C++ open file Dialog

//insert picture to picturebox
DrawCVImage(pictureBox1, img);
void DrawCVImage(System::Windows::Forms::Control^ control, cv::Mat& colorImage)
{
System::Drawing::Graphics^ graphics = control->CreateGraphics();
System::IntPtr ptr(colorImage.ptr());
System::Drawing::Bitmap^ b = gcnew System::Drawing::Bitmap(colorImage.cols, colorImage.rows, colorImage.step, System::Drawing::Imaging::PixelFormat::Format24bppRgb, ptr);
System::Drawing::RectangleF rect(0, 0, control->Width, control->Height);
graphics->DrawImage(b, rect);
}

//simulate button click
private: System::Void trackBar1_Scroll(System::Object^  sender, System::EventArgs^  e)
{
button1->PerformClick();
label1->Text = trackBar1->Value.ToString();
}