LuaYard/LuaEngine.cpp

#include "LuaEngine.h"
#include <iostream>
#include <string>
#include <vector>
#include "SDL2/include/SDL.h"
#include "SDL2/include/SDL_mixer.h"
#include "SDL2/include/SDL_ttf.h"
#include "SDL2/include/SDL_image.h"
using namespace std;

void check(lua_State* L, const vector<int>& typearr)
{
	int sz = typearr.size();
	for (int i = 0; i < sz; i++)
	{
		if (lua_type(L, i + 1) != typearr[i])
		{
			char tmp[128] = { 0 };
			sprintf(tmp, "Bad argument #%d. %s expected, got %s", i + 1, lua_typename(L, typearr[i]), lua_typename(L, lua_type(L, i + 1)));
			luaL_error(L, tmp);
		}
	}
}

struct LuaTimerCallbackData
{
	void* p;
	int id;
	int type; // 0=setTimeout, 1=setInterval
};

Uint32 LuaTimerCallbackGate(Uint32 interval, void* param)
{
	SDL_Event e;
	e.type = SDL_USEREVENT;
	e.user.code = 1001;
	e.user.data1 = param;
	SDL_PushEvent(&e);
	return ((LuaTimerCallbackData*)(param))->type ? interval : 0;
}

#define setfn(L, cfunc, name) lua_pushcfunction(L, cfunc); lua_setfield(L, -2, name)

struct Window
{
	SDL_Window* wnd;

	static int close(lua_State* L)
	{
		check(L, { LUA_TUSERDATA });
		Window* p = (Window*)lua_touserdata(L, 1);
		if (p->wnd)
		{
			// release data table
			lua_pushlightuserdata(L, p);
			lua_pushnil(L);
			lua_settable(L, LUA_REGISTRYINDEX);
			SDL_DestroyWindow(p->wnd);
			p->wnd = nullptr;
		}
		return 0;
	}

	static int start(lua_State* L)
	{
		check(L, { LUA_TUSERDATA });
		Window* p = (Window*)lua_touserdata(L, 1);
		lua_settop(L, 1);
		lua_pushlightuserdata(L, p);
		lua_gettable(L, LUA_REGISTRYINDEX);

		bool running = true;

		SDL_Event e;
		while (running && SDL_WaitEvent(&e))
		{
			switch (e.type)
			{
			case SDL_MOUSEBUTTONDOWN:
			{
				if (lua_getfield(L, -1, "onclick") != LUA_TNIL)
				{
					lua_pushnumber(L, e.button.x);
					lua_pushnumber(L, e.button.y);
					lua_call(L, 2, LUA_MULTRET);
				}
				else lua_pop(L, 1);
				break;
			}
			case SDL_QUIT:
			{
				if (lua_getfield(L, -1, "onquit") != LUA_TNIL)
				{
					lua_call(L, 0, LUA_MULTRET);
				}
				else lua_pop(L, 1);
				running = 0;
				break;
			}
			case SDL_KEYDOWN:
			{
				if (lua_getfield(L, -1, "onkeydown") != LUA_TNIL)
				{
					lua_pushnumber(L, e.key.keysym.sym);
					lua_call(L, 1, LUA_MULTRET);
				}
				else lua_pop(L, 1);
				break;
			}
			case SDL_USEREVENT:
			{
				switch (e.user.code)
				{
				case 1001:
				{
					LuaTimerCallbackData* pd = (LuaTimerCallbackData* )e.user.data1;
					lua_pushlightuserdata(L, pd->p);
					lua_gettable(L, LUA_REGISTRYINDEX);
					lua_pushfstring(L, "tmcb%d", pd->id);
					lua_gettable(L, -2);
					delete pd;
					lua_call(L, 0, LUA_MULTRET);
					lua_pop(L, 1);
					break;
				}
				}
				break;
			}
			}
		}

		return 0;
	}

	static int set_event_handler(lua_State* L)
	{
		check(L, { LUA_TUSERDATA, LUA_TSTRING, LUA_TFUNCTION });
		Window* p = (Window*)lua_touserdata(L, 1);
		lua_pushlightuserdata(L, p);
		lua_gettable(L, LUA_REGISTRYINDEX);
		lua_pushfstring(L, "on%s", lua_tostring(L, 2));
		lua_pushvalue(L, 3);
		lua_settable(L, -3);
		return 0;
	}

	static int setTimeout(lua_State* L)
	{
		check(L, { LUA_TUSERDATA, LUA_TFUNCTION, LUA_TNUMBER }); // ms
		Window* p = (Window*)lua_touserdata(L, 1);

