c#与c++交互的一些东西

最近做一个项目，对方公司只提供了一个c++的DLL,但没封住，c#无法DllImport.所以只能自己写c++来封住了。

对方的Dll只接收yuv420的图片格式，所以在c++里用opencv来转换。本来想C#来写，但总觉得麻烦。

【C#】代码

public void Do(Bitmap bp)

{　

Bitmap outIMG = new Bitmap(bp.Width,bp.Height);

System.Drawing.Imaging.BitmapData bmpData = bp.LockBits(new System.Drawing.Rectangle(0, 0, bp.Width, bp.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite,
bp.PixelFormat);

System.Drawing.Imaging.BitmapData bmpData1 = outIMG .LockBits(new System.Drawing.Rectangle(0, 0, outIMG .Width, outIMG .Height), System.Drawing.Imaging.ImageLockMode.ReadWrite,
outIMG .PixelFormat);
CFunction(bmpData.Scan0, bp.Width, bp.Height, 3, 0,bmpData1.Scan0);
img.UnlockBits(bmpData);

outIMG.UnlockBits(bmpData1 );

}

【C++】代码

extern "C" __declspec(dllexport) void WINAPI CFunction(unsigned char* img,int width,int height,int ch,int format,unsigned char* outImg)
{
　　Mat frame(Size(width, height), CV_8UC(ch), img);　

　　Mat dest;
　　cvtColor(frame, dest, format == 0 ? CV_BGR2YUV_I420 : CV_RGB2YUV_I420);

　　第三方Dll(dest);

　　Mat rgb;

　　cvtColor(dest, rgb, format == 0 ? CV_YUV2BGR_I420 : CV_YUV2RGB_I420);

　　memcpy((void*)outImg, (void*)dest.data, rgb.cols * rgb.rows * rgb.channels());
}

这基本实现了c++和c#直接图片的对接。但是这种做法会卡C#的程序，我试过backgroundworker,task，很多种方法，但是c#就是会卡住的。具体原因不太清楚，所以觉得这部分的处理在c++中用线程来做，

做完之后通知c#，因为我需要在第三方DLL来生成四个结果图片。所以定义了结构体。

【C#】

[StructLayout(LayoutKind.Sequential)]
public struct ImageResult
{
public IntPtr First;
public IntPtr Second;
public IntPtr Third;
public IntPtr Forth;
}

【C++】

struct ImgeResult
{
void * FirstIMG;
void* SecondIMG;
void* ThirdIMG;
void* FouthIMG;
};

接着要在c#做定义给C++回调的委托。

【c#】

public delegate void CSCallback(ImageResult ir);

public static CSCallback callback;

callback = CSCallbackFunction；

SetCallback(callback );

public static void CSCallbackFunction(ImageResult tick)
{
　　处理c++返回的数据
}

调用c++线程函数

public void Do(Bitmap bp)

{　

Bitmap outIMG = new Bitmap(bp.Width,bp.Height);

System.Drawing.Imaging.BitmapData bmpData = bp.LockBits(new System.Drawing.Rectangle(0, 0, bp.Width, bp.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite,
bp.PixelFormat);

DoImage(bmpData.Scan0, bp.Width, bp.Height, 3, 0,bmpData1.Scan0);
img.UnlockBits(bmpData);

outIMG.UnlockBits(bmpData1 );

}

【c++】

typedef void(__stdcall *CPPCallback)(ImgeResult ir);

CPPCallback myCallback;

extern "C" __declspec(dllexport) void WINAPI SetCallback(CPPCallback callback)
{
myCallback = callback;
}

void  OperateImage(unsigned char* img,int width,int height,int ch,int format)
{
Mat frame(Size(width, height), CV_8UC(ch), img);
Mat dest;
cvtColor(frame, dest, format == 0 ? CV_BGR2YUV_I420 : CV_RGB2YUV_I420);
Mat second;
cvtColor(frame, second, format == 0 ? CV_BGR2YUV_I420 : CV_RGB2YUV_I420);
Mat third;
cvtColor(frame, third, format == 0 ? CV_BGR2YUV_I420 : CV_RGB2YUV_I420);
Mat forth;
cvtColor(frame, forth, format == 0 ? CV_BGR2YUV_I420 : CV_RGB2YUV_I420);
Mat nextFirst;
Mat nextSecond;
Mat nextThird;
Mat nextTForth;
 //第三方库处理图片

cvtColor(dest, nextFirst, format == 0 ? CV_YUV2BGR_I420 : CV_YUV2RGB_I420);
cvtColor(second, nextSecond, format == 0 ? CV_YUV2BGR_I420 : CV_YUV2RGB_I420);
cvtColor(third, nextThird, format == 0 ? CV_YUV2BGR_I420 : CV_YUV2RGB_I420);
cvtColor(forth, nextTForth, format == 0 ? CV_YUV2BGR_I420 : CV_YUV2RGB_I420);
ReleaseBelleFaceEngine();
ir.FirstIMG = (void *)malloc(nextFirst.cols * nextFirst.rows * nextFirst.channels());
ir.SecondIMG = (void *)malloc(nextSecond.cols * nextSecond.rows * nextSecond.channels());
ir.ThirdIMG = (void *)malloc(nextThird.cols * nextThird.rows * nextThird.channels());
ir.FouthIMG = (void *)malloc(nextTForth.cols * nextTForth.rows * nextTForth.channels());
memcpy(ir.FirstIMG, (void*)nextFirst.data, nextFirst.cols * nextFirst.rows * nextFirst.channels());
memcpy(ir.SecondIMG, (void*)nextSecond.data, nextSecond.cols * nextSecond.rows * nextSecond.channels());
memcpy(ir.ThirdIMG, (void*)nextThird.data, nextThird.cols * nextThird.rows * nextThird.channels());
memcpy(ir.FouthIMG, (void*)nextTForth.data, nextTForth.cols * nextTForth.rows * nextTForth.channels());

myCallback(ir);
}

extern "C" __declspec(dllexport) void WINAPI DoImage(unsigned char* img,int width,int height,int ch,int format)
{
std::thread th1(OperateImage, img, width, height,ch,format);
th1.detach();
}

到此不会卡住c#程序。

由于本人第一次用c++，也是一边查，一边写的。

c++写的一些心得.

(1)使用opencv要注意链接库是debug还是release的。

(2)到纯净系统下要安装redist，我的目标机是64位，开发环境是2013，所以要装vs2013redist.

(3)最后要注意将 msvcp120.dll，msvcp120d.dll，msvcr120.dll，msvcr120d.dll，vccorlib120.dll，vccorlib120d.dll放到C:WindowsSysWOW64目录下，32位的目标机器则放到win32下面。

如果有更好的办法，请告诉小弟。