Patch #757827: Aspect-ratio correction

svn-id: r8605

10 files changed, 267 insertions, 111 deletions

diff --git a/README b/README
index 7bba62e258..30f140988c 100644
--- a/README
+++ b/README
@@ -339,33 +339,36 @@ Command Line Options:
 
         scummvm [OPTIONS] [GAME]
 
-        [GAME]        - Short name of game to load. For example, 'monkey' for
-                        Monkey Island.
-
-        -p<path>      - Path to where the game is installed. Default is Cwd.
-        -x[<num>]     - Save game slot to load (default: autosave)
-        -f            - Full-screen mode.
-        -g<mode>      - Select graphics scaler. See below.
-        -e<mode>      - Select sound engine. See below.
-        -a            - Enable amiga pal conversion, for playing Amiga versions
-        -q<lang>      - Select language. See below.
-        -c<num>       - Drive to play cd audio from.  E.g., 0 is first drive.
-        -m<num>       - Set the music volume, 0-255.  Default is '192'
-        -o<num>       - Set the master volume, 0-255. Default is '192'
-        -s<num>       - Set the sfx volume, 0-255.    Default is '192'
-        -t<num>       - Set music tempo. 50-200. Default is '100' (percent)
-        -n            - Disable subtitles. Use with games that have voice.
-        -y            - Set talk speed ('yak option'). Default is '60'
-        -l<file>      - Load alternate configuration file
-        -w[<file>]    - Write configuration file
-        -v            - Show version information and exit
-        -z            - Display list of games
-        -b<num>       - Start in room <num>.
-        -d[<num>]     - Set debug verbosity to <num>
-        -u            - Dump scripts if a directory called 'dumps' exists in
-                        current directory
-        --multi-midi  - enable combination Adlib and native MIDI
-        --native-mt32 - true Roland MT-32 (disable GM emulation)
+        [GAME]         - Short name of game to load. For example, 'monkey' for
+                         Monkey Island.
+
+        -p<path>       - Path to where the game is installed. Default is Cwd.
+        -x[<num>]      - Save game slot to load (default: autosave)
+        -f             - Full-screen mode.
+        -g<mode>       - Select graphics scaler. See below.
+        -e<mode>       - Select sound engine. See below.
+        -a             - Enable amiga pal conversion, for playing Amiga
+                         versions
+        -q<lang>       - Select language. See below.
+        -c<num>        - Drive to play cd audio from.  E.g., 0 is first drive.
+        -m<num>        - Set the music volume, 0-255.  Default is '192'
+        -o<num>        - Set the master volume, 0-255. Default is '192'
+        -s<num>        - Set the sfx volume, 0-255.    Default is '192'
+        -t<num>        - Set music tempo. 50-200. Default is '100' (percent)
+        -n             - Disable subtitles. Use with games that have voice.
+        -y             - Set talk speed ('yak option'). Default is '60'
+        -l<file>       - Load alternate configuration file
+        -w[<file>]     - Write configuration file
+        -v             - Show version information and exit
+        -z             - Display list of games
+        -b<num>        - Start in room <num>.
+        -d[<num>]      - Set debug verbosity to <num>
+        -u             - Dump scripts if a directory called 'dumps' exists in
+                         current directory
+        --multi-midi   - enable combination Adlib and native MIDI
+        --native-mt32  - true Roland MT-32 (disable GM emulation)
+        --aspect-ratio - enable aspect ratio correction
+
 
 
 Hot Keys:
@@ -380,9 +383,13 @@ simon games.
         Ctrl-Alt 0-9           - Switch between graphics filters
         Ctrl-Alt b             - Switch beetwen bilinear and non-linear
                                  filtering [OpenGL backend]
-        Ctrl-Alt a             - Switch between: [OpenGL backend]
-                                 - Fit the game in the whole screen (No black borders)
-                                 - Don't fit the game in the whole screen (Black borders) 
+        Ctrl-Alt a             - Toggle aspect-ratio correction on/off.
+                                 Most of the games use a 320x200 pixel
+                                 resolution, which may look squashed on
+                                 modern monitors. Aspect-ratio correction
+                                 stretches the image to use 320x240 pixels
+                                 instead, or a multiple thereof.
+
     Scumm:
         Ctrl 0-9 and Alt 0-9   - load and save game state
         Ctrl-g                 - runs in really REALLY fast mode.
diff --git a/backends/sdl/sdl-common.cpp b/backends/sdl/sdl-common.cpp
index 1095d4b68f..cd3b99430c 100644
--- a/backends/sdl/sdl-common.cpp
+++ b/backends/sdl/sdl-common.cpp
@@ -41,22 +41,23 @@
 #define JOY_BUT_SPACE 4
 #define JOY_BUT_F5 5
 
