MFC应用程序中的fork Dialog及控制子窗口问题

Question

我正在用 C++ 在 Visual Studio 2017 上编写 MFC 应用程序。该应用程序是用于与 USB 设备通信的用户界面。在我的应用程序中有Start 按钮。当用户按下Start 按钮时，USB 设备开始流式传输数据，即它开始发送数据包，直到我告诉它停止（我知道每个数据包的最大大小，但我不知道我有多少数据包会得到）。我正在将流数据写入 .CSV 文件。

为此，我使用了循环板（我仍然没有原始板）。 我正在尝试模拟一个真实的场景，所以我编写了一个发送和读取数据的 while 循环。

在我的应用程序中，我还添加了一个Stop 按钮，它应该通过退出这个while循环来停止数据传输。

由于我无法从主对话框中执行此操作，因此我想创建一个子对话框来执行通信（它将执行从循环板发送和接收包的 while 循环）并且我将控制它我的主对话框中的子窗口。

为此，我根据 Barrnet Chou 的建议创建了另一个类，如下所示：

header 文件：

#pragma once

#include <string>
#include "libusb.h"

class ChildDlg : public CDialog
{
public:

    DECLARE_MESSAGE_MAP()
    afx_msg void OnButton1Clicked();
    afx_msg void OnButton2Clicked();
};

cpp 文件：

#pragma once

#include "stdafx.h"
#include "ChildDlg.h"


#ifdef _DEBUG
#define new DEBUG_NEW
#endif

// constants definition for packet transfers
constexpr auto VID = 0x04B4;
constexpr auto PID = 0x00F0;
constexpr auto OUT_ENDPOINT_ID = 1;
constexpr auto IN_ENDPOINT_ID = 1;
constexpr auto MAX_PACKET_SIZE = 512;
constexpr int INIT_PACKET_SIZE = 4;

bool flag;

struct libusb_device_descriptor DeviceDescriptor;

libusb_context* context = NULL; //a libusb session
libusb_device_handle* DeviceHandle = NULL; //a device handle


BEGIN_MESSAGE_MAP(ChildDlg, CDialog)
    ON_BN_CLICKED(IDC_BUTTON1, &ChildDlg::OnButton1Clicked)
    ON_BN_CLICKED(IDC_BUTTON2, &ChildDlg::OnButton2Clicked)
END_MESSAGE_MAP()

void startCommunication() {
    /* Prepare device for communication */
    int RetVal = libusb_init(&context); //initialize a library session

    if (RetVal < 0) {
        // MessageBox(hwnd, "Error in libusb_init", "Error:", MB_OK);
        return;
    }

    else {
        libusb_set_debug(context, 3); //set verbosity level to 3, as suggested in the documentation

        DeviceHandle = libusb_open_device_with_vid_pid(context, VID, PID); //these are vendorID and productID for Cypress FX3 specific device
    }

    if (DeviceHandle == NULL) {
        // MessageBox(hwnd, "Cannot open device", "Notice:", MB_OK);
        return;
    }

    if (libusb_kernel_driver_active(DeviceHandle, 0) == 1) { //find out if kernel driver is attached
        //detach it
        if (libusb_detach_kernel_driver(DeviceHandle, 0) != 0) {
            // MessageBox(hwnd, "Failed To Detach Kernel Driver!", "Error:", MB_OK);
            return;
        }
    }

    RetVal = libusb_claim_interface(DeviceHandle, 0); //claim interface 0 (the first) of device (desired device FX3 has only 1)

    if (RetVal < 0) {
        // MessageBox(hwnd, "Cannot Claim Interface", "Error:", MB_OK);
        return;
    }
}

void endCommunication() {

    libusb_close(DeviceHandle); //close the device we opened
    libusb_exit(context); //needs to be called at the end 
}


void ChildDlg::OnButton1Clicked() {
    // Insert Start button handler here

    flag = true;

    startCommunication();

    unsigned char* DataOut = new unsigned char[INIT_PACKET_SIZE]; //data to write
    unsigned char* DataIn = new unsigned char[MAX_PACKET_SIZE]; //data to read
    int BytesWritten; //used to find out how many bytes were written
    int BytesRead; //used to find out how many bytes were read

