how to pass data between threads in c++ winform? - c++

Question

in this program i want to capture frames of my webcam with a thread and then send the frames to another frame named MainThread and the show the webcam in a picturebox
so i want to pass the captured frame(_frame1) from capture_frame_1_Thread to MainThread.
any ideas how to do it?
Here is the code
VideoCapture cap1(0);
Mat _frame1;
void capture_frame_1() {
for (;;) {
cap1 >> _frame1;
if (waitKey(1) == 27) {
break;
}
}
}
void invoke_capture_frame_1() {
Invoke(gcnew System::Action(this, &MyForm::capture_frame_1));
}
void start_picture_Boxes() {
for (;;) {
mat2picture bimapconvert;
this->pictureBox1->Image = bimapconvert.Mat2Bimap(_frame1);
pictureBox1->Refresh();
if (waitKey(1) == 27) {
break;
}
}
}
void picture_Boxes() {
Invoke(gcnew System::Action(this, &MyForm::start_picture_Boxes));
}
private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e)
{
ThreadStart^ ThreadMethod1 = gcnew ThreadStart(this, &MyForm::invoke_capture_frame_1);
Thread^ capture_frame_1_Thread = gcnew Thread(ThreadMethod1);
ThreadStart^ ThreadMethod3 = gcnew ThreadStart(this, &MyForm::picture_Boxes);
Thread^ MainThread = gcnew Thread(ThreadMethod3);
capture_frame_1_Thread->Start();
MainThread->Start();
}
};
}

Answer 1

You could create a class named webcam, and have those methods. Then you can have some method that starts threads webcam.startThreads();.
Then you can create private variable called frame, so you can share between threads, but don't forget to use lock to eliminate race condition.
info about lock https://www.cplusplus.com/reference/mutex/mutex/lock/
I hope it helps, I used this structure when making network filter.