用Windows窗体在Visual Studio C++中绘制线程图

Question

我正在使用Visual Studio C++ 2010编写一个应用程序来执行数据采集并实时绘制这些信息。我正在使用Windows窗体来创建GUI。我正在从串行端口和DAQ卡（我有图书馆和使用过的）中获取数据，并且想要实时绘制它们。我之前在Python中已经完成了这个工作，但是我必须使用另一个用C++完成的库，所以这次我不能使用Python。

我的想法是让串口和daq卡在单独的线程中获取数据，然后将更新信息发送到主程序以使用新数据更新绘图。我终于得到了线程正常工作，但我似乎无法弄清楚的是如何更新线程内部的情节，因为我有导致崩溃。

这是我到目前为止有：

#pragma once 
#include <math.h> 

namespace PlotUpdate { 

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; 

/// <summary> 
/// Summary for Form1 
/// </summary> 
public ref class Form1 : public System::Windows::Forms::Form 
{ 
public: 
    Form1(void) 
    { 
     InitializeComponent(); 
     // 
     //TODO: Add the constructor code here 
     // 
     th1 = gcnew Thread(gcnew ThreadStart(this, &Form1::th1Method)); 
    } 

    delegate void UpdatePlot(); 
    UpdatePlot^ myDelegate; 

protected: 
    /// <summary> 
    /// Clean up any resources being used. 
    /// </summary> 
    ~Form1() 
    { 
     if (components) 
     { 
      delete components; 
     } 
    } 
private: System::Windows::Forms::Button^ button1; 
protected: 

private: 
    /// <summary> 
    /// Required designer variable. 
    /// </summary> 
    System::ComponentModel::Container ^components; 
private: System::Windows::Forms::DataVisualization::Charting::Chart^ chart1; 
     Thread ^th1; 

#pragma region Windows Form Designer generated code 
    /// <summary> 
    /// Required method for Designer support - do not modify 
    /// the contents of this method with the code editor. 
    /// </summary> 
    void InitializeComponent(void) 
    { 
     System::Windows::Forms::DataVisualization::Charting::ChartArea^ chartArea1 = (gcnew System::Windows::Forms::DataVisualization::Charting::ChartArea()); 
     System::Windows::Forms::DataVisualization::Charting::Series^ series1 = (gcnew System::Windows::Forms::DataVisualization::Charting::Series()); 
     this->button1 = (gcnew System::Windows::Forms::Button()); 
     this->chart1 = (gcnew System::Windows::Forms::DataVisualization::Charting::Chart()); 
     (cli::safe_cast<System::ComponentModel::ISupportInitialize^ >(this->chart1))->BeginInit(); 
     this->SuspendLayout(); 
     // 
     // button1 
     // 
     this->button1->Location = System::Drawing::Point(291, 369); 
     this->button1->Name = L"button1"; 
     this->button1->Size = System::Drawing::Size(75, 23); 
     this->button1->TabIndex = 0; 
     this->button1->Text = L"button1"; 
     this->button1->UseVisualStyleBackColor = true; 
     this->button1->Click += gcnew System::EventHandler(this, &Form1::button1_Click); 
     // 
     // chart1 
     // 
     chartArea1->Name = L"ChartArea1"; 
     this->chart1->ChartAreas->Add(chartArea1); 
     this->chart1->Location = System::Drawing::Point(32, 30); 
     this->chart1->Name = L"chart1"; 
     series1->ChartArea = L"ChartArea1"; 
     series1->ChartType = System::Windows::Forms::DataVisualization::Charting::SeriesChartType::Line; 
     series1->Name = L"Series1"; 
     series1->XValueMember = L"xvals"; 
     series1->YValueMembers = L"yvals"; 
     this->chart1->Series->Add(series1); 
     this->chart1->Size = System::Drawing::Size(669, 314); 
     this->chart1->TabIndex = 1; 
     this->chart1->Text = L"chart1"; 
     // 
     // Form1 
     // 
     this->AutoScaleDimensions = System::Drawing::SizeF(6, 13); 
     this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font; 
     this->ClientSize = System::Drawing::Size(778, 415); 
     this->Controls->Add(this->chart1); 
     this->Controls->Add(this->button1); 
     this->Name = L"Form1"; 
     this->Text = L"Form1"; 
     (cli::safe_cast<System::ComponentModel::ISupportInitialize^ >(this->chart1))->EndInit(); 
     this->ResumeLayout(false); 

    } 
#pragma endregion 
static double time = 0.0; 

private: System::Void th1Method() 
     { 
      for(int i=0;i<500;i++) 
      { 
       this->chart1->Series["Series1"]->Points->AddXY(time, sin(time)); 
       time += 0.1; 
       Thread::Sleep(1); 
      } 
     } 

private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e) { 
      th1->Start(); 
     } 
}; 
} 

的代码编译和运行，直到我开始线程，它崩溃。我知道，我无法从另一个进程更新GUI，所以我不知道我应该如何执行此操作。我已经尝试过（并且我没有示例代码对此表示歉意）来创建DataPoint对象的临时集合，然后使用TimerEvent更新这个图，但是我遇到了无法在静态方法中使用this-> notation的问题班上。

这种情况的任何提示/提示/建议？

Answer 1

除非我错了，否则您尝试从不是UI线程的线程中修改UI，这是一个错误。

如果是这种情况，您应该使用表单的BeginInvoke方法从UI线程内执行代码。

我不熟悉C++/CLI +的WinForms代码，所以我无法给你提供代码修正，但在C＃中，它会一直是这样的：

private void th1Method() 
    { 
     for(int i=0;i<500;i++) 
     { 
      this.BeginInvoke 
      ((Action)(
       () => 
       { 
        this.chart1.Series["Series1"].Points.AddXY(time, sin(time)); 
        time += 0.1; 
       } 
      )) ; 

      Thread.Sleep(1); 
     } 
    } 

注意的BeginInvoke呼叫，这里需要一个lambda函数（类型为Action，意思是没有参数，没有返回值）。这个lambda函数将在UI线程中排队，稍后在UI线程中执行。

有关BeginInvoke的更多信息，请参见：http://msdn.microsoft.com/en-us/library/0b1bf3y3.aspx