-OSystem *OSystem_SDL_create(int gfx_mode, bool full_screen) {
-	return OSystem_SDL_Common::create(gfx_mode, full_screen);
+OSystem *OSystem_SDL_create(int gfx_mode, bool full_screen, bool aspect_ratio) {
+	return OSystem_SDL_Common::create(gfx_mode, full_screen, aspect_ratio);
 }
 
-OSystem *OSystem_SDL_Common::create(int gfx_mode, bool full_screen) {
+OSystem *OSystem_SDL_Common::create(int gfx_mode, bool full_screen, bool aspect_ratio) {
 	OSystem_SDL_Common *syst = OSystem_SDL_Common::create_intern();
 
-	syst->init_intern(gfx_mode, full_screen);
+	syst->init_intern(gfx_mode, full_screen, aspect_ratio);
 
 	return syst;
 }
 
-void OSystem_SDL_Common::init_intern(int gfx_mode, bool full_screen) {
+void OSystem_SDL_Common::init_intern(int gfx_mode, bool full_screen, bool aspect_ratio) {
 
 	_mode = gfx_mode;
 	_full_screen = full_screen;
+	_adjustAspectRatio = aspect_ratio;
 
 	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER | SDL_INIT_JOYSTICK) ==-1) {
 		error("Could not initialize SDL: %s.\n", SDL_GetError());
@@ -129,6 +130,10 @@ void OSystem_SDL_Common::init_size(uint w, uint h) {
 
 	_screenWidth = w;
 	_screenHeight = h;
+
+	if (h != 200)
+		_adjustAspectRatio = false;
+
 	CKSUM_NUM = (_screenWidth * _screenHeight / (8 * 8));
 	if (_dirty_checksums)
 		free(_dirty_checksums);
@@ -576,20 +581,18 @@ bool OSystem_SDL_Common::poll_event(Event *event) {
 				}
 			}
 
-			// Ctr-Alt-a will change aspect ratio in OpenGL backend
+			// Ctr-Alt-a will change aspect ratio
 			if (b == (KBD_CTRL|KBD_ALT) && ev.key.keysym.sym=='a') {
-					Property prop;
-					prop.gfx_mode = 11;
-					property(PROP_SET_GFX_MODE, &prop);
-					break;
+				property(PROP_TOGGLE_ASPECT_RATIO, NULL);
+				break;
 			}
 
 			// Ctr-Alt-b will change bilinear filtering in OpenGL backend
 			if (b == (KBD_CTRL|KBD_ALT) && ev.key.keysym.sym=='b') {
-					Property prop;
-					prop.gfx_mode = 12;
-					property(PROP_SET_GFX_MODE, &prop);
-					break;
+				Property prop;
+				prop.gfx_mode = GFX_BILINEAR;
+				property(PROP_SET_GFX_MODE, &prop);
+				break;
 			}
 
 #ifdef QTOPIA
@@ -698,6 +701,8 @@ bool OSystem_SDL_Common::poll_event(Event *event) {
 			event->mouse.x /= _scaleFactor;
 			event->mouse.y /= _scaleFactor;
 
+			if (_adjustAspectRatio)
+				event->mouse.y = aspect2Real(event->mouse.y);
 			return true;
 
 		case SDL_MOUSEBUTTONDOWN:
@@ -718,6 +723,9 @@ bool OSystem_SDL_Common::poll_event(Event *event) {
 			event->mouse.x /= _scaleFactor;
 			event->mouse.y /= _scaleFactor;
 
