RmlUi/Source/Lua/LuaEventListener.cpp

/*
 * This source file is part of RmlUi, the HTML/CSS Interface Middleware
 *
 * For the latest information, see http://github.com/mikke89/RmlUi
 *
 * Copyright (c) 2008-2010 CodePoint Ltd, Shift Technology Ltd
 * Copyright (c) 2019-2023 The RmlUi Team, and contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

#include "LuaEventListener.h"
#include <RmlUi/Core/Element.h>
#include <RmlUi/Lua/Interpreter.h>
#include <RmlUi/Lua/LuaType.h>
#include <RmlUi/Lua/Utilities.h>

namespace Rml {
namespace Lua {
typedef ElementDocument Document;

LuaEventListener::LuaEventListener(const String& code, Element* element) : EventListener()
{
	// compose function
	String function = "return function (event,element,document) ";
	function.append(code);
	function.append(" end");

	// make sure there is an area to save the function
	lua_State* L = Interpreter::GetLuaState();
	int top = lua_gettop(L);
	lua_getglobal(L, "EVENTLISTENERFUNCTIONS");
	if (lua_isnoneornil(L, -1))
	{
		lua_newtable(L);
		lua_setglobal(L, "EVENTLISTENERFUNCTIONS");
		lua_pop(L, 1); // pop the unsucessful getglobal
		lua_getglobal(L, "EVENTLISTENERFUNCTIONS");
	}
	int tbl = lua_gettop(L);

	// compile,execute,and save the function
	if (!Interpreter::LoadString(function, code) || !Interpreter::ExecuteCall(0, 1))
	{
		return;
	}

	luaFuncRef = luaL_ref(L, tbl); // creates a reference to the item at the top of the stack in to the table we just created
	lua_pop(L, 1);                 // pop the EVENTLISTENERFUNCTIONS table

	attached = element;
	if (element)
		owner_document = element->GetOwnerDocument();
	else
		owner_document = nullptr;
	strFunc = function;
	lua_settop(L, top);
}

// if it is passed in a Lua function
LuaEventListener::LuaEventListener(lua_State* L, int narg, Element* element)
{
	int top = lua_gettop(L);
	lua_getglobal(L, "EVENTLISTENERFUNCTIONS");
	if (lua_isnoneornil(L, -1))
	{
		lua_newtable(L);
		lua_setglobal(L, "EVENTLISTENERFUNCTIONS");
		lua_pop(L, 1); // pop the unsucessful getglobal
		lua_getglobal(L, "EVENTLISTENERFUNCTIONS");
	}
	lua_pushvalue(L, narg);
	luaFuncRef = luaL_ref(L, -2); // put the funtion as a ref in to that table
	lua_pop(L, 1);                // pop the EVENTLISTENERFUNCTIONS table

	attached = element;
	if (element)
		owner_document = element->GetOwnerDocument();
	else
		owner_document = nullptr;
	lua_settop(L, top);
}

LuaEventListener::~LuaEventListener()
{
	// Remove the Lua function from its table
	lua_State* L = Interpreter::GetLuaState();
	lua_getglobal(L, "EVENTLISTENERFUNCTIONS");
	luaL_unref(L, -1, luaFuncRef);
	lua_pop(L, 1); // pop table
}

void LuaEventListener::OnDetach(Element* /*element*/)
{
	// We consider this listener owned by its element, so we must delete ourselves when
	// we detach (probably because element was removed).
	delete this;
}

/// Process the incoming Event
void LuaEventListener::ProcessEvent(Event& event)
{
	// not sure if this is the right place to do this, but if the element we are attached to isn't a document, then
	// the 'owner_document' variable will be nullptr, because element->ower_document hasn't been set on the construction. We should
	// correct that
	if (!owner_document && attached)
		owner_document = attached->GetOwnerDocument();
	lua_State* L = Interpreter::GetLuaState();
	int top = lua_gettop(L);

	// push the arguments
	lua_getglobal(L, "EVENTLISTENERFUNCTIONS");
	lua_rawgeti(L, -1, luaFuncRef);
	LuaType<Event>::push(L, &event, false);
	LuaType<Element>::push(L, attached, false);
	LuaType<Document>::push(L, owner_document, false);

	Interpreter::ExecuteCall(3, 0); // call the function at the top of the stack with 3 arguments

	lua_settop(L, top);             // balanced stack makes Lua happy
}

} // namespace Lua
} // namespace Rml