Add: INR currency (#8136)

[openttd-github.git] / src / video / sdl_v.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 sdl_v.cpp Implementation of the SDL video driver. */

#ifdef WITH_SDL

#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 "sdl_v.h"
#include <SDL.h>
#include <mutex>
#include <condition_variable>
#include <algorithm>

#include "../safeguards.h"

static FVideoDriver_SDL iFVideoDriver_SDL;

static SDL_Surface *_sdl_screen;
static SDL_Surface *_sdl_realscreen;
static bool _all_modes;

/** Whether the drawing is/may be done in a separate thread. */
static bool _draw_threaded;
/** Mutex to keep the access to the shared memory controlled. */
static std::recursive_mutex *_draw_mutex = nullptr;
/** Signal to draw the next frame. */
static std::condition_variable_any *_draw_signal = nullptr;
/** Should we keep continue drawing? */
static volatile bool _draw_continue;
static Palette _local_palette;

#define MAX_DIRTY_RECTS 100
static SDL_Rect _dirty_rects[MAX_DIRTY_RECTS];
static int _num_dirty_rects;
static int _use_hwpalette;
static int _requested_hwpalette; /* Did we request a HWPALETTE for the current video mode? */

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].unused = 0;
        }

        SDL_SetColors(_sdl_screen, pal, _local_palette.first_dirty, _local_palette.count_dirty);

        if (_sdl_screen != _sdl_realscreen && init) {
                /* When using a shadow surface, also set our palette on the real screen. This lets SDL
                 * allocate as much 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_SetColors(_sdl_realscreen, pal, _local_palette.first_dirty, _local_palette.count_dirty);
        }

        if (_sdl_screen != _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_screen, nullptr, _sdl_realscreen, nullptr);
                SDL_UpdateRect(_sdl_realscreen, 0, 0, 0, 0);
        }
}

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_screen != _sdl_realscreen) {
                        SDL_BlitSurface(_sdl_screen, nullptr, _sdl_realscreen, nullptr);
                }
                SDL_UpdateRect(_sdl_realscreen, 0, 0, 0, 0);
        } else {
                if (_sdl_screen != _sdl_realscreen) {
                        for (int i = 0; i < n; i++) {
                                SDL_BlitSurface(_sdl_screen, &_dirty_rects[i], _sdl_realscreen, &_dirty_rects[i]);
                        }
                }
                SDL_UpdateRects(_sdl_realscreen, n, _dirty_rects);
        }
}

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 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 GetVideoModes()
{
        SDL_Rect **modes = SDL_ListModes(nullptr, SDL_SWSURFACE | SDL_FULLSCREEN);
        if (modes == nullptr) usererror("sdl: no modes available");

        _resolutions.clear();

        _all_modes = (SDL_ListModes(nullptr, SDL_SWSURFACE | (_fullscreen ? SDL_FULLSCREEN : 0)) == (void*)-1);
        if (modes == (void*)-1) {
                for (uint i = 0; i < lengthof(_default_resolutions); i++) {
                        if (SDL_VideoModeOK(_default_resolutions[i].width, _default_resolutions[i].height, 8, SDL_FULLSCREEN) != 0) {
                                _resolutions.push_back(_default_resolutions[i]);
                        }
                }
        } else {
                for (int i = 0; modes[i]; i++) {
                        uint w = modes[i]->w;
                        uint h = modes[i]->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 (_all_modes || _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)
{
        SDL_Surface *newscreen, *icon;
        char caption[50];
        int bpp = BlitterFactory::GetCurrentBlitter()->GetScreenDepth();
        bool want_hwpalette;

        GetAvailableVideoMode(&w, &h);

