Adding the blur action

Most of the actions we will add in this chapter will be used to edit an image, so we should categorize them in a new menu and toolbar. First, we will declare three members, that is, the edit menu, the edit toolbar, and the blur action, in the private section of the mainwindow.h header file:

         QMenu *editMenu;
         QToolBar *editToolBar;
         QAction *blurAction;

Then, we will create them in the MainWindow::initUI and MainWindow::createActions methods, respectively, as follows:

In MainWindow::initUI, this is executed as follows:

         editMenu = menuBar()->addMenu("&Edit");
         editToolBar = addToolBar("Edit");

In MainWindow::createActions, this is executed as follows:

         blurAction = new QAction("Blur", this);
         editMenu->addAction(blurAction);
         editToolBar->addAction(blurAction);

Up until now, we have an edit menu and an edit toolbar with a blur action on both of them. But, if the user clicks either the blur buttons on the toolbar or the blur items under the edit menu, nothing will happen. This is because we haven't connected a slot to that action yet. Let's give the action a slot now. First, we will declare a slot in the private slots section of mainwindow.h, as follows:

         // for editting
         void blurImage();

   Then, we will give it a dummy implementation in mainwindow.cpp:

     void MainWindow::blurImage()
     {
         qDebug() << "Blurring the image!";
     }

Now that the slot is ready, it's time to connect the triggered signal of the blur action with this slot at the end of the mainwindow::createActions method:

         connect(blurAction, SIGNAL(triggered(bool)), this, SLOT(blurImage()));

When you compile and run the application, you will see the menu, toolbar, and the action. If you trigger the action by clicking it, you will see the message Blurring the image! being printed.

This is what the window and printed message look like:

The UI part is now ready, which means that we can focus on how to blur the image by using OpenCV in the slot in the following sections.