+			if (_adjustAspectRatio)
+				event->mouse.y = aspect2Real(event->mouse.y);
+
 			return true;
 
 		case SDL_MOUSEBUTTONUP:
@@ -731,6 +739,10 @@ bool OSystem_SDL_Common::poll_event(Event *event) {
 			event->mouse.y = ev.button.y;
 			event->mouse.x /= _scaleFactor;
 			event->mouse.y /= _scaleFactor;
+
+			if (_adjustAspectRatio)
+				event->mouse.y = aspect2Real(event->mouse.y);
+
 			return true;
 
 		case SDL_JOYBUTTONDOWN:
@@ -835,6 +847,10 @@ bool OSystem_SDL_Common::poll_event(Event *event) {
 			event->mouse.y = km.y;
 			event->mouse.x /= _scaleFactor;
 			event->mouse.y /= _scaleFactor;
+
+			if (_adjustAspectRatio)
+				event->mouse.y = aspect2Real(event->mouse.y);
+
 			return true;
 
 		case SDL_VIDEOEXPOSE:
diff --git a/backends/sdl/sdl-common.h b/backends/sdl/sdl-common.h
index c5e6847ffa..9c4bf91ab7 100644
--- a/backends/sdl/sdl-common.h
+++ b/backends/sdl/sdl-common.h
@@ -123,7 +123,7 @@ public:
 	virtual int16 RGBToColor(uint8 r, uint8 g, uint8 b);
 	virtual void colorToRGB(int16 color, uint8 &r, uint8 &g, uint8 &b);
 
-	static OSystem *create(int gfx_mode, bool full_screen);
+	static OSystem *create(int gfx_mode, bool full_screenm, bool aspect_ratio);
 
 protected:
 	OSystem_SDL_Common();
@@ -131,7 +131,7 @@ protected:
 
 	static OSystem_SDL_Common *create_intern();
 
-	void init_intern(int gfx_mode, bool full_screen);
+	void init_intern(int gfx_mode, bool full_screen, bool aspect_ratio);
 
 	// unseen game screen
 	SDL_Surface *_screen;
@@ -142,6 +142,8 @@ protected:
 	int _tmpScreenWidth;
 	bool _overlayVisible;
 
+	bool _adjustAspectRatio;
+
 	// CD Audio
 	SDL_CD *_cdrom;
 	int cd_track, cd_num_loops, cd_start_frame, cd_end_frame;
diff --git a/backends/sdl/sdl.cpp b/backends/sdl/sdl.cpp
index 2caa4d2d67..ecb00cd2d8 100644
--- a/backends/sdl/sdl.cpp
+++ b/backends/sdl/sdl.cpp
@@ -147,12 +147,13 @@ normal_mode:;
 	//
 	// Create the surface that contains the scaled graphics in 16 bit mode
 	//
-	_hwscreen = SDL_SetVideoMode(_screenWidth * _scaleFactor, _screenHeight * _scaleFactor, 16, 
+
+	_hwscreen = SDL_SetVideoMode(_screenWidth * _scaleFactor, (_adjustAspectRatio ? 240 : _screenHeight) * _scaleFactor, 16, 
 		_full_screen ? (SDL_FULLSCREEN|SDL_SWSURFACE) : SDL_SWSURFACE
 	);
 	if (_hwscreen == NULL)
 		error("_hwscreen failed");
-	
+
 	//
 	// Create the surface used for the graphics in 16 bit before scaling, and also the overlay
 	//
@@ -192,7 +193,7 @@ void OSystem_SDL::unload_gfx_mode() {
 		SDL_FreeSurface(_hwscreen); 
 		_hwscreen = NULL;
 	}
-	
+
 	if (_tmpscreen) {
 		free(_tmpscreen->pixels);
 		SDL_FreeSurface(_tmpscreen);
@@ -281,7 +282,7 @@ void OSystem_SDL::update_screen() {
 		uint32 srcPitch, dstPitch;
 		SDL_Rect *last_rect = _dirty_rect_list + _num_dirty_rects;
 
-		if (_scaler_proc == Normal1x) {
+		if (_scaler_proc == Normal1x && !_adjustAspectRatio) {
 			SDL_Surface *target = _overlayVisible ? _tmpscreen : _screen;
 			for (r = _dirty_rect_list; r != last_rect; ++r) {
 				dst = *r;
@@ -314,23 +315,32 @@ void OSystem_SDL::update_screen() {
 			for (r = _dirty_rect_list; r != last_rect; ++r) {
 				register int dst_y = r->y + _currentShakePos;
 				register int dst_h = 0;
+				register int orig_dst_y = 0;
+
 				if (dst_y < _screenHeight) {
 					dst_h = r->h;
 					if (dst_h > _screenHeight - dst_y)
 						dst_h = _screenHeight - dst_y;
 
-						dst_y *= _scaleFactor;
+					dst_y *= _scaleFactor;
 