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

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

        char icon_path[MAX_PATH];
        if (FioFindFullPath(icon_path, lastof(icon_path), BASESET_DIR, "openttd.32.bmp") != nullptr) {
                /* Give the application an icon */
                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_SRCCOLORKEY, rgbmap);
                        SDL_WM_SetIcon(icon, nullptr);
                        SDL_FreeSurface(icon);
                }
        }

        if (_use_hwpalette == 2) {
                /* Default is to autodetect when to use SDL_HWPALETTE.
                 * In this case, SDL_HWPALETTE is only used for 8bpp
                 * blitters in fullscreen.
                 *
                 * When using an 8bpp blitter on a 8bpp system in
                 * windowed mode with SDL_HWPALETTE, OpenTTD will claim
                 * the system palette, making all other applications
                 * get the wrong colours. In this case, we're better of
                 * trying to approximate the colors we need using system
                 * colors, using a shadow surface (see below).
                 *
                 * On a 32bpp system, SDL_HWPALETTE is ignored, so it
                 * doesn't matter what we do.
                 *
                 * When using a 32bpp blitter on a 8bpp system, setting
                 * SDL_HWPALETTE messes up rendering (at least on X11),
                 * so we don't do that. In this case, SDL takes care of
                 * color approximation using its own shadow surface
                 * (which we can't force in 8bpp on 8bpp mode,
                 * unfortunately).
                 */
                want_hwpalette = bpp == 8 && _fullscreen && _support8bpp == S8BPP_HARDWARE;
        } else {
                /* User specified a value manually */
                want_hwpalette = _use_hwpalette;
        }

        if (want_hwpalette) DEBUG(driver, 1, "SDL: requesting hardware palette");

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

        if (_sdl_realscreen != nullptr) {
                if (_requested_hwpalette != want_hwpalette) {
                        /* SDL (at least the X11 driver), reuses the
                         * same window and palette settings when the bpp
                         * (and a few flags) are the same. Since we need
                         * to hwpalette value to change (in particular
                         * when switching between fullscreen and
                         * windowed), we restart the entire video
                         * subsystem to force creating a new window.
                         */
                        DEBUG(driver, 0, "SDL: Restarting SDL video subsystem, to force hwpalette change");
                        SDL_QuitSubSystem(SDL_INIT_VIDEO);
                        SDL_InitSubSystem(SDL_INIT_VIDEO);
                        ClaimMousePointer();
                        SetupKeyboard();
                }
        }
        /* Remember if we wanted a hwpalette. We can't reliably query
         * SDL for the SDL_HWPALETTE flag, since it might get set even
         * though we didn't ask for it (when SDL creates a shadow
         * surface, for example). */
        _requested_hwpalette = want_hwpalette;

        /* DO NOT CHANGE TO HWSURFACE, IT DOES NOT WORK */
        newscreen = SDL_SetVideoMode(w, h, bpp, SDL_SWSURFACE | (want_hwpalette ? SDL_HWPALETTE : 0) | (_fullscreen ? SDL_FULLSCREEN : SDL_RESIZABLE));
        if (newscreen == nullptr) {
                DEBUG(driver, 0, "SDL: Couldn't allocate a window to draw on");
                return false;
        }
        _sdl_realscreen = newscreen;

        if (bpp == 8 && (_sdl_realscreen->flags & SDL_HWPALETTE) != SDL_HWPALETTE) {
                /* Using an 8bpp blitter, if we didn't get a hardware
                 * palette (most likely because we didn't request one,
                 * see above), we'll have to set up a shadow surface to
                 * render on.
                 *
                 * Our palette will be applied to this shadow surface,
                 * while the real screen surface will use the shared
                 * system palette (which will partly contain our colors,
                 * but most likely will not have enough free color cells
                 * for all of our colors). SDL can use these two
                 * palettes at blit time to approximate colors used in
                 * the shadow surface using system colors automatically.
                 *
                 * Note that when using an 8bpp blitter on a 32bpp
                 * system, SDL will create an internal shadow surface.
                 * This shadow surface will have SDL_HWPALLETE set, so
                 * we won't create a second shadow surface in this case.
                 */
                DEBUG(driver, 1, "SDL: using shadow surface");
                newscreen = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, bpp, 0, 0, 0, 0);
                if (newscreen == nullptr) {
                        DEBUG(driver, 0, "SDL: Couldn't allocate a shadow surface to draw on");
                        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_screen = 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();

