Added sRGB (gamma-correct) support for Images, Canvases, and the main screen.

love.graphics.newImage(path, “srgb”) creates a new Image whose texels are treated as being in the sRGB color space, so they are linearized when drawing/sampling from the image.

love.graphics.newCanvas(w, h, “srgb”) creates a new Canvas whose texels are treated as being in the sRGB color space, so drawing to the Canvas does a linear->sRGB conversion (but blends linearly), and sampling from it (drawing it or using it in a shader) converts from sRGB to linear space.

The "srgb" window flag does the same as Canvases for the main screen.

src/modules/window/Window.cpp

@@ -50,6 +50,7 @@ WindowSettings::WindowSettings()
 	, centered(true)
 	, display(0)
 	, highdpi(false)
+	, sRGB(false)
 {
 }
 
@@ -86,6 +87,7 @@ StringMap<Window::Setting, Window::SETTING_MAX_ENUM>::Entry Window::settingEntri
 	{"centered", SETTING_CENTERED},
 	{"display", SETTING_DISPLAY},
 	{"highdpi", SETTING_HIGHDPI},
+	{"srgb", SETTING_SRGB},
 };
 
 StringMap<Window::Setting, Window::SETTING_MAX_ENUM> Window::settings(Window::settingEntries, sizeof(Window::settingEntries));

src/modules/window/Window.h

@@ -57,6 +57,7 @@ public:
 		SETTING_CENTERED,
 		SETTING_DISPLAY,
 		SETTING_HIGHDPI,
+		SETTING_SRGB,
 		SETTING_MAX_ENUM
 	};
 
@@ -157,6 +158,7 @@ struct WindowSettings
 	bool centered; // = true
 	int display; // = 0
 	bool highdpi; // false
+	bool sRGB; // false
 
 }; // WindowSettings
 

src/modules/window/sdl/Window.cpp

@@ -154,7 +154,7 @@ bool Window::setWindow(int width, int height, WindowSettings *settings)
 	if (!window)
 	{
 		// In Windows and Linux, some GL attributes are set on window creation.
-		setWindowGLAttributes(f.fsaa);
+		setWindowGLAttributes(f.fsaa, f.sRGB);
 
 		const char *title = windowTitle.c_str();
 		int pos = f.centered ? centeredpos : uncenteredpos;
@@ -190,7 +190,7 @@ bool Window::setWindow(int width, int height, WindowSettings *settings)
 
 	SDL_RaiseWindow(window);
 
-	if (!setContext(f.fsaa, f.vsync))
+	if (!setContext(f.fsaa, f.vsync, f.sRGB))
 		return false;
 
 	created = true;
@@ -206,7 +206,7 @@ bool Window::setWindow(int width, int height, WindowSettings *settings)
 		SDL_GL_GetDrawableSize(window, &width, &height);
 #endif
 
-		gfx->setMode(width, height);
+		gfx->setMode(width, height, curMode.settings.sRGB);
 	}
 
 	// Make sure the mouse keeps its previous grab setting.
@@ -226,7 +226,7 @@ bool Window::onWindowResize(int width, int height)
 	return true;
 }
 
-bool Window::setContext(int fsaa, bool vsync)
+bool Window::setContext(int fsaa, bool vsync, bool sRGB)
 {
 	// We would normally only need to recreate the context if FSAA changes or
 	// SDL_GL_MakeCurrent is unsuccessful, but in Windows MakeCurrent can
@@ -238,7 +238,7 @@ bool Window::setContext(int fsaa, bool vsync)
 	}
 
 	// Make sure the proper attributes are set.
-	setWindowGLAttributes(fsaa);
+	setWindowGLAttributes(fsaa, sRGB);
 
 	context = SDL_GL_CreateContext(window);
 
@@ -290,7 +290,7 @@ bool Window::setContext(int fsaa, bool vsync)
 	return true;
 }
 
-void Window::setWindowGLAttributes(int fsaa) const
+void Window::setWindowGLAttributes(int fsaa, bool sRGB) const
 {
 	// Set GL window attributes.
 	SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
@@ -304,6 +304,10 @@ void Window::setWindowGLAttributes(int fsaa) const
 	SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, (fsaa > 0) ? 1 : 0);
 	SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, (fsaa > 0) ? fsaa : 0);
 
+#if SDL_VERSION_ATLEAST(2,0,1)
+	SDL_GL_SetAttribute(SDL_GL_FRAMEBUFFER_SRGB_CAPABLE, sRGB ? 1 : 0);
+#endif
+
 	// Do we want a debug context?
 	const char *debugenv = SDL_GetHint("LOVE_GRAPHICS_DEBUG");
 	if (debugenv && *debugenv == '1')
@@ -370,6 +374,8 @@ void Window::updateSettings(const WindowSettings &newsettings)
 	else
 #endif
 		SDL_SetHint(SDL_HINT_VIDEO_MINIMIZE_ON_FOCUS_LOSS, "0");
+
+	curMode.settings.sRGB = newsettings.sRGB;
 }
 
 void Window::getWindow(int &width, int &height, WindowSettings &settings)

src/modules/window/sdl/Window.h

@@ -90,8 +90,8 @@ public:
 
 private:
 
-	bool setContext(int fsaa, bool vsync);
-	void setWindowGLAttributes(int fsaa) const;
+	bool setContext(int fsaa, bool vsync, bool sRGB);
+	void setWindowGLAttributes(int fsaa, bool sRGB) const;
 
 	// Update the saved window settings based on the window's actual state.
 	void updateSettings(const WindowSettings &newsettings);

src/modules/window/wrap_Window.cpp

@@ -96,6 +96,7 @@ int w_setMode(lua_State *L)
 	settings.centered = luax_boolflag(L, 3, settingName(Window::SETTING_CENTERED), true);
 	settings.display = luax_intflag(L, 3, settingName(Window::SETTING_DISPLAY), 1);
 	settings.highdpi = luax_boolflag(L, 3, settingName(Window::SETTING_HIGHDPI), false);
+	settings.sRGB = luax_boolflag(L, 3, settingName(Window::SETTING_SRGB), false);
 
 	// Display index is 1-based in Lua and 0-based internally.
 	settings.display--;
@@ -151,6 +152,9 @@ int w_getMode(lua_State *L)
 	luax_pushboolean(L, settings.highdpi);
 	lua_setfield(L, -2, settingName(Window::SETTING_HIGHDPI));
 
+	luax_pushboolean(L, settings.sRGB);
+	lua_setfield(L, -2, settingName(Window::SETTING_SRGB));
+
 	return 3;
 }