Exercises and Challenges - Learning C# by Programming Games - page 406

Content.RootDirectory = "Content";
position = Vector2.Zero;

}

protected override void LoadContent()
{ spriteBatch = new SpriteBatch(GraphicsDevice);
background = Content.Load<Texture2D>("background");

}

protected override void Draw(GameTime gameTime)
{ GraphicsDevice.Clear(Color.White);
spriteBatch.Begin();
spriteBatch.Draw( this .background, this .position, Color.White);
spriteBatch.End();

}

}

The background sprite has the same height as the screen, but it is a lot wider.
As a result, we can only draw a part of the sprite. The goal of this exercise is to
implement side scrolling. We do this by using the mouse position. If the mouse
is positioned left to the screen, the background moves to the right. If the mouse is
positioned right to the screen, the background moves to the left. Write the Update
method that results in this behavior.

8. Decorator streams
The Stream class has (among others) the following methods:

− 1 if there is no more byte int ReadByte(); // returns the next byte, or

int Read( byte [] goal, int n); /

∗

reads a maximum of n bytes and puts them in goal,
and returns the number of bytes read. ∗ /

In many cases it is more efficient to read an entire block with the Read method.
On the other hand, it's easier to read a separate byte whenever you need it.
The class BufferedStream can help out here. The constructor method of these class
has a Stream object as a parameter. When the ReadByte method is called on an
object of type BufferedStream ,itusesthe Stream object it manages to read 1000
bytes. It then returns the first one it read, the rest is saved temporarily in an array
(in other words, a buffer). The next time the ReadByte method is called, the byte
can be retrieved from the array and we don't have to access the underlying file.
Only when there are no more bytes left in the array, a new block of 1000 bytes is
read.
Implement the BufferedReader class, containing a constructor method and the
ReadByte method.