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

        GameSizeChanged();

        return true;
}

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

struct VkMapping {
#if SDL_VERSION_ATLEAST(1, 3, 0)
        SDL_Keycode vk_from;
#else
        uint16 vk_from;
#endif
        byte vk_count;
        byte map_to;
};

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

static const VkMapping _vk_mapping[] = {
        /* Pageup stuff + up/down */
        AM(SDLK_PAGEUP, SDLK_PAGEDOWN, WKC_PAGEUP, WKC_PAGEDOWN),
        AS(SDLK_UP,     WKC_UP),
        AS(SDLK_DOWN,   WKC_DOWN),
        AS(SDLK_LEFT,   WKC_LEFT),
        AS(SDLK_RIGHT,  WKC_RIGHT),

        AS(SDLK_HOME,   WKC_HOME),
        AS(SDLK_END,    WKC_END),

        AS(SDLK_INSERT, WKC_INSERT),
        AS(SDLK_DELETE, WKC_DELETE),

        /* Map letters & digits */
        AM(SDLK_a, SDLK_z, 'A', 'Z'),
        AM(SDLK_0, SDLK_9, '0', '9'),

        AS(SDLK_ESCAPE,    WKC_ESC),
        AS(SDLK_PAUSE,     WKC_PAUSE),
        AS(SDLK_BACKSPACE, WKC_BACKSPACE),

        AS(SDLK_SPACE,     WKC_SPACE),
        AS(SDLK_RETURN,    WKC_RETURN),
        AS(SDLK_TAB,       WKC_TAB),

        /* Function keys */
        AM(SDLK_F1, SDLK_F12, WKC_F1, WKC_F12),

        /* Numeric part. */
        AM(SDLK_KP0, SDLK_KP9, '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;

        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;
                        break;
                }
        }

        /* check scancode for BACKQUOTE key, because we want the key left of "1", not anything else (on non-US keyboards) */
#if defined(_WIN32) || defined(__OS2__)
        if (sym->scancode == 41) key = WKC_BACKQUOTE;
#elif defined(__APPLE__)
        if (sym->scancode == 10) key = WKC_BACKQUOTE;
#elif defined(__SVR4) && defined(__sun)
        if (sym->scancode == 60) key = WKC_BACKQUOTE;
        if (sym->scancode == 49) key = WKC_BACKSPACE;
#elif defined(__sgi__)
        if (sym->scancode == 22) key = WKC_BACKQUOTE;
#else
        if (sym->scancode == 49) key = WKC_BACKQUOTE;
#endif

        /* META are the command keys on mac */
        if (sym->mod & KMOD_META)  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;

        *character = sym->unicode;
        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_WarpMouse(_cursor.pos.x, _cursor.pos.y);
                        }
                        HandleMouseEvents();
                        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;

                                case SDL_BUTTON_WHEELUP:   _cursor.wheel--; break;
                                case SDL_BUTTON_WHEELDOWN: _cursor.wheel++; 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_ACTIVEEVENT:
                        if (!(ev.active.state & SDL_APPMOUSEFOCUS)) break;

