[分享] LuaJIT的FFI调用WINDOWS API功能示例
发表于关于LuaJIT,以下是官网的介绍.
LuaJIT is a Just-In-Time Compiler (JIT) for the Lua programming language. Lua is a powerful, dynamic and light-weight programming language. It may be embedded or used as a general-purpose, stand-alone language.
LuaJIT is Copyright © 2005-2013 Mike Pall, released under the MIT open source license.
LuaJIT对原版LUA进行了一些扩展,功能更强大,实用,速度也更快.本文主要介绍一下FFI扩展功能.
FFI库允许调用外部C函数以及使用C数据结构.这意味着我们可以通过它来调用一些系统API或DLL的函数,像调用LIBCURL来实现网络功能.等…
比如以下来自官网最简单的应用代码
--Load the FFI library.
local ffi = require("ffi")
--Add a C declaration for the function. The part inside the double-brackets (in green) is just standard C syntax.
ffi.cdef[[
int printf(const char *fmt, ...);
]]
--Call the named C function — Yes, it's that simple!
ffi.C.printf("Hello %s!", "world")
local ffi = require("ffi")
ffi.cdef[[
int MessageBoxA(void *w, const char *txt, const char *cap, int type);
]]
ffi.C.MessageBoxA(nil, "Hello world!", "Test", 0)
看起来很简单不是吗?
这里给一个稍微复杂一些的例子,这是我在是学习过程中碰到的一些问题的总结,里面包括了一些常用的操作,像ffi.new 创建一个C的类型,ffi.cast数据类型转换,等.有兴趣的可以通过这个例子来学习一下如何应用.少走一些弯路.希望对大家有用.
本代码要保存为ANSI格式才可以正常运行
local ffi = require("ffi")
ffi.cdef[[
typedef char TCHAR;
typedef unsigned int UINT;
typedef TCHAR _LPTSTR;
typedef const TCHAR *LPCTSTR;
typedef LPCTSTR LPCSTR;
typedef UINT WPARAM;
typedef unsigned long LPARAM;
typedef UINT HWND;
typedef struct {
long x;
long y;
} POINT,_PPOINT;
void* malloc(size_t size);
void* free(void* memblock);
bool GetCursorPos(PPOINT lpPoint);
HWND WindowFromPoint(POINT Point);
int GetWindowTextA(HWND hWnd, LPTSTR lpString, int nMaxCount);
bool SetWindowTextA(HWND hWnd, LPCTSTR lpString);
int SendMessageA(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
int MessageBoxA(HWND hWnd,LPCSTR lpText,LPCSTR lpCaption,UINT uType);
]]
local user32 = ffi.load("User32.dll")--WINDOWS API函数所在DLL文件
local win32 = ffi.load('msvcrt.dll')--malloc和free函数
local pos=ffi.new("POINT");
local oks = user32.GetCursorPos(pos)--获取当前鼠标位置
local IDYES = 6
local IDNO = 7
local WM_SETTEXT = 0x000C
local WM_GETTEXT = 0x000D
if oks then
local hwnd = user32.WindowFromPoint(pos)--获取指定位置下窗体的句柄
local lpString = ffi.new("char*",win32.malloc(1024))--分配内存
local test = user32.GetWindowTextA(hwnd,lpString,1023)--获取文本
local str1 = ffi.string(lpString);
local strtest ="FFI 调用SetWindowText功能测试"
local t = user32.MessageBoxA(0,"是否把以下窗体\n<"..str1..">\n的标题修改为以下内容:\n"..strtest,"LUAJIT FFI 调用WINAPI测试",0x44)--MB_ICONINFORMATION || 0x00000004L
if t == IDYES then
if user32.SetWindowTextA(hwnd,strtest) == true then
user32.MessageBoxA(0,"修改成功","测试",0x40)
end
end
--[[注: Windows API 的SendMessage就是SendMessageA或SendMessageW
像MessageBox也是类型的MessageBoxA和MessageBoxW
本文例子使用了ffi.cast进行了数据类型的转换,如果不想转换可以修改一下SendMessageA的定义改为如下(我最早就是不知道有ffi.cast所以用的修改定义的方法)
int SendMessageA(HWND hwnd, UINT msg, WPARAM wParam, LPCTSTR lParam);
就可以直接使用了,例:
user32.SendMessageA(hwnd,WM_SETTEXT,1024,"用SendMessage和WM_SETTEXT功能改写目标字符串")
这个SendMessage是WINDOWS一个很重要的API,后面的两个参数很灵活,根据不同的功能需求,可以是这符串/数字或指针,数组之类的.--]]
user32.MessageBoxA(0,"测试使用SendMessage来实现同样的功能","测试2",0x40)
user32.SendMessageA(hwnd,WM_GETTEXT,1024,ffi.cast("LPARAM",lpString))--通过ffi.cast功能进行类型转换
user32.MessageBoxA(0,"用SendMessage和WM_GETTEXT功能获取到的窗体标题为\n"..ffi.string(lpString),"测试2",0x40);
user32.SendMessageA(hwnd,WM_SETTEXT,1024,ffi.cast("LPARAM","用SendMessage和WM_SETTEXT功能改写目标字符串"))
user32.MessageBoxA(0,"目标标题已改变","测式2",0x40)
win32.free(lpString)--释放内存
end