		LuaTimerCallbackData* pd = new LuaTimerCallbackData();
		pd->p = p;
		pd->type = 0;
		pd->id = SDL_AddTimer(lua_tointeger(L, 3), LuaTimerCallbackGate, pd);

		lua_pushlightuserdata(L, p);
		lua_gettable(L, LUA_REGISTRYINDEX);
		lua_pushfstring(L, "tmcb%d", pd->id);
		lua_pushvalue(L, 2);
		lua_settable(L, -3);
		return 0;
	}
	
	static int create(lua_State* L)
	{
		check(L, { LUA_TSTRING, LUA_TNUMBER, LUA_TNUMBER });
		cout << "In SDLWindow::Create" << endl;
		Window* p = (Window*) lua_newuserdata(L, sizeof(Window));
		// Data table (for storing lua values)
		lua_pushlightuserdata(L, p);
		lua_newtable(L);
		lua_settable(L, LUA_REGISTRYINDEX);
		// Metatable
		lua_getfield(L, LUA_REGISTRYINDEX, "__window_mt");
		if (lua_type(L, -1) == LUA_TNIL)
		{
			lua_pop(L, 1);
			lua_newtable(L);
			// GC
			lua_pushcfunction(L, close);
			lua_setfield(L, -2, "__gc");

			// Fields
			lua_newtable(L);
			lua_pushstring(L, "window"); lua_setfield(L, -2, "type");
			setfn(L, close, "close");
			setfn(L, set_event_handler, "on");
			setfn(L, start, "start");
			setfn(L, setTimeout, "setTimeout");

			// Binding
			lua_setfield(L, -2, "__index");
			
			lua_setfield(L, LUA_REGISTRYINDEX, "__window_mt");
			lua_getfield(L, LUA_REGISTRYINDEX, "__window_mt");
		}
		lua_setmetatable(L, -2);

		// Internal logic
		p->wnd = SDL_CreateWindow(lua_tostring(L, 1), SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, lua_tointeger(L, 2), lua_tointeger(L, 3), SDL_WINDOW_SHOWN);
		return 1;
	}
};

struct Renderer
{
	SDL_Renderer* rnd;

	static int close(lua_State* L)
	{
		check(L, { LUA_TUSERDATA });
		Renderer* p = (Renderer*)lua_touserdata(L, 1);
		if (p->rnd)
		{
			SDL_DestroyRenderer(p->rnd);
			p->rnd = nullptr;
		}
		return 0;
	}

	static int update(lua_State* L)
	{
		check(L, { LUA_TUSERDATA });
		Renderer* p = (Renderer*)lua_touserdata(L, 1);
		SDL_RenderPresent(p->rnd);
		return 0;
	}

	static int clear(lua_State* L)
	{
		check(L, { LUA_TUSERDATA });
		Renderer* p = (Renderer*)lua_touserdata(L, 1);
		SDL_RenderClear(p->rnd);
		return 0;
	}

	static int create(lua_State* L)
	{
		check(L, { LUA_TUSERDATA });
		cout << "In SDLWindow::Create" << endl;
		Renderer* p = (Renderer*)lua_newuserdata(L, sizeof(Renderer));
		lua_getfield(L, LUA_REGISTRYINDEX, "__renderer_mt");
		if (lua_type(L, -1) == LUA_TNIL)
		{
			lua_pop(L, 1);
			lua_newtable(L);
			// GC
			lua_pushcfunction(L, close);
			lua_setfield(L, -2, "__gc");

			// Fields
			lua_newtable(L);
			lua_pushstring(L, "renderer"); lua_setfield(L, -2, "type");
			setfn(L, close, "close");
			setfn(L, update, "update");
			setfn(L, clear, "clear");			

			// Set __index of metatable.
			lua_setfield(L, -2, "__index");

			lua_setfield(L, LUA_REGISTRYINDEX, "__renderer_mt");
			lua_getfield(L, LUA_REGISTRYINDEX, "__renderer_mt");
		}
		lua_setmetatable(L, -2);

		// Internal logic
		p->rnd = SDL_CreateRenderer(static_cast<Window*>(lua_touserdata(L, 1))->wnd, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC | SDL_RENDERER_TARGETTEXTURE);
		return 1;
	}
};

#define reg_in_lua(L, cfunc, name) lua_pushcfunction(L, cfunc); lua_setglobal(L, name)

int InitEngine(lua_State* L)
{
	SDL_Init(SDL_INIT_EVERYTHING);
	IMG_Init(IMG_INIT_JPG | IMG_INIT_PNG);
	TTF_Init();
	Mix_Init(MIX_INIT_MP3);

	lua_newtable(L);
	reg_in_lua(L, Window::create, "Window");
	reg_in_lua(L, Renderer::create, "Renderer");

	return 0;
}