Add #6173: New SDL 2 based video and sound drivers (#7086)

2 files changed, 883 insertions, 0 deletions

diff --git a/src/video/sdl2_v.cpp b/src/video/sdl2_v.cpp
new file mode 100644
index 000000000..0bee44949
--- /dev/null
+++ b/src/video/sdl2_v.cpp
@@ -0,0 +1,830 @@
+/* $Id$ */
+
+/*
+ * 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 sdl2_v.cpp Implementation of the SDL2 video driver. */
+
+#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 "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;
+
+/** 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;
+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;
+
+		if (_fullscreen) {
+			flags |= SDL_WINDOW_FULLSCREEN;
+		} else {
+			flags |= SDL_WINDOW_RESIZABLE;
+		}
+
+		_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_CreateRGBSurfaceWithFormat(0, w, h, 8, SDL_PIXELFORMAT_INDEX8);
+
+		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;
+}
+
+struct VkMapping {
+	SDL_Keycode vk_from;
+	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_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;
+
+	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_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_SHIFT ||
+		sym->mod & KMOD_CTRL ||
+		sym->mod & KMOD_ALT) {
+		*character = WKC_NONE;
+	} else {
+		*character = sym->sym;
+	}
+
+	return key;
+}
+
+/**
+ * Like ConvertSdlKeyIntoMy(), but takes an SDL_Keycode as input
+ * instead of an SDL_Keysym.
+ */
+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 (keycode == WKC_DELETE ||
+					keycode == WKC_NUM_ENTER ||
+					keycode == WKC_LEFT ||
+					keycode == WKC_RIGHT ||
+					keycode & WKC_META ||
+					keycode & WKC_SHIFT ||
+					keycode & WKC_CTRL ||
+					keycode & WKC_ALT ||
+					(keycode >= WKC_F1 && keycode <= WKC_F12) ||
+					!IsValidChar(character, CS_ALPHANUMERAL)) {
+					HandleKeypress(keycode, character);
+				}
+			}
+			break;
+
+		case SDL_TEXTINPUT: {
+			WChar character;
+			SDL_Keycode kc = SDL_GetKeyFromName(ev.text.text);
+			uint keycode = ConvertSdlKeycodeIntoMy(kc);
+
+			Utf8Decode(&character, ev.text.text);
+			HandleKeypress(keycode, character);
+			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_GetVideoDriver(0);
+	DEBUG(driver, 1, "SDL2: using driver '%s'", dname);
+
+	MarkWholeScreenDirty();
+
+	_draw_threaded = GetDriverParam(parm, "no_threads") == nullptr && GetDriverParam(parm, "no_thread") == nullptr;
+
+	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 */
diff --git a/src/video/sdl2_v.h b/src/video/sdl2_v.h
new file mode 100644
index 000000000..ba7e322ed
--- /dev/null
+++ b/src/video/sdl2_v.h
@@ -0,0 +1,53 @@
+/* $Id$ */
+
+/*
+ * 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 sdl2_v.h Base of the SDL2 video driver. */
+
+#ifndef VIDEO_SDL_H
+#define VIDEO_SDL_H
+
+#include "video_driver.hpp"
+
+/** The SDL video driver. */
+class VideoDriver_SDL : public VideoDriver {
+public:
+	const char *Start(const char * const *param) override;
+
+	void Stop() override;
+
+	void MakeDirty(int left, int top, int width, int height) override;
+
+	void MainLoop() override;
+
+	bool ChangeResolution(int w, int h) override;
+
+	bool ToggleFullscreen(bool fullscreen) override;
+
+	bool AfterBlitterChange() override;
+
+	void AcquireBlitterLock() override;
+
+	void ReleaseBlitterLock() override;
+
+	bool ClaimMousePointer() override;
+
+	const char *GetName() const override { return "sdl"; }
+private:
+	int PollEvent();
+	bool CreateMainSurface(uint w, uint h, bool resize);
+};
+
+/** Factory for the SDL video driver. */
+class FVideoDriver_SDL : public DriverFactoryBase {
+public:
+	FVideoDriver_SDL() : DriverFactoryBase(Driver::DT_VIDEO, 5, "sdl", "SDL Video Driver") {}
+	Driver *CreateInstance() const override { return new VideoDriver_SDL(); }
+};
+
+#endif /* VIDEO_SDL_H */