    DataOut[0] = 'a'; DataOut[1] = 'b'; DataOut[2] = 'c'; DataOut[3] = 'd'; //some dummy values

    int RetVal = libusb_bulk_transfer(DeviceHandle, (OUT_ENDPOINT_ID | LIBUSB_ENDPOINT_OUT), DataOut, sizeof(DataOut), &BytesWritten, 0);

    if (RetVal == 0 && BytesWritten == sizeof(DataOut)) //we wrote the 4 bytes successfully
        MessageBox("Writing Successful!", "Notice:");
    else
        MessageBox("Write Error", "Notice:");
    int counter = 0;

    while ((libusb_bulk_transfer(DeviceHandle, (IN_ENDPOINT_ID | LIBUSB_ENDPOINT_IN), DataIn, sizeof(DataIn), &BytesRead, 200) == 0) && flag == true) {
        std::string cleanData = std::to_string(DataIn[0]) + std::to_string(DataIn[1]) + std::to_string(DataIn[2]) + std::to_string(DataIn[3]);
        MessageBox(cleanData.c_str(), "DATA IN ");
        int RetVal = libusb_bulk_transfer(DeviceHandle, (OUT_ENDPOINT_ID | LIBUSB_ENDPOINT_OUT), DataOut, sizeof(DataOut), &BytesWritten, 0); //the out endpoint of current device is 1
        if (RetVal != 0 || BytesWritten != sizeof(DataOut)) MessageBox("Write Error", "Error:");
    }

    while (libusb_bulk_transfer(DeviceHandle, (IN_ENDPOINT_ID | LIBUSB_ENDPOINT_IN), DataIn, sizeof(DataIn), &BytesRead, 200)) {
        MessageBox("Garbage", "Notice:");
    }


    delete[] DataOut; //delete the allocated memory for data

    delete[] DataIn; //delete the allocated memory for data

    endCommunication();
}

void ChildDlg::OnButton2Clicked() {
    flag == false;
}

当在主对话框中按下Start 按钮时，我向子对话框发送消息如下：

/* Start Handler */
void CEditableListControlDlg::OnBnClickedButton1()
{
    // TODO: Add your control notification handler code here

    dlg->SendDlgItemMessageA(IDC_BUTTON1, BM_CLICK);

    return;
}

当在主对话框中按下Stop 按钮时，我会向子对话框发送一条消息，如下所示：

/* Stop Handler */
void CEditableListControlDlg::OnBnClickedButton2()
{
    // TODO: Add your control notification handler code here

    dlg->SendDlgItemMessageA(IDC_BUTTON2, BM_CLICK);
}

我有两个问题，第一个是我不知道如何将消息从子对话框发送回主对话框。

第二个问题是我得到如下编译错误：

Severity    Code    Description Project File    Line    Suppression State
Error   C2065   'IDC_BUTTON1': undeclared identifier    

Severity    Code    Description Project File    Line    Suppression State
Error   C2065   'IDC_BUTTON2': undeclared identifier    

但我不知道如何声明这些按钮？在我的主对话框中，我通过将它们添加到 Resource view 并单击它们两次来创建这些按钮（这会自动创建足够的处理程序）

有没有办法将Resource view 添加到子对话框中？如果没有我想如何创建这些标识符IDC_BUTTON1 和ICD_BUTTON2？

谢谢。

Answer 1

如果你想点击按钮并弹出窗口，我建议你参考下面的例子。

1. 创建一个新对话框并添加一个新类（如“Test”）

2. 添加以下代码

#include "Test.h"
void CMFCApplication7Dlg::OnBnClickedButton1()
{
  // TODO: Add your control notification handler code here
  Test *pDlg = new Test;
  pDlg->Create(IDD_DIALOG1, this); //IDD_DIALOG1
  pDlg->ShowWindow(SW_SHOW);
  
}

如果control的意思是你想通过父窗口的控件来操作子窗口中的控件，你可以通过包含子窗口头文件看到子窗口的所有控件。例如，如果子窗口是Test.h，则将#include Test.h添加到父窗口。