Machine vision Series 2: vs DLL debugging

List of articles

Chapter one ：Visual Studio 2019 Dynamic link library DLL establish

Chapter two ：VS Dynamic link library DLL debugging

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Catalog

List of articles

Preface

Two 、 debugging DLL

1. Implicit call / Static call

1.1 File settings

1.2 To write C++ Debugging code

1.3 Change solution launch project

2. Explicit call

summary

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Preface

The last chapter is finished DLL The establishment of the , but DLL Only when called will it execute , This chapter records the use of C++ Item mode DLL The process of .

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One 、 newly build C++ project ？

In the same solution explorer , Right-click the solution —— add to —— New projects —— Add empty items

Two 、 debugging DLL

1. Implicit call / Static call

1.1 File settings

        hold DLL In the catalog .h Document and DLL Compile generated .lib File copy to C++ Project .cpp In the same directory

        

1.2 To write C++ Debugging code

        Where changes need to be made         

•         Change the two introductions in the header

                #include "dedip.h"

                 #pragma comment(lib, "dedip.lib")

•         Change external functions

                extern "C" __declspec(dllimport) bool eyeCloseCheck(BYTE*, int, int, int);

•         Change the function when calling

                cout << eyeCloseCheck(buffer, width, height, VailImgNum) << endl;

#include <stdio.h>
#include <opencv2/opencv.hpp>
#include <windows.h>
#include "dedip.h" 
#pragma comment(lib, "dedip.lib")
#include <opencv2/dnn/dnn.hpp>

using namespace cv;
using namespace std;

extern "C" __declspec(dllimport) bool eyeCloseCheck(BYTE*, int, int, int);

int main()
{
	Mat srcImg = imread("D:/ImgEnglish/redeye_img_test/1.bmp");
	int width = srcImg.cols;
	int height = srcImg.rows;

	//imshow("1", srcImg);
	//waitKey(0);

	//DLL debugging 
	int length = (int)(srcImg.total() * srcImg.elemSize());
	BYTE* buffer = new BYTE[length];
	memcpy(buffer, srcImg.data, length * sizeof(BYTE));
	int VailImgNum = 1;
	cout << eyeCloseCheck(buffer, width, height, VailImgNum) << endl;

	//imshow("2", OutImg);
	//waitKey(0);
}

1.3 Change solution launch project

        Right-click on the project —— Set as startup project

2. Explicit call

The display call is troublesome , Post a sample code , Own reference

The general idea is not to copy .h and .lib, One solution debug or release when , The generated files are in a folder .

#include <stdio.h>
#include <windows.h>

void main(void)
{
    typedef int(*MyFunDll)(void);

    HMODULE hdll = LoadLibrary("Win32Project1.dll");   // load dll file 
    if (hdll != NULL)
    {
        MyFunDll MyFunCall = (MyFunDll)GetProcAddress(hdll, "main");// Retrieve the address of the function to call 
        if (MyFunCall != NULL)
        {
            MyFunCall();							    // Call the interface function 
        }
    }

    FreeLibrary(hdll);								    // Release dll file 
}

adopt LoadLibrary() Function pair dll File to load ; Re pass GetProcAddress() Function to get the address of the interface function to be called （ In the example above MyFunCall To store the address of the interface function ）; Then call the interface function (MyFunCall); Finally through FreeLibrary() Function pair dll File release . therefore , If it is used to load other dll file , The places that need to be changed in the above example are ：

Loaded dll file name ( In the previous example "Win32Project1.dll");
Interface function name to retrieve ( In the previous example "main");
The format of the interface function called ( In the example above MyFunCall(), The parameter information of the function should be maintained with the interface function to be called "main" Agreement ).

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summary

summary ： Implicit call is more convenient to write code , But you need to copy the file again when there are changes .
quote ：https://blog.csdn.net/weixin_44536482/article/details/91519413

           C++ To write Dynamic link library dll and call dll- Experience in baidu (baidu.com)