-						_scaler_proc((byte *)_tmpscreen->pixels + (r->x * 2 + 2) + (r->y + 1) * srcPitch, srcPitch,
+					if (_adjustAspectRatio) {
+						orig_dst_y = dst_y;
+						dst_y = real2Aspect(dst_y);
+					}
+
+					_scaler_proc((byte *)_tmpscreen->pixels + (r->x * 2 + 2) + (r->y + 1) * srcPitch, srcPitch,
 						(byte *)_hwscreen->pixels + r->x * 2 * _scaleFactor + dst_y * dstPitch, dstPitch, r->w, dst_h);
 				}
-			
+
 				r->x *= _scaleFactor;
 				r->y = dst_y;
 				r->w *= _scaleFactor;
 				r->h = dst_h * _scaleFactor;
-			}
 
+				if (_adjustAspectRatio && orig_dst_y / _scaleFactor < _screenHeight)
+					r->h = stretch200To240((uint8 *) _hwscreen->pixels, dstPitch, r->w, r->h, r->x, r->y, orig_dst_y);
+			}
 			SDL_UnlockSurface(_tmpscreen);
 			SDL_UnlockSurface(_hwscreen);
 		}
@@ -339,7 +349,7 @@ void OSystem_SDL::update_screen() {
 		// This is necessary if shaking is active.
 		if (_forceFull) {
 			_dirty_rect_list[0].y = 0;
-			_dirty_rect_list[0].h = _screenHeight * _scaleFactor;
+			_dirty_rect_list[0].h = (_adjustAspectRatio ? 240 : _screenHeight) * _scaleFactor;
 		}
 
 		// Finally, blit all our changes to the screen
@@ -374,6 +384,12 @@ uint32 OSystem_SDL::property(int param, Property *value) {
 		hotswap_gfx_mode();
 
 		return 1;
+	} else if (param == PROP_TOGGLE_ASPECT_RATIO) {
+		if (_screenHeight == 200) {
+			assert(_hwscreen != 0);
+			_adjustAspectRatio ^= true;
+			hotswap_gfx_mode();
+		}
 	}
 
 	return OSystem_SDL_Common::property(param, value);
diff --git a/backends/sdl/sdl_gl.cpp b/backends/sdl/sdl_gl.cpp
index d29029ddfe..949baf7b1d 100644
--- a/backends/sdl/sdl_gl.cpp
+++ b/backends/sdl/sdl_gl.cpp
@@ -54,7 +54,6 @@ protected:
 	int _glFlags;
 	int _glScreenStart;
 	bool _glBilinearFilter;
-	bool _glAspectRatio;
 	bool _usingOpenGL;
 	SDL_Surface *tmpSurface; // Used for black rectangles blitting 
 	SDL_Rect tmpBlackRect;   // Black rectangle at end of the GL screen
@@ -79,7 +78,6 @@ OSystem_SDL_OpenGL::OSystem_SDL_OpenGL()
 {
   _glScreenStart = 0; 
   _glBilinearFilter = true;
-  _glAspectRatio = false;
   _usingOpenGL = false; // false => Switch to filters used in the sdl.cpp version
   _glBottomOfTexture = 256; // height is always 256
   // 640x480 resolution
@@ -165,7 +163,7 @@ void OSystem_SDL_OpenGL::load_gfx_mode() {
 
 	case GFX_NORMAL:
 normal_mode:;
-		_scaleFactor = 1;
+		_scaleFactor = _usingOpenGL ? 2 : 1;
 		_scaler_proc = Normal1x;
 		break;
 	default:
@@ -199,8 +197,7 @@ normal_mode:;
 		fb2gl.init(_glWindow.w, _glWindow.h, 0, _glScreenStart? 15: 70, 
 		    _glFlags);
 		
-	}
-	else { // SDL backend
+	} else { // SDL backend
 	  
 		_hwscreen = SDL_SetVideoMode(_screenWidth * _scaleFactor, _screenHeight * _scaleFactor, 16, 
 		  _full_screen ? (SDL_FULLSCREEN|SDL_SWSURFACE) : SDL_SWSURFACE
@@ -234,8 +231,7 @@ normal_mode:;
 						Gmask,
 						Bmask,
 						Amask);
-	}
-	else { // SDL backend
+	} else { // SDL backend
 		_tmpscreen = SDL_CreateRGBSurfaceFrom(tmp_screen,
 						_tmpScreenWidth, 
 						_screenHeight + 3, 
@@ -346,8 +342,7 @@ void OSystem_SDL_OpenGL::update_screen() {
 		
