What am I doing wrong in drawing a line in wxWidgets? - wxwidgets

Question

// cMain.cpp
#include "cMain.h"
cMain::cMain() : wxFrame(nullptr, wxID_ANY, "ImProcGUI", wxPoint(50, 50), wxSize(800, 600)) {
m_MenuBar = new wxMenuBar();
// File Menu
m_FileMenu = new wxMenu();
m_FileMenu->Append(wxID_OPEN, _T("&Open"));
m_FileMenu->Append(wxID_OPEN, _T("&Save"));
m_FileMenu->Append(wxID_OPEN, _T("&Quit"));
m_MenuBar->Append(m_FileMenu, _T("&File"));
// About Menu
m_HelpMenu = new wxMenu();
m_HelpMenu->Append(wxID_ABOUT, _T("&About"));
m_MenuBar->Append(m_HelpMenu, _T("&Help"));
SetMenuBar(m_MenuBar);
}
wxBEGIN_EVENT_TABLE(cMain, wxFrame)
EVT_PAINT(cMain::OnPaint)
wxEND_EVENT_TABLE()
cMain::~cMain() {
}
void cMain::onPaint(wxPaintEvent& event) {
wxPaintDC dc(this);
wxCoord x1 = 50, y1 = 60;
wxCoord x2 = 190, y2 = 60;
dc.DrawLine(x1, y1, x2, y2);
}
// cMain.h
#include "wx/wx.h"
class cMain : public wxFrame
{
public:
cMain();
~cMain();
wxWindow* m_Window = nullptr;
wxMenuBar* m_MenuBar = nullptr;
wxMenu* m_FileMenu = nullptr;
wxMenu* m_HelpMenu = nullptr;
void onPaint(wxPaintEvent& event);
DECLARE_EVENT_TABLE()
};
Above is the code I have. I am not sure what I am doing wrong. I have a main frame, onto which I want to draw. When I run the code, however, the line is not there. (in my first attempt, I tried to put a window onto the frame and to draw onto it, but the line was not there in that case too)

Answer 1

You're drawing on the frame, but your entire frame is covered by m_Window, which hides whatever you draw. You probably don't need this window at all, but if you do, you need to draw on it, not on the frame itself.
Also note that you're using both the event table and Connect() with your handler, which is not catastrophic, but still wrong and, at best, useless. Use one or the other, or, better, use Bind() (rather than Connect()).
Moreover, you've made a typo in your handler name: you used OnPaint() in EVT_PAINT macro, which just happens to be the name of a base class handler doing nothing, rather than your onPaint(). So your handler is not called at all.