Silverlight5通过P/Invoke调用自定义C/C++ DLL(Lua)

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　　上一篇《Silverlight5通过P/Invoke调用系统win32的三个示例》展示了silverlight5通过P/Invoke调用系统win32的三个示例，本篇给出自定义win32 dll及其在Silverlight5中调用的代码。

　　注1：为了确保silverilght5在浏览器或桌面上成功调用win32 DLL，必须在项目属性中勾选相应的权限：

　　　　勾选Enable running application out of the browser及其Require elevated trust when running in-browser

　　　　勾选Require elevated trust when running in-browser

　　注2：win32 dll文件编译后放在\windows\system32或\windows\system目录下，win7 x64的系统放在后者。

　　注3：winform/wpf中调用类似

// The following ifdef block is the standard way of creating macros which make exporting 
// from a DLL simpler. All files within this DLL are compiled with the MYDLL_EXPORTS
// symbol defined on the command line. This symbol should not be defined on any project
// that uses this DLL. This way any other project whose source files include this file see 
// MYDLL_API functions as being imported from a DLL, whereas this DLL sees symbols
// defined with this macro as being exported.
#ifdef MYDLL_EXPORTS
#define MYDLL_API __declspec(dllexport)
#else
#define MYDLL_API __declspec(dllimport)
#endif

struct HHFC_SET 
{
 	;char* UID;
  	int     code;
};

// This class is exported from the MyDLL.dll
class MYDLL_API CMyDLL {
public:
	CMyDLL(void);
	// TODO: add your methods here.
};
//extern MYDLL_API int nMyDLL;
extern "C" MYDLL_API int nMyDLL; 
extern "C" MYDLL_API float fnMyDLL(float x ,float y);// 注意得加上extern  "C"，否则无法P/Invoke

.cpp

#include "stdafx.h"
#include "MyDLL.h"

#include <iostream>   
#include "LuaPlus.h" 
#include "LuaPlusHelper.h" 
#pragma comment(lib,"LuaPlusLib.lib")   
using namespace LuaPlus; 
using namespace std;

// This is an example of an exported variable
MYDLL_API int nMyDLL=0;
// This is an example of an exported function. 
MYDLL_API float fnMyDLL(float x ,float y)
{
 　　 //调用Lua脚本并计算
　　  string str;
　　  str.append("function Add(x, y)\n");
　　  str.append(" return x*y;\n");
　　  str.append("end\n");
　　  int iret = state->DoString(str.c_str());// state->DoFile("a.lua");
　　  LuaFunction Add = state->GetGlobal("Add");
　　  float myret = Add(x,y);
　　  return myret;
} 
extern "C" __declspec(dllexport)  int WINAPI add()
{
	return 101;
}

extern "C" __declspec(dllexport)  int WINAPI add2(HHFC_SET* stru )
 {
stru->UID="this is a win32 test about struct";
stru->code=3;
   	return 1;
 }

extern "C" __declspec(dllexport) float* WINAPI add3()
{
  float* num=(float*)malloc(4);
  num[0]=11.2f;
  num[1]=21.3f;
  num[2]=33.5f;
  num[3]=46.2f;
  return num;
}

// This is the constructor of a class that has been exported.
// see MyDLL.h for the class definition
CMyDLL::CMyDLL()
{
	return;
}

.xaml

    <Grid x:Name="LayoutRoot" Background="White">

        <StackPanel Orientation="Horizontal" VerticalAlignment="Top" Margin="24,24,0,0">
            <TextBlock Name="textBlock1" Text="add       函数结果:" Height="23" />
            <TextBox Name="textBox1" Width="120" Height="23" />
        </StackPanel>

        <StackPanel Orientation="Horizontal" VerticalAlignment="Top" Margin="24,64,0,0">
            <TextBlock Name="textBlock2" Text="fnMyDLL函数结果:" Height="23"/>
            <TextBox Name="textBox2" VerticalAlignment="Top" Width="120" Height="23"/>
        </StackPanel>
       

        <Button Content="Button" Height="32" Margin="120,101,202,0" Name="button1" VerticalAlignment="Top" Width="78" Click="button1_Click" />
    </Grid>

