Coding the derived classes for the select screen
So far, we have coded the fundamental classes that represent the user interface, as well as the logical division of our game into screens. Next, we will code specific implementations of each of them. Remember that Space Invaders ++ will have two screens: select and game. The select screen will be represented by the SelectScreen class and will have a single UIPanel instance, a single InputHandler instance, and two buttons. The play screen will be represented by the GameScreen class and it will have two UIPanel instances. One is called GameUIPanel and will display the score, lives, and invader wave number. The other is called GameOverUIPanel and will display two buttons, giving the player the option to go back to the select screen or play again. As the GameScreen class is composed of two UIPanel instances, it will also be composed of two InputHandler instances.
Coding the SelectScreen class
Create a new header file in the Header...