libGDX: Screens, Fonts and Preferences

1. libGDX:
Screens,
Fonts
and
Pref
Jussi
Pohjolainen
Tampere
University
of
Applied
Sciences

2. SCREENS

3. Screen
and
Game
• Screen
– Use
to
add
different
screens
to
your
game
– Screen
is
a
interface
and
contains
all
the
same
methods
than
ApplicationListener.
Also
show() and
hide() when
screen
is
shown
and
hidden
• Game
– Game
is
an
ApplicationListener
that
holds
also
methods
for
changing
the
screen:
setScreen(Screen s)

4. public class ScreensFontsPref extends Game {
private MainMenuScreen mainmenu;
// Common objects to all screens!
private SpriteBatch batch;
// Returns the SpriteBatch
public SpriteBatch getBatch() {
return batch;
}
@Override
public void create () {
batch = new SpriteBatch();
// Create MainMenuScreen
mainmenu = new MainMenuScreen(this);
// Set it visible
setScreen(mainmenu);
}
@Override
public void render () {
super.render(); // Remember this, otherwise nothing is shown!
}
}

5. public class GameScreen implements Screen {
private ScreensFontsPref game;
private SpriteBatch batch;
private OrthographicCamera camera;
public GameScreen(ScreensFontsPref g) {
game = g;
batch = game.getBatch();
camera = new OrthographicCamera();
camera.setToOrtho(false, 800, 480);
}
@Override
public void render(float delta) {
batch.setProjectionMatrix(camera.combined);
Gdx.gl.glClearColor(1, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.begin();
// Do same drawing
Gdx.app.log("GameScreen", "render");
batch.end();
if (Gdx.input.isTouched()) {
game.setScreen(new GameScreen(game));
}
}

6. FONTS

7. About
Fonts
• libGDX
does
not
support
TrueType
Fonts
(TTF)
– Rendering
vector
graphics
is
costly
• libGDX
makes
use
of
bitmap
files
(pngs)
to
render
fonts
• Use
external
tool
to
convert
TTF
to
PNG!
• Each
glyph
in
the
font
has
a
corresponding
TextureRegion
• Default
font
Arial
provided,
other
fonts
you
have
to
create!
• If
you
use
same
font
in
different
screens,
create
font
once
and
share
it
with
other
screens.

8. Simple
to
Use
BitmapFont f = new BitmapFont();
f.draw(batch, "Hello World", 10, 10);
f.dispose();

9. Tools
for
CreaPng
own
Fonts
• Hiero
(http://bit.ly/16EpREP)
– Free
and
buggy?
Java
app
• Glyphite
(https://www.glyphite.com/)
– Free
web
app
• LiFera
(http://kvazars.com/littera/)
– Free
web
app

10. LiFera
Usage
1. Upload
some
.S
font
2. Export
format
.txt
3. Add
to
assets
(.png
and
.txt)
to
libGDX
project

11. Simple
to
Use
BitmapFont f = new new
BitmapFont(Gdx.files.internal("font.txt"));
f.draw(batch, "Hello World", 10, 10);
f.dispose();

12. Calculate
PosiPon
Libgdx
getAscent()
getDescent()
getLineHeight()

13. Calculate
PosiPon
String fontText = "Main Menu";
float fontX = game.getDefaultFont().getBounds(fontText).width;
float fontY = game.getDefaultFont().getBounds(fontText).height;

14. PREF

15. Persistent
Storage
• Simple
preferences
mechanism
for
storing
and
retrieving
• Windows,
Linux,
OS
X:
xml-­‐file
in
home
dir
– Windows:
%UserProfile%/.prefs/My Preferences
– Mac:
~/.prefs/My Preferences
• On
Android,
the
system's
SharedPreferences
class
is
used.
– Preferences
will
survive
app
updates,
but
are
deleted
when
the
app
is
uninstalled.

16. Usage
Preferences prefs =
Gdx.app.getPreferences("MyPreferences");
prefs.putString("name", "Donald Duck");
String name = prefs.getString("name", "No name stored");
prefs.putBoolean("soundOn", true);
prefs.putInteger("highscore", 10);
prefs.flush();

17. file
<?xml version="1.0" encoding="UTF-8"
standalone="no"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/
dtd/properties.dtd">
<properties>
<entry key="score">221</entry>
</properties>