rects;

/* Size of window */
static int _window_size_w;
static int _window_size_h;

void VideoDriver_SDL::MakeDirty(int left, int top, int width, int height)
{
  if (_num_dirty_rects < MAX_DIRTY_RECTS) {
    _dirty_rects[_num_dirty_rects].x = left;
    _dirty_rects[_num_dirty_rects].y = top;
    _dirty_rects[_num_dirty_rects].w = width;
    _dirty_rects[_num_dirty_rects].h = height;
  }
  _num_dirty_rects++;
}

static void UpdatePalette(bool init = false)
{
  SDL_Color pal[256];

  for (int i = 0; i != _local_palette.count_dirty; i++) {
    pal[i].r = _local_palette.palette[_local_palette.first_dirty + i].r;
    pal[i].g = _local_palette.palette[_local_palette.first_dirty + i].g;
    pal[i].b = _local_palette.palette[_local_palette.first_dirty + i].b;
    pal[i].a = 0;
  }

  SDL_SetPaletteColors(_sdl_palette, pal, _local_palette.first_dirty, _local_palette.count_dirty);
  SDL_SetSurfacePalette(_sdl_surface, _sdl_palette);

  if (_sdl_surface != _sdl_realscreen && init) {
    /* When using a shadow surface, also set our palette on the real screen. This lets SDL
     * allocate as many colors (or approximations) as
     * possible, instead of using only the default SDL
     * palette. This allows us to get more colors exactly
     * right and might allow using better approximations for
     * other colors.
     *
     * Note that colors allocations are tried in-order, so
     * this favors colors further up into the palette. Also
     * note that if two colors from the same animation
     * sequence are approximated using the same color, that
     * animation will stop working.
     *
     * Since changing the system palette causes the colours
     * to change right away, and allocations might
     * drastically change, we can't use this for animation,
     * since that could cause weird coloring between the
     * palette change and the blitting below, so we only set
     * the real palette during initialisation.
     */
    SDL_SetSurfacePalette(_sdl_realscreen, _sdl_palette);
  }

  if (_sdl_surface != _sdl_realscreen && !init) {
    /* We're not using real hardware palette, but are letting SDL
     * approximate the palette during shadow -> screen copy. To
     * change the palette, we need to recopy the entire screen.
     *
     * Note that this operation can slow down the rendering
     * considerably, especially since changing the shadow
     * palette will need the next blit to re-detect the
     * best mapping of shadow palette colors to real palette
     * colors from scratch.
     */
    SDL_BlitSurface(_sdl_surface, nullptr, _sdl_realscreen, nullptr);
    SDL_UpdateWindowSurface(_sdl_window);
  }
}

static void InitPalette()
{
  _local_palette = _cur_palette;
  _local_palette.first_dirty = 0;
  _local_palette.count_dirty = 256;
  UpdatePalette(true);
}

static void CheckPaletteAnim()
{
  if (_cur_palette.count_dirty != 0) {
    Blitter *blitter = BlitterFactory::GetCurrentBlitter();

    switch (blitter->UsePaletteAnimation()) {
      case Blitter::PALETTE_ANIMATION_VIDEO_BACKEND:
        UpdatePalette();
        break;

      case Blitter::PALETTE_ANIMATION_BLITTER:
        blitter->PaletteAnimate(_local_palette);
        break;

      case Blitter::PALETTE_ANIMATION_NONE:
        break;

      default:
        NOT_REACHED();
    }
    _cur_palette.count_dirty = 0;
  }
}

static void DrawSurfaceToScreen()
{
  PerformanceMeasurer framerate(PFE_VIDEO);

  int n = _num_dirty_rects;
  if (n == 0) return;

  _num_dirty_rects = 0;

  if (n > MAX_DIRTY_RECTS) {
    if (_sdl_surface != _sdl_realscreen) {
      SDL_BlitSurface(_sdl_surface, nullptr, _sdl_realscreen, nullptr);
    }

    SDL_UpdateWindowSurface(_sdl_window);
  } else {
    if (_sdl_surface != _sdl_realscreen) {
      for (int i = 0; i < n; i++) {
        SDL_BlitSurface(
          _sdl_surface, &_dirty_rects[i],
          _sdl_realscreen, &_dirty_rects[i]);
      }
    }

    SDL_UpdateWindowSurfaceRects(_sdl_window, _dirty_rects, n);
  }
}

static void DrawSurfaceToScreenThread()
{
  /* First tell the main thread we're started */
  std::unique_lock<std::recursive_mutex> lock(*_draw_mutex);
  _draw_signal->notify_one();

  /* Now wait for the first thing to draw! */
  _draw_signal->wait(*_draw_mutex);

  while (_draw_continue) {
    CheckPaletteAnim();
    /* Then just draw and wait till we stop */
    DrawSurfaceToScreen();
    _draw_signal->wait(lock);
  }
}

static void GetVideoModes()
{
  int modes = SDL_GetNumDisplayModes(0);
  if (modes == 0) usererror("sdl: no modes available");

