dll如何用

www.myexceptions.net 网友分享于：2013-03-06 浏览：29次

dll怎么用
请各位大虾帮帮忙，小弟以前都没有及出国dll,现在由于学习需要，遇到一个难题——如何将BMP文件转换为JPEG文件。网上查到说用IJL15.DLL 会比较方便。但是小弟不知道应该怎么用DLL文件，还请各位大虾指点。特别是IJL15.DLL的用法

------解决方案--------------------
可以用下列函数直接调用dll
LoadLibrary()
GetProcAddress()
FreeLibrary()

------解决方案--------------------

C/C++ code

/*TW04显示屏DLL*/
HINSTANCE LPRSEDLL,HDQUEDLL;
HINSTANCE TW04Dll;
bool  loadLPRDLL=false,loadHDDLL=false;
bool  LoadTW04=false;
LPRDEVICEINFO m_DevInfo[100]; //设备信息
extern "C"
{
     int (__stdcall *NetShut)(int LocalPort,char *DescIP,int index);
     int (__stdcall *NetSendPicData) (int LocalPort,char* DescIP,int CommandByte ,HDC GDC,int Width, int Height, int PColorSign, int SendMode );
     int (__stdcall * NetListSend)(int LocalPort,char *DescIP, Byte buff[256],int bufflen);
     int (__stdcall * NetSendPicOnce)(int  LocalPort,char * DescIP,HDC GDC,int Width, int Height, int PColorSign, int SendMode, int showmode, int showspeed, int showtime);
     int (__stdcall *NetCheckDateTime)(int LocalPort,char* DescIP,int checkValue);
     int (__stdcall *NetSetLightness)(int LocalPort,char* DescIP,int lightValue);
     int (__stdcall *NetIPSet)(int LocalPort,char *DescIP,int NewPort,char *NewIP);
     int (__stdcall *NetCardParamGet)(int LocalPort,char *DescIP, Byte  buff[256]);
     int (__stdcall *ClearMemory)();
     long (__stdcall *NetListSendType)(long LocalPort , char *DescIP , unsigned char* buff ,long arrlen,long bufflen);
     HDC (__stdcall *GDCCreate)(int Width,int Height);
     int (__stdcall *GDCFree)(HDC GDC);
     int (__stdcall *DrawRectString)(HDC GDC,char *UserData,char *FontName,int FontSize,int FontColor,int Left,int Top,int Width,int Height);
   
}
//-----------
bool __fastcall  TMainFrm::LoadTW04DLL()
{
    try
    {
        TW04Dll=::LoadLibrary(".//EV_SocketUdpDll.DLL");
        if(TW04Dll)
        {
        NetShut=(int (__stdcall *)(int LocalPort,char *DescIP,int index))GetProcAddress(TW04Dll,"NetShut");
        NetSendPicData=(int (__stdcall *) (int LocalPort,char* DescIP,int CommandByte ,HDC GDC,int Width, int Height, int PColorSign, int SendMode ))GetProcAddress(TW04Dll,"NetSendPicData");
        NetListSend=(int (__stdcall * )(int LocalPort,char *DescIP, Byte buff[256],int bufflen))GetProcAddress(TW04Dll,"NetListSend");
        NetSendPicOnce=(int (__stdcall * )(int  LocalPort,char * DescIP,HDC GDC,int Width, int Height, int PColorSign, int SendMode, int showmode, int showspeed, int showtime))GetProcAddress(TW04Dll,"NetSendPicOnce");
        NetCheckDateTime=(int (__stdcall *)(int LocalPort,char* DescIP,int checkValue))GetProcAddress(TW04Dll,"NetCheckDateTime");
        NetSetLightness=(int (__stdcall *)(int LocalPort,char* DescIP,int lightValue))GetProcAddress(TW04Dll,"NetSetLightness");
        NetIPSet=(int (__stdcall *)(int LocalPort,char *DescIP,int NewPort,char *NewIP))GetProcAddress(TW04Dll,"NetIPSet");
        NetCardParamGet=(int (__stdcall *)(int LocalPort,char *DescIP, Byte  buff[256]))GetProcAddress(TW04Dll,"NetCardParamGet");
        ClearMemory=(int (__stdcall *)())GetProcAddress(TW04Dll,"ClearMemory");
        NetListSendType=(long (__stdcall *)(long LocalPort , char *DescIP , unsigned char* buff ,long arrlen,long bufflen))GetProcAddress(TW04Dll,"NetListSendType");
        GDCCreate=(HDC (__stdcall *)(int Width,int Height))(TW04Dll,"GDCCreate");
        GDCFree=(int (__stdcall *)(HDC GDC))(TW04Dll,"GDCFree");
        DrawRectString=(int (__stdcall *)(HDC GDC,char *UserData,char *FontName,int FontSize,int FontColor,int Left,int Top,int Width,int Height))(TW04Dll,"DrawRectString");//DrawRectString
        return true;
        }
        return false;
    }
    catch(...)
    {
        return false;
    }
    return true;
}
//--------
void __fastcall  TMainFrm::InitTW04()
{
    try
    {
        LoadTW04=LoadTW04DLL();
        if(LoadTW04)
        {
         int ret=NetShut(LEDIpPort,LedIp.c_str(),1); //功能：开关屏控制。       参数：index：0：关屏，1，开屏
          // PICHDC=GDCCreate(144,56);
         if(ret==0)
            InfoLedEdt->Text="开屏成功！";
         else
            InfoLedEdt->Text="开屏失败！";
        }

    }
    catch(...)
    {
        //
    }
}
void __fastcall  TMainFrm::UnInitTW04()
{
    try
    {

        ClearMemory();
    }
    catch(...)
    {
        //
    }
}