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:\Windows\SysWOW64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。