  _resolutions.clear();

  SDL_DisplayMode mode;
  for (int i = 0; i < modes; i++) {
    SDL_GetDisplayMode(0, i, &mode);

    uint w = mode.w;
    uint h = mode.h;

    if (w < 640 || h < 480) continue; // reject too small resolutions

    if (std::find(_resolutions.begin(), _resolutions.end(), Dimension(w, h)) != _resolutions.end()) continue;
    _resolutions.emplace_back(w, h);
  }
  if (_resolutions.empty()) usererror("No usable screen resolutions found!\n");
  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::find(_resolutions.begin(), _resolutions.end(), 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;
}

bool VideoDriver_SDL::CreateMainSurface(uint w, uint h, bool resize)
{
  SDL_Surface *newscreen;
  char caption[50];
  int bpp = BlitterFactory::GetCurrentBlitter()->GetScreenDepth();

  GetAvailableVideoMode(&w, &h);

  DEBUG(driver, 1, "SDL2: using mode %ux%ux%d", w, h, bpp);

  if (bpp == 0) usererror("Can't use a blitter that blits 0 bpp for normal visuals");

  /* Free any previously allocated shadow surface */
  if (_sdl_surface != nullptr && _sdl_surface != _sdl_realscreen) SDL_FreeSurface(_sdl_surface);

  seprintf(caption, lastof(caption), "OpenTTD %s", _openttd_revision);

  if (_sdl_window == nullptr) {
    Uint32 flags = SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE;

    if (_fullscreen) {
      flags |= SDL_WINDOW_FULLSCREEN;
    }

    _sdl_window = SDL_CreateWindow(
      caption,
      SDL_WINDOWPOS_UNDEFINED,
      SDL_WINDOWPOS_UNDEFINED,
      w, h,
      flags);

    if (_sdl_window == nullptr) {
      DEBUG(driver, 0, "SDL2: Couldn't allocate a window to draw on");
      return false;
    }

    char icon_path[MAX_PATH];
    if (FioFindFullPath(icon_path, lastof(icon_path), BASESET_DIR, "openttd.32.bmp") != nullptr) {
      /* Give the application an icon */
      SDL_Surface *icon = SDL_LoadBMP(icon_path);
      if (icon != nullptr) {
        /* Get the colourkey, which will be magenta */
        uint32 rgbmap = SDL_MapRGB(icon->format, 255, 0, 255);

        SDL_SetColorKey(icon, SDL_TRUE, rgbmap);
        SDL_SetWindowIcon(_sdl_window, icon);
        SDL_FreeSurface(icon);
      }
    }
  }

  if (resize) SDL_SetWindowSize(_sdl_window, w, h);

  newscreen = SDL_GetWindowSurface(_sdl_window);
  if (newscreen == NULL) {
    DEBUG(driver, 0, "SDL2: Couldn't get window surface: %s", SDL_GetError());
    return false;
  }

  _sdl_realscreen = newscreen;

  if (bpp == 8) {
    newscreen = SDL_CreateRGBSurface(0, w, h, 8, 0, 0, 0, 0);

    if (newscreen == nullptr) {
      DEBUG(driver, 0, "SDL2: Couldn't allocate shadow surface: %s", SDL_GetError());
      return false;
    }
  }

  if (_sdl_palette == nullptr) {
    _sdl_palette = SDL_AllocPalette(256);
  }

  if (_sdl_palette == nullptr) {
    DEBUG(driver, 0, "SDL_AllocPalette() failed: %s", SDL_GetError());
    return false;
  }

  /* Delay drawing for this cycle; the next cycle will redraw the whole screen */
  _num_dirty_rects = 0;

  _screen.width = newscreen->w;
  _screen.height = newscreen->h;
  _screen.pitch = newscreen->pitch / (bpp / 8);
  _screen.dst_ptr = newscreen->pixels;
  _sdl_surface = newscreen;

  /* 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;

  Blitter *blitter = BlitterFactory::GetCurrentBlitter();
  blitter->PostResize();

  InitPalette();

  GameSizeChanged();

  return true;
}

bool VideoDriver_SDL::ClaimMousePointer()
{
  SDL_ShowCursor(0);
  return true;
}

void VideoDriver_SDL::EditBoxGainedFocus()
{
  if (!this->edit_box_focused) {
    SDL_StartTextInput();
    this->edit_box_focused = true;
  }
}

void VideoDriver_SDL::EditBoxLostFocus()
{
  if (this->edit_box_focused) {
    SDL_StopTextInput();
    this->edit_box_focused = false;
  }
}


struct VkMapping {
  SDL_Keycode vk_from;
  byte vk_count;
  byte map_to;
  bool unprintable;
};