 			SDL_FillRect(tmpSurface, &blackrect, 0);
 			fb2gl.blit16(tmpSurface, 1, &blackrect, 0, 0);
-		}
-		else { // SDL backend
+		} else { // SDL backend
 			SDL_Rect blackrect = {0, 0, _screenWidth * _scaleFactor, _newShakePos * _scaleFactor};
 			SDL_FillRect(_hwscreen, &blackrect, 0);
 		}
@@ -545,9 +540,30 @@ uint32 OSystem_SDL_OpenGL::property(int param, Property *value) {
 #endif
 
 		return 1;
-	}
-	else if (param == PROP_SET_GFX_MODE) {
+	} else if (param == PROP_TOGGLE_ASPECT_RATIO) {
+		if (!_usingOpenGL) {
+			_usingOpenGL = true;
+			_mode = GFX_NORMAL;
+			hotswap_gfx_mode();
+		}
+
+		_adjustAspectRatio ^= true;
+		if (_adjustAspectRatio) {
+			// Don't use the whole screen (black borders)
+			fb2gl.init(0, 0, 0, 15, _glFlags);
+			_glScreenStart = 20;
+			SDL_FillRect(tmpSurface, &tmpBlackRect, 0);
+			fb2gl.blit16(tmpSurface, 1, &tmpBlackRect, 0, 0);
+		} else {
+			// Use the whole screen
+			fb2gl.init(0, 0, 0, 70, _glFlags);
+			_glScreenStart = 0;
+		}
+
 		SDL_Rect full = {0, 0, _screenWidth, _screenHeight};
+		fb2gl.blit16(_tmpscreen, 1, &full, 0, _glScreenStart);
+		fb2gl.display();
+	} else if (param == PROP_SET_GFX_MODE) {
 
 		if (value->gfx_mode > 10) { // OpenGL modes
 			if (!_usingOpenGL) {
@@ -562,20 +578,6 @@ uint32 OSystem_SDL_OpenGL::property(int param, Property *value) {
 				_glBilinearFilter ^= true;
 				fb2gl.setBilinearMode(_glBilinearFilter);
 				break;
-			case GFX_ASPECTRATIO: 
-				_glAspectRatio ^= true;
-				if (_glAspectRatio) {
-					// Don't use the whole screen (black borders)
-					fb2gl.init(0, 0, 0, 15, _glFlags);
-					_glScreenStart = 20;
-					SDL_FillRect(tmpSurface, &tmpBlackRect, 0);
-					fb2gl.blit16(tmpSurface, 1, &tmpBlackRect, 0, 0);
-				} else {
-					// Use the whole screen
-					fb2gl.init(0, 0, 0, 70, _glFlags);
-					_glScreenStart = 0;
-				}
-				break;
 			default: // SDL backend
 				if (value->gfx_mode >= 10)
 				  return 0;
@@ -589,6 +591,7 @@ uint32 OSystem_SDL_OpenGL::property(int param, Property *value) {
 		};
 