.cs

public partial class MainPage : UserControl
    {
        [DllImportAttribute("user32.dll", EntryPoint = "MessageBoxW")]
        public static extern int MessageBoxW(int hWnd, [In][MarshalAs(UnmanagedType.LPWStr)] string lpText, [In][MarshalAs(UnmanagedType.LPWStr)] string lpCaption, int uType);

        [DllImport("MyDll.dll", EntryPoint = "add", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall, SetLastError = false)]
        public static extern int add();

        [DllImport("MyDll.dll", EntryPoint = "fnMyDLL", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Winapi, SetLastError = false)]
        public static extern float fnMyDLL(float x,float y);

        [DllImport("MyDLL.dll", EntryPoint = "add2", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Winapi, SetLastError = false)]
        public static extern int add2(ref HHFC_SET stru);

        [DllImport("MYDLL.dll", EntryPoint = "add3", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Winapi, SetLastError = false)]
        public static extern IntPtr add3();

        //EntryPoint: 指定要调用的 DLL 入口点。默认入口点名称是托管方法的名称 。 
        //CharSet: 控制名称重整和封送 String 参数的方式 (默认是UNICODE) 
        //CallingConvention指示入口点的函数调用约定(默认WINAPI) 
        //SetLastError 指示被调用方在从属性化方法返回之前是否调用 SetLastError Win32 API 函数 (C#中默认false )

        public MainPage()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            this.textBox1.Text = add().ToString();
            this.textBox2.Text = fnMyDLL(12,2).ToString();
            MessageBoxW(0, "提交成功", "温馨提示", 0);

            HHFC_SET stru = new HHFC_SET(); 
            stru.Uid = ""; 
            Console.WriteLine(stru.Uid); 
            int a = add2(ref stru); 
            Console.WriteLine(stru.Uid);

            IntPtr d = add3();
            float[] bytes2 = new float[Marshal.SizeOf(d)];
            Marshal.Copy(d, bytes2, 0, 4);


        }
    }

    [StructLayout(LayoutKind.Sequential)]
     public struct HHFC_SET
     {
         [MarshalAs(UnmanagedType.LPStr)]
         public String Uid;

         [MarshalAs(UnmanagedType.I4)]
         public int code;
     }

-----------------------------------------------------------------------------------------　　

.net调用C DLL

编写C程序如下：

#include "stdio.h"
__declspec(dllexport) void MyFun() { printf("this is a dll\n"); }

保存，取名为My.C

运行 VS 命令提示，Cl /c 路径/My.c

运行以后会生成 My.Obj，默认在vs安装文件夹的VC目录下

再运行 link/dll 路径/My.obj

在同一个目录会生成My.dll

在C#中调用：

将dll复制到bin目录，编写如下C#代码：

static void Main(string[] args)
{
MyFun();
}
[DllImport("My.dll")]
public extern static void MyFun();

-----------------------------------------------------------------------------------------　　

C#传委托给C的函数指针调用问题

C代码如下：

#include "stdio.h"
__declspec(dllexport) int Call(int (*qq)(int num),char * str)
{    
    printf(str);
    return qq(123);
}

多次验证发现在C#中传委托给C中的函数指针，如果委托不带参数则都能成功运行，但是委托一带参数不管是int参数还是string参数或者其他参数，都会报“ 尝试读取或写入受保护的内存。这通常指示其他内存已损坏”的错误，找了一天才找到解决方法，既在C#的委托声明上加[UnmanagedFunctionPointer(CallingConvention.Cdecl)]，正确调用如下：

 [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    public delegate int MyDeg(int num);
    class Program
    {
        static void Main(string[] args)
        {
            
            try
            {
                MyDeg myd = new MyDeg(FF);
                Console.WriteLine(Call(myd, "helloworld"));
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }

        }

        static int FF(int num)
        {
            Console.WriteLine(num);
            return num + 1;

        }

        [DllImport("my.dll", EntryPoint = "Call")]
        public extern static int Call(MyDeg mm ,string  str);
    }