C++, QT. Function call for QShortcut does not exist - c++

Question

I have a class, MainWindow with a pointer to a Canvas, mCanvas...
mainwindow.h...
#include "canvas.h"
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
//snip
private:
Canvas* mCanvas;
};
canvas.h...
class MainWindow;
class Canvas
{
public:
Canvas(MainWindow* parent);
//snip
public slots:
void doSomething();
private:
MainWindow* mParent;
};
Canvas.cpp...
Canvas::Canvas(MainWindow* parent)
{
mParent = parent;
}
void Canvas::doSomething()
{
//snip
}
In MainWindow.cpp, within the MainWindow constructor, I point mCanvas to an Canvas(this). I then attempt to create a new QShortcut with the action Canvas::doSomething().
MainWindow.cpp...
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
new QShortcut(QKeySequence(Qt::Key_BracketLeft),
mCanvas, SLOT(doSomething()) );
However, when I attempt to run the program, I recieve the error NO MATCHING FUNCTION CALL for doSomething(), meaning the compiler does not think that doSomething() exists. In the new QShortcut, I have written mCanvas as mCanvas, *mCanvas, &mCanvas; nothing works.
What is going wrong?

Answer 1

To use signals and slots in Canvas you need to inherit it from QObject (from QWidget in your case) and use Q_OBJECT macro. Also your mCanvas is not initialized before using in new QShortcut ....
Or do something like this:
auto shortcut = new QShortcut(QKeySequence(Qt::Key_BracketLeft), this);
QObject::connect(shortcut, &QShortcut::activated, this, [ this ] { mCanvas->doSomething(); } );