Game Development Reference
In-Depth Information
Listing 5-2. Main Activity Life Cycle
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Full screen
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
// No title
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.doom);
mView = (ImageView)findViewById(R.id.doom_iv);
if (mGameStarted) {
setGameUI();
setupPanControls();
return;
}
// Pan controls
setupPanControls();
}
onCreate()
is the first function called when the game starts, and it is called only once while
the application is in memory. Next, let's look at the game layout loaded by this function.
Game Layout
GUIs in Android are defined by XML layouts, where visual components are placed in a
variety of layout schemes. Doom's layout (
doom.xml
) is a relative layout, which has widgets
placed relative to each other (meaning they can overlap depending on the widget size).
The master layout contains an image view and two table layouts.
In Android, an image view encapsulates an array of pixels representing an image. The great
thing about image views is that they have efficient automatic resize capabilities. This allows
the game to be resized on the fly!
The two table layouts are for the navigation controls. The first table layout defines a three-row
table that contains image buttons for up, down, left, and right navigation. The second table
layout is a one-row table that contains buttons for the level map, object pick up, and strafing
left and right.
Listing 5-3 shows Doom's relative layout XML. The most important attributes are explained
in Table
5-3
.