                        if (ev.active.gain) { // mouse entered the window, enable cursor
                                _cursor.in_window = true;
                        } else {
                                UndrawMouseCursor(); // mouse left the window, undraw cursor
                                _cursor.in_window = false;
                        }
                        break;

                case SDL_QUIT:
                        HandleExitGameRequest();
                        break;

                case SDL_KEYDOWN: // Toggle full-screen on ALT + ENTER/F
                        if ((ev.key.keysym.mod & (KMOD_ALT | KMOD_META)) &&
                                        (ev.key.keysym.sym == SDLK_RETURN || ev.key.keysym.sym == SDLK_f)) {
                                ToggleFullScreen(!_fullscreen);
                        } else {
                                WChar character;
                                uint keycode = ConvertSdlKeyIntoMy(&ev.key.keysym, &character);
                                HandleKeypress(keycode, character);
                        }
                        break;

                case SDL_VIDEORESIZE: {
                        int w = max(ev.resize.w, 64);
                        int h = max(ev.resize.h, 64);
                        CreateMainSurface(w, h);
                        break;
                }
                case SDL_VIDEOEXPOSE: {
                        /* Force a redraw of the entire screen. Note
                         * that SDL 1.2 seems to do this automatically
                         * in most cases, but 1.3 / 2.0 does not. */
                        _num_dirty_rects = MAX_DIRTY_RECTS + 1;
                        break;
                }
        }
        return -1;
}

const char *VideoDriver_SDL::Start(const char * const *parm)
{
        char buf[30];
        _use_hwpalette = GetDriverParamInt(parm, "hw_palette", 2);

        /* 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_EVERYTHING) == 0) {
                ret_code = SDL_Init(SDL_INIT_VIDEO | SDL_INIT_NOPARACHUTE);
        } else if (SDL_WasInit(SDL_INIT_VIDEO) == 0) {
                ret_code = SDL_InitSubSystem(SDL_INIT_VIDEO);
        }
        if (ret_code == -1) return SDL_GetError();

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

        SDL_VideoDriverName(buf, sizeof buf);
        DEBUG(driver, 1, "SDL: using driver '%s'", buf);

        MarkWholeScreenDirty();
        SetupKeyboard();

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

        return nullptr;
}

void VideoDriver_SDL::SetupKeyboard()
{
        SDL_EnableKeyRepeat(SDL_DEFAULT_REPEAT_DELAY, SDL_DEFAULT_REPEAT_INTERVAL);
        SDL_EnableUNICODE(1);
}

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;
        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, "SDL: 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();
#if SDL_VERSION_ATLEAST(1, 3, 0)
                keys = SDL_GetKeyboardState(&numkeys);
#else
                keys = SDL_GetKeyState(&numkeys);
#endif
#if defined(_DEBUG)
                if (_shift_pressed)
#else
                /* Speedup when pressing tab, except when using ALT+TAB
                 * to switch to another application */
#if SDL_VERSION_ATLEAST(1, 3, 0)
                if (keys[SDL_SCANCODE_TAB] && (mod & KMOD_ALT) == 0)
#else
                if (keys[SDLK_TAB] && (mod & KMOD_ALT) == 0)
#endif /* SDL_VERSION_ATLEAST(1, 3, 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 (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 =
#if SDL_VERSION_ATLEAST(1, 3, 0)
                                (keys[SDL_SCANCODE_LEFT]  ? 1 : 0) |
                                (keys[SDL_SCANCODE_UP]    ? 2 : 0) |
                                (keys[SDL_SCANCODE_RIGHT] ? 4 : 0) |
                                (keys[SDL_SCANCODE_DOWN]  ? 8 : 0);
#else
                                (keys[SDLK_LEFT]  ? 1 : 0) |
                                (keys[SDLK_UP]    ? 2 : 0) |
                                (keys[SDLK_RIGHT] ? 4 : 0) |
                                (keys[SDLK_DOWN]  ? 8 : 0);
#endif
                        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);
}

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);

        _fullscreen = fullscreen;
        GetVideoModes(); // get the list of available video modes
        bool ret = !_resolutions.empty() && CreateMainSurface(_cur_resolution.width, _cur_resolution.height);

        if (!ret) {
                /* switching resolution failed, put back full_screen to original status */
                _fullscreen ^= true;
        }

        return ret;
}

bool VideoDriver_SDL::AfterBlitterChange()
{
        return CreateMainSurface(_screen.width, _screen.height);
}

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

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

#endif /* WITH_SDL */