从非gui工作线程错误调用gui线程 [英] Calling gui thread from non-gui worker thread error

问题描述

你好CP成员，

是的，我知道不能从非GUI线程使用GUI的东西。这就是为什么我试图在工作线程（非GUI）中进行处理而不是回到GUI线程（主线程）来显示图形。但得到以下错误。

 QObject：无法为的父级创建子 -keyword>   另一个主题。 
（父  QCustomPlot（0x15b9a988），parent '  s线程是QThread（0x14547f90），当前线程是QThread（0x15ba56c8） 

whar我在我的代码中做的如下..

从主线程转到工作线程（NON-GUI）。工作线程处理数据并将其写入txt文件。完成处理后我试图杀死工作线程。
$ AnalysisworkerThread.cpp中的b $ b

 AnalysisWorkerThread :: BusLoadAvg（）; 
 GenSetPayloadAna gSetPayloadAnalysis; 
 gSetPayloadAnalysis.PayloadAnalysisDisplay（）; 
 / / emit AnalysisThreadFinished（）; 
 emit OnFinishAnalysis（）; 

SIGNAL OnFinishAnalysis（）连接到SLOT AfterFinishAnalysis（）

 connect（ this ，SIGNAL（OnFinishAnalysis（）），此，SLOT（AfterF inishAnalysis（）））; 

  void  AnalysisWorkerThread :: AfterFinishAnalysis（）
 {
 
 mwobj.DisplayGraph（）;  //   mwobj是MainThread的对象 
  / /   DisplayWraph是MainWindow.cpp中的一个函数 
} 

在mainWindow中。 cpp DisplayGraph（）只是试图上传样本图

  void  MainWindow :: DisplayGraph（）
 {
 qDebug（）<<  返回主线; 
 QVector< double> x（ 101 ），y（ 101 ）;  //  初始化条目0..100  
  for （ int  i =  0 ; i< 101; ++ i）
 {
x [i] = i / 50.  0   -   1 ;  //   x从-1变为1  
y [i] = x [i] * X [I];  //  让我们绘制二次函数 
} 
 
 ui- > customPlot-> addGraph（）; 
 ui-> customPlot-> graph（ 0 ） - > setData（x，y）; 
 ui-> customPlot-> xAxis-> setLabel（  x） ; 
 ui-> customPlot-> yAxis-> setLabel（  y） ; 
 ui-> customPlot-> xAxis-> setRange（-1， 1 ）; 
 ui-> customPlot-> yAxis-> setRange（ 0 ， 1 ） ; 
 ui-> customPlot-> replot（）; 
 
} 

将会是好，如果有人能帮助我，我做错了.....

谢谢



我尝试过的：



我正在尝试，因为我在上面添加时尝试杀死线程，因为它完成了它将导致应用程序崩溃
$ b $ a in anlysisworkerthread.cpp

connect（this，SIGNAL（finished（）），this，SLOT（deleteLater（）））;

解决方案

< blockquote>您可以使用我在回答您的问题时建议的事件更新/更改QListWidget项目值 [ ^ ]：



在MainWindow.cpp和AnalysisWorkerThread.cpp包含的头文件中（值应该是应用程序范围唯一的）：

 #d efine DISPLAY_GRAPH_EV（QEvent :: User + 1）

处理MainWindow.cpp中的自定义事件：

 void MainWindow :: customEvent（QEvent * event）
 {
 if（static_cast< int>（event-> type（））== DISPLAY_GRAPH_EV）
 {
 DisplayGraph（）; 
} 
} 

工作线程结束后发布事件（可能不再需要信号）所以事件也可以发布而不是发出信号）：

 void AnalysisWorkerThread :: AfterFinishAnalysis（）
 {
 QCoreApplication :: postEvent（pMainWindow） ，新的QEvent（（QEvent :: Type）DISPLAY_GRAPH_EV））; 
} 

Hello CP members,
Yes, I know that one cannot use GUI things from non-GUI threads. thats why i am trying to "do process" in worker thread(Non-GUI) than coming back to GUI thread(main thread) to display Graph. but getting following error.

QObject: Cannot create children for a parent that is in a different thread.
(Parent is QCustomPlot(0x15b9a988), parent's thread is QThread(0x14547f90), current thread is QThread(0x15ba56c8)

whar i am doing in my code is as following..
from Main thread going to worker thread(NON-GUI). Worked thread is processing data and writing it into a txt FILE. after finishing the processing I am trying to kill the worker thread.
in AnalysisworkerThread.cpp

AnalysisWorkerThread::BusLoadAvg();
    GenSetPayloadAna gSetPayloadAnalysis;
    gSetPayloadAnalysis.PayloadAnalysisDisplay();  
    //emit AnalysisThreadFinished();
    emit OnFinishAnalysis();

SIGNAL OnFinishAnalysis() is connected to SLOT AfterFinishAnalysis()

connect(this, SIGNAL(OnFinishAnalysis()),this,SLOT(AfterFinishAnalysis()));

void AnalysisWorkerThread::AfterFinishAnalysis()
{

   mwobj.DisplayGraph();  //mwobj is object of MainThread
   //DisplayGraph is a function in MainWindow.cpp
}

in mainWindow.cpp DisplayGraph() simply trying to upload a Sample graph

void MainWindow::DisplayGraph()
{
    qDebug()<<"Back to Main Thread";
    QVector<double> x(101), y(101); // initialize with entries 0..100
    for (int i=0; i<101; ++i)
    {
      x[i] = i/50.0 - 1; // x goes from -1 to 1
      y[i] = x[i]*x[i]; // let's plot a quadratic function
    }
    
    ui->customPlot->addGraph();
    ui->customPlot->graph(0)->setData(x, y);
    ui->customPlot->xAxis->setLabel("x");
    ui->customPlot->yAxis->setLabel("y");  
    ui->customPlot->xAxis->setRange(-1, 1);
    ui->customPlot->yAxis->setRange(0, 1);
    ui->customPlot->replot();

}

WOULD BE NICE IF SOMEONE CAN help me where i am doing wrong .....
Thanks

What I have tried:

I am trying as i added above when i try to Kill the thread as it finished than it is going to crash the Application
in Anlysisworkerthread.cpp
connect(this, SIGNAL(finished()), this, SLOT(deleteLater()));

解决方案

You can use an event as already suggested in my answer to your question update/change QListWidget item value[^]:

In a header file included by MainWindow.cpp and AnalysisWorkerThread.cpp (value should be application wide unique):

# define DISPLAY_GRAPH_EV (QEvent::User + 1)

Handle custom event in MainWindow.cpp:

void MainWindow::customEvent(QEvent *event)
{
    if (static_cast<int>(event->type()) == DISPLAY_GRAPH_EV)
    {
        DisplayGraph();
    }
}

Post the event when the worker thread has finished (the signal might be no longer necessary so the event can be also posted instead of emitting the signal):

void AnalysisWorkerThread::AfterFinishAnalysis()
{
    QCoreApplication::postEvent(pMainWindow, new QEvent((QEvent::Type)DISPLAY_GRAPH_EV)); 
}

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