#define AS(x, z) {x, 0, z, false}
#define AM(x, y, z, w) {x, (byte)(y - x), z, false}
#define AS_UP(x, z) {x, 0, z, true}
#define AM_UP(x, y, z, w) {x, (byte)(y - x), z, true}

static const VkMapping _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. */
  AM(SDLK_KP_0, SDLK_KP_9, '0', '9'),
  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, WChar *character)
{
  const VkMapping *map;
  uint key = 0;
  bool unprintable = false;

  for (map = _vk_mapping; map != endof(_vk_mapping); ++map) {
    if ((uint)(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)
{
  const VkMapping *map;
  uint key = 0;

  for (map = _vk_mapping; map != endof(_vk_mapping); ++map) {
    if ((uint)(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;
}

int VideoDriver_SDL::PollEvent()
{
  SDL_Event ev;

  if (!SDL_PollEvent(&ev)) return -2;

  switch (ev.type) {
    case SDL_MOUSEMOTION:
      if (_cursor.UpdateCursorPosition(ev.motion.x, ev.motion.y, true)) {
        SDL_WarpMouseInWindow(_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++;
      }
      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 {
        WChar 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()) {
        WChar 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.
        _num_dirty_rects = MAX_DIRTY_RECTS + 1;
      } else if (ev.window.event == SDL_WINDOWEVENT_SIZE_CHANGED) {
        int w = max(ev.window.data1, 64);
        int h = 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;
      } else if (ev.window.event == SDL_WINDOWEVENT_LEAVE) {
        // mouse left the window, undraw cursor
        UndrawMouseCursor();
        _cursor.in_window = false;
      }
      break;
    }
  }
  return -1;
}

const char *VideoDriver_SDL::Start(const char * const *parm)
{
  /* Explicitly disable hardware acceleration. Enabling this causes
   * UpdateWindowSurface() to update the window's texture instead of
   * its surface. */
  SDL_SetHint(SDL_HINT_FRAMEBUFFER_ACCELERATION , "0");

  /* Just on the offchance the audio subsystem started before the video system,
   * check whether any part of SDL has been initialised before getting here.
   * Slightly duplicated with sound/sdl_s.cpp */
  int ret_code = 0;
  if (SDL_WasInit(SDL_INIT_VIDEO) == 0) {
    ret_code = SDL_InitSubSystem(SDL_INIT_VIDEO);
  }
  if (ret_code < 0) return SDL_GetError();

  GetVideoModes();
  if (!CreateMainSurface(_cur_resolution.width, _cur_resolution.height, false)) {
    return SDL_GetError();
  }

  const char *dname = SDL_GetCurrentVideoDriver();
  DEBUG(driver, 1, "SDL2: using driver '%s'", dname);

  MarkWholeScreenDirty();

  _draw_threaded = GetDriverParam(parm, "no_threads") == nullptr && GetDriverParam(parm, "no_thread") == nullptr;

  SDL_StopTextInput();
  this->edit_box_focused = false;

  return nullptr;
}

void VideoDriver_SDL::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::MainLoop()
{
  uint32 cur_ticks = SDL_GetTicks();
  uint32 last_cur_ticks = cur_ticks;
  uint32 next_tick = cur_ticks + MILLISECONDS_PER_TICK;
  uint32 mod;
  int numkeys;
  const Uint8 *keys;

  CheckPaletteAnim();

  std::thread draw_thread;
  std::unique_lock<std::recursive_mutex> draw_lock;
  if (_draw_threaded) {
    /* Initialise the mutex first, because that's the thing we *need*
     * directly in the newly created thread. */
    _draw_mutex = new std::recursive_mutex();
    if (_draw_mutex == nullptr) {
      _draw_threaded = false;
    } else {
      draw_lock = std::unique_lock<std::recursive_mutex>(*_draw_mutex);
      _draw_signal = new std::condition_variable_any();
      _draw_continue = true;

      _draw_threaded = StartNewThread(&draw_thread, "ottd:draw-sdl", &DrawSurfaceToScreenThread);

      /* Free the mutex if we won't be able to use it. */
      if (!_draw_threaded) {
        draw_lock.unlock();
        draw_lock.release();
        delete _draw_mutex;
        delete _draw_signal;
        _draw_mutex = nullptr;
        _draw_signal = nullptr;
      } else {
        /* Wait till the draw mutex has started itself. */
        _draw_signal->wait(*_draw_mutex);
      }
    }
  }

  DEBUG(driver, 1, "SDL2: using %sthreads", _draw_threaded ? "" : "no ");

  for (;;) {
    uint32 prev_cur_ticks = cur_ticks; // to check for wrapping
    InteractiveRandom(); // randomness

    while (PollEvent() == -1) {}
    if (_exit_game) break;

    mod = SDL_GetModState();
    keys = SDL_GetKeyboardState(&numkeys);

