Added love.window.toPixels(x [, y]) and love.window.fromPixels(x [, y]), for easier conversion between window-space and pixel-space values when highdpi mode is enabled on a retina display in OS X (and in the iOS and Android ports of LÖVE.)

src/modules/window/Window.h

@@ -148,6 +148,11 @@ public:
 
 	virtual double getPixelScale() const = 0;
 
+	virtual double toPixels(double x) const = 0;
+	virtual void toPixels(double wx, double wy, double &px, double &py) const = 0;
+	virtual double fromPixels(double x) const = 0;
+	virtual void fromPixels(double px, double py, double &wx, double &wy) const = 0;
+
 	virtual const void *getHandle() const = 0;
 
 	virtual bool showMessageBox(MessageBoxType type, const std::string &title, const std::string &message, bool attachtowindow) = 0;

src/modules/window/sdl/Window.cpp

@@ -682,6 +682,30 @@ double Window::getPixelScale() const
 	return scale;
 }
 
+double Window::toPixels(double x) const
+{
+	return x * getPixelScale();
+}
+
+void Window::toPixels(double wx, double wy, double &px, double &py) const
+{
+	double scale = getPixelScale();
+	px = wx * scale;
+	py = wy * scale;
+}
+
+double Window::fromPixels(double x) const
+{
+	return x / getPixelScale();
+}
+
+void Window::fromPixels(double px, double py, double &wx, double &wy) const
+{
+	double scale = getPixelScale();
+	wx = px / scale;
+	wy = py / scale;
+}
+
 const void *Window::getHandle() const
 {
 	return window;

src/modules/window/sdl/Window.h

@@ -85,6 +85,11 @@ public:
 
 	double getPixelScale() const;
 
+	double toPixels(double x) const;
+	void toPixels(double wx, double wy, double &px, double &py) const;
+	double fromPixels(double x) const;
+	void fromPixels(double px, double py, double &wx, double &wy) const;
+
 	const void *getHandle() const;
 
 	bool showMessageBox(MessageBoxType type, const std::string &title, const std::string &message, bool attachtowindow);

src/modules/window/wrap_Window.cpp

@@ -333,6 +333,48 @@ int w_getPixelScale(lua_State *L)
 	return 1;
 }
 
+int w_toPixels(lua_State *L)
+{
+	double wx = luaL_checknumber(L, 1);
+
+	if (lua_isnoneornil(L, 2))
+	{
+		lua_pushnumber(L, instance()->toPixels(wx));
+		return 1;
+	}
+
+	double wy = luaL_checknumber(L, 2);
+	double px = 0.0, py = 0.0;
+
+	instance()->toPixels(wx, wy, px, py);
+
+	lua_pushnumber(L, px);
+	lua_pushnumber(L, py);
+
+	return 2;
+}
+
+int w_fromPixels(lua_State *L)
+{
+	double px = luaL_checknumber(L, 1);
+
+	if (lua_isnoneornil(L, 2))
+	{
+		lua_pushnumber(L, instance()->fromPixels(px));
+		return 1;
+	}
+
+	double py = luaL_checknumber(L, 2);
+	double wx = 0.0, wy = 0.0;
+
+	instance()->fromPixels(px, py, wx, wy);
+
+	lua_pushnumber(L, wx);
+	lua_pushnumber(L, wy);
+
+	return 2;
+}
+
 int w_minimize(lua_State* /*L*/)
 {
 	instance()->minimize();
@@ -421,6 +463,8 @@ static const luaL_Reg functions[] =
 	{ "hasMouseFocus", w_hasMouseFocus },
 	{ "isVisible", w_isVisible },
 	{ "getPixelScale", w_getPixelScale },
+	{ "toPixels", w_toPixels },
+	{ "fromPixels", w_fromPixels },
 	{ "minimize", w_minimize },
 	{ "showMessageBox", w_showMessageBox },
 	{ 0, 0 }

src/modules/window/wrap_Window.h

@@ -49,6 +49,8 @@ int w_hasFocus(lua_State *L);
 int w_hasMouseFocus(lua_State *L);
 int w_isVisible(lua_State *L);
 int w_getPixelScale(lua_State *L);
+int w_toPixels(lua_State *L);
+int w_fromPixels(lua_State *L);
 int w_minimize(lua_State *L);
 int w_showMessageBox(lua_State *L);
 extern "C" LOVE_EXPORT int luaopen_love_window(lua_State *L);