以 Windows 形式通过线程传递参数 C++/CLI

Question

我真的很难做一些可能很简单的事情。基本上，我试图编写一个 Windows Form C++/CLI 程序来从串行端口读取 arduino 流，并且至少在最初，将每个值添加到列表框。 Arduino 代码没问题，它每 2 秒给我一个字符串，当我调试带断点的 Windows 表单时，我可以看到字符串变量 "Message" 的值很好。但是我运行遇到了这个 "thread" 问题，我知道我必须创建一个不同的线程来更新列表框...好的。现在，我找不到办法将 "message" 字符串传递给函数 "UpdateList"。我见过很多关于传递对象、class 等的事情……但无法设法将其放入我的代码中。有人可以帮忙吗？

完整代码如下：

#pragma once

namespace ArduComm {
using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;
using namespace System::Threading;

public ref class MyForm : public System::Windows::Forms::Form
{
public:
    MyForm(void)
    {
        InitializeComponent();
    }

protected:
    ~MyForm()
    {
        if (components)
        {
            delete components;
        }
    }

private: System::IO::Ports::SerialPort^  Arduino;
private: System::Windows::Forms::Button^  StartButton;
private: System::Windows::Forms::Button^  StopButton;
private: System::Windows::Forms::ListBox^  ListBox;
private: System::ComponentModel::IContainer^  components;

#pragma region Windows Form Designer generated code

    void InitializeComponent(void)
    {
        this->components = (gcnew System::ComponentModel::Container());
        this->Arduino = (gcnew System::IO::Ports::SerialPort(this->components));
        this->StartButton = (gcnew System::Windows::Forms::Button());
        this->StopButton = (gcnew System::Windows::Forms::Button());
        this->ListBox = (gcnew System::Windows::Forms::ListBox());
        this->SuspendLayout();
        // 
        // Arduino
        // 
        this->Arduino->PortName = L"COM3";
        this->Arduino->DataReceived += gcnew System::IO::Ports::SerialDataReceivedEventHandler(this, &MyForm::ArduinoDataReceived);
        // 
        // StartButton
        // 
        this->StartButton->Location = System::Drawing::Point(12, 12);
        this->StartButton->Name = L"StartButton";
        this->StartButton->Size = System::Drawing::Size(75, 23);
        this->StartButton->TabIndex = 3;
        this->StartButton->Text = L"Start";
        this->StartButton->UseVisualStyleBackColor = true;
        this->StartButton->Click += gcnew System::EventHandler(this, &MyForm::StartReadingSerial);
        // 
        // StopButton
        // 
        this->StopButton->Location = System::Drawing::Point(12, 41);
        this->StopButton->Name = L"StopButton";
        this->StopButton->Size = System::Drawing::Size(75, 23);
        this->StopButton->TabIndex = 4;
        this->StopButton->Text = L"Stop";
        this->StopButton->UseVisualStyleBackColor = true;
        this->StopButton->Click += gcnew System::EventHandler(this, &MyForm::StopReadingSerial);
        // 
        // ListBox
        // 
        this->ListBox->FormattingEnabled = true;
        this->ListBox->Location = System::Drawing::Point(117, 12);
        this->ListBox->Name = L"ListBox";
        this->ListBox->Size = System::Drawing::Size(273, 277);
        this->ListBox->TabIndex = 5;
        // 
        // MyForm
        // 
        this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
        this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
        this->ClientSize = System::Drawing::Size(409, 303);
        this->Controls->Add(this->ListBox);
        this->Controls->Add(this->StopButton);
        this->Controls->Add(this->StartButton);
        this->Name = L"MyForm";
        this->Text = L"ArduComm";
        this->ResumeLayout(false);

    }
#pragma endregion

/* My functions */


private: System::Void UpdateList() {
    ListBox->Items->Add("xxx");
}

private: System::Void InvokeThread()    {
    this->Invoke(gcnew MethodInvoker(this, &MyForm::UpdateList));
}

private: System::Void ArduinoDataReceived(System::Object^ sender, System::IO::Ports::SerialDataReceivedEventArgs^ e) {
    String^ Message;
    Message = Arduino -> ReadLine();
    Thread^ oThread = gcnew Thread(gcnew ThreadStart(this, &MyForm::InvokeThread));
    oThread->Start();
}

private: System::Void StartReadingSerial(System::Object^  sender, System::EventArgs^  e) {
    this->Arduino->Open();
}

private: System::Void StopReadingSerial(System::Object^  sender, System::EventArgs^  e) {
    this->Arduino->Close();
}

};
}

非常感谢任何帮助...

谢谢。

Answer 1

不要启动一个线程。 SerialPort::DataReceived 事件处理程序已经在工作线程上运行，添加另一个线程无济于事。您需要编写一个可以从事件处理程序调用的方法，它应该如下所示：

    void UpdateList(String^ message) {
        ListBox->Items->Add(message);
    }

现在您需要声明一个与此方法兼容的委托，这是您忽略的关键步骤，也是您卡住的地方：

    delegate void UpdateListDelegate(String^ Message);

或者您可以使用内置的 Action<String^> 通用类型。现在您可以从事件处理程序中调用它。使用 BeginInvoke() 非常重要，使用 Invoke() 在关闭串口时死锁的几率非常高：

    System::Void Arduino_DataReceived(System::Object^  sender, System::IO::Ports::SerialDataReceivedEventArgs^  e) {
        String^ message = Arduino->ReadLine();
        this->BeginInvoke(gcnew UpdateListDelegate(this, &MyForm::UpdateList), message);
    }

以 Windows 形式通过线程传递参数 C++/CLI

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