#if defined(_DEBUG)
    if (_shift_pressed)
#else
    /* Speedup when pressing tab, except when using ALT+TAB
     * to switch to another application */
    if (keys[SDL_SCANCODE_TAB] && (mod & KMOD_ALT) == 0)
#endif /* defined(_DEBUG) */
    {
      if (!_networking && _game_mode != GM_MENU) _fast_forward |= 2;
    } else if (_fast_forward & 2) {
      _fast_forward = 0;
    }

    cur_ticks = SDL_GetTicks();
    if (SDL_TICKS_PASSED(cur_ticks, next_tick) || (_fast_forward && !_pause_mode) || cur_ticks < prev_cur_ticks) {
      _realtime_tick += cur_ticks - last_cur_ticks;
      last_cur_ticks = cur_ticks;
      next_tick = cur_ticks + MILLISECONDS_PER_TICK;

      bool old_ctrl_pressed = _ctrl_pressed;

      _ctrl_pressed  = !!(mod & KMOD_CTRL);
      _shift_pressed = !!(mod & KMOD_SHIFT);

      /* 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();

      /* The gameloop is the part that can run asynchronously. The rest
       * except sleeping can't. */
      if (_draw_mutex != nullptr) draw_lock.unlock();

      GameLoop();

      if (_draw_mutex != nullptr) draw_lock.lock();

      UpdateWindows();
      _local_palette = _cur_palette;
    } else {
      /* Release the thread while sleeping */
      if (_draw_mutex != nullptr) draw_lock.unlock();
      CSleep(1);
      if (_draw_mutex != nullptr) draw_lock.lock();

      NetworkDrawChatMessage();
      DrawMouseCursor();
    }

    /* End of the critical part. */
    if (_draw_mutex != nullptr && !HasModalProgress()) {
      _draw_signal->notify_one();
    } else {
      /* Oh, we didn't have threads, then just draw unthreaded */
      CheckPaletteAnim();
      DrawSurfaceToScreen();
    }
  }

  if (_draw_mutex != nullptr) {
    _draw_continue = false;
    /* Sending signal if there is no thread blocked
     * is very valid and results in noop */
    _draw_signal->notify_one();
    if (draw_lock.owns_lock()) draw_lock.unlock();
    draw_lock.release();
    draw_thread.join();

    delete _draw_mutex;
    delete _draw_signal;

    _draw_mutex = nullptr;
    _draw_signal = nullptr;
  }
}

bool VideoDriver_SDL::ChangeResolution(int w, int h)
{
  std::unique_lock<std::recursive_mutex> lock;
  if (_draw_mutex != nullptr) lock = std::unique_lock<std::recursive_mutex>(*_draw_mutex);

  return CreateMainSurface(w, h, true);
}

bool VideoDriver_SDL::ToggleFullscreen(bool fullscreen)
{
  std::unique_lock<std::recursive_mutex> lock;
  if (_draw_mutex != nullptr) lock = std::unique_lock<std::recursive_mutex>(*_draw_mutex);

  /* Remember current window size */
  if (fullscreen) {
    SDL_GetWindowSize(_sdl_window, &_window_size_w, &_window_size_h);

    /* Find fullscreen window size */
    SDL_DisplayMode dm;
    if (SDL_GetCurrentDisplayMode(0, &dm) < 0) {
      DEBUG(driver, 0, "SDL_GetCurrentDisplayMode() failed: %s", SDL_GetError());
    } else {
      SDL_SetWindowSize(_sdl_window, dm.w, dm.h);
    }
  }

  DEBUG(driver, 1, "SDL2: Setting %s", fullscreen ? "fullscreen" : "windowed");
  int ret = SDL_SetWindowFullscreen(_sdl_window, fullscreen ? SDL_WINDOW_FULLSCREEN : 0);
  if (ret == 0) {
    /* Switching resolution succeeded, set fullscreen value of window. */
    _fullscreen = fullscreen;
    if (!fullscreen) SDL_SetWindowSize(_sdl_window, _window_size_w, _window_size_h);
  } else {
    DEBUG(driver, 0, "SDL_SetWindowFullscreen() failed: %s", SDL_GetError());
  }

  return ret == 0;
}

bool VideoDriver_SDL::AfterBlitterChange()
{
  int w, h;
  SDL_GetWindowSize(_sdl_window, &w, &h);
  return CreateMainSurface(w, h, false);
}

void VideoDriver_SDL::AcquireBlitterLock()
{
  if (_draw_mutex != nullptr) _draw_mutex->lock();
}

void VideoDriver_SDL::ReleaseBlitterLock()
{
  if (_draw_mutex != nullptr) _draw_mutex->unlock();
}

#endif /* WITH_SDL2 */