The circle application

In this section, we look into a simple circle application. As the name implies, it enables the user to handle circles in a graphical application. The user can add a new circle by pressing the left mouse button. The user can also move an existing circle by dragging it. Moreover, the user can change the color of a circle as well as save and open the document:

The main window

As we will see throughout this book, the MainWindow function always does the same thing: it sets the application name and creates the main window of the application. The name is used by the Save and Open standard dialogs, the About menu item, and the registry.

The difference between the main window and other windows of the application is that, when the user closes the main window, the application exits. Moreover, when the user selects the Exit menu item, the main window is closed, and its destructor is called:

MainWindow.cpp

#include "..\\SmallWindows\\SmallWindows.h" 
#include "Circle.h" 
...