 		if (_usingOpenGL) {
+			SDL_Rect full = {0, 0, _screenWidth, _screenHeight};
 			fb2gl.blit16(_tmpscreen, 1, &full, 0, _glScreenStart);
 			fb2gl.display();
 		}
diff --git a/common/gameDetector.cpp b/common/gameDetector.cpp
index 3cd1a742cb..a4841ed72b 100644
--- a/common/gameDetector.cpp
+++ b/common/gameDetector.cpp
@@ -50,38 +50,39 @@ static const char USAGE_STRING[] =
 	"Syntax:\n"
 	"\tscummvm [-v] [-d[<num>]] [-n] [-b<num>] [-t<num>] [-s<num>] [-p<path>] [-m<num>] [-f] game\n"
 	"Flags:\n"
-	"\t-p<path>      - look for game in <path>\n"
-	"\t-x[<num>]     - load this savegame (default: 0 - autosave)\n"
-	"\t-f            - fullscreen mode\n"
-	"\t-g<mode>      - graphics mode (normal,2x,3x,2xsai,super2xsai,supereagle,advmame2x,advmame3x,tv2x,dotmatrix)\n"
-	"\t-e<mode>      - set music engine (see README for details)\n"
-	"\t-a            - specify game is amiga version\n"
-	"\t-q<lang>      - specify language (en,de,fr,it,pt,es,jp,zh,kr,hb)\n"
+	"\t-p<path>       - look for game in <path>\n"
+	"\t-x[<num>]      - load this savegame (default: 0 - autosave)\n"
+	"\t-f             - fullscreen mode\n"
+	"\t-g<mode>       - graphics mode (normal,2x,3x,2xsai,super2xsai,supereagle,advmame2x,advmame3x,tv2x,dotmatrix)\n"
+	"\t-e<mode>       - set music engine (see README for details)\n"
+	"\t-a             - specify game is amiga version\n"
+	"\t-q<lang>       - specify language (en,de,fr,it,pt,es,jp,zh,kr,hb)\n"
 	"\n"
-	"\t-c<num>       - use cdrom <num> for cd audio\n"
-	"\t-m<num>       - set music volume to <num> (0-255)\n"
-	"\t-o<num>       - set master volume to <num> (0-255)\n"
-	"\t-s<num>       - set sfx volume to <num> (0-255)\n"
-	"\t-t<num>       - set music tempo (50-200, default 100%%)\n"
+	"\t-c<num>        - use cdrom <num> for cd audio\n"
+	"\t-m<num>        - set music volume to <num> (0-255)\n"
+	"\t-o<num>        - set master volume to <num> (0-255)\n"
+	"\t-s<num>        - set sfx volume to <num> (0-255)\n"
+	"\t-t<num>        - set music tempo (50-200, default 100%%)\n"
 	"\n"
-	"\t-n            - no subtitles for speech\n"
-	"\t-y            - set text speed (default: 60)\n"
+	"\t-n             - no subtitles for speech\n"
+	"\t-y             - set text speed (default: 60)\n"
 	"\n"
-	"\t-l<file>      - load config file instead of default\n"
+	"\t-l<file>       - load config file instead of default\n"
 #if defined(UNIX)
-	"\t-w[<file>]    - write to config file [~/.scummvmrc]\n"
+	"\t-w[<file>]     - write to config file [~/.scummvmrc]\n"
 #else
-	"\t-w[<file>]    - write to config file [scummvm.ini]\n"
+	"\t-w[<file>]     - write to config file [scummvm.ini]\n"
 #endif
-	"\t-v            - show version info and exit\n"
-	"\t-z            - display list of games\n"
+	"\t-v             - show version info and exit\n"
+	"\t-z             - display list of games\n"
 	"\n"
-	"\t-b<num>       - start in room <num>\n"
-	"\t-d[<num>]     - enable debug output (debug level [1])\n"
-	"\t-u            - dump scripts\n"
+	"\t-b<num>        - start in room <num>\n"
+	"\t-d[<num>]      - enable debug output (debug level [1])\n"
+	"\t-u             - dump scripts\n"
 	"\n"
-	"\t--multi-midi  - enable combination Adlib and native MIDI\n"
-	"\t--native-mt32 - true Roland MT-32 (disable GM emulation)\n"
+	"\t--multi-midi   - enable combination Adlib and native MIDI\n"
+	"\t--native-mt32  - true Roland MT-32 (disable GM emulation)\n"
+	"\t--aspect-ratio - enable aspect ratio correction\n"
 ;
 #endif
 // This contains a pointer to a list of all supported games.
@@ -148,6 +149,7 @@ static int countVersions(const VersionSettings *v) {
 
 GameDetector::GameDetector() {
 	_fullScreen = false;
+	_aspectRatio = false;
 
 	_use_adlib = false;
 
@@ -245,6 +247,7 @@ void GameDetector::updateconfig() {
 		}
 
 	_fullScreen = g_config->getBool("fullscreen", _fullScreen);
+	_aspectRatio = g_config->getBool("aspect_ratio", _aspectRatio);
 
