Game States - Learning C# by Programming Games - page 241

was pressed or not. Then, we override the HandleInput method to check if the player
has clicked the left mouse button. If the mouse position is within the boundaries of
the sprite at that time, we know that the player has pressed the button and we set
the value of the member variable to true . How can we check if the mouse position
is within the boundaries of the sprite? For that, we can use the Rectangle class. As a
first step, we construct a Rectangle object that encompasses the sprite, as follows:
Rectangle rect = new Rectangle(( int )GlobalPosition.X, ( int )GlobalPosition.Y,
sprite.Width, sprite.Height);
We pass four parameters to the Rectangle constructor. The first two indicate at which
position the rectangle is located. Note that we use the global position here, because
we want to check if the mouse pointer is within the sprite at its actual, global po-
sition. The second two parameters provide the width and height of the rectangle,
which is the same as the width and height of the sprite. Then, we can simply use
the Contains method to find out if the current mouse position is within the rectan-
gle boundaries. The Contains method returns a boolean value, which we store in the
member variable:
pressed = inputHelper.MouseLeftButtonPressed() &&
rect.Contains(( int )inputHelper.MousePosition.X,
( int )inputHelper.MousePosition.Y);
Finally, we add a property Pressed to the Button class, that indicates if the button is
currently pressed or not. For the complete class, see Listing 17.1 .
Now that we have a button class, we can add a help button to the game world
(see the JewelJamGameWorld class):
helpButton = new Button("spr_button_help", 2, "help_button");
helpButton.Position = new Vector2(1268, 20);
this .Add(helpButton);
Since we want to display a help frame when the player presses the help button, we
also add a help frame to the game world. We set its visibility flag to false so that it
is not yet visible:
helpFrame = new SpriteGameObject("spr_frame_help", 2, "help_frame");
helpFrame.Position = new Vector2(636, 120);
helpFrame.Visible = false ;
this .Add(helpFrame);
Now we have to make sure that when the player presses the help button, the help
frame visibility is toggled. We can do this using the following if -instruction in the
HandleInput method of the JewelJamGameWorld class:
if (helpButton.Pressed)
helpFrame.Visible = !helpFrame.Visible;