c#與c++交互的一些東西

最近做一個項目，對方公司只提供了一個c++的DLL,但沒封住，c#無法DllImport.所以只能自己寫c++來封住了。

對方的Dll只接收yuv420的圖片格式，所以在c++里用opencv來轉換。本來想C#來寫，但總覺得麻煩。

【C#】代碼

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++】代碼

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());}

這基本實現了c++和c#直接圖片的對接。但是這種做法會卡C#的程序，我試過backgroundworker,task，很多種方法，但是c#就是會卡住的。具體原因不太清楚，所以覺得這部分的處理在c++中用線程來做，

做完之后通知c#，因為我需要在第三方DLL來生成四個結果圖片。所以定義了結構體。

【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;};

接著要在c#做定義給C++回調的委托。

【c#】

public delegate void CSCallback(ImageResult ir);

public static CSCallback callback;

callback =CSCallbackFunction；

SetCallback(callback);

public static void CSCallbackFunction(ImageResult tick) {　　處理c++返回的數據 }

調用c++線程函數

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;//第三方庫處理圖片

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();}

到此不會卡住c#程序。

由于本人第一次用c++，也是一邊查，一邊寫的。

c++寫的一些心得.

(1)使用opencv要注意鏈接庫是debug還是release的。

(2)到純凈系統下要安裝redist，我的目標機是64位，開發環境是2013，所以要裝vs2013redist.

(3)最后要注意將msvcp120.dll，msvcp120d.dll，msvcr120.dll，msvcr120d.dll，vccorlib120.dll，vccorlib120d.dll放到C:/Windows/SysWOW64目錄下，32位的目標機器則放到win32下面。

如果有更好的辦法，請告訴小弟。