 	if ((val = g_config->get("gfx_mode")))
 		if ((_gfx_mode = parseGraphicsMode(val)) == -1) {
@@ -453,6 +456,9 @@ void GameDetector::parseCommandLine(int argc, char **argv) {
 				} else if (!strcmp (s, "native-mt32")) {
 					_native_mt32 = true;
 					g_config->setBool ("native_mt32", true);
+				} else if (!strcmp (s, "aspect-ratio")) {
+					_aspectRatio = true;
+					g_config->setBool ("aspect_ratio", true);
 				} else {
 					goto ShowHelpAndExit;
 				}
@@ -673,7 +679,7 @@ OSystem *GameDetector::createSystem() {
 	return OSystem_PALMOS_create(_gfx_mode);
 #else
 	/* SDL is the default driver for now */
-	return OSystem_SDL_create(_gfx_mode, _fullScreen);
+	return OSystem_SDL_create(_gfx_mode, _fullScreen, _aspectRatio);
 #endif
 }
 
diff --git a/common/gameDetector.h b/common/gameDetector.h
index f73f20cd56..d9e5b104a5 100644
--- a/common/gameDetector.h
+++ b/common/gameDetector.h
@@ -110,6 +110,7 @@ public:
 	const String& getGameName(void);
 	
 	bool _fullScreen;
+	bool _aspectRatio;
 
 	bool _use_adlib;
 
diff --git a/common/scaler.cpp b/common/scaler.cpp
index 1607fef214..0d952110c1 100644
--- a/common/scaler.cpp
+++ b/common/scaler.cpp
@@ -30,7 +30,9 @@ static uint32 lowPixelMask = 0x08210821;
 static uint32 qcolorMask = 0xE79CE79C;
 static uint32 qlowpixelMask = 0x18631863;
 static uint32 redblueMask = 0xF81F;
-static uint32 greenMask = 0x7E0;
+static uint32 redMask = 0xF800;
+static uint32 greenMask = 0x07E0;
+static uint32 blueMask = 0x001F;
 
 static const uint16 dotmatrix_565[16] = {
 	0x01E0, 0x0007, 0x3800, 0x0000,
@@ -53,7 +55,9 @@ int Init_2xSaI(uint32 BitFormat) {
 		qcolorMask = 0xE79CE79C;
 		qlowpixelMask = 0x18631863;
 		redblueMask = 0xF81F;
-		greenMask = 0x7E0;
+		redMask = 0xF800;
+		greenMask = 0x07E0;
+		blueMask = 0x001F;
 		dotmatrix = dotmatrix_565;
 	} else if (BitFormat == 555) {
 		colorMask = 0x7BDE7BDE;
@@ -61,7 +65,9 @@ int Init_2xSaI(uint32 BitFormat) {
 		qcolorMask = 0x739C739C;
 		qlowpixelMask = 0x0C630C63;
 		redblueMask = 0x7C1F;
-		greenMask = 0x3E0;
+		redMask = 0x7C00;
+		greenMask = 0x03E0;
+		blueMask = 0x001F;
 		dotmatrix = dotmatrix_555;
 	} else {
 		return 0;
@@ -634,3 +640,93 @@ void DotMatrix(const uint8 *srcPtr, uint32 srcPitch, uint8 *dstPtr, uint32 dstPi
 		q += nextlineDst << 1;
 	}
 }
+
+
+static inline uint32 interpolate5(uint16 A, uint16 B, int scale) {
+	uint16 r = ((A & redMask) * scale + (B & redMask) * (5 - scale)) / 5;
+	uint16 g = ((A & greenMask) * scale + (B & greenMask) * (5 - scale)) / 5;
+	uint16 b = ((A & blueMask) * scale + (B & blueMask) * (5 - scale)) / 5;
+
+	return (r & redMask) | (g & greenMask) | (b & blueMask);
+}
+
+static inline void interpolate5Line(uint16 *dst, const uint16 *srcA, const uint16 *srcB, int scale, int width) {
+#if 1
+	// Accurate but slightly slower code
+	while (width--) {
+		*dst++ = interpolate5(*srcA++, *srcB++, scale);
+	}
+#else
+	// Not fully accurate, but a bit faster
+	width /= 2;
+	const uint32 *sA = (const uint32 *)srcA;
+	const uint32 *sB = (const uint32 *)srcB;
+	uint32 *d = (uint32 *)dst;
+	if (scale == 1) {
+		while (width--) {
+			uint32 B = *sB++;
+			*d++ = Q_INTERPOLATE(*sA++, B, B, B);
+		}
+	} else {
+		while (width--) {
+			*d++ = INTERPOLATE(*sA++, *sB++);
+		}
+	}
+#endif
+}
+
+/**
+ * Stretch a 16bpp image vertically by factor 1.2. Used to correct the
+ * aspect-ratio in games using 320x200 pixel graphics with non-qudratic
+ * pixels. Applying this method effectively turns that into 320x240, which
+ * provides the correct aspect-ratio on modern displays.
+ *
+ * The image would normally have occupied y coordinates origSrcY through
+ * origSrcY + height - 1.
+ *
+ * However, we have already placed it at srcY - the aspect-corrected y
+ * coordinate - to allow in-place stretching.
+ *
+ * Therefore, the source image now occupies Y coordinates srcY through
+ * srcY + height - 1, and it should be stretched to Y coordinates srcY
+ * through real2Aspect(srcY + height - 1).
+ */
+int stretch200To240(uint8 *buf, uint32 pitch, int width, int height, int srcX, int srcY, int origSrcY) {
+	int maxDstY = real2Aspect(origSrcY + height - 1);
+	int off = srcY - origSrcY;
+	int y;
+
+	uint8 *dstPtr = buf + srcX * 2 + maxDstY * pitch;
+
+	for (y = maxDstY; y >= srcY; y--) {
+		uint8 *srcPtr = buf + srcX * 2 + (aspect2Real(y) + off) * pitch;
+
+		if (srcPtr == dstPtr)
+			break;
+		
+#if 0
+		// Don't use bilinear filtering, rather just duplicate pixel lines:
+		// a little bit faster, but looks ugly
+		memcpy(dstPtr, srcPtr, width * 2);
+#else
+		// Bilinear filter
+		switch (y % 6) {
+		case 0:
+		case 5:
+			memcpy(dstPtr, srcPtr, width * 2);
+			break;
+		case 1:
+		case 4:
+			interpolate5Line((uint16 *)dstPtr, (uint16 *)(srcPtr - pitch), (uint16 *)srcPtr, 1, width);
+			break;
+		case 2:
+		case 3:
+			interpolate5Line((uint16 *)dstPtr, (uint16 *)(srcPtr - pitch), (uint16 *)srcPtr, 2, width);
+			break;
+		}
+#endif
+		dstPtr -= pitch;
+	}
+
+	return 1 + maxDstY - srcY;
+}
diff --git a/common/scaler.h b/common/scaler.h
index e3246587c9..b8000ddccd 100644
--- a/common/scaler.h
+++ b/common/scaler.h
@@ -41,6 +41,15 @@ DECLARE_SCALER(Normal3x);
 DECLARE_SCALER(TV2x);
 DECLARE_SCALER(DotMatrix);
 
+FORCEINLINE int real2Aspect(int y) {
+	return y + (y + 1) / 5;
+}
+
+FORCEINLINE int aspect2Real(int y) {
+	return (y * 5 + 3) / 6;
+}
+
+extern int stretch200To240(uint8 *buf, uint32 pitch, int width, int height, int srcX, int srcY, int origSrcY);
 
 enum {
 	GFX_NORMAL = 0,
@@ -54,7 +63,6 @@ enum {
 	GFX_TV2X = 8,
 	GFX_DOTMATRIX = 9,
 
-	GFX_ASPECTRATIO = 11, // OpenGL backend
 	GFX_BILINEAR = 12,    // OpenGL backend
 	
 	GFX_FLIPPING = 100,	// Palmos
diff --git a/common/system.h b/common/system.h
index 68408a6a13..32e55e4879 100644
--- a/common/system.h
+++ b/common/system.h
@@ -94,7 +94,8 @@ public:
 		PROP_GET_SAMPLE_RATE = 6,
 		PROP_GET_FULLSCREEN = 7,
 		PROP_GET_FMOPL_ENV_BITS = 8,
-		PROP_GET_FMOPL_EG_ENT = 9
+		PROP_GET_FMOPL_EG_ENT = 9,
+		PROP_TOGGLE_ASPECT_RATIO = 10
 	};
 	union Property {
 		const char *caption;
@@ -363,7 +364,7 @@ public:
 /* Factory functions. This means we don't have to include the headers for
  * all backends.
  */
-extern OSystem *OSystem_SDL_create(int gfx_driver, bool full_screen);
+extern OSystem *OSystem_SDL_create(int gfx_driver, bool full_screen, bool aspect_ratio);
 extern OSystem *OSystem_NULL_create();
 extern OSystem *OSystem_MorphOS_create(int game_id, int gfx_driver, bool full_screen);
 extern OSystem *OSystem